Order this document
Anaesth Intensive Care 2003 Apr;31(2):236-7
[Medline record in process]
Publication Types:
PMID: 12712800, UI: 22599022
Other Formats:
Anaesth Intensive Care 2003 Apr;31(2):235-6
PMID: 12712798, UI: 22599020
Anaesth Intensive Care 2003 Apr;31(2):217-20
Department of Anaesthesia and Intensive Care, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong, China.
Larsen syndrome is a rare congenital connective tissue disorder which is characterized by multiple dislocations of major joints, typical facial appearance, cervical spine narrowing and instability and respiratory difficulties secondary to laryngotracheomalacia. A case of general anaesthesia for laparoscopic hernia repair in a male child aged 16 months with this syndrome is presented. Anaesthesia was well tolerated though intubation proved difficult. Cervical spine instability and postoperative respiratory complications are potential problems.
PMID: 12712791, UI: 22599013
Anaesth Intensive Care 2003 Apr;31(2):193-5
Department of Anaesthesia, Royal United Hospital, Combe Park, Bath BA1 3NG, England, United Kingdom.
Insertion of the flexible Laryngeal Mask Airway has been achieved by a variety of techniques. We have evaluated the Flexiguide for aiding introduction of a flexible Laryngeal Mask Airway in 100 anaesthetised patients. We were successful in establishing a clear airway on the first attempt on 84 (84%) occasions and within two attempts in 97 (97%). The positioning of the laryngeal mask airway was assessed by five measures and was optimally placed in 85% of cases and good in 96%. A clear airway was achieved in 92% of cases. Insertion of the flexible Laryngeal Mask Airway with the Flexiguide was easy in 82 (82%) and slightly difficult in 15 (15%) of cases. Removal of the Flexiguide from the device was easy in 95 (95%) of cases. Airway manoeuvres were used to assist airway placement in 55% of cases with jaw thrust being most common. Minor complications occurred in three (3%) patients: two coughed and one experienced minor tissue trauma during mask insertion. There were no complications associated with use of the Flexiguide during the procedure or after anaesthesia. The Flexiguide is a useful tool to assist insertion of the flexible Laryngeal Mask Airway and is associated with few complications.
PMID: 12712785, UI: 22599007
Anaesth Intensive Care 2003 Apr;31(2):187-92
Department of Anaesthesia, Faculty of Medicine, University of Malaya, Lembah Pantai, 59100 Kuala Lumpur, Malaysia.
We have compared the use of the laryngeal mask airway with the new modified laryngeal tube in a prospective randomized controlled study. Sixty ASA 1 or 2 patients, aged 18 to 65 years, scheduled for elective surgery and breathing spontaneously under general anaesthesia, were studied. After preoxygenation, anaesthesia was induced with fentanyl and propofol. The patients were randomized to receive either a laryngeal mask airway or a laryngeal tube. Anaesthesia was maintained with nitrous oxide, oxygen and isoflurane. We recorded the speed and the ease of insertion, the number of attempts needed to successfully secure the airway and intraoperative complications, such as partial airway obstruction needing airway manipulation. The airway devices were removed with the patients fully awake at the end of surgery. Systolic arterial blood pressure, heart rate and end-tidal CO2 were recorded at various time intervals. Postoperative complications were recorded. We found that the incidence of partial airway obstruction needing intraoperative airway manipulation was higher with the laryngeal tube than with the laryngeal mask airway. We conclude that during spontaneous ventilation the modified laryngeal tube is not as reliable in providing a satisfactory airway and we consider it is not a suitable alternative to the laryngeal mask airway.
PMID: 12712784, UI: 22599006
Anaesth Intensive Care 2003 Apr;31(2):184-6
Department of Anaesthesia and Pain Management, Royal Melbourne Hospital and Department of Pharmacology, University of Melbourne, Melbourne, Victoria.
A robust test that reliably demonstrates implicit memory during general anaesthesia is required. The Word Stem Completion (WSC) test has been used as a measurement tool in a number of recent studies that have detected implicit memory during anaesthesia. However, target words used in the WSC test need to be culturally appropriate in order to maximize the sensitivity of the test. Therefore, fifty postoperative patients with English as a first language were recruited at The Royal Melbourne Hospital in order to assess the frequency of 98 target words in response to a word stem presentation. This generated a list of 32 target words that is suitable for use in studies of implicit memory during anaesthesia in Australian patients.
PMID: 12712783, UI: 22599005
Anaesth Intensive Care 2003 Apr;31(2):181-3
Department of Anaesthesia and Pain Management and Department of Cardiothoracic Surgery, Royal Melbourne Hospital, Parkville, Victoria.
Alfentanil and propofol total intravenous anaesthesia was assessed in 25 patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass (CPB). A manually controlled alfentanil infusion, calculated from estimated lean body mass and published pharmacokinetic data, was effective in achieving target plasma concentrations, while the "Diprifusor" system was used to vary propofol target concentrations according to changes in haemodynamics and anaesthetic requirement. The effects of CPB on alfentanil plasma concentrations were offset by changes in protein binding and free-fraction of the drug. With the use of only two target plasma concentrations for alfentanil (changed after CPB), a pre-determined infusion profile ensured effective plasma concentrations during surgery and concentrations unlikely to inhibit extubation within six hours of sternal closure.
PMID: 12712782, UI: 22599004
Anaesth Intensive Care 2003 Apr;31(2):176-80
Department of Anaesthesiology, Intensive Care and Operating Service, Alice Ho Miu Ling Nethersole Hospital, Tai Po, Hong Kong, SAR.
This prospective randomized controlled trial examined the effect of an "alveolar recruitment strategy" (ARS) in healthy patients having laparoscopic cholecystectomy. Twenty-four consecutive ASA 1 or 2 patients were randomly allocated to an ARS or control group. All patients were manually ventilated to a maximal airway pressure of 25 to 30 cmH2O or a tidal volume of 10 ml/kg during induction of general anaesthesia. After intubation, the control group was ventilated with standardized mechanical ventilation settings. The ARS group was manually ventilated to an airway pressure of 40 cmH2O for 10 breaths over one minute, followed by mechanical ventilation with similar standardized settings plus 5 cmH2O positive end-expiratory pressure. Blood pressure, heart rate, arterial oxygen and carbon dioxide tension (PaO2 and PaCO2) was measured pre-induction, 20 minutes post induction but before abdominal insufflation, 20 minutes after abdominal insufflation, and 20 minutes after arrival in the recovery room. Demographic and operation data were similar. The ARS group pre-insufflation PaO2 [30.16 (9.43)] was higher than the control group [22.19 (9.08)] (P = 0.047). There was a significant difference in PaO2 between the ARS [23.94 (4.87)] and control [17.26 (3.93)] groups during the post-insufflation period (P = 0.001). There were no significant differences in PaO2 between the groups during baseline and recovery periods. No adverse effects were reported. ARS improved arterial oxygenation intraoperatively in healthy patients having laparoscopic cholecystectomy, without clinical cardiovascular compromise or respiratory complication. We conclude that this alveolar recruitment strategy is a useful method of increasing arterial oxygenation.
PMID: 12712781, UI: 22599003
Anaesth Intensive Care 2003 Apr;31(2):172-5
Departments of Intensive Care Medicine and Anaesthesiology and Reanimatology, School of Medicine, Gunma University, Gunma, Japan.
The purpose of this study was to compare the effect of propofol versus thiopentone on haemodynamics during electroconvulsive therapy (ECT), as estimated by echocardiography. Twenty-eight ASA 1 or 2 patients scheduled for ECT were randomly divided into two groups, to receive propofol 1 mg/kg (propofol group, n = 14) or thiopentone 2 mg/kg (thiopentone group, n = 14). Bilateral ECT was performed after the administration of propofol or thiopentone, succinylcholine and following assisted mask ventilation with 100% oxygen. Cardiac function was examined by transthoracic echocardiography, prior to induction of anaesthesia and throughout ECT until ten minutes after the seizure. In the propofol group, increased end-systolic area (ESA) and decreased fractional area change (FAC) were observed at one minute after the electrical shock compared with the awake condition. In the thiopentone group, increased ESA and decreased FAC were observed from one to three minutes after the electrical shock compared with the awake condition. There was no statistically significant change in afterload in the propofol group during the study. In contrast, increased afterload was observed from one to three minutes after the electrical shock in the thiopentone group (awake condition, 26 +/- 7 mmHg/cm2 [mean +/- SD]; one minute after ECT, 42 +/- 7*; two minutes after ECT, 44 +/- 6*; three minutes after ECT; 40 +/- 5*, respectively) (*P < 0.05). We concluded that a lesser haemodynamic change occurs after propofol anaesthesia (1 mg/kg) compared with thiopentone anaesthesia (2 mg/kg) during ECT.
PMID: 12712780, UI: 22599002
Anaesth Intensive Care 2003 Apr;31(2):164-71
Departments of Anesthesiology and Reanimation, General Surgery, and Otorhinolaryngology and Head and Neck Surgery, Kirikkale University, School of Medicine, Kirikkale, Turkey.
This study was performed to investigate the quality of different intravenous sedation techniques, and the correlation between the Bispectral Index (BIS) values and the Observer's Assessment of Alertness/Sedation (OAA/S) scores. Eighty patients undergoing sinonasal surgery were randomly assigned to one of four groups. Group MF received midazolam and fentanyl, group PF received propofol and fentanyl, group MR received midazolam and remifentanil, and group PR received propofol and remifentanil. Heart rate and mean arterial pressure values were not different among the groups. SpO2 decreased only after intravenous medication in groups MF and MR (P < 0.017). Emesis was less common with propofol. A positive relationship existed between the BIS values and OAA/S scores during the operation in all groups and the strongest correlation was observed in group PR (r = 0.565 and P < 0.001). In conclusion, these four intravenous sedation techniques did not change mean arterial pressure, heart rate or SpO2 clinically and produced a similar level of light sedation. The BIS was useful for monitoring of sedation during sinonasal surgery under local anaesthesia with intravenous sedation.
PMID: 12712779, UI: 22599001
Anaesth Intensive Care 2003 Apr;31(2):155-63
Departments of Psychology and Anaesthesiology, University of Auckland and Department of Anaesthesiology, Waikato Hospital, Hamilton, New Zealand.
Anaesthetic-induced spatial inhomogeneities of the electrencephalogram(EEG) using "high density" electrode mapping have not previously been reported. We measured the scalp EEG with a dense electrode (128-channel) montage during the course of light general anaesthesia with xenon and then propofol in normal human subjects. EEG was measured during induction and recovery of general anaesthesia in five normal subjects, and we obtained analysable data from three of these subjects. EEG topographies were plotted on a realistic head surface. Scalp fields were spatially de-blurred using a realistic head model and projected onto an averaged cortical surface Both xenon and propofol elicited large increases in midline frontal theta-band EEG power. Propofol reliably elicited orbitofrontal delta activity. Xenon, but not propofol, caused large increases in delta over the posterior cortex. Increased gamma power was observed for both anaesthetic agents at midline electrodes over the posterior cortex, but not anteriorly. Anaesthesia-induced delta and theta waves were differentially distributed along the anterior-posterior axis of the brain in a manner that corresponds well to the anatomy of putative neuronal generators. The distribution of anaesthetic-induced changes in fast gamma-band power seems to reflect functional differences between the posterior and anterior aspects of the cerebral cortex. These preliminary observations were consistent within our small sample, indicating that larger studies of anaesthetic effects using high-density recordings are warranted.
PMID: 12712778, UI: 22599000
Anaesthesist 2003 Apr;52(4):349-52
Klinik fur Anaesthesiologie, Universitat Wurzburg,Deutschland.
The Cochrane Collaboration is an international non-profit organisation that aims to help clinicians in making well-informed decisions about health care issues.This is done through preparing, maintaining and disseminating systematic reviews on the effects of health care interventions.To facilitate this task, review groups have been established. These groups cover specific health care areas and form the organisational basis of the collaboration. They provide methodological and logistic help to the authors of the systematic reviews.The Cochrane Anaesthesia Review Group (CARG) covers anaesthesia, perioperative medicine, intensive care,pre-hospital medicine, resuscitation, and emergency medicine.Protocols and completed Cochrane reviews are published in a structured format in the electronic Cochrane Library.Beside this Cochrane database of systematic reviews, the Cochrane library contains a database with summaries of non-Cochrane systematic reviews (database of abstracts of reviews of effectiveness), and a comprehensive database with controlled clinical trials (Cochrane central register of controlled trials). Thus the Cochrane library is a useful source of information on health care interventions for anaesthetists.
PMID: 12715138, UI: 22599342
Anaesthesist 2003 Apr;52(4):329-40
Abteilung Anasthesie,Orthopadische Universitatsklinik Balgrist, Zurich.
Local anesthetics provoke reversible blockade of nerves by interaction with sodium channels in membranes of nerves.The uncharged molecular configuration of the local anesthetic penetrates the membrane from the outside and the charged configuration then interacts with the sodium channel from the inside.The potency of a local anesthetic is determined mainly by lipid solubility, the time of onset by the pK(a) of the substance and the duration of action by protein binding. Local anesthetic molecules consist of a hydrophilic tertiary amine and a lipophilic aromatic system combined by an ester or amide linkage.Local anesthetics may therefore be classified as aminoester or aminoamide compounds.Aminoesters are hydrolysed by plasmacholinesterase whereas aminoamides undergo metabolisation in the liver.Aminoamides cause fewer allergic reactions.Local anesthetics show dose-dependent CNS and cardiac toxicity.Reports of toxicity, mainly involving bupivacaine and etidocaine initiated the development of ropivacaine which is the first aminoamide marketed as a pure S-enantiomer.Recently introduced was levo-bupivacaine, the S-enantiomer of bupivacaine.
PMID: 12715136, UI: 22599340
Anaesthesist 2003 Apr;52(4):326-8
Institut fur Anasthesiologie und Intensivmedizin,Stadtspital Triemli, Zurich.
Complete atrioventricular block occurred during spinal and subsequent general anaesthesia in a 74-year-old patient with known arterial hypertension but without heart conduction abnormality. Drug therapy and intermittent transcutaneous pacing was successful. A decrease of arterial pressure by more than 40% preceded the heart blockade in the course of both events.Subsequent cardiologic examination revealed evidence of a discrete hypertensive heart disease.Relative ischemia of the atrioventricular region during anaesthesia was suggested as an aetiology.When the patient presented for the next operation, again general anaesthesia was applied, and invasive arterial blood pressure monitoring as well as catecholamine support were used and no further atrioventricular blockade occurred.The case demonstrates the possible recurrence of an intraoperative complete atrioventricular blockade in an older patient without pre-existing conduction abnormalities and only minor signs of heart disease, irrespective of the anaesthesia technique.Under these circumstances transcutaneous pacing should always be in place.Maintenance of coronary perfusion pressure is essential and invasive blood pressure monitoring is recommended.
PMID: 12715135, UI: 22599339
Anaesthesist 2003 Apr;52(4):321-5
Institut fur Anasthesiologie und Operative Intensivmedizin, Universitatsklinikum Mannheim, Fakultat fur Klinische Medizin der Universitat Heidelberg.
CASE REPORT. In our case, a 48-year-old healthy woman undergoing elective tympanoplasty under general anesthesia received an infusion of 2 g dipyrone in 100 ml 0.9% sodium chloride solution for pain prophylaxis. After receiving 1 g dipyrone within 5 min, the patient exhibited a cardiocirculatory failure and cyanosis and had to be resuscitated.After 20 min of cardiopulmonary resuscitation and administration of 3mg epinephrine and 2 mg norepinephrine, a stable circulation was reestablished.After exclusion of a fulminant pulmonary embolism and a primary cardiac event by computer tomography, electrocardiogram and enzyme diagnostics, the patient was transferred to an intensive care unit where she was mechanically ventilated for a period of 6 h.After 2 days of intensive monitoring, she was transferred to a peripheral ward,where she exhibited a normal neurological status and stable cardiocirculatory condition. A postoperatively performed allergy testing revealed a type I sensitization to dipyrone, which was responsible for the intraoperative cardiocirculatory failure due to a massive anaphylactic reaction.However, in this case, the typical symptoms of allergic reactions such as erythema, edema or bronchospasm were missing, which did not allow for an immediate diagnosis. CONCLUSION. Regarding the frequent perioperative use of dipyrone and the severity of anaphylaxis observed in this case, it should be considered that this analgesic should be applied intravenously only if adequate safety measures such as emergency therapy option and patient monitoring are guaranteed as recommended by the German drug regulation authority since 1982.
PMID: 12715134, UI: 22599338
Anaesthesist 2003 Apr;52(4):311-20
Klinik fur Anasthesiologie, Universitat zu Lubeck.
OBJECTIVE. The Anaesthesiological Questionnaire (ANP) is a self-rating method for the assessment of postoperative complaints and patient satisfaction.The questionnaire consists of two parts.Part 1 assesses the intensity of symptoms regarding the postoperative period in the "recovery-room and the first hours on the ward" (19 items) and the "current state" (17 items).Part 2 assesses patient satisfaction with the anaesthetic care as well as the unspecific perioperative care and postoperative convalescence. The questionnaire was designed to fulfill the criteria of reliability and validity and to serve as a practicable means of auditing the quality of routine clinical practice. METHODS. A total of 1,112 patients older than 18 years completed the questionnaire after an elective operation.Additionally data concerning the type of anaesthesia were recorded from the anaesthesia chart.To determine retest-reliability, 94 patients competed the ANP twice postoperatively. RESULTS. The participants of the survey represented 74.6% of the total collective. Out of 19 items 16 had a retest-reliability of r(tt)>0.70, the 3 other items had a reliabilty of r(tt)>0.50.Reliability (Cronbach's Alpha) of the patient satisfaction scales was between r(tt)=0.76 and r(tt)=0.91.In relation to the period immediately after anaesthesia,women reported more postoperative complaints than men but no differences were found between male and female patients with regard to satisfaction with perioperative care. Younger patients (18-49 years old) described more postoperative complaints than older patients and a lesser degree of satisfaction with perioperative care.There were plausible differences in postoperative complaints between patients who received general vs. regional anaesthesia.Patients reported less postoperative complaints after TIVA than after volatile anaesthetics.The configuration of patient characteristics and anaesthesia gives indications to "risk groups" who predominantely suffer after anaesthesia. CONCLUSIONS. The Anaesthesiological Questionnaire (ANP) is a reliable and valid method for the assessment of postoperative complaints and patient satisfaction.
PMID: 12715133, UI: 22599337
Anesth Analg 2003 May;96(5):1534
Department of Anesthesia and Critical Care, University of Chicago, Chicago, IL, Dr. Akpek does not wish to respond.
PMID: 12707175, UI: 22592034
Anesth Analg 2003 May;96(5):1527
PMID: 12707165, UI: 22592024
Anesth Analg 2003 May;96(5):1522-5
Nuffield Department of Anesthetics, University of Oxford, England. Department of Anaesthesiology, University of Leiden, The Netherlands.
PMID: 12707161, UI: 22592020
Anesth Analg 2003 May;96(5):1516-21
Department of Anesthesiology and the. Research Institute of Medical Sciences, Chonnam National University Medical School, Gwangju, South Korea.
Nitrous oxide (N(2)O) exerts a sympathomimetic action. We investigated whether N(2)O modifies the cardiovascular responses to tracheal intubation during general anesthesia. One-hundred healthy patients were assigned randomly to receive one of four concentrations (0%, 25%, 50%, or 75%; n = 25 each) of N(2)O in oxygen throughout the study beginning 3 min before tracheal intubation. Anesthesia was induced with IV thiopental (5-7 mg/kg) whereas patients were ventilated with designated concentrations of N(2)O. Tracheal intubation was facilitated with IV vecuronium (0.12 mg/kg). After intubation, all received 2% sevoflurane in oxygen via a semiclosed anesthesia circuit. Systolic arterial blood pressure, heart rate and rhythm, and plasma catecholamine concentrations were measured. The intubation significantly increased arterial blood pressure and heart rate. The maximum pressure changes were 46 +/- 21 and 65 +/- 24 mm Hg in 75% N(2)O and control groups, respectively (P < 0.05), being attenuated by N(2)O without affecting the tachycardiac response. Norepinephrine concentrations were increased at 1 min after the intubation, the magnitude of which was augmented by N(2)O. N(2)O did not affect the incidence of arrhythmias. It was shown that N(2)O suppressed the pressor response to endotracheal intubation, despite the augmented increase of norepinephrine concentrations. IMPLICATIONS: We examined whether nitrous oxide modifies the cardiovascular response to endotracheal intubation because it activates the sympathetic nervous system. Nitrous oxide attenuated the pressor response, whereas it augmented the norepinephrine response to laryngoscopy and endotracheal intubation.
PMID: 12707160, UI: 22592019
Anesth Analg 2003 May;96(5):1510-5
Department of Anesthesiology and Intensive Care, European Hospital Georges Pompidou, Paris, France.
We studied the effectiveness of the intubating laryngeal mask airway (ILMA) in morbidly obese patients scheduled for bariatric surgery. We included 118 consecutive morbidly obese patients (body mass index, 45 +/- 5 kg/m(2)). After the induction of general anesthesia, the laryngeal view was classified by the first observer according to the method of Cormack and Lehane. The ILMA was then inserted, and the trachea was intubated through the ILMA by a second observer. The rate of successful tracheal intubation with ILMA was 96.3%. The success rate, the number of attempts, and the total duration of the procedure were not different among patients with low-grade (Cormack 1-2) and patients with high-grade (Cormack 3-4) laryngeal views. The time required for insertion of the ILMA was slightly longer in patients with high-grade laryngeal views. Failures of the technique were not explained by the experience of the practitioner or airway characteristics. No adverse effect related to the technique was reported. Results of this study suggest that using the ILMA provides an additional technique for airway management of morbidly obese patients. IMPLICATIONS: The intubating laryngeal mask airway (ILMA) provides an additional technique for airway management of morbidly obese patients. The best choice of the primary technique (laryngoscopy or ILMA) for tracheal intubation of an adult obese patient remains to be determined.
PMID: 12707159, UI: 22592018
Anesth Analg 2003 May;96(5):1496-503
Departments of Anesthesiology and Intensive Care and. Surgery, University Hospital, Orebro, Sweden.
The aim of this randomized double-blinded study was to see whether the addition of small-dose clonidine to small-dose bupivacaine for spinal anesthesia prolonged the duration of postoperative analgesia and also provided a sufficient block duration that would be adequate for inguinal herniorrhaphy. We randomized 45 patients to 3 groups receiving intrathecal hyperbaric bupivacaine 6 mg combined with saline (Group B), clonidine 15 micro g (Group BC15), or clonidine 30 micro g (Group BC30); all solutions were diluted with saline to 3 mL. The sensory block level was insufficient for surgery in five patients in Group B, and these patients were given general anesthesia. Patients in Groups BC15 and BC30 had a significantly higher spread of analgesia (two to four dermatomes) than those in Group B. Two-segment regression, return of S1 sensation, and regression of motor block were significantly longer in Group BC30 than in Group B. The addition of clonidine 15 and 30 micro g to bupivacaine prolonged time to first analgesic request and decreased postoperative pain with minimal risk of hypotension. We conclude that clonidine 15 micro g with bupivacaine 6 mg produced an effective spinal anesthesia and recommend this dose for inguinal herniorrhaphy, because it did not prolong the motor block. IMPLICATIONS: The addition of clonidine 15 micro g to 6 mg of hyperbaric bupivacaine increases the spread of analgesia, prolongs the time to first analgesic request, and decreases postoperative pain, compared with bupivacaine alone, during inguinal herniorrhaphy under spinal anesthesia.
PMID: 12707157, UI: 22592016
Anesth Analg 2003 May;96(5):1491-5
Department of Anesthesiology, Intensive Care Medicine, and Pain Therapy, University Hospital Giessen, Giessen, Germany.
In this investigation we assessed whether patients receiving spinal anesthesia (SPA) as part of combined spinal-epidural anesthesia (CSE) more often experience relevant hypotension than patients receiving SPA alone. From January 1, 1997, until August 5, 2000, electronic anesthesia records from 1596 patients having received SPA and 1023 patients having received CSE for elective surgery were collected by using a computerized anesthesia record-keeping system. Relevant hypotension was defined as a decrease of mean arterial blood pressure of more than 30% within a 10-min interval and a therapeutic action of the attending anesthesiologist within 20 min after onset. Electronic patient charts were reviewed by using logistic regression with a forward stepwise algorithm to identify independent risk factors that were associated with an increased incidence of hypotension after CSE. Univariate analysis was performed to assess differences in biometric data and relevant risk factors for hypotension between the two procedures. The incidence of relevant hypotension was more frequent with CSE than with SPA alone (10.9% versus 5.0%; P < 0.001). In the multivariate analysis, arterial hypertension (odds ratio, 1.83; 95% confidence interval, 1.21-2.78) and sensory block height >T6 (odds ratio, 2.81; 95% confidence interval, 1.88-4.22) were found to be factors associated with hypotension in the CSE group. Compared with patients receiving SPA alone, patients undergoing CSE had a significantly more frequent prevalence of arterial hypertension and higher sensory block levels (P < 0.01) despite smaller amounts of local anesthetics. In this study, patients receiving CSE had an increased risk for relevant hypotension as compared with patients with SPA alone. Part of this effect seems to be due to the procedure alone and not only because this population is at higher risk. IMPLICATIONS: This study, based on a large number of patients with a retrospective design by using on-line recorded data, suggests that spinal anesthesia as part of combined spinal-epidural anesthesia may more often lead to relevant hypotension than spinal anesthesia alone. Preexisting arterial hypertension and a sensory block height exceeding T6 are major risk factors for the development of this complication.
PMID: 12707156, UI: 22592015
Anesth Analg 2003 May;96(5):1489-90
Departments of Anesthesiology and Obstetrics, University of Virginia Health Systems, Charlottesville.
IMPLICATIONS: The management of parturients with a strong history of allergy to local anesthetics poses significant challenges to the obstetric anesthesiologist. We recommend that when such patients have a strong desire to receive labor analgesia with local anesthetics, they undergo provocative challenge testing with preservative-free bupivacaine performed in labor and delivery with preparations for emergent cesarean delivery after 24-wk gestation.
PMID: 12707155, UI: 22592014
Anesth Analg 2003 May;96(5):1480-5
Department of Obstetrics and Gynecology, New York Presbyterian Hospital, Weill Medical College of Cornell University, USA.
PMID: 12707153, UI: 22592012
Anesth Analg 2003 May;96(5):1467-72, table of contents
Department of Diagnostic Radiology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
The adequacy of cerebral tissue oxygenation (PtO(2)) is a central therapeutic end point in critically ill and anesthetized patients. Clinically, PtO(2) is currently measured indirectly, based on measurements of cerebrovascular oxygenation using near infrared spectroscopy and experimentally, using positron emission tomographic scanning. Recent developments in electron paramagnetic resonance (EPR) oximetry facilitate accurate, sensitive, and repeated measurements of PtO(2). EPR is similar to nuclear magnetic resonance but detects paramagnetic species. Because these species are not abundant in brain (or other tissues) in vivo, oxygen-responsive paramagnetic lithium phthalocyanine crystals implanted into the cerebral cortex are used for the measurement of oxygen. The line widths of the EPR spectra of these materials are linear functions of PtO(2). We used EPR oximetry in anesthetized rats to study the patterns of PtO(2) during exposure to various inhaled and injected general anesthetics and to varying levels of inspired oxygen. Rats anesthetized with 2.0 minimum alveolar anesthetic concentration isoflurane maintained the largest PtO(2) (38.0 +/- 4.5 mm Hg) and rats anesthetized with ketamine/xylazine had the smallest PtO(2) (3.5 +/- 0.3 mm Hg) at a fraction of inspired oxygen (FIO(2)) of 0.21, P < 0.05. The maximal PtO(2) achieved under ketamine/xylazine anesthesia with FIO(2) of 1.0 was 8.8 +/- 0.3 mm Hg, whereas PtO(2) measured during isoflurane anesthesia with FIO(2) of 1.0 was 56.3 +/- 1.7 mm Hg (P < 0.05). These data highlight the experimental utility of EPR in measuring PtO(2) during anesthesia and serve as a foundation for further study of PtO(2) in response to physiologic perturbations and therapeutic interventions directed at preventing cerebral ischemia. IMPLICATIONS: Using in vivo electron paramagnetic resonance oximetry, we studied the patterns of cerebral tissue oxygenation (PtO(2)) during exposure to various inhaled and injected general anesthetics, and to varying levels of inspired oxygen. These data show that inhaled anesthetics result in larger levels of PtO(2) in the brain than do several injectable anesthetics. The results highlight the experimental utility of electron paramagnetic resonance in measuring PtO(2) during anesthesia and serve as a foundation for further study of PtO(2) in response to physiologic perturbations and therapeutic interventions directed at preventing cerebral ischemia.
PMID: 12707151, UI: 22592010
Anesth Analg 2003 May;96(5):1460-6
Department of Anesthesiology, Mayo Clinic and Mayo Medical School, Rochester, Minnesota.
Because anesthetic technique has the potential to dramatically affect cerebral blood flow and metabolism (two determinants of brain thermoregulation), we tested the hypothesis that, after craniotomy, anesthetic technique would influence brain temperature independent of core temperature. Twenty-one cats (2.7 +/- 0.4 kg; mean +/- SD) undergoing a uniform right parasagittal craniotomy received 1) halothane 1.5% end-expired and normocapnia (HN), 2) halothane 1.5% and hypocapnia (HH), or 3) large-dose pentobarbital and normocapnia (PN) (n = 7 per group). Heating devices initially maintained core and right subdural normothermia (38.0 degrees C). Thereafter, cranial heating was discontinued. Brain-to-core temperature gradients during the 3 h study were greatest in the right subdural area, averaging -2.5 degrees C +/- 0.9 degrees C in HN, -2.5 degrees C +/- 0.8 degrees C in HH, and -4.1 degrees C +/- 1.1 degrees C in PN. Gradients within the unexposed left subdural area and in the right cortex 0.5 and 1.0 cm below the brain surface were -0.8 degrees C +/- 0.5 degrees C to -1.1 degrees C +/- 0.6 degrees C for both HN and HH but were twice this amount in PN (-1.9 degrees C +/- 0.5 degrees C to -2.1 degrees C +/- 0.7 degrees C) (P < 0.05 for PN versus HN and HH). Deep barbiturate anesthesia can reduce brain temperature independently of core temperature, presumably by reducing the metabolic rate and associated brain heat production. The magnitude is sufficient to augment any direct cerebroprotective properties of the barbiturates. IMPLICATIONS: Deep barbiturate anesthesia reduced brain temperature independently of body temperature in cats and significantly more than the reduction seen with halothane anesthesia. The magnitude of temperature reduction was sufficient to account for cerebral protection by barbiturates independently of any other properties of the drug.
PMID: 12707150, UI: 22592009
Anesth Analg 2003 May;96(5):1432-46, table of contents
University of Michigan Medical Center, Ann Arbor 48109, USA. ktremper@umich.edu
In February 2000, a demographic, service, and finance survey was sent to the directors of anesthesiology training programs in the United States under the auspices of the Society of Academic Anesthesia Chairs/Association of Academic Program Directors. In August of 2000, 2001, and 2002, shorter follow-up surveys were sent to the same program directors requesting the numbers of vacancies in faculty positions and certified registered nurse anesthetists (CRNA) positions. The August 2001 survey also inquired if departments had positive or negative financial margins for the fiscal year ending June 2001. The August 2002 survey included the questions of the 2001 survey and additionally asked if the departments had had an increase or decrease in institutional support and the amount of that current support. The survey results revealed that the average program had 36 anesthetizing locations and 36 faculty. Those faculty spent 69% of their time providing clinical service. Approximately one-half of the departments paid for some of their residents, whereas the other 50% paid for none. Eighty-five percent of the departments employed CRNAs who were funded by the hospital in one third of the departments. In 2000, departments received $34,319/yr in support per faculty full-time equivalent (FTE) from their institutions and had a mean revenue of $407,000/yr/faculty FTE. In 2002, the department's institutional support per FTE increased to $59,680 (a 74% increase since 2000). The departments in academic medical centers paid 20% in overhead expenses, whereas departments in nonacademic medical centers paid 10%. In 2000, 2001, and 2002, the percentage of departments with positive margins was 53%, 53%, and 65%, respectively, whereas the departments with a negative margin decreased from 44% in the year 2000 to 38% in 2001 and 33% in 2002. For the departments with a positive margin, the amount of margin per FTE over this 3-yr period was approximately $50,000, $15,000, and $30,000, respectively. Although the percentage of departments with a negative margin has been decreasing, the negative margin per FTE seems to be increasing from approximately $24,000 to $43,000. The number of departments with open faculty positions has decreased from 91.5% in the year 2000 to 83.5% in 2001 and 78.4% in 2002; in these departments, the number of open faculty positions has also decreased from 3.8 in 2000 to 3.9 in 2001 to 3.4 in 2002. The number of open CRNA positions seems to have been relatively constant with approximately two thirds of the departments requiring an average of approximately four CRNAs each. Overall, academic anesthesiology departments fiscal security seems to have eroded with an increased dependence on institutional support. Departments pay larger overhead rates relative to private practice, and there seems to be a continued, but possibly decreasing, shortage of faculty. IMPLICATIONS: A survey was conducted of anesthesia training program directors that demonstrated that their departments' financial conditions have been eroding over the years 2000 to 2002. During this same period of time, departments were receiving an increase in institutional support from $34,319/full-time equivalent (FTE) faculty in the year 2000 to $59,680/FTE in the year 2002. Although there seems to be an approximate 10% shortage in academic faculty, the number of departments with open positions has progressively decreased from 91% to 73% over the past 3 yr. On average, the financial condition of the training departments has deteriorated over the past 3 yr despite a significant increase in institutional support to enable departments to recruit and retain faculty in an era of an apparent national shortage of anesthesiologists.
PMID: 12707147, UI: 22592006
Anesth Analg 2003 May;96(5):1424-31
Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China.
In this systematic review, we compared the effectiveness of media-based patient education about anesthesia. Fifteen randomized controlled trials (n = 1506) were identified after a systematic search of electronic databases (MEDLINE, EMBASE, CINAHL, PSYCINFO, The Cochrane Controlled Trials Registry), published articles, and contact with authors. Outcomes assessed were anxiety, knowledge, and patient satisfaction. Anxiety levels before anesthesia were less intense in subjects receiving the video and printed information compared with those receiving no intervention (weighted mean difference of 3; 95% confidence interval [95%CI], 1-5 Spielberger's State and Trait Anxiety Inventory). Patients in the video group were more likely to answer all knowledge questions correctly compared with patients with no intervention (relative risk of 6.64; 95%CI, 2.05-21.52). The level of knowledge about pain management was higher in the video group compared with patients with no intervention (weighted mean difference of 17%; 95%CI, 9-25). However, the level of patient satisfaction with the intervention (expectation versus actual anesthetic experience) was similar between the groups (relative risk of 1.06; 95%CI, 0.93-1.22). This systematic review supports the use of video and printed information about general process and risks of anesthesia for patient education before surgery. IMPLICATIONS: The effectiveness of media-based interventions for educating patients about general process and risks of anesthesia were compared in this systematic review. The use of video and/or printed information can decrease patient anxiety and increase patient knowledge. However, patient satisfaction was similar between media-based intervention and nonintervention groups.
PMID: 12707146, UI: 22592005
Anesth Analg 2003 May;96(5):1397-402
Department of Anesthesia and Perioperative Care, University of California-San Francisco, San Francisco, California.
Local anesthetics are used for local irrigation after many types of operations. However, recent evidence of toxic effects of local anesthetics at large concentrations during continuous administration suggests an advantage of using decreased local anesthetic concentrations for irrigation solutions. In this study, we determined whether smaller concentrations of local anesthetics may maintain an antiinflammatory and, therefore, analgesic effect without the risk of possible toxicity. Lidocaine and bupivacaine were studied for their ability to inhibit both components of neurogenic inflammation-C fiber-mediated and sympathetic postganglionic neuron (SPGN)-mediated inflammation-in the rat knee joint. Intraarticular lidocaine 0.02% reduced 5-hydroxytryptamine (5-HT)-induced (SPGN-mediated) plasma extravasation (PE) by 35%, and further decreases were obtained by perfusing larger concentrations of lidocaine. Intraarticular bupivacaine 0.025% inhibited 5-HT-induced PE by 60%, and a 95% inhibition was obtained with bupivacaine 0.05%. Larger local anesthetic concentrations were necessary to inhibit C fiber-mediated PE than those required to inhibit SPGN-mediated PE. Lidocaine 0.4% was required to reduce mustard oil-induced PE by 60%. Lidocaine 2% inhibited mustard oil-induced PE to baseline levels. Bupivacaine 0.1% was required for an 80% reduction of PE. Bupivacaine 0.25% inhibited mustard oil-induced PE to baseline levels. Our results demonstrate differential effects of local anesthetics on SPGN- and C fiber-mediated PE but confirm the concept of using smaller concentrations of local anesthetics to achieve inhibition of postoperative inflammation. IMPLICATIONS: Local anesthetic wound irrigation is often used to treat postoperative surgical pain. Large concentrations of local anesthetics are usually used, and these concentrations may have possible neurotoxic and myotoxic effects. Our results demonstrate antiinflammatory effects of lidocaine and bupivacaine at concentrations smaller than used clinically.
PMID: 12707141, UI: 22592000
Anesth Analg 2003 May;96(5):1369-73
Department of Anesthesiology, Nagasaki University School of Medicine, Nagasaki, Japan.
The hemodynamic interaction of dantrolene, a specific drug for malignant hyperthermia, and propofol which appears to be safe in malignant hyperthermia-susceptible patients, has not been investigated. We performed this study to examine the hemodynamic actions of dantrolene at a therapeutic dose during propofol anesthesia. Ten dogs were chronically instrumented for the measurements of systemic and coronary hemodynamics. The dogs were assigned to receive propofol with vehicle or dantrolene in a random manner on separate experimental days. Propofol significantly decreased mean arterial blood pressure, left ventricular systolic and end-diastolic pressure, the maximal rate of increase in left ventricular pressure, and left ventricular regional segment shortening. Coronary blood flow (CBF) was unchanged but coronary vascular resistance (CVR) decreased. Dantrolene reversed the decrease in mean arterial blood pressure and left ventricular systolic pressure caused by propofol, and significantly increased heart rate. However, left ventricular end-diastolic pressure, cardiac output, maximal rate of increase in left ventricular pressure, and segment shortening were unchanged. CBF was significantly increased with a decrease in CVR. These results suggest that dantrolene reverses the hypotensive action produced by propofol and causes an increase in CBF with a decrease in CVR, but does not significantly change the negative inotropic effects. Thus, dantrolene exerts favorable hemodynamic effects during propofol anesthesia. IMPLICATIONS: Our study suggests that dantrolene reverses the hypotensive action produced by propofol and causes an increase in coronary blood flow with a decrease in coronary vascular resistance, but does not significantly change the negative inotropic effects.
PMID: 12707135, UI: 22591994
Anesth Analg 2003 May;96(5):1345-9
Department of Anesthesia and Perioperative Care, University of California, San Francisco, California.
Several reports suggest that clinically used concentrations of inhaled anesthetics can increase conductance through noninactivating potassium channels and that the resulting hyperpolarization might decrease excitability, thereby leading to the anesthetic state. We speculated that animals deficient in such potassium channels might be resistant to the effects of anesthetics. Thus, in the present study, we measured the minimum alveolar anesthetic concentration (MAC) needed to prevent movement in response to a noxious stimulus in 50% of adult mice lacking functional KCNK5 potassium channel subunits and compared these results with those for heterozygous and wild-type mice. We also measured MAC in weaver mice that had a mutation in the potassium channel Kir3.2 and compared the resulting values with those for wild-type mice. MAC values for desflurane, halothane, and isoflurane for KCNK5-deficient mice and isoflurane MAC values for weaver mice did not differ from MAC values found in control mice. Our results do not support the notion that these potassium channels mediate the capacity of inhaled anesthetics to produce immobility. In addition, we found that the weaver mice did not differ from control mice in their susceptibility to convulsions from the nonimmobilizers flurothyl [di-(2,2,2,-trifluoroethyl)ether] or 2N (1,2-dichlorohexafluorocyclobutane). IMPLICATIONS: Mice harboring mutations in either of two different potassium channels have minimum alveolar anesthetic concentration (MAC) values that do not differ from MAC values found in control mice. Such findings do not support the notion that these potassium channels mediate the capacity of inhaled anesthetics to produce immobility in the face of noxious stimulation.
PMID: 12707131, UI: 22591990
Anesth Analg 2003 May;96(5):1340-4
Neuronal baseline K(+) channels were activated by several volatile anesthetics. Whole-cell recordings from cultured cerebellar granule neurons of 7-day-old male Sprague-Dawley rats showed outward-rectifying K(+) currents with a conductance of approximately 1.1 +/- 0.3 nS (n = 20) at positive potentials. The channel activity was noninactivating, exhibited no voltage gating, and was insensitive to conventional K(+) channel blockers. Clinically relevant concentrations of halothane (112, 224, 336, and 448 micro M) dissolved in Ringer's solution increased outward currents by 29%, 50%, 63%, and 94%, respectively (n = 5; P < 0.05; analysis of variance [ANOVA]). Similar increases in currents were produced by isoflurane (274, 411, 548, and 822 micro M), which increased outward currents by 22%, 47%, 52%, and 60%, respectively (n = 5; P < 0.05; ANOVA). Sevoflurane 518 micro M increased outward currents by 225% (n = 10; P < 0.05; ANOVA). In all experiments, channel activity quickly returned to baseline levels during wash. The outward-rectifying whole-cell current-voltage curves were consistent with the properties of anesthetic-sensitive KCNK channels. These results support the idea that noninactivating baseline K(+) channels are important target sites of volatile general anesthetics. IMPLICATIONS: The volatile anesthetics halothane, isoflurane, and sevoflurane, reversibly enhanced a noninactivating outwardly rectifying K(+) current in rat cerebellar granule neurons. These findings support a model of anesthesia that includes a site of action at baseline K(+) channels.
PMID: 12707130, UI: 22591989
Anesth Analg 2003 May;96(5):1336-9
Department of Anesthesiology, Inonu University, School of Medicine, Malatya, Turkey.
Tracheal intubation may be accomplished with remifentanil and a non-opioid IV anesthetic without a muscle relaxant. In this study, we evaluated in double-blinded, prospective, randomized manner the dose requirements for remifentanil with thiopental without muscle relaxant administration to obtain clinically acceptable intubation conditions and cardiovascular responses. After premedication with midazolam 0.03 mg/kg IV, 105 patients were randomized equally to one of three study groups, each receiving the following: remifentanil 2 micro g/kg (Group I), 3 micro g/kg (Group II), and 4 micro g/kg (Group III). Remifentanil was administered over 30 s, and anesthesia was induced with thiopental 5 mg/kg. Tracheal intubation conditions were assessed by the anesthesiologist performing the intubation as: (a) excellent, (b) satisfactory, (c) fair, and (d) unsatisfactory. There were no statistically significant differences among groups regarding to demographic data. Blood pressure and heart rate did not increase in any group after accomplishing intubation. There was a significant improvement in intubation conditions between Groups I and II, I and III, and II and III (P < 0.001). We conclude that remifentanil 4 micro g/kg administered before thiopental 5 mg/kg provided excellent or satisfactory intubation conditions in 94% of patients and prevented cardiovascular responses to intubation. IMPLICATIONS: We evaluated in a double-blinded manner the dose requirements for remifentanil with thiopental without muscle relaxants for obtaining acceptable intubation condition. Our results show that remifentanil 4 micro g/kg administered before thiopental provided excellent or satisfactory intubation condition in 94% of patients.
PMID: 12707129, UI: 22591988
Anesth Analg 2003 May;96(5):1328-35
Anesthesia Clinical Research Unit, Departments of Anesthesiology and Health Sciences Research, Mayo Clinic, Rochester, Minnesota.
The goal of this study was to determine whether the preoperative diagnosis of obstructive sleep apnea (OSA) is an independent risk factor for perioperative complications in patients undergoing nonotorhinolaryngologic outpatient surgical procedures. We used existing databases to identify 234 patients with polysomnography-confirmed OSA who had outpatient surgical procedures in the years 1997 through 2000. Control patients were matched for type of anesthesia, age, sex, body mass index, surgical procedure, and surgical date. Their perioperative medical records were reviewed. There was no significant difference in the intraoperative management of OSA and control patients, except that the laryngeal mask airway was less likely to be used in OSA patients. There was no significant difference in the rate of unplanned hospital admissions (23.9% versus 18.8%; odds ratio, 1.4; 95% confidence interval, 0.8-2.5) or other adverse events (2.1% versus 1.3%; odds ratio, 1.7; 95% confidence interval, 0.4-7.0) between OSA and non-OSA patients. Further, when admission did occur, it was generally unrelated to cardiac or respiratory events. In this retrospective analysis, the preoperative diagnosis of OSA was not a risk factor for either unanticipated hospital admission or for other adverse events among patients undergoing outpatient surgical procedures in a tertiary referral center. IMPLICATIONS: In patients scheduled for outpatient surgery in a large academic practice, the diagnosis of obstructive sleep apnea confirmed by polysomnography was not an independent risk factor for unanticipated hospital admission or for other adverse perioperative events.
PMID: 12707128, UI: 22591987
Anesth Analg 2003 May;96(5):1325-7
Department of Anesthesiology, American University of Beirut Medical Center, Lebanon.
IMPLICATIONS: Supplementing a sevoflurane induction of anesthesia in children with IV lidocaine 2 mg/kg can suppress cough after tracheal intubation and thus improve intubating conditions. In addition, lidocaine minimizes blood pressure fluctuations after tracheal intubation.
PMID: 12707127, UI: 22591986
Anesth Analg 2003 May;96(5):1320-4
Department of Anesthesiology, Division of Pediatric Anesthesiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina.
In this study, we examined the emergence characteristics of children tracheally extubated while deeply anesthetized with desflurane (Group D) or sevoflurane (Group S). Forty-eight children were randomly assigned to one of the two groups. At the end of the operation, all subjects were tracheally extubated while breathing 1.5 times the minimal effective concentration of assigned inhaled anesthetic. Recovery characteristics and complications were noted. Group D patients had higher arousal scores on arrival to the postanesthesia care unit than Group S patients. Later arousal scores were not significantly different. No serious complications occurred in either group. Coughing episodes and the overall incidence of complications after extubation were more frequent in Group D. Readiness for discharge and actual time to discharge were not significantly different between groups. Emergence agitation was common in both groups (33% overall, 46% for Group D, and 21% for Group S). Narcotic administration in the postanesthesia care unit occurred more frequently in Group D (10 of 24 patients) versus Group S (3 of 24 patients). Premedication with oral midazolam resulted in significantly longer emergence times regardless of the potent inhaled anesthetic administered. IMPLICATIONS: Deep extubation of children can be performed safely with desflurane or sevoflurane. Airway problems occur more frequently with desflurane. Awakening occurs more quickly with desflurane. Midazolam premedication has a greater effect on emergence times than does the choice of inhaled anesthetic. Emergence agitation occurs frequently with either technique.
PMID: 12707126, UI: 22591985
Anesth Analg 2003 May;96(5):1280-7
Institute of Anesthesiology and Intensive Therapy, Division of Cardiac Surgery, and. Department of Medical Informatics and Engineering, University of Szeged, Szeged, Hungary.
We investigated the role of cardiopulmonary bypass (CPB) in compromised lung function associated with cardiac surgery. Low-frequency respiratory impedance (Zrs) was measured in patients undergoing cardiac surgery with (n = 30; CPB group) or without (n = 29; off-pump coronary artery bypass [OPCAB] group) CPB. Another group of CPB patients received dopamine (DA) (n = 12; CPB-DA group). Extravascular lung water was determined in five CPB subjects. Zrs was measured before skin incision and after chest closure. Airway resistance and inertance and tissue damping and elastance were determined from Zrs data. Airway resistance increased in the CPB group (74.9% +/- 20.8%; P < 0.05), whereas it did not change in the OPCAB group (11.8% +/- 7.9%; not significant) and even decreased in the CPB-DA patients (-40.6% +/- 9.2%; P < 0.05). Tissue damping increased in the CPB and OPCAB groups, whereas it remained constant in the CPB-DA patients. Significant increases in elastance were observed in all groups. There was no difference in extravascular lung water before and after CPB, suggesting that edema did not develop. These results indicate a significant and heterogeneous airway narrowing during CPB, which was counteracted by the administration of DA. The mild deterioration in tissue mechanics, reflecting partial closure of the airways, may be a consequence of the anesthesia itself. IMPLICATIONS: We observed that cardiopulmonary bypass deteriorates lung function by inducing a heterogeneous airway constriction, whereas no such effects were observed in patients undergoing cardiac surgery without bypass. The impairment in parenchymal mechanics, which was obtained in both groups, may result from peripheral airway closure and/or be a consequence of mediator release.
PMID: 12707120, UI: 22591979
Anesth Analg 2003 May;96(5):1274-9
Department of Pharmacology, University of Melbourne. Departments of Anaesthesia and Pain Management and. Cardiothoracic Surgery, The Royal Melbourne Hospital, Australia.
Baseline measurements of systolic and diastolic function performed after the induction of anesthesia may be compared with subsequent measurements acquired under different physical conditions such as open pericardium and different heart rate or rhythm. We acquired data from 21 patients undergoing coronary artery surgery. Combined echocardiographic and pulmonary artery catheter measurements were performed before and after pericardial opening, atrial pacing at the native rate, and atrial pacing 30 bpm faster. Indices of systolic function included fractional area change, afterload corrected fractional area change, and myocardial performance index; diastolic function included mitral inflow and pulmonary vein Doppler profiles, color M-Mode Doppler flow propagation velocity, instantaneous end-diastolic stiffness, and isovolumetric relaxation time. Hemodynamic indices included cardiac index, mean arterial, right atrial, and pulmonary capillary wedge pressures, and systemic vascular resistance index. There were no changes in measurements after opening of the pericardium or with institution of atrial pacing. With increased heart rate, there were no changes in systolic function, but instantaneous end-diastolic stiffness increased. Propagation velocity showed a paradoxical improvement with increased heart rate opposite to other trends. Beat fusion occurs with increasing heart rate for mitral inflow Doppler. We recommend that serial measurements are performed at a similar heart rate. IMPLICATIONS: Pericardial restraint or the institution of atrial pacing do not alter left ventricular function, as assessed by pulmonary artery catheter and transesophageal echocardiography measurements. Diastolic (but not systolic) measurements showed inconsistency with increased heart rate.
PMID: 12707119, UI: 22591978
Anesth Analg 2003 May;96(5):1254-7
Department of Anesthesia, University Hospital, Regensburg, Germany.
Assessment of cardiac performance and adequate fluid replacement of a critically ill patient are important goals of a clinician. We designed this study to evaluate the ability of stroke volume variation (SVV), derived from pulse contour analysis, and frequently used preload variables (central venous pressure and pulmonary capillary wedge pressure) to predict the response of stroke volume index and cardiac index to volume replacement in normoventilated cardiac surgical patients. We studied 20 patients undergoing elective coronary artery bypass grafting. After the induction of anesthesia, hemodynamic measurements were performed before (T1) and subsequent to volume replacement by infusion of 6% hydroxyethyl starch 200/0.5 (7 mL/kg) with a rate of 1 mL. kg(-1). min(-1). Except for heart rate, all hemodynamic variables changed significantly (P < 0.01) after volume loading. Linear regression analysis between SVV at baseline (T1) and DeltaSVV after volume application showed a significant correlation (r = -0.97; P < 0.01), whereas linear regression analysis between SVV (T1) and percentage changes of stroke volume index (r = 0.19) and cardiac index (r = 0.17) did not reveal a significant relationship between variables. The results of our study suggest that SVV derived from pulse contour analysis cannot serve as an indicator of fluid responsiveness in normoventilated cardiac surgical patients.
PMID: 12707116, UI: 22591975
Anesth Analg 2003 May;96(5):1248-50
University of Pennsylvania, Department of Anesthesia and the Johnson Research Foundation, Philadelphia, Pennsylvania.
PMID: 12707114, UI: 22591973
Anesth Analg 2003 Apr;96(4):1230
PMID: 12651691, UI: 22537626
Anesth Analg 2003 Apr;96(4):1218, table of contents
Department of Anesthesia and Intensive Care, Bichat Claude-Bernard Hospital, 46 Rue Henri Huchard, 75018 Paris, France. pjuvin@free.fr
IMPLICATIONS: This work shows that the insertion of a peripheral venous line is more difficult in obese than in lean patients. The usual recommendation, that a central venous line should be inserted routinely in obese patients to perform anesthesia, is not valid.
PMID: 12651688, UI: 22537623
Anesth Analg 2003 Apr;96(4):1209-13, table of contents
Department of Anesthesiology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan. mshimoka@naramed-u.ac.jp
In hypothermic patients, a tendency to bleed may be observed even when hemostatic tests seem to be normal. Coagulation and platelet function tests are usually performed at 37 degrees C. We investigated the influence of induced hypothermia on temperature-adjusted hemostasis function testing using Sonoclot Analyzer (Sonoclot) and Thromboelastography (TEG). Anesthesia was induced and maintained with IV ketamine and fentanyl on 15 male New-Zealand White rabbits. A water blanket was used to induce hypothermia to 30 degrees C and to rewarm to 37 degrees C. Blood samples were obtained at four points: before hypothermia, at 34 degrees C, at 30 degrees C, and after rewarming. Standard coagulation tests were performed at 37 degrees C (C method), and simultaneously, real temperature hemostasis function tests (R method) were run. In Sonoclot(R), activated clotting time and time to peak increased and clot rate decreased significantly at 30 degrees C in the R method compared with those in the C method. In TEG(R), reaction time and clot formation time were prolonged and clot formation rate was diminished at 30 degrees C in the R method compared with those in the C method. Induced hypothermia delayed the coagulation cascade and reduced platelet function. During hypothermia, hemostatic measurements should be performed at real temperature to avoid overestimating patient hemostatic function based on results measured at the standard 37 degrees C. IMPLICATIONS: We investigated the influence of induced hypothermia on temperature-adjusted hemostasis function tests in rabbits using Sonoclot Analyzer and Thromboelastography. Induced hypothermia delayed the coagulation cascade and reduced platelet function. The conventional coagulation tests performed at 37 degrees C failed to detect these hypothermia-induced degradations in hemostasis performance.
PMID: 12651686, UI: 22537621
Anesth Analg 2003 Apr;96(4):1201-8, table of contents
Klinik fur Anaesthesiologie, Ludwig-Maximilians-Universitat, Klinikum Grosshadern, Marchioninistrasse 15, D-18377 Munich, Germany. markus.rehm@ ana.med.uni-muenchen.de
In this study, we evaluated the action of two buffer solutions on acid-base equilibrium in cases of hyperchloremic acidosis. Twenty-four patients undergoing major gynecological intraabdominal surgery received 40 mL. kg(-1). h(-1) of 0.9% saline per protocol. During surgery, in every patient, hyperchloremic acidosis occurred. At a standard base excess of -7 mmol/L, the patients were randomly assigned to receive within 20 min either a mean of 130 +/- 26 mmol of sodium bicarbonate (BIC, 1 M; n = 12) or a mean of 128 +/- 18 mmol of tris-hydroxymethyl aminomethane (THAM, 3 M; n = 12). PaCO(2), pH, serum bicarbonate concentration, standard base excess, and serum concentrations of sodium, potassium, chloride, lactate, phosphate, total protein, and albumin were determined before and 0, 10, and 20 min after buffering. The apparent strong ion difference was calculated as: serum sodium plus serum potassium minus serum chloride minus serum lactate. The effective strong ion difference and the amount of weak plasma acid were calculated by using a computer program. Immediately after buffering, standard base excess increased by 9.8 mmol/L in the BIC group and by 7.2 mmol/L in the THAM group. In both groups, PaCO(2) and the amount of weak plasma acid remained constant. Mainly because of hypernatremia, the apparent and effective strong ion difference increased in the BIC group by 8.5 and 7.9 mEq/L, respectively. In the THAM group, the apparent strong ion difference remained constant; however, the effective strong ion difference increased by 6.4 mEq/L and the anion gap decreased by 5.8 mmol/L because of the occurrence of an unmeasured cation. In conclusion, in case of buffering with BIC or THAM, the changes in pH were accompanied by, and probably caused by, an increase in strong ion difference. IMPLICATIONS: By comparing two groups of patients with intraoperative hyperchloremic acidosis receiving equal doses of either sodium bicarbonate or tris-hydroxymethyl aminomethane, we assessed the action of both drugs on acid-base equilibrium. In case of "buffering," the changes in pH were accompanied by, and probably caused by, an increase in strong ion difference.
PMID: 12651685, UI: 22537620
Anesth Analg 2003 Apr;96(4):1191-2, table of contents
Department of Anesthesia and Perioperative Care, University of California San Francisco, 521 Parnassus Avenue, San Francisco, CA 94143-0468, USA.
IMPLICATIONS: We report a case of upper airway obstruction after subclavian perivascular block in a patient with a preexisting unrecognized paralyzed vocal cord on the opposite side. We discuss the incidence of vocal cord paralysis after subclavian perivascular block and the risk of airway compromise if contralateral vocal cord paralysis is known or suspected.
PMID: 12651683, UI: 22537618
Anesth Analg 2003 Apr;96(4):1188-90, table of contents
Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1009, USA. jcrews@wfubmc.edu
IMPLICATIONS: This case report describes a patient who demonstrated generalized seizure activity after an injection of 30 mL of levobupivacaine 0.5% for interscalene brachial plexus block. No evidence of cardiovascular toxicity was noted.
PMID: 12651682, UI: 22537617
Anesth Analg 2003 Apr;96(4):1183-7, table of contents
Department of Anesthesiology and Pain Therapy, Jeroen Bosch Ziekenhuis, Nieuwstraat 34, 5200 ME 's-Hertogenbosch, The Netherlands. anesthesie@boschmedicentrum.nl
Sixty patients scheduled for lumbar epidural anesthesia were included in a study in which we evaluated the efficacy of localizing the epidural space by means of an acoustic signal. A prototype of an acoustic puncture assist device, connected to the epidural needle by an extension tube, generated the pressure needed to perform the epidural puncture and translated this pressure into corresponding acoustic and visible signals. The device frees the anesthesiologist to handle the epidural needle with both hands and to detect the epidural space by means of these signals. In all 60 patients (100%), the epidural space was successfully located by using the acoustic signal. In all cases, this was confirmed by the pressure measurement, which proved to be a reliable indicator for correct identification of the epidural space. We conclude that it is possible to locate the epidural space by means of the acoustic puncture assist device. The method proved to be reliable, safe, and simple in this study. The benefits of this new epidural puncture technique include better needle control, teaching, control of correct catheter placement, and documentation. The last can be an important adjunct to anesthesia practice. IMPLICATIONS: The authors demonstrate that it is possible to identify the epidural space by an acoustic and visible signal. An experimental setup constructed for this purpose makes the epidural puncture procedure audible and visible.
PMID: 12651681, UI: 22537616
Anesth Analg 2003 Apr;96(4):1167-72, table of contents
Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, 251 E Huron Street, Feinberg 5-704, Chicago, IL 60611, USA.
Labor analgesia initiated with intrathecal bupivacaine and fentanyl, without a local anesthetic epidural test dose, provides effective analgesia and allows ambulation. In this study, we sought to determine the effect of a lidocaine-epinephrine test dose administered immediately after the initiation of combined spinal-epidural (CSE) analgesia with bupivacaine 2.5 mg and fentanyl 25 micro g on parturients' hemodynamic stability, posterior column function, motor strength, and subjective ability to walk. Parturients (n = 153) were randomized to receive either 3 mL of epidural saline or lidocaine 1.5% with epinephrine 1:200,000. Hemodynamic variables, proprioception, straight leg raise, and the modified Bromage score were analyzed in 110 parturients who completed the study protocol and were not different between groups. Vibratory sense, the ability to perform a partial deep knee bend and to step up on a stool, and the subjective ability to walk were impaired in a larger number of parturients in the lidocaine-epinephrine group at 30 min (P < 0.05). At 60 min, there were no differences between the groups except that fewer parturients in the lidocaine-epinephrine group could step up on a stool. The straight leg raise against resistance and the modified Bromage scale did not correlate well with other tests of motor strength (Spearman's rho, 0.273-0.405). These data suggest that the test dose should be avoided immediately after initiation of CSE analgesia when early ambulation is desired. IMPLICATIONS: A lidocaine-epinephrine epidural test dose (3 mL of lidocaine 1.5% with epinephrine 1:200,000), injected immediately after the initiation of combined spinal-epidural labor analgesia with bupivacaine 2.5 mg and fentanyl 25 microg, may interfere with the ability to perform simple tests of motor function and ambulation.
PMID: 12651678, UI: 22537613
Anesth Analg 2003 Apr;96(4):1155-60, table of contents
Department of Anesthesiology, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, 500 University Drive, Hershey, PA 17033, USA.
Successful somatosensory-evoked potential (SEP) monitoring has been performed during the administration of dexmedetomidine to patients, but a systematic investigation of the dose response of the SEP to dexmedetomidine has not been reported. In this study, we evaluated the effect of a range of dexmedetomidine doses on the cortical SEP in rats. Twelve rats were initially anesthetized with ketamine and the lungs were mechanically ventilated. Femoral arterial and venous catheters were placed. Anesthesia was maintained with constant infusions of remifentanil (5-15 microg. kg(-1). min(-1)) and vecuronium (56 microg. kg(-1). min(-1)). Dexmedetomidine was infused at 0.1, 0.25, 0.5, 1.0, and 2.0 microg. kg(-1). min(-1) in a stepwise manner with 10-min infusion periods at each step. In eight rats, an additional large-dose infusion of dexmedetomidine at 10 microg. kg(-1). min(-1) was administered for 30 min. The cortical SEPs were recorded after stimulation of the tibial nerve. At all infusion rates, there was a statistically insignificant increase in the SEP amplitude. Dexmedetomidine consistently increased the SEP latency, but these increases were not statistically significant. These data demonstrate that dexmedetomidine maintains technically adequate conditions for SEP monitoring in rats and provides support for future studies of the effect of dexmedetomidine on SEP monitoring in humans. IMPLICATIONS: In rats, the administration of a wide range of infusion rates of dexmedetomidine did not significantly affect the somatosensory-evoked potential. These results suggest that dexmedetomidine might be a useful adjunctive drug in patients undergoing intraoperative somatosensory-evoked potential monitoring.
PMID: 12651676, UI: 22537611
Anesth Analg 2003 Apr;96(4):1089-95, table of contents
Department of Anesthesiology, University of Florida College of Medicine, Gainesville, FL 32610-0254, USA.
In this study, we investigated the efficacy of patient-controlled regional analgesia for outpatients undergoing moderately painful orthopedic surgery of the shoulder. Preoperatively, patients (n = 20) received an interscalene nerve block and perineural catheter. Postoperatively, patients were discharged home with both oral opioids and a portable infusion pump delivering either 0.2% ropivacaine or 0.9% saline, determined randomly in a double-blinded manner. Daily end points included pain scores, opioid use and side effects, sleep quality, and technique complications. Ropivacaine (n = 10) infusion significantly reduced pain compared with saline (n = 10) infusion. The average pain at rest (scale: 0-10) on postoperative day 1 (median, 25th-75th percentiles) was 4.8 (4.0-5.0) for the saline group, versus 0.0 (0.0-2.0) for the ropivacaine group (P < 0.001). Oral opioid use and related side effects were also significantly decreased in the ropivacaine group. On postoperative day 1, median tablet consumption was 8.0 (6.5-9.5) and 0.5 (0.0-1.0) for the saline and ropivacaine groups, respectively (P < 0.001). Sleep disturbance scores were nearly threefold greater on the first postoperative night for patients receiving saline (P = 0.013). We conclude that after moderately painful orthopedic surgery of the shoulder, ropivacaine infusion using a portable infusion pump and an interscalene perineural catheter at home decreased pain, opioid use and related side effects, and sleep disturbances. IMPLICATIONS: This randomized, double-blinded, placebo-controlled study demonstrated that ropivacaine, infused with a portable infusion pump via an interscalene perineural catheter for 3 days at home, significantly decreased postoperative pain after orthopedic surgery of the shoulder. In addition to providing potent analgesia and increasing patient satisfaction, perineural infusion decreased opioid requirements and their associated side effects.
PMID: 12651666, UI: 22537601
Anesth Analg 2003 Apr;96(4):1079-82, table of contents
Department of Anesthesia, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka, Japan 565-0871. kueta@anes.med.osaka-u.ac.jp
Because individual variation is a likely factor affecting both the incidence and severity of side effects and the analgesic efficacy of epidural opioids, assessment of individual variation could be useful in deciding optimal dosage. By evaluating the response to a small test dose of IV fentanyl, we designed this study to predict the degree of pain relief and the incidence of side effects in patients who would be receiving postoperative epidural fentanyl. Before the induction of anesthesia, 50 micro g of fentanyl was administered IV, and 2 min after fentanyl, the patient response was evaluated. Twenty-three patients, who reported nausea, sleepiness, dizziness, sensation of warmth, and other symptoms, were categorized as responders (Group R); the remaining 20 patients were categorized as nonresponders (Group NR). At the completion of surgery, infusion of epidural fentanyl was administered (0.3 mg/d in 0.25% bupivacaine) for 96 h. At postoperative Hours 6 and 24, Group R had significantly lower visual analog scale scores for postoperative pain intensity and required fewer analgesics than Group NR. The incidence of side effects, however, was 74% for Group R and 10% for Group NR (P < 0.05), and side effects were more serious in Group R. This study demonstrates that preoperative administration of a small dose of fentanyl during the induction of anesthesia enables prediction of the analgesic efficacy of postoperative epidural fentanyl and the incidence and severity of side effects. IMPLICATIONS: Preoperative administration of a small dose of fentanyl during the induction of anesthesia enables prediction of the analgesic efficacy of postoperative epidural fentanyl and the incidence and severity of side effects.
PMID: 12651664, UI: 22537599
Anesth Analg 2003 Apr;96(4):1047-50, table of contents
Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9068, USA.
We designed this prospective, randomized, double-blinded, placebo-controlled, crossover study to evaluate the effect of different doses of remifentanil on the acute hemodynamic response and duration of seizure activity after a standardized electroconvulsive therapy (ECT) stimulus. Twenty consenting patients with major depressive disorders receiving maintenance ECT participated in this study. Eighty ECT treatments were evaluated. All patients were premedicated with glycopyrrolate 0.2 mg IV, unconsciousness was induced with methohexital 1 mg/kg IV, and muscle paralysis was produced with succinylcholine 1.2 mg/kg IV. Subsequently, patients received 1 of 3 different doses of remifentanil 25, 50, and 100 microg or saline (control) in a random sequence immediately after methohexital at 4 consecutive ECT treatments. Labetalol, in 5-mg IV boluses, was used as a rescue antihypertensive medication. A fixed suprathreshold electrical stimulus was administered to elicit a seizure, and the times from the stimulus to the cessation of the motor and electroencephalographic (EEG) seizure activity were noted. Pre- and post-ECT blood pressure values were significantly decreased in the 100- microg remifentanil group compared with the control group. The durations of motor (38 +/- 9 s to 43 +/- 15 s) and EEG (55 +/- 29 s to 60 +/- 21 s) seizure activity were not significantly different among the four groups. Similarly, recovery times to eye opening, obeying commands, and discharge from the recovery room did not differ among the four study groups. The requirement for labetalol after ECT was nonsignificantly decreased in the remifentanil groups. In conclusion, remifentanil 100 microg IV attenuated the acute hemodynamic response to ECT. Furthermore, remifentanil had no adverse effect on the duration of ECT-induced seizure activity. Finally, adjunctive use of remifentanil did not prolong recovery times or increase post-ECT side effects. IMPLICATIONS: Remifentanil (100 microg IV) attenuated the acute hemodynamic response after electroconvulsive therapy (ECT) without adversely affecting the length of the ECT-induced seizure activity or prolonging recovery times.
PMID: 12651657, UI: 22537592
Anesth Analg 2003 Apr;96(4):1042-6, table of contents
Department of Anesthesiology, Hanyang University Hospital, #17 Haengdang dong, Sungdong gu, Seoul 133-792, Korea. kimks@hanyang.ac.kr
A small dose of ephedrine decreases the onset time of rocuronium and cisatracurium; however, ephedrine might be associated with adverse hemodynamic effects. The appropriate dose of ephedrine has not been determined. We, therefore, studied 120 patients anesthetized with fentanyl 2 microg/kg and propofol 2-2.5 mg/kg who were randomly divided to receive either ephedrine (30, 70, or 110 microg/kg) or saline. During propofol anesthesia, the neuromuscular block was monitored by mechanomyography by using submaximal current of train-of-four stimulation every 10 s. To determine cardiac output, a transcutaneous Doppler probe was placed externally at the suprasternal notch. Tracheal intubation was performed by a blinded investigator at 2 min after vecuronium. Neuromuscular block, intubating conditions, and hemodynamic effects were measured during the induction of anesthesia. Both ephedrine 70 and 110 microg/kg improved intubating conditions at 2 min after vecuronium; however, 110 microg/kg was associated with adverse hemodynamic effects. We conclude that ephedrine 70 microg/kg given before the induction of anesthesia improved intubating conditions at 2 min after vecuronium, probably by increased cardiac output without significant adverse hemodynamic effects. IMPLICATIONS:Ephedrine 70 microg/kg given before the induction of anesthesia improved tracheal intubating conditions at 2 min after vecuronium by increased cardiac output without significant adverse hemodynamic effects.
PMID: 12651656, UI: 22537591
Anesth Analg 2003 Apr;96(4):1035-41, table of contents
Laboratoire de Physiologie Cellulaire Respiratoire, INSERM EMI9937, Universite Victor Segalen, Bourdeaux 2, 146 rue Leo-Saignat, 33076 Bordeaux cedex, France.
We investigated the effect of two IV anesthetics, propofol and etomidate, on airway responsiveness in a rat model of chronic hypoxia (CH) in comparison with normoxic rats. CH rats were obtained using a hypobaric chamber (14 days at a barometric pressure of 380 mm Hg). The ability of both anesthetics to relax and prevent agonist-induced contraction was assessed in isolated tracheal rings precontracted with the muscarinic agonist carbachol (CCh) and the depolarizing agent KCl. Cumulative concentrations of both compounds relaxed tracheal rings precontracted with CCh or KCl with a similar amplitude in CH and normoxic rats. In tracheal rings precontracted with CCh, the negative logarithm of anesthetics that reduced the maximal contraction by 30%, i.e., -log half-maximal inhibitory concentration, for propofol and etomidate were 4.10 +/- 0.09 and 4.12 +/- 0.15 in normoxic rats and 4.20 +/- 0.22 and 3.61 +/- 0.19 in CH rats, respectively. At a fixed concentration, propofol (3 x 10(-4) M) or etomidate (10(-4) M) also inhibited CH tracheal rings contraction in response to cumulative concentrations of CCh and KCl. However, in contrast with the equivalent relaxant effect of both anesthetics, etomidate was two-fold less effective than propofol for inhibiting the subsequent contraction to CCh and KCl. These results indicate that propofol and etomidate retain their relaxant properties in CH rat airways by acting on the pharmaco- and electromechanical coupling. IMPLICATIONS: Anesthesia may cause airway constriction or bronchospasm in patients with normal or pathological airways. This study investigated the ability of propofol and etomidate to both reverse precontraction and inhibit contraction of tracheal rings isolated from chronically hypoxic rats.
PMID: 12651655, UI: 22537590
Anesth Analg 2003 Apr;96(4):1010-8, table of contents
Department of Anesthesia and Perioperative Care, University of California-San Francisco, San Francisco, CA 94143-0464. egere@anesthesia.ucsf.edu
In animals, the conventional inhaled anesthetic, isoflurane, impairs learning fear to context and fear to tone, doing so at concentrations that produce amnesia in humans. Nonimmobilizers are inhaled compounds that do not produce immobility in response to noxious stimulation, nor do they decrease the requirement for conventional inhaled anesthetics. Like isoflurane, the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (2N) impairs learning at concentrations less than those predicted from its lipophilicity to produce anesthesia. The capacity of the nonimmobilizer di-(2,2,2,-trifluoroethyl) ether (flurothyl) to affect learning and memory has not been studied. Both nonimmobilizers can cause convulsions. We hypothesized that if isoflurane, 2N, and flurothyl act by the same mechanism to impair learning and memory, their effects should be additive. We found that isoflurane, 2N, and flurothyl (each, alone) impaired learning fear to context and fear to tone in rats, with the nonimmobilizers doing so at concentrations less than those that cause convulsions. (Fear was defined by freezing [volitional immobility] in the presence of the conditioned stimulus [context or tone].) However, the combination of isoflurane and 2N or flurothyl produced an antagonistic rather than an additive effect on learning, a finding in conflict with our hypothesis. And flurothyl was no less potent than 2N (at least no less potent relative to the concentration of each that produced convulsions) in its capacity to impair learning. We conclude that conventional inhaled anesthetics and nonimmobilizers impair learning and memory by different mechanisms. The basis for this impairment remains unknown. IMPLICATIONS: Conventional inhaled anesthetics and nonimmobilizers are antagonistic in their effects on learning and memory, and this finding suggests that they impair learning and memory, at least in part, by different mechanisms.
PMID: 12651651, UI: 22537586
Anesth Analg 2003 Apr;96(4):982-6, table of contents
Department of Anesthesiology, Virginia Mason Medical Center, 1100 Ninth Avenue (B2-AN), Seattle, WA 98101, USA. anejmn@vmmc.org
Suprascapular nerve block (SSNB) reportedly improves analgesia and 24-h outcomes after arthroscopic shoulder surgery performed under general anesthesia. In this study, we assessed the analgesic and clinical outcome efficacy of SSNB as an adjunct to interscalene brachial plexus block (ISB) for ambulatory nonarthroscopic shoulder surgery. Fifty patients were randomized to receive either a SSNB or sham injection as part of a standardized ISB-general anesthesia regimen. Time to first significant pain (the primary outcome measure) was significantly delayed in the SSNB group (594 +/- 369 min versus 375 +/- 273 min, respectively; P = 0.02). There were no other differences between groups with regard to postanesthesia recovery unit measures, 24-h assessment of pain, supplemental analgesic use, or quality of life outcomes. We conclude that adjunctive SSNB adds minimal value to a primary ISB anesthetic for nonarthroscopic shoulder surgery. IMPLICATIONS: When used as an adjunct to an interscalene block combined with general anesthesia, suprascapular nerve block with bupivacaine moderately prolongs analgesia without improving other outcome measures after ambulatory nonarthroscopic shoulder surgery.
PMID: 12651646, UI: 22537581
Anesth Analg 2003 Apr;96(4):976-81, table of contents
Department of Paediatric Anaesthesia, IWK Health Centre, Box 3070, Halifax, Nova Scotia, Canada B3J 3G9. thomas.hackmann@dal.ca
In this randomized, double-blinded, placebo-controlled trial, we investigated whether clonidine lessened the requirements for isoflurane, fentanyl, and labetalol to provide controlled hypotension in children who underwent oromaxillofacial surgery. We also studied preoperative sedative effects, the hemodynamic response to nasotracheal intubation, and recovery characteristics. Thirty-nine healthy children, aged 10-16 yr, received clonidine 5 micro g/kg or placebo on the night before surgery and 90 min before surgery. By self-assessment, children in both groups showed similar anxiety, whereas observers rated clonidine patients as more sedated (P < 0.01). Heart rate during induction remained significantly decreased in clonidine patients compared with placebo patients (P < 0.001), as did arterial blood pressure before induction (P < 0.01) and peak pressure after intubation (P < 0.001). Children who took clonidine required significantly less isoflurane to maintain a mean arterial blood pressure of 60 +/- 4 mm Hg (mean isoflurane concentration, clonidine 0.99% versus placebo 1.33; P = 0.0004) and required less fentanyl than placebo patients (P = 0.002). Fewer treatment patients received labetalol (clonidine, n = 3 versus placebo, n = 13; P = 0.004). There was a trend toward faster recovery in the clonidine group, with a shortened recovery room stay (P = 0.03). We conclude that clonidine is a useful adjunct for controlled hypotension in children. IMPLICATIONS: This study shows that adolescents having major jaw surgery are helped by the blood pressure-decreasing drug clonidine. This drug allows smaller doses of anesthetics, pain relievers, and blood pressure-decreasing drugs to be used; reduces changes in heart rate and blood pressure; and provides faster recovery from the anesthetic.
PMID: 12651645, UI: 22537580
Anesth Analg 2003 Apr;96(4):970-5, table of contents
Department of Anesthesiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA. kain@biomed.med.yale.edu
No studies have examined parental preference for a preoperative intervention in healthy children undergoing subsequent surgeries. We collected data prospectively from 83 children who previously underwent surgery and were part of an investigation by our study group, then returned for a subsequent surgery. At the initial surgery, children were assigned (no parental intervention) to receive oral midazolam (n = 13), or parental presence during the induction of anesthesia (PPIA, n = 27), or PPIA + midazolam (n = 10) or no intervention (n = 33). At a subsequent surgery, parents chose the preoperative intervention. We found that >80% of all parents chose PPIA (with or without midazolam) at the subsequent surgery regardless of the intervention they received previously. Of parents whose children received PPIA at the initial surgery, 70% chose PPIA again. In contrast, only 23% of the patients who received midazolam at the initial surgery requested midazolam at the subsequent surgery and only 15% of the patients who received no intervention at the initial surgery requested no intervention at the subsequent surgery. All parents of very anxious children at the initial surgery chose some intervention at the subsequent surgery (P = 0.022). Parents of children who underwent a subsequent surgery preferred PPIA regardless of any previous intervention. Also, parents' intervention preferences at the subsequent surgery were influenced by children's anxiety at the initial surgery. IMPLICATIONS: Parents of children who undergo a subsequent surgery prefer to be present during the induction of anesthesia regardless of whether the child was medicated or had parents present or did not receive anything at the initial surgery. Also, parents' preference for medication or parental presence at the subsequent surgery was influenced by the child's anxiety at the initial surgery.
PMID: 12651644, UI: 22537579
Anesth Analg 2003 Apr;96(4):965-9, table of contents
Department of Anesthesiology and Critical Care Medicine, Division of Biostatistics and Epidemiology, Children's Hospital of Philadelphia, 34th Street & Civic Center Boulevard, Philadelphia, PA 19104, USA. sather@email.chop.edu
Recommended preoperative fasting intervals for infant formula vary from 4 to 8 h. We conducted a prospective, randomized, observer-blinded trial of 97 ASA physical status I and II infants scheduled for elective surgery to determine whether average gastric fluid volume (GFV) recovered from infants formula-fasted for 4 h (liberalized fast, Group L) differed from that recovered from infants allowed clear liquids up until 2 h, but fasted 8 h for formula and solids (traditional fast, Group T). In Group L, 31 of 39 subjects followed protocol and ingested formula 4-6 h before surgery. In Group T, 36 of 58 subjects followed protocol, taking clear liquids 2-5 h before the induction of anesthesia. Thirty subjects had prolonged fasts and were included only in a secondary intent-to-treat analysis. Respective mean age (5.7 +/- 2.3 versus 6.4 +/- 2.4 mo; range, 0.7-10.5 mo), weight (7.5 +/- 1.8 versus 7.5 +/- 1.1 kg), and volume of last feed (4.9 +/- 2.2 versus 4.0 +/- 2.3 oz.) did not vary between Groups L and T. GFV (L: 0.19 +/- 0.38 versus T: 0.16 +/- 0.30 mL/kg) and gastric fluid pH (L: 2.5 +/- 0.5 versus T: 2.9 +/- 1.3) did not vary. For all subjects, GFV (mL/kg) increased with age (Spearman correlation coefficient = +0.23, P = 0.03). Infant irritability and hunger and parent satisfaction were similar between groups. We conclude that average GFV after either a 4- to 6-h fast for infant formula or 2-h fast after clear liquids is small and not significantly different between groups. On the basis of these findings, clinicians may consider liberalizing formula feedings to 4 h before surgery in selected infants. IMPLICATIONS: Healthy infants aged < or =10.5 mo may drink formula up to 4 h before surgery without increasing gastric fluid volume compared with infants allowed clear liquids up to 2 h and formula 8 h before surgery.
PMID: 12651643, UI: 22537578
Anesth Analg 2003 Apr;96(4):962-4, table of contents
Department of Anesthesiology, Montreal Heart Institute, 5000 Belanger Street East, Montreal, Quebec, H1T 1C8 Canada.
IMPLICATIONS: We describe a patient scheduled for coronary artery bypass who developed carbon dioxide (CO2) embolism with acute pulmonary hypertension during endoscopic saphenectomy. Transesophageal echocardiography was useful in the diagnosis of CO2 embolism and to assess response to inhaled epoprostenol.
PMID: 12651642, UI: 22537577
Anesth Analg 2003 Apr;96(4):944-8, table of contents
Department of Anaesthesia, Christchurch Hospital, Rolleston Avenue, Christchurch, New Zealand. ross.kennedy@chmeds.ac.nz
The frequency of automated noninvasive blood pressure (NIBP) measurements during routine anesthesia is a balance between potentially deleterious effects of frequent cycling and a delay in detecting changes caused by a long cycle time. A computer model generated systolic blood pressures that changed to a new, random value after a period of stability. We sampled these data at intervals between 1 and 10 min to simulate NIBP measurements. A separate algorithm, based on Trigg's Tracking Variable, indicated when a change had been detected. For each set of variables, the simulation was repeated 1000 times, and the average time to detect a change was recorded. The mean time to detect a change was 8.0 min with a 1-min cycle, 8.9 min with a 2-min cycle, 10.8 min with a 5-min cycle, and 13.0 min with a 10-min cycle. As the cycle time increased, the delay in detecting changes increased but only by approximately half the increase in the cycle time. The optimum variables for the trend detection algorithm also changed as the NIBP interval increased. Provided that abrupt changes in blood pressure are not anticipated, a 1- or 2-min cycle time for NIBP offers little advantage over a longer period. IMPLICATIONS: We used a computer model to study the effect of increasing noninvasive blood pressure (NIBP) sampling interval on the detection of blood pressure changes. The detection time increased only 50% of the increase in the sampling interval. This information may help optimize NIBP intervals in different circumstances.
PMID: 12651638, UI: 22537573
Anesth Analg 2003 Apr;96(4):919-22
Department of Veterinary Clinical Medicine, University of Illinois, 1008 W Hazelwood Drive, Urbana, IL 60102, USA. p-constable@uiuc.edu
PMID: 12651634, UI: 22537569
Ann Fr Anesth Reanim 2003 Feb;22(2):145
Service d'anesthesie-reanimation, centre hospitalo-universitaire de Monastir, avenue du 1er Juin, 5000, Monastir, Tunisie
PMID: 12706771, UI: 22592099
Ann Fr Anesth Reanim 2003 Feb;22(2):119-29
Unite fonctionnelle d'anesthesie-reanimation, institut Claudius Regaud, 20-24, rue du Pont-Saint-Pierre, 31052 cedex, Toulouse, France
Objective. - Identifying risk factors and predictive models for Postoperative Nausea and Vomiting (PONV) and developing antiemetic guidelines for its prevention and treatment.Data sources. - Medline((R)) (1997-2002) searches, using "postoperative nausea and vomiting" [MESH], complemented by handsearch.Study selection and data extraction. - Published randomised controlled trials, systematic reviews and multivariable analysis of large cohort studies were evaluated.Data synthesis. - Avoiding PONV seems to be one of the highest priority for most patients. Its most important risk factors are volatile anaesthetics and opioids. If these are given to susceptible patients such as female, those with previous history of PONV or motion sickness and non-smoker, this is likely to result in PONV. For patients receiving volatile anaesthesia, simplified risk scores are available to estimate the individual risk of PONV. Patients at high risk for PONV may benefit from a multimodal approach which involves a) lowering the baseline risk (e.g. by total intravenous anaesthesia with propofol) with b) prophylactically given antiemetics such as droperidol, dexamethasone and serotonin antagonists, alone or in combination. In these selected patients, antiemetics are cost effective.Conclusions. - A strategy to prevent and treat PONV should depend on the individuals risk. However, its clinical usefulness and economic implications needs to be validated.
PMID: 12706765, UI: 22592093
Ann Fr Anesth Reanim 2003 Feb;22(2):96-102
Service de reanimation polyvalente, departement d'anesthesie-reanimation-urgences, HIA Legouest, BP10, 57998, Metz-Armee, France
[Record supplied by publisher]
Objective. - To evaluate the combination of inhalational induction with sevoflurane and fiberoptic intubation through a specific facial mask for anticipated difficult tracheal intubation (DI) in adults.Study design. - Prospective study.Patients and methods. - Eighteen consecutive patients at risk of DI. After premedication made of hydroxyzine 2 mg kg(-1), preoxygenation, 0.1 &mgr;g kg(-1) sufentanil was administered (T0), then, inhalational induction was started: sevoflurane 8% in 100% O(2) l min(-1). After 1 min, sevoflurane was decreased to 5% and, if necessary, adapted to obtain an adequate depth of anaesthesia (Ramsay score > 3). Fiberoptic bronchoscopy was performed through a Fibroxy mask. BP was measured every 2.5 min, HR, SpO(2), RR were recorded. The results were analyzed by Newman-Keuls test.Results. - Intubation was easily realized but it was necessary to assist ventilation in patients presenting prolonged apnea lasting more than 30 s (5 out of 9 patients who presented apnea during procedure). Intubation was quickly realized (T+ 4 +/- 3 min). Haemodynamics and saturation were not altered during procedure. Inhalatory induction using sevoflurane costs 6 10 versus 16 80 for intravenous target controlled propofol anesthesia (using only one preconditionned syringe).Conclusion. - Inhalational induction with sevoflurane and fiberoptic intubation appeared easy, fast and cheap.
PMID: 12706762
Ann Fr Anesth Reanim 2003 Feb;22(2):91-5
Departement d'anesthesie-reanimation, hopital Antoine-Beclere, 157, rue de la Porte-de-Trivaux, 92141 cedex, Clamart, France
Objective. - Previous spine surgery theoretically exposes the obstetric patient to a greater technical difficulty during regional analgesia for labour or during anaesthesia for caesarean delivery. Published experience suggests that epidural puncture is however technically possible in the majority of cases.Study design. - Retrospective study.Patients. - Analysis of the files of parturients who gave birth in a maternity hospital during a six year period and who had previously undergone spine surgery.Methods. - Technical failures (during puncture), analgesic failures (complete block inefficiency and/or requirement of a general anaesthetic) and complications (important bleeding at the puncture site, dural tap, infection) observed during epidural analgesia/anaesthesia were recorded.Results. - Except for two paraplegic parturients who had been operated for dorsocervical traumatic injuries and who were excluded from the analysis, 31 parturients had undergone spine surgery and delivered during the period of analysis. Twenty patients underwent 22 epidural punctures. Technical failure were noted in two cases (9%) and analgesic failure in two other cases (9%). No significant complication was recorded.Conclusion. - With an overall 18% failure rate, epidural anaesthesia is not contra-indicated in these patients but appears to be less reliable than in patients with normal spine. Psychological and technical preparation to the occurrence of failure is necessary.
PMID: 12706761, UI: 22592089
Br Dent J 2003 Jan 11;194(1):43-5
Glasgow Dental Hospital and School, Glasgow. leitch@bigfoot.com
OBJECTIVE: To assess the safety and efficacy of a new patient-maintained propofol system for conscious sedation in dentistry. DESIGN: Prospective clinical trial SETTING: Department of Sedation, Glasgow Dental Hospital and School, 2001 SUBJECTS AND METHODS: Patients scheduled for oral surgery with conscious sedation. Exclusions included ASA IV -V, inability to use the handset, opioid use and severe respiratory disease. INTERVENTIONS: Patients were given intravenous propofol to a level of 1.0 microg/ml (reducing from 1.5 microg/ml) using a target controlled infusion system, they then controlled their sedation level by double-clicking a handset which on each activation increased the propofol concentration by 0.2 microg/ml. MAIN OUTCOME MEASURES: Oxygen saturation, patient satisfaction, and surgeon satisfaction. RESULTS: Twenty patients were recruited, 16 female and four male. Nineteen patients completed sedation and treatment successfully. Mean lowest oxygen saturation was 94%. No patients were over-sedated. All patients successfully used the system to maintain a level of sedation adequate for their comfort. Patient and surgeon satisfaction were consistently high. CONCLUSIONS: Initial experience with this novel system has confirmed safety, patient satisfaction and surgeon satisfaction.
PMID: 12540939, UI: 22428414
Eur J Anaesthesiol 2003 Jan;20(1):74-5
PMID: 12553394, UI: 22440426
Eur J Anaesthesiol 2003 Jan;20(1):72-3
PMID: 12553393, UI: 22440425
Eur J Anaesthesiol 2003 Jan;20(1):65-9
University of Queensland James Cook University, Department of Anaesthesia and Intensive Care, Cairns Base Hospital, The Esplanade, Australia. jbrimacombe@austarnet.com.au
BACKGROUND AND OBJECTIVE: The LMA-ProSeal laryngeal mask airway is a new laryngeal mask airway with a modified cuff and drainage tube. We compared oropharyngeal leak pressure, intracuff pressure and anatomical position (assessed fibreoptically) for the Size 5 LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway in different head-neck positions and using different intracuff inflation volumes. METHODS: Thirty paralysed anaesthetized adult male patients were studied. The LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway were inserted into each patient in random order. The oropharyngeal leak pressure, intracuff pressure, and anatomical position of the airway tube and drainage tube (LMA-ProSeal laryngeal mask airway only) were documented in four head and neck positions (neutral first, then flexion, extension and rotation in random order), and at 0-40 mL cuff volumes in the neutral position in 10 mL increments. RESULTS: Compared with the neutral position, the oropharyngeal leak pressure for both the LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway was higher in flexion and rotation (all P < or = 0.02), but lower in extension (all P < or = 0.01). Changes in head-neck position did not alter the anatomical position of the airway tube or the drainage tube. The oropharyngeal leak pressure was always higher for the LMA-ProSeal laryngeal mask airway (all P < or = 0.005) and anatomical position better for the classic laryngeal mask airway (all P < or = 0.04). CONCLUSIONS: The anatomical position of the LMA-ProSeal and the classic laryngeal mask airway is stable in different head-neck positions, but head-neck flexion and rotation are associated with an increase, and head-neck extension a decrease, in oropharyngeal leak pressure and intracuff pressure. The Size 5 LMA-ProSeal laryngeal mask airway is capable of forming a more effective seal than the Size 5 classic laryngeal mask airway in males.
PMID: 12553391, UI: 22440423
Eur J Anaesthesiol 2003 Jan;20(1):56-60
Dicle University Hospital, Department of Anaesthesiology, Diyarbakir, Turkey. gaturhanoglu@superonline.com
BACKGROUND AND OBJECTIVE: A need exists for a safe and effective oral preanaesthetic medication for use in children undergoing elective surgery. The study sought to define the dose of oral ketamine that would facilitate induction of anaesthesia without causing significant side-effects. METHODS: We studied 80 children undergoing elective surgery under general anaesthesia who received oral ketamine 4, 6 or 8 mg kg(-1) in a prospective, randomized, double-blind placebo controlled study. We compared the reaction to separation from parents, transport to the operating room, the response to intravenous cannula insertion and application of an anaesthetic facemask, the induction of anaesthesia and recovery from anaesthesia. RESULTS: In the group receiving ketamine 8 mg kg(-1), the children were significantly calmer than those of the other groups, and anaesthesia induction was more comfortable. Recovery from anaesthesia was longer in the group receiving ketamine 8 mg kg(-1) compared with the other groups, but no differences between the groups were observed after 2 h in the recovery room. CONCLUSIONS: It is concluded that oral ketamine 8 mg kg(-1) is an effective oral premedication in inpatient children undergoing elective surgery.
PMID: 12553389, UI: 22440421
Eur J Anaesthesiol 2003 Jan;20(1):52-5
University of Wales College of Medicine, Department of Anaesthetics and Intensive Care Medicine, Cardiff, UK.
BACKGROUND AND OBJECTIVE: The application of cricoid force is central to techniques that reduce the risk of gastric regurgitation and the subsequent pulmonary aspiration associated with obstetric and emergency anaesthesia. The discomfort associated with cricoid force in awake preoperative patients increases the incidence of coughing, struggling and pain during induction of anaesthesia. This study determined if increasing the surface area of a cricoid yoke reduced the associated discomfort in volunteers. METHODS: Fifty volunteers participated in a randomized single-blinded study. The cricoid yoke was positioned using standard anatomical landmarks and forces of 10, 20, 30 and 40 N were applied in a random order for 20s, using two different yoke attachments with surface areas of 3 and 10 cm2. A rest of 30s was allowed between the application of forces. Discomfort was graded by volunteers on a scale from 0 to 10 (0: no discomfort; 10: worse discomfort imaginable). A score of 10 was allocated if the volunteers could not tolerate the applied force for 20s. RESULTS: Median scores for the small yoke were always higher than those for the large yoke at each force. There were significant differences between the scores for the small and large yokes at 10 and 20 N (P < 0.001) and 30 N (P = 0.0233), but there was no significant difference at 40 N. CONCLUSIONS: The larger yoke was tolerated better by volunteers when clinically relevant cricoid forces were applied.
PMID: 12553388, UI: 22440420
Eur J Anaesthesiol 2003 Jan;20(1):44-51
Medical School of Hannover, Department of Anaesthesiology, Hannover, Germany. KRaymondos@aol.com
BACKGROUND AND OBJECTIVE: Many anaesthesiologists still interpret haemodynamic responses as signs of insufficient cortical suppression. The aim was to illustrate how haemodynamics may only poorly reflect the level of cortical suppression and that electroencephalographic monitoring could indicate different relationships between cortical effects and haemodynamics. METHODS: Anaesthesia was induced with thiopental (7 mg kg(-1)), and fentanyl (2 microg kg(-1)) with succinylcholine (1.5 mg kg(-1)) for neuromuscular blockade in the 11 patients of Group 1. In Group 2 (n = 15), thiopental (7 mg kg(-1)) and succinylcholine (1.5 mg kg(-1)) were given. In Group 3, the patients (n = 13) received thiopental (7 mg kg(-1)), fentanyl (2 microg kg(-1)) and cisatracurium (0.1 mg kg(-1)), and they were intubated 3 min later than the patients in Groups 1 and 2. We determined conventional electroencephalographic (EEG) variables and classified 14 EEG stages in real-time ranging from A (= 1), indicating full wakefulness, to F1 (= 14), at profound cortical suppression. RESULTS: All groups had profound cortical suppression 45 s after thiopental administration, which rapidly decreased (EEG stage, 11 (6-13) versus 7 (2-13) at 4 min, P < 0.0001). Decreasing EEG stages were associated with increasing SEF 95, relative alpha and beta power and decreasing relative delta power. During tracheal intubation, profound cortical suppression remained unchanged in Groups 1 and 2. In Group 3, cortical suppression had decreased before laryngoscopy (P < 0.005). In Group 2, 11 patients had heart rate responses to tracheal intubation, whereas only two responded in Group 1 (P = 0.015) and three in Group 3 (P = 0.02). Thirteen patients in Group 2 had arterial pressure responses, and five in Group 1 (P = 0.038). Circulatory responses did not differ between Groups 1 and 3. CONCLUSIONS: Electroencephalographic monitoring was suitable to indicate in real-time that haemodynamics only poorly reflect rapidly changing levels of cortical suppression, and how haemodynamics and cortical activity depend on the applied combination of hypnotic and analgesic drugs during anaesthesia induction with thiopental.
PMID: 12553387, UI: 22440419
Eur J Anaesthesiol 2003 Jan;20(1):31-6
Beaumont Hospital, Department of Anaesthesia and Intensive Care, Dublin, Ireland. iohom@hotmail.com
BACKGROUND AND OBJECTIVE: Preoperative bedside screening tests for difficult tracheal intubation may be neither sensitive nor specific enough for clinical use. The aim was to investigate if a combination of the Mallampati classification of the oropharyngeal view with either the thyromental or sternomental distance measurement improved the predictive value. METHODS: A total of 212 (109 male, 103 female) non-obstetric surgical patients, aged >18 yr, undergoing elective surgical procedures requiring tracheal intubation were assessed preoperatively with respect to the oropharyngeal (modified Mallampati) classification, thyromental and sternomental distances. An experienced anaesthetist, blinded to the preoperative airway assessment, performed laryngoscopy and graded the view according to Cormack and Lehane's classification. RESULTS: Twenty tracheal intubations (9%) were difficult as defined by a Cormack and Lehane Grade 3 or 4, or the requirement for a bougie in patients with Cormack and Lehane Grade 2. Used alone, the Mallampati oropharyngeal view, and thyromental and sternomental distances were associated with poor sensitivity, specificity and positive predictive values. Combining the Mallampati Class III or IV with either a thyromental distance <6.5cm or a sternomental distance <12.5cm decreased the sensitivity (from 40 to 25 and 20%, respectively), but maintained a negative predictive value of 93%. The specificity and positive predictive values increased from 89 and 27% respectively for Mallampati alone to 100%. CONCLUSIONS: The findings suggest that the Mallampati classification, in conjunction with measurement of the thyromental and sternomental distances, may be a useful routine screening test for preoperative prediction of difficult tracheal intubation.
PMID: 12553386, UI: 22440417
Eur J Anaesthesiol 2003 Jan;20(1):21-5
Department of Anaesthesia and Critical Care, City Hospital, Lainz, Vienna, Austria. herbert.krenn@chello.at
BACKGROUND AND OBJECTIVE: Ropivacaine used for axillary plexus block provides effective motor and sensory blockade. Varying clinical dosage recommendations exist. Increasing the dosage by increasing the concentration showed no improvement in onset. We compared the behaviour of a constant dose of ropivacaine 150 mg diluted in a 30, 40 or 60 mL injection volume for axillary (brachial) plexus block. METHODS: A prospective, randomized, observer-blinded study on patients undergoing elective hand surgery was conducted in a community hospital. Three groups of patients with a constant dose of ropivacaine 150 mg, diluted in 30,40 or 60 mL NaCl 0.9%, for axillary plexus blockade were compared for onset times of motor and sensory block onset by assessing muscle strength, two-point discrimination and constant-touch sensation. RESULTS: Increasing the injection volume of ropivacaine 150 mg to 60 mL led to a faster onset of motor block, but not of sensory block, in axillary plexus block, compared with 30 or 40 mL volumes of injection. CONCLUSIONS: The data show that the onset of motor, but not of sensory block, is accelerated by increasing the injection volume to 60 mL using ropivacaine 150 mg for axillary plexus block. This may be useful for a more rapid determination of whether the brachial plexus block is effective. However, when performing surgery in the area of the block, sensory block onset seems more important.
PMID: 12553384, UI: 22440415