Acta Anaesthesiol Scand 2001 Sep;45(8):1036-41
Departments of Anaesthesiology and Intensive Care, and Biometrics, Epidemiology and Statistics, Essen University, Essen, Germany.
[Medline record in process]
BACKGROUND: To define the rocuronium doses which would provide 50%, 90%, and 95% probability of 'acceptable' intubation conditions during light sevoflurane anaesthesia, we studied 60 children aged 2-7 years in a prospective, randomised, assessor blinded study. METHODS: After mask ventilation with 1 MAC sevoflurane/N2O for 17+/-1 (x+/-SD) min we administered rocuronium (either 0.15, 0.22, 0.3, 0.5, or 1.0 mg. kg-1) or placebo, and quantified the evoked force of the adductor pollicis muscle. Intubation conditions were assessed before and 2 min after injection of the test drug. RESULTS: Intubation conditions were improved significantly with rocuronium and scored 'acceptable' in 70%, 90%, and 100% of the children after injection of rocuronium 0.15, 0.22, and 0.3 mg. kg-1, respectively. In parallel, twitch tension decreased to 53% (6-100), 26% (11-100), and 11% (0-19) of baseline (median (range)). Recovery of train-of-four ratio to 0.8 was achieved 13 (7-19), 16 (8-28), and 27 (23-44) min after injection of the respective rocuronium doses. Higher rocuronium doses did not further improve intubation conditions but only prolonged time of neuromuscular recovery. Logistic regression analysis revealed that rocuronium 0.11 (CI 0.05-0.16), 0.21 (0.14-0.28), and 0.25 (0.15-0.34) mg. kg-1 provides a 50%, 90%, and 95% probability of 'acceptable' intubation conditions in children during 1 MAC sevoflurane/N2O anaesthesia, respectively. Furthermore, we calculated that force depression of adductor pollicis muscle to 81% (CI 72-90), 58% (42-74), and 50% (29-71) of baseline is associated with 50%, 90%, and 95% probability of 'acceptable' intubation conditions. CONCLUSIONS: Submaximal depression of muscle force with low dose rocuronium improves intubation conditions in children during light sevoflurane anaesthesia while allowing rapid recovery of neuromuscular function. However, when using low dose rocuronium neuromuscular monitoring may be helpful to detect children with inadequate response to the relaxant so as to avoid an unsuccessful intubation attempt.
PMID: 11576058, UI: 21460052
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Acta Anaesthesiol Scand 2001 Sep;45(8):1032-5
Department of Anaesthesiology, Herlev Hospital, University of Copenhagen, Herlev, Denmark.
BACKGROUND: Clinical malignant hyperthermia (MH) is rare and usually occurs unexpectedly. Prompt diagnosis and correct treatment is crucial for survival of the patient developing fulminant MH. The aims of the present study were to investigate whether anaesthesiologists could make a correct diagnosis of MH and to evaluate their treatment of fulminant MH in a simulator. METHODS: Thirty-two teams (one anaesthesiologist/one nurse anaesthetist) were exposed to an event of clinical MH in a full-scale simulator. Their performance was videotaped for retrospective analysis of the treatment on the basis of the recommendations of the Danish Malignant Hyperthermia Register. RESULTS: All 32 teams asked the surgeon to terminate the surgery as fast as possible, switched off the vaporiser and administered 100% oxygen. Although all intended to hyperventilate the patient, only 14 teams actually managed to perform the hyperventilation. Most problems were found in teams that switched to manual ventilation. All teams treated the patient with dantrolene, and symptomatic treatment was initiated by all even though some elements of the full treatment were lacking, possibly due to the limited time available. CONCLUSION: All teams diagnosed MH in the simulator satisfactorily. The surprising negative finding was that more than half of the participants failed to hyperventilate the "patient" although they intended to do so. This investigation shows that the problem in these teams' treatment of MH was more a question of practical management of the resources than lack of theoretical knowledge.
PMID: 11576057, UI: 21460051
Acta Anaesthesiol Scand 2001 Sep;45(8):945-53
Departments of Anesthesia and Research Computing & Biostatistics, Children's Hospital, Boston, and Departments of Anaesthesia and Radiology, Harvard Medical School, Boston, Massachusetts, USA.
BACKGROUND: Tachyphylaxis to sciatic nerve blockade in rats correlates with hyperalgesia. Spinal inhibition of nitric oxide synthase with NGnitro-L-arginine methyl ester (L-NAME) has been shown to prevent hyperalgesia. Given systemically, L-NAME also prevents tachyphylaxis. The action of L-NAME in preventing tachyphylaxis therefore may be mediated at spinal sites. We compared systemic versus intrathecal potency of L-NAME in modulating tachyphylaxis to sciatic nerve block. METHODS: Rats were prepared with intrathecal catheters. Three sequential sciatic nerve blocks were placed. Duration of block of thermal nocifensive, proprioceptive and motor responses was recorded. We compared spinal versus systemic dose-response to L-NAME, and examined effects of intrathecal arginine on tachyphylaxis. An additional group of rats underwent testing after T10 spinal cord transection. In these rats duration of sciatic nerve block was assessed by determining the heat-induced flexion withdrawal reflex. RESULTS: L-NAME was 25-fold more potent in preventing tachyphylaxis given intrathecally than intraperitoneally. Intrathecal arginine augmented tachyphylaxis. Spinalized rats exhibited tachyphylaxis to sciatic block. CONCLUSION: The increased potency of intrathecal versus systemic L-NAME suggests a spinal site of action in inhibiting tachyphylaxis. Descending pathways are not necessary for the development of tachyphylaxis since it occurs even after T10 spinal cord transection. Thus tachyphylaxis, like hyperalgesia, is mediated at least in part by a spinal site of action.
PMID: 11576044, UI: 21460038
Anaesthesia 2001 Oct;56(10):1021-2
Singapore General Hospital, Singapore 169608.
PMID: 11576139, UI: 21460236
Anaesthesia 2001 Oct;56(10):1020
Princess Royal Hospital, Haywards Heath RH16 4EX, UK wisali@hotmail.com
PMID: 11576137, UI: 21460234
Chelsea and Westminster Hospital, London, UK arjtillyard@hotmail.com
PMID: 11576136, UI: 21460233
Anaesthesia 2001 Oct;56(10):1018-9
City General Hospital, Stoke-on-Trent, UK.
PMID: 11576132, UI: 21460229
Anaesthesia 2001 Oct;56(10):1008-9
Royal Adelaide Hospital, South Australia.
PMID: 11576113, UI: 21460210
Anaesthesia 2001 Oct;56(10):1007-8
Wycombe Hospital, High Wycombe HP11 2TT, UK.
PMID: 11576112, UI: 21460209
Anaesthesia 2001 Oct;56(10):1006-7
Princess of Wales Hospital, Bridgend CF31 1RQ, UK.
PMID: 11576110, UI: 21460207
Anaesthesia 2001 Oct;56(10):1006
Toronto Western Hospital, Toronto, Canada rjsawyer@hotmail.com
PMID: 11576109, UI: 21460206
Anaesthesia 2001 Oct;56(10):965-79
Senior Lecturer, The Department of Anaesthesia and Pain Management, Royal North Shore Hospital, St Leonards, NSW 2065, Australia.
Pharmaceutics is that branch of science concerned with the manufacture and formulation of pharmaceutical products, and is a subject almost exclusively in the domain of pharmacists and those concerned with pharmaceutical manufacture. However, there are some aspects of pharmaceutics that are of particular importance to the anaesthetist, such as the pharmacology of the various preservatives, antimicrobials and other additives found in anaesthetic products, and an understanding of basic processes such as emulsification and lyophylisation. This review aims to survey those areas.
PMID: 11576099, UI: 21460196
Anaesthesia 2001 Oct;56(10):947-952
Professor of Emergency & Critical Care Medicine, Instructor of Emergency & Critical Care Medicine, Assistant Professor of Emergency & Critical Care Medicine, Postgraduate Student of Emergency & Critical Care Medicine, and Assistant Professor of Anaesthesiology, Niigata University Faculty of Medicine 1-757 Asahimachi, Niigata 951-8520, Japan.
[Record supplied by publisher]
We investigated dynamic cerebral autoregulation in 24 normocapnic adult patients during propofol and fentanyl anaesthesia. Hypotension was induced, to a mean arterial pressure (MAP) of 60-65 mmHg, using nitroglycerin or prostaglandin E1. Time-averaged mean cerebral blood flow velocity in the right middle cerebral artery was measured continuously using transcranial Doppler sonography. Dynamic autoregulatory response was activated by a sudden decrease in MAP following release of bilateral thigh cuffs (thigh cuff test) and evaluated as a dynamic rate of autoregulation (dRoR in %.s-1). The cuff test was repeated to obtain two values of dRoR during baseline and during induced hypotension; the data were then averaged. The mean value of dRoR during baseline and during induced hypotension was 14.2 (2.9) and 14.2 (1.6) %.s-1, respectively, in the nitroglycerin group, and 14.6 (2.6) and 14.4 (2.4) %.s-1, in the prostaglandin E1 group. We were unable to demonstrate significant between- or within-group differences in dRoR. Thus, we conclude that nitroglycerin and prostaglandin E1 do not attenuate dynamic cerebral autoregulation.
PMID: 11576096
Anaesthesia 2001 Oct;56(10):933-939
Director, Department of Anaesthesia, and Visiting Thoracic Surgeon, Thoracic Surgery Unit, The Queen Elizabeth Hospital, North Western Adelaide Health Service, 28 Woodville Road, Woodville, South Australia 5011 Registrar, Department of Anaesthesia, St. George Hospital, Sydney, Australia.
By enhancing gaseous uptake from the non-ventilated lung during procedures performed thoracoscopically, the rapid diffusion properties of nitrous oxide would be expected to speed lung collapse and so facilitate surgery. To assess the effect of nitrous oxide on the speed of absorptive lung collapse, a study was conducted using 11 anaesthetised sheep. Speed of collapse was assessed in an indirect manner by recording the time required in a closed-chest situation for the airway pressure distal to a single lung airway occlusion to decrease to - 1.0 kPa. The influence of nitrous oxide was assessed by comparing the time taken for this decrease in airway pressure when the animal was being mechanically ventilated with 50% nitrous oxide in oxygen with the time taken when using 100% oxygen. In all assessments, it was found that the decrease in airway pressure to - 1.0 kPa occurred in a shorter time when nitrous oxide was used. The findings lend support to the hypothesis that during thoracoscopic surgery, mechanical lung ventilation with an oxygen/nitrous oxide mixture will increase the rate of gaseous uptake from the non-ventilated lung and so hasten its absorptive collapse.
PMID: 11576094
Anaesthesia 2001 Aug;56(8):802
Publication Types:
PMID: 11494434, UI: 21384522
Anaesthesia 2001 Aug;56(8):800-2
PMID: 11494427, UI: 21384515
Anaesthesia 2001 Aug;56(8):817-8
PMID: 11494426, UI: 21384514
Anaesthesia 2001 Aug;56(8):811-2
PMID: 11494418, UI: 21384506
Anaesthesia 2001 Aug;56(8):809
PMID: 11493257, UI: 21384501
Anaesthesia 2001 Aug;56(8):790-4
Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
In a randomised, double-blind study, we investigated rapid extension of epidural analgesia to surgical anaesthesia for emergency Caesarean section. Parturients receiving epidural analgesia in labour who subsequently required Caesarean section were given a test dose of 3 ml lidocaine 2% with epinephrine 1 : 200 000, followed 3 min later by 12 ml lidocaine 2% with epinephrine 1 : 200 000 and fentanyl 75 microg, to which was added 1.2 ml sodium bicarbonate 8.4% (bicarbonate group; n = 20) or saline (saline group; n = 20). Mean (SD [range]) time to surgical anaesthesia was less in the bicarbonate group (5.2 (1.5) [2-8] min) than the saline group (9.7 (1.6) [6-12] min; mean difference 4.5 min (95% CI 3.5-5.5) min; p < 0.001). Maternal side-effects and neonatal outcome were similar between groups. We conclude that pH-adjusted lidocaine 2% with epinephrine and fentanyl is effective for rapidly establishing surgical anaesthesia in patients with a functioning epidural catheter for labour who require emergency Caesarean section.
PMID: 11493247, UI: 21384491
Anaesthesia 2001 Aug;56(8):768-71
Department of Respiratory Medicine, James Connolly Memorial Hospital, Dublin 15, Ireland.
A 65-year-old patient undergoing total hip replacement under general anaesthesia suffered acute pulseless electrical activity with a fatal outcome. A kinin-mediated analphylactoid reaction following administration of a polygeline plasma expander (Haemaccel) was implicated by in vitro testing. This case report illustrates the diagnostic difficulties posed by non-histaminoid anaphylactoid reactions and the resistance to epinephrine of kinin-mediated hypotension.
PMID: 11493241, UI: 21384485
Anaesthesia 2001 Aug;56(8):720-8
Anaesthesia Service, Hospital de Clinicas de Porto Alegre, Brazil.
We identified risk factors for postoperative anxiety and quantified their effect on 712 adults between 18 and 60 years of age (ASA I-III physical status) undergoing elective surgery under general anaesthesia, neural blockade or both. The measuring instruments were a structured questionnaire, a pain visual analogue scale, the McGill Pain Questionnaire, the State-Trait Anxiety Inventory, the Montgomery-Asberg Depression Rating Scale, a Self-Reporting Questionnaire-20, and a Self-Perception of Future Questionnaire. Multivariate conditional regression modelling taking into account the hierarchical relationship between risk factors revealed that postoperative anxiety was associated with ASA status III (OR = 1.48), history of smoking (1.62), moderate to intense postoperative pain (OR = 2.62) and high pain rating index (OR = 2.35), minor psychiatric disorders (OR = 1.87), pre-operative state-anxiety (OR = 2.65), and negative future perception (OR = 2.20). Neural block anaesthesia (OR = 0.72), systemic multimodal analgesia (OR = 0.62) and neuroaxial opioids with or without local anaesthesia (OR = 0.63) were found to be protective factors against postoperative anxiety.
PMID: 11493233, UI: 21384477
Anaesthesia 2001 Aug;56(8):717-9
PMID: 11493232, UI: 21384476
Anesth Analg 2001 Oct;93(4):1076-7
Departments of Anesthesiology and Surgery, CHUM Hopital Notre-Dame, Montreal, Quebec, Canada.
IMPLICATIONS: A 68-yr-old man developed a tracheogastric fistula after esophageal resection with gastric interposition. We report the anesthetic management of this patient undergoing tracheal repair and fistula closure.
PMID: 11574387, UI: 21458242
Anesth Analg 2001 Oct;93(4):991-5
Division of Maternal-Fetal-Medicine and Department of Anesthesia, New England Medical Center and Tufts University School of Medicine, Boston, Massachusetts.
Spinal anesthesia for the cesarean delivery of triplets is associated with an increased incidence of maternal hypotension and placental hypoperfusion. We performed a retrospective case series analysis between January 1992 and June 2000 to evaluate the effects of regional anesthetic techniques for cesarean delivery in triplet pregnancies on maternal and neonatal outcome. Spinal and epidural anesthesia were compared with respect to intraoperative hemodynamics and neonatal outcomes. Ninety-six triplet pregnancies were delivered by cesarean section, of which 91 received regional anesthesia. A statistically significant decrease in systolic blood pressure was demonstrated immediately after the induction of spinal as compared with epidural anesthesia. The total volume of IV crystalloid used was significantly larger in the Spinal Anesthesia group. The number of patients receiving more than 15 mg of ephedrine and the cumulative dose of ephedrine was significantly larger in the Spinal group compared with the Epidural group. There were no differences in the rate of perioperative complications between the Spinal and Epidural Anesthesia groups. Neonatal Apgar scores were similar in both groups. The data suggest that both epidural and spinal anesthesia for triplet cesarean delivery are safe techniques, but the latter is associated with a larger initial decrease in systolic blood pressure. This decreasing of systolic blood pressure, however, remained within the physiological range and did not seem to be clinically significant. The need for more crystalloid fluids and ephedrine should be anticipated when spinal anesthesia is used for these cases. IMPLICATIONS: A large retrospective case series of the effects of spinal and epidural anesthesia on maternal hemodynamic profile during cesarean delivery for triplet gestation was performed. Our findings suggest that spinal anesthesia results in outcomes comparable to epidural anesthesia for both mother and newborns.
PMID: 11574371, UI: 21458226
Anesth Analg 2001 Oct;93(4):975-80
Departments of Public Health and Preventive Medicine and Anesthesiology, Louisiana State University School of Medicine, New Orleans, Louisiana.
Nurse anesthesia may be a high-risk occupation for carpal tunnel syndrome (CTS) in the workplace. We designed a cross-sectional investigation to study the prevalence of CTS in nurse anesthetists (NAs) as compared with operating room nurses (ORNs). Two-hundred forty-four female operating room workers were classified by job title as NAs (n = 63) and ORNs (n = 181). The case definition of CTS was established by a history of surgical correction or a combination of four positive historical and physical findings. There were 10 cases of CTS in NAs and 10 cases of CTS in ORNs. The crude odds ratio (OR) for CTS in NAs was 3.23 (95% confidence interval, 1.27-8.17, P = 0.021). The crude OR for left-hand CTS in NAs was also 3.23 and 3.58 for bilateral CTS. When adjusted for nondominant left-hand or bilateral CTS, the OR for CTS in NAs was 3.85. The Yates-corrected chi(2) for CTS in NAs was 5.346 (P = 0.021) and 5.075 (P = 0.024) for nondominant left-hand or bilateral CTS in NAs as compared with ORNs. On the basis of our data analysis, nondominant left-hand CTS and bilateral CTS were significantly more prevalent in NAs than ORNs. IMPLICATIONS: Repetitive stress injuries have now exceeded back injuries as the most commonly reported workplace injuries in the United States. Female nurse anesthetists may face greater occupational risks for developing left hand and bilateral carpal tunnel syndrome than female operating room nurses.
PMID: 11574368, UI: 21458223
Anesth Analg 2001 Oct;93(4):947-53
Department of Anesthesia and Perioperative Care, University of California, San Francisco, California.
Two defining effects of inhaled anesthetics (immobility in the face of noxious stimulation, and absence of memory) correlate with the end-tidal concentrations of the anesthetics. Such defining effects are characterized as MAC (the concentration producing immobility in 50% of patients subjected to a noxious stimulus) and MAC-Awake (the concentration suppressing appropriate response to command in 50% of patients; memory is usually lost at MAC-Awake). If the concentrations are monitored and corrected for the effects of age and temperature, the concentrations may be displayed as multiples of MAC for a standard age, usually 40 yr. This article provides an algorithm that might be used to produce such a display, including provision of an estimate of the effect of nitrous oxide. IMPLICATIONS: Two defining effects of inhaled anesthetics (immobility in the face of noxious stimulation, and absence of memory) correlate with the end-tidal concentrations of the anesthetics. Thus, these defining effects may be monitored and the results displayed if the concentrations are known and corrected for the effects of age and temperature.
PMID: 11574362, UI: 21458217
Anesth Analg 2001 Oct;93(4):934-8
Department of Anesthesia, Nagoya Ekisaikai Hospital, Nagoya, Japan.
Hypothermia after induction of general anesthesia results largely from core-to-peripheral redistribution of body heat. Both central inhibition of tonic thermoregulatory vasoconstriction in arteriovenous shunts and anesthetic-induced arteriolar and venous dilation contribute to this redistribution. Ketamine, unique among anesthetics, increases peripheral arteriolar resistance; in contrast, propofol causes profound venodilation that other anesthetics do not. We therefore tested the hypothesis that induction of anesthesia with ketamine causes less core hypothermia than induction with propofol. Twenty patients undergoing elective surgery were randomly assigned to anesthetic induction with either 1.5 mg/kg ketamine (n = 10) or 2.5 mg/kg propofol (n = 10). Anesthesia in both groups was subsequently maintained with sevoflurane and 60% nitrous oxide in oxygen. Forearm minus finger, skin-temperature gradients <0 degrees C were considered indicative of significant arteriovenous shunt vasodilation. Ketamine did not cause vasodilation just after induction, whereas propofol rapidly induced vasodilation. Core temperatures in the patients given ketamine remained significantly greater than those in the patients induced with propofol. These data suggest that maintaining vasoconstriction during induction of anesthesia reduces the magnitude of redistribution hypothermia. IMPLICATIONS: Core hypothermia during the first hour of anesthesia was less after induction of anesthesia with ketamine than propofol. Maintaining arteriovenous shunt vasoconstriction during induction of anesthesia reduces the magnitude of redistribution hypothermia.
PMID: 11574360, UI: 21458215
Anesth Analg 2001 Oct;93(4):922-7
Department of Anesthesia, University of California, San Francisco, California.
The differences in potencies of optical isomers of anesthetics support the hypothesis that anesthetics act by specific receptor interactions. Diastereoisomerism and geometrical isomerism offer further tests of this hypothesis but have not been explored. They are the subject of this report. We quantified the nonimmobilizing and convulsant properties of the cis and trans diastereomers of the nonimmobilizer 2N (1,2-dichlorohexafluorocyclobutane). Although the lipophilicity of the diastereomers predicts complete anesthesia at the partial pressures applied, neither diastereomer had anesthetic activity alone, and the cis form may have a small (10%) capacity to antagonize anesthesia, as defined by additive effects on the MAC (the minimum alveolar concentration required to suppress movement to a noxious stimulus in 50% of rats) of desflurane. Both diastereomers produced convulsions, the cis form being nearly twice as potent as the trans form: convulsant 50% effective dose (mean +/- SD) was 0.039 +/- 0.009 atmospheres (atm) for the purified cis and 0.064 +/- 0.009 atm for the purified trans isomer. The MAC value for cis-1,2-dichloroethylene equaled 0.0071 +/- 0.0006 atm, and MAC for trans-1,2-dichloroethylene equaled 0.0183 +/- 0.0031 atm. In qualitative accord with the Meyer-Overton hypothesis, the greater cis potency was associated with a greater lipophilicity. However, the product of MAC x solubility differed between the cis and trans isomers by 40%-50%. We conclude that neither the cis nor trans isomers of 2N have anesthetic properties, but isomerism does influence 2N's convulsant properties and the anesthetic properties of dichloroethylene. These isomeric effects may be as useful in defining receptor-anesthetic interactions as those found with optical isomers. IMPLICATIONS: Cis-trans isomerism can influence the convulsant properties of the nonimmobilizer 2N (1,2-dichlorohexafluorocyclobutane) and the anesthetic properties of dichloroethylene. Such isomeric effects may be as useful as those found with optical isomers in defining receptor-anesthetic interactions.
PMID: 11574358, UI: 21458213
Anesth Analg 2001 Oct;93(4):917-21
Department of Anesthesiology and Department of Health Evaluation Sciences, Division of Epidemiology & Biostatistics, University of Virginia, Charlottesville, Virginia.
We compared outpatients transported to the postanesthesia care unit (PACU) while breathing room air to 2-4 L/min nasal cannula oxygen (O(2)) to test the hypothesis that routine supplemental O(2) during transport is not required after general anesthesia in an ambulatory surgery center. We also examined whether the arbitrary arrival PACU O(2) saturations of >92% may be used to predict an infrequent incidence of subsequent significant desaturations (<90%) in the PACU. One-hundred-ninety patients were randomized to receive either room air or 2-4 L/min nasal cannula for transport to PACU after receiving general anesthesia. O(2) saturations were recorded before surgery, just before leaving the operating room, and upon arrival in the PACU. The lowest O(2) saturation occurring in the PACU was also recorded. The mean arrival PACU O(2) saturation was 95.0 in the Room Air group, compared with 97.2 for the Nasal Cannula (NC) group, a statistically significant difference (P < 0.001). In the Room Air group, 20% had arrival O(2) saturations </=92%, and half of these (10%) had O(2) saturations <90%. In the NC group, 6% had O(2) saturations </=92%, of which one third (2%) were <90% on arrival in the PACU. All of these initial desaturations were easily corrected with face-tent O(2) administration, deep breathing, or both. Subgroup analysis revealed that patients whose ages were 60 yr or older or those weighing 100 kg or more had lower arrival room air saturations than their younger or slimmer counterparts. In the Room Air group, only three (3.9%) of the patients that arrived in PACU with O(2) saturations >92% had subsequent desaturations <90%, compared with seven (7.9%) in the NC group. We conclude that most adult patients undergoing ambulatory surgery can be transported safely to the PACU breathing room air after general anesthesia. However, patients whose age was >/=60 yr or weight was >/=100 kg, or for whom transient O(2) desaturation on transport may be harmful, should be transported while breathing nasal O(2) via nasal cannula. IMPLICATIONS: Most adult patients undergoing ambulatory surgery can be transported safely to the PACU breathing room air after general anesthesia. However, patients whose age was >/=60 yr or weight >/=100 kg, or for whom transient O(2) desaturation on transport may be harmful, should be transported while breathing oxygen via nasal cannula.
PMID: 11574357, UI: 21458212
Anesth Analg 2001 Oct;93(4):912-6
Departments of Anesthesia and Psychology, Maisonneuve-Rosemont Hospital and University of Montreal, Montreal, Quebec, Canada.
Ambulatory surgery can create significant anxiety. This prospective study measured whether music can influence anxiety and perioperative sedative requirements in outpatients undergoing surgery with spinal anesthesia. We also evaluated the correlation between two anxiety measures, the State-Trait Anxiety Inventory test (STAI) and the 0- to 10-cm visual analog scale (VAS 0-10), with 0 meaning complete relaxation and 10 the worst feeling of anxiety possible. Fifty unpremedicated patients were randomly assigned to listen to music of their choice via headset during the perioperative period (Group I) or to have no music (Group II). All participants used patient-controlled IV midazolam sedation and underwent repeated evaluations of their anxiety level with the STAI and the VAS 0-10. Midazolam requirements during surgery (Group I, 0.6 +/- 0.7 versus Group II, 1.3 +/- 1.1 mg; P < 0.05) and for the whole perioperative period (Group I, 1.2 +/- 1.3 versus Group II, 2.5 +/- 2.0 mg; P < 0.05) were smaller in patients listening to music. Anxiety levels, measured with STAI or VAS 0-10, were similar in both groups. The Spearman's coefficient values between STAI and VAS 0-10 ranged from 0.532 to 0.687. We conclude that patients listening to music require less midazolam to achieve a similar degree of relaxation as controls and that measures of anxiety obtained from the STAI and the VAS 0-10 are positively, but only moderately, correlated. IMPLICATIONS: It is possible to decrease sedative requirements during surgery under spinal anesthesia by allowing patients to listen to music to reduce their anxiety.
PMID: 11574356, UI: 21458211
Anesth Analg 2001 Oct;93(4):903-5
Department of Anesthesiology, Doernbecher Children's Hospital, Oregon Health Sciences University, Portland, Oregon.
IMPLICATIONS: Tracheoesophageal fistula may be either a congenital lesion or an acquired condition, most often resulting from foreign body ingestion. Location of the lesion has implications for anesthetic management and single lung ventilation may be required to facilitate surgical repair. In pediatric patients, intentional mainstem intubation may be required.
PMID: 11574354, UI: 21458209
Anesth Analg 2001 Oct;93(4):898-902
Pediatric Intensive Care Unit, Pediatric Department, CHUV University Hospital, Lausanne, Switzerland.
Asthmatic children having their tracheas intubated with sevoflurane often have an increase in respiratory system resistance (Rrs). In this randomized, placebo-controlled, double-blinded study, we investigated the protective effect of an inhaled beta(2)-adrenergic agonist. Either salbutamol or placebo was administered 30 to 60 min before anesthesia to 30 mildly to moderately asthmatic children scheduled for elective surgery. Induction was performed with sevoflurane in a mixture of 50% nitrous oxide in oxygen and maintained at 3%, with children breathing spontaneously via a face mask and Jackson-Rees modification of the T-piece. Airway opening pressure and flow were measured before and after insertion of an oral endotracheal tube. Rrs and respiratory system compliance were calculated with multilinear regression analysis. The groups were comparable with respect to age, weight, asthma history, and breathing pattern. Intubation induced a different Rrs response in the two groups: children treated with salbutamol showed a 6.0% (-25.2% to +13.2%) decrease (mean, 95% confidence interval), whereas in the Placebo group there was a 17.7% (+4.4% to +30.9%) increase (P = 0.04). Neither asthma history nor the serum inflammation marker eosinophilic cationic protein was predictive for this response. We conclude that when using sevoflurane in mildly to moderately asthmatic children, a preanesthetic treatment with inhaled salbutamol is protective of an increase in Rrs. IMPLICATIONS: Tracheal intubation with sevoflurane as the sole anesthetic is now often performed in children. It can induce an increase in respiratory system resistance in children with asthma. This study shows that in children with mild to moderate asthma, a preanesthetic treatment with inhaled salbutamol can prevent the increase of respiratory system resistance.
PMID: 11574353, UI: 21458208
Anesth Analg 2001 Oct;93(4):859-64
Departments of Anesthesiology and Research, St. Vincent Mercy Medical Center, Toledo, Ohio.
Cardiac surgery is estimated to cost $27 billion annually in the United States. In an attempt to decrease the costs of cardiac surgery, fast-track programs have become popular. The purpose of this study was to compare the effects of three different opioid techniques for cardiac surgery on postoperative pain, time to extubation, time to intensive care unit discharge, time to hospital discharge, and cost. Ninety adult patients undergoing cardiac surgery were randomized to a fentanyl-based, sufentanil-based, or remifentanil-based anesthetic. Postoperative pain was measured at 30 min after extubation and at 6:30 AM on the first postoperative day. Pain scores at both times were similar in all three groups (P > 0.05). Median ventilator times of 167, 285, and 234 min (P > 0.05), intensive care unit stays of 18.8, 19.8, and 21.5 h (P > 0.05), and hospital stays of 5, 5, and 5 days (P > 0.05) for the Fentanyl, Sufentanil, and Remifentanil groups did not differ. Three patients needed to be tracheally reintubated: two in the Sufentanil group and one in the Fentanyl group. Median anesthetic costs were largest in the Remifentanil group ($140.54 [$113.54-$179.29]) and smallest in the Fentanyl group ($43.33 [$39.36-$56.48]) (P </= 0.01), but hospital costs were similar in the three groups: $7841 (Fentanyl), $5943 (Sufentanil), and $6286 (Remifentanil) (P > 0.05). We conclude that the more expensive but shorter-acting opioids, sufentanil and remifentanil, produced equally rapid extubation, similar stays, and similar costs to fentanyl, indicating that any of these opioids can be recommended for fast-track cardiac surgery. IMPLICATIONS: To conserve resources for cardiac surgery, fentanyl-, sufentanil-, and remifentanil-based anesthetics were compared for duration of mechanical ventilation, intensive care unit length of stay, hospital length of stay, and cost. The shorter-acting anesthetics, sufentanil and remifentanil, produced equally rapid extubation, similar stays, and similar costs to fentanyl; thus, any of these opioids can be recommended for fast-track cardiac surgery.
PMID: 11574346, UI: 21458201
Anesth Analg 2001 Oct;93(4):853-8
Departments of Anesthesia, McMaster University, Hamilton, Ontario, Canada.
Postoperative cardiac morbidity and mortality continue to pose considerable risks to surgical patients. Postoperative epidural analgesia is considered to have beneficial effects on cardiac outcomes. The use in high-risk cardiac patients remains controversial. No study has shown that postoperative epidural analgesia decreases postoperative myocardial infarction (PMI) or death. All studies are underpowered to show such a result, and the cost of conducting a large trial is prohibitive. We performed a metaanalysis to determine whether postoperative epidural analgesia continued for more than 24 h after surgery reduces PMI or in-hospital death. The available databases were searched for randomized controlled trials of epidural analgesia that was extended at least 24 h into the postoperative period. The search yielded 17 studies, of which 11 were randomized controlled trials comprising 1173 patients. Metaanalysis was conducted by using the fixed-effects model, calculating both an odds ratio and a rate difference. Postoperative epidural analgesia resulted in better analgesia for the first 24 h after surgery. The rate of PMI was 6.3%, with lower rates in the Epidural group (rate difference, -3.8%; 95% confidence interval [CI] -7.4%, -0.2%; P = 0.049). The frequency of in-hospital death was 3.3%, with no significant difference between Epidural and Nonepidural groups (rate difference, -1.3%; 95% CI, -3.8%, 1.2%, P = 0.091). Subgroup analysis of postoperative thoracic epidural analgesia showed a significant reduction in PMI in the Epidural group (rate difference, -5.3%; 95% CI, -9.9%, -0.7%; P = 0.04). IMPLICATIONS: Postoperative epidural analgesia, especially thoracic epidural analgesia, continued for more than 24 h reduces postoperative myocardial infarctions.
PMID: 11574345, UI: 21458200
Anesthesiology 2001 Sep;95(3):814
PMID: 11575568, UI: 21459389
Anesthesiology 2001 Sep;95(3):813-4
PMID: 11575567, UI: 21459388
Anesthesiology 2001 Sep;95(3):799-801
Department of Anesthesiology, College of Medicine, University of Florida, Gainesville, USA.
PMID: 11575559, UI: 21459380
Anesthesiology 2001 Sep;95(3):781-8
Department of Anesthesia, University of Pennsylvania School of Medicine, Philadelphia, USA. hansonb@mail.med.upenn.edu
PMID: 11575554, UI: 21459375
Anesthesiology 2001 Sep;95(3):756-65
Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, USA.
BACKGROUND: Volatile anesthetics are known to ameliorate experimental ischemic brain injury. A possible mechanism is inhibition of excitotoxic cascades induced by excessive glutamatergic stimulation. This study examined interactions between volatile anesthetics and excitotoxic stress. METHODS: Primary cortical neuronal-glial cultures were exposed to N-methyl-D-aspartate (NMDA) or glutamate and isoflurane (0.1-3.3 mM), sevoflurane (0.1-2.9 mM), halothane (0.1-2.9 mM), or 10 microM (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine hydrogen maleate (MK-801). Lactate dehydrogenase release was measured 24 h later. In other cultures, effects of volatile anesthetics on Ca++ uptake and mitochondrial membrane potential were determined in the presence or absence of NMDA (0-200 microM). RESULTS: Volatile anesthetics reduced excitotoxin induced lactate dehydrogenase release by up to 52% in a dose-dependent manner. At higher concentrations, this protection was reversed. When corrected for olive oil solubility, the three anesthetics offered equivalent protection. MK-801 provided near-complete protection. Ca++ uptake was proportionally reduced with increasing concentrations of anesthetic but did not account for reversal of protection at higher anesthetic concentrations. Given equivalent NMDA-induced Ca++ loads, cells treated with volatile anesthetic had greater lactate dehydrogenase release than those left untreated. At protective concentrations, volatile anesthetics partially inhibited NMDA-induced mitochondrial membrane depolarization. At higher concentrations, volatile anesthetics alone were sufficient to induce mitochondrial depolarization. CONCLUSIONS: Volatile anesthetics offer similar protection against excitotoxicity, but this protection is substantially less than that provided by selective NMDA receptor antagonism. Peak effects of NMDA receptor antagonism were observed at volatile anesthetic concentrations substantially greater than those used clinically.
PMID: 11575551, UI: 21459372
Anesthesiology 2001 Sep;95(3):734-9
Department of Anesthesiology, Centre Hospitalo-Universitaire Necker-Enfants Malades, Assistance Publique-Hjpitaux de Paris, France. gorlia@club-internet.fr
BACKGROUND: Although neonatal rats have become widely used as experimental laboratory animals, minimum alveolar concentration (MAC) values of volatile anesthetics in rats during postnatal maturation remain unknown. METHODS: We determined MAC values of volatile anesthetics in spontaneously breathing neonatal (2-, 9-, and 30-day-old) and adult Wistar rats exposed to increasing (in 0.1-0.2% steps) concentrations of halothane, isoflurane, or sevoflurane (n = 12-20 in each group), using the tail-clamp technique. MAC and its 95% confidence intervals were calculated using logistic regression and corrected for body temperature (37 degrees C). RESULTS: In adult rats, inspired MAC values corrected at 37 degrees C were as follows: halothane, 0.88% (confidence interval, 0.82-0.93%); isoflurane, 1.12% (1.07-1.18%); and sevoflurane, 1.97% (1.84-2.10%). In 30-day-old rats, the values were as follows: halothane, 1.14% (1.07-1.20%); isoflurane, 1.67% (1.58-1.76%); and sevoflurane, 2.95% (2.75-3.15%). In 9-day-old rats, inspired MAC values were as follows: halothane, 1.68% (1.58-1.78%); isoflurane, 2.34% (2.21-2.47%); and sevoflurane, 3.74% (3.64-3.86%). In 2-day-old rats, inspired MAC values were as follows: halothane, 1.54% (1.44-1.64%); isoflurane, 1.86% (1.72-2.01%); and sevoflurane, 3.28% (3.09-3.47%). CONCLUSION: As postnatal age increases, MAC value significantly increases, reaching the greatest value in 9-day-old rats, and decreases thereafter, and at 30 days is still greater than the adult MAC value.
PMID: 11575548, UI: 21459369
Anesthesiology 2001 Sep;95(3):668-74
Departement d'Anesthesie-Reanimation, Hjpital Antoine Beclere, Clamart France. frederic.mercier@abc.ap-hop-paris.fr
BACKGROUND: Because ephedrine infusion (2 mg/min) does not adequately prevent spinal hypotension during cesarean delivery, the authors investigated whether adding phenylephrine would improve its efficacy. METHODS: Thirty-nine parturients with American Society of Anesthesiologists physical status I-II who were scheduled for cesarean delivery received a crystalloid preload of 15 ml/kg. Spinal anesthesia was performed using 11 mg hyperbaric bupivacaine, 2.5 microg sufentanil, and 0.1 mg morphine. Maternal heart rate and systolic blood pressure were measured at frequent intervals. A vasopressor infusion was started immediately after spinal injection of either 2 mg/min ephedrine plus 10 microg/min phenylephrine or 2 mg/min ephedrine alone. Treatments were assigned randomly in a double-blind fashion. The infusion rate was adjusted according to systolic blood pressure using a predefined algorithm. Hypotension, defined as systolic blood pressure less than 100 mmHg and less than 80% of baseline, was treated with 6 mg ephedrine bolus doses. RESULTS: Hypotension occurred less frequently in the ephedrine-phenylephrine group than in the ephedrine-alone group: 37% versus 75% (P = 0.02). Ephedrine (36+/-16 mg, mean +/- SD) plus 178+/-81 microg phenylephrine was infused in former group, whereas 54+/-18 mg ephedrine was infused in the latter. Median supplemental ephedrine requirements and nausea scores (0-3) were less in the ephedrine-phenylephrine group (0 vs. 12 mg, P = 0.02; and 0 vs. 1.5, P = 0.01, respectively). Umbilical artery pH values were significantly higher in the ephedrine-phenylephrine group than in the group that received ephedrine alone (7.24 vs. 7.19). Apgar scores were similarly good in both groups. CONCLUSION: Phenylephrine added to an infusion of ephedrine halved the incidence of hypotension and increased umbilical cord pH.
PMID: 11575540, UI: 21459361
Anesthesiology 2001 Sep;95(3):627-31
Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA. peter.atanassoff@yale.edu
BACKGROUND: A longer-acting local anesthetic agent, such as ropivacaine, may offer advantages over lidocaine for intravenous regional anesthesia. The objectives of this study were to evaluate whether the findings of volunteer investigations with intravenous regional anesthesia with ropivacaine (which have shown prolonged analgesia after release of the tourniquet) translates into improved pain control after surgery. METHODS: With Human Investigation Committee approval and a double-blind study design, 20 healthy patients with American Society of Anesthesiologists physical status I or II classification who were scheduled to undergo forearm and hand surgery were randomly assigned to administration of 40 ml of either 0.2% ropivacaine or 0.5% lidocaine for intravenous regional anesthesia. Evidence of central nervous system side effects, such as lightheadedness, tinnitus, and metallic taste, as well as cardiac arrhythmias, were evaluated and treated (if necessary) after local anesthetic administration, before and during surgery, and after release of the tourniquet until discharge from the postanesthesia care unit. Regression of sensory anesthesia in the nerve distributions of the forearm and hand was recorded. Verbal numerical pain scores were monitored and quantified until the patients were discharged to home from the postanesthesia care unit. Patient pain scores, side effect profiles, time to first oral intake, and total amount of oral analgesics were recorded 24 h postoperatively. RESULTS: Intravenous regional anesthesia with 0.2% ropivacaine and 0.5% lidocaine provided equivalent levels of surgical anesthesia. After release of the tourniquet, the first evidence for return of sensation in the distribution of the five peripheral nerves occurred later in the ropivacaine group (median, 20 min; range, 15-40 min) than in the lidocaine group (median, 1 min; range, 1-25 min). Verbal numerical pain scores were significantly lower at the time of admission, whereas during the remainder of the postanesthesia care unit stay and later at home, the difference in verbal numerical pain scores between the two groups was no longer statistically significant. CONCLUSIONS: Ropivacaine 0.2% may be an alternative to 0.5% lidocaine for intravenous regional anesthesia in the outpatient surgical setting. Longer-lasting analgesia in the immediate postoperative period may be due to a more profound and prolonged tissue binding effect of ropivacaine.
PMID: 11575533, UI: 21459354
Anesthesiology 2001 Sep;95(3):616-26
Department of Anesthesiology, Academic Medical Center, University of Amsterdam, The Netherlands.
BACKGROUND: To assess the incidence of postoperative nausea and vomiting after total intravenous anesthesia (TIVA) with propofol versus inhalational anesthesia with isoflurane-nitrous oxide, the authors performed a randomized trial in 2,010 unselected surgical patients in a Dutch academic institution. An economic evaluation was also performed. METHODS: Elective inpatients (1,447) and outpatients (563) were randomly assigned to inhalational anesthesia with isoflurane-nitrous oxide or TIVA with propofol-air. Cumulative incidence of postoperative nausea and vomiting was recorded for 72 h by blinded observers. Cost data of anesthetics, antiemetics, disposables, and equipment were collected. Cost differences caused by duration of postanesthesia care unit stay and hospitalization were analyzed. RESULTS: Total intravenous anesthesia reduced the absolute risk of postoperative nausea and vomiting up to 72 h by 15% among inpatients (from 61% to 46%, P < 0.001) and by 18% among outpatients (from 46% to 28%, P < 0.001). This effect was most pronounced in the early postoperative period. The cost of anesthesia was more than three times greater for propofol TIVA. Median duration of stay in the postanesthesia care unit was 135 min after isoflurane versus 115 min after TIVA for inpatients (P < 0.001) and 160 min after isoflurane versus 150 min after TIVA for outpatients (P = 0.039). Duration of hospitalization was equal in both arms. CONCLUSION: Propofol TIVA results in a clinically relevant reduction of postoperative nausea and vomiting compared with isoflurane-nitrous oxide anesthesia (number needed to treat = 6). Both anesthetic techniques were otherwise similar. Anesthesia costs were more than three times greater for propofol TIVA, without economic gains from shorter stay in the postanesthesia care unit
PMID: 11575532, UI: 21459353
Br J Anaesth 2001 May;86(5):738
PMID: 11575360, UI: 21459202
Br J Anaesth 2001 May;86(5):736-7
PMID: 11575358, UI: 21459200
Br J Anaesth 2001 May;86(5):734-5
PMID: 11575356, UI: 21459198
Br J Anaesth 2001 May;86(5):734
PMID: 11575355, UI: 21459197
Br J Anaesth 2001 May;86(5):723-6
Department of Anaesthesia, Leeds General Infirmary, UK.
We describe a new approach to anaesthesia for elective Caesarean section in a woman with Eisenmenger's syndrome. Incremental regional anaesthesia was performed using a microspinal catheter and haemodynamic monitoring included transthoracic bioimpedance cardiography. This approach allowed the disadvantages of general anaesthesia and invasive cardiac output monitoring to be avoided.
PMID: 11575352, UI: 21459194
Br J Anaesth 2001 May;86(5):709-16
Shackleton Department of Anaesthetics, Southampton General Hospital, UK.
PMID: 11575349, UI: 21459191
Br J Anaesth 2001 May;86(5):645-9
St Andrew's Centre for Plastic Surgery and Burns, Broomfield Hospital, Chelmsford, Essex, UK.
Recent evidence has suggested that the rate of uptake of inhalational anaesthetic is constant during maintenance of anaesthesia, contrary to the predictions of multi-compartment uptake models. We measured isoflurane uptake using a totally closed anaesthetic system during up to 10 h of stable anaesthesia for maxillo-facial surgery on 12 adult patients. Liquid isoflurane was injected into the system under computer control to produce an end tidal concentration of 1.3 MAC of isoflurane. Bench tests demonstrated that the leakage from the system was less than 8 microl min(-1), confirming that the rate of injection of isoflurane into the system was a close upper bound on the patients' uptake. Anaesthetic usage for a 70 kg patient was 0.44e(-0.51t)+0.044e(-0.013t)+0.058e(-0.00098t) ml min(-1) of liquid isoflurane, where t is duration of anaesthesia in minutes. There was a continuing reduction in anaesthetic requirement even at the end of the period of study that was statistically significant. These data do not support the notion that isoflurane uptake is constant during stable maintenance of anaesthesia but is compatible with the conventional multi-compartment model of anaesthetic uptake and distribution.
PMID: 11575339, UI: 21459181
Br J Anaesth 2001 May;86(5):639-44
Department of Anaesthetics, Royal Infirmary, Edinburgh, UK.
We assessed change of the pattern of breathing as a marker of induction of anaesthesia, using a method of maintaining spontaneous breathing throughout the induction period. We compared this index with a measure used clinically, the lash reflex, and measures used for drug investigations such as loss of grip of an object, cessation of finger tapping, and loss of arm tone. Ninety female patients (mean age 32 (17-63) yr, mean weight 63 (10) kg) were randomly allocated to induction of anaesthesia using propofol, methohexital, or sevoflurane. The i.v. agents were given by slow injection estimated to give an induction dose (for weight drop end point) in 90 s. Sevoflurane was given by progressively increasing the inhaled concentration to 8% so that induction should occur within 90-120 s. We measured time to change in breathing pattern, loss of voluntary finger tapping, loss of the lash reflex (tested at 15 s intervals), loss of postural tone in an outstretched arm, and loss of grip of a small metal cylinder held between finger and thumb. For methohexital and sevoflurane, the mean times for induction of anaesthesia occurred in the above order. With propofol, the lash reflex and tone were lost at the same time. The mean (SD) time to induction, by loss of arm tone was 64 (16) s for propofol, 83 (23) s for methohexital, and 94 (31) s for sevoflurane. The mean time to change in breathing pattern was 47 (20) s for propofol, 53 (14) s for methohexital, and 78 (29) s for sevoflurane. Although the time to achieve each end point was different, all the end points (except the lash reflex) appeared to provide similar measures of induction of anaesthesia. The pattern of breathing is an early sign of the onset of anaesthesia.
PMID: 11575338, UI: 21459180
Br J Anaesth 2001 May;86(5):627-32
Institute of Anaesthesiology, University Hospital Zurich, Switzerland.
Assessment of the effect of clonidine on depth of anaesthesia is difficult because clonidine combines analgesic, sedative and direct haemodynamic effects. We thus evaluated the influence of clonidine on the bispectral index (BIS) and its potential dose-sparing effect on propofol. After induction of anaesthesia with target-controlled infusion of propofol and obtaining an unchanged bispectral index (pre-BIS), clonidine 4 microg kg(-1) or placebo was administered randomly to 50 patients in a double-blind manner. Subsequently, if there was a decrease in BIS we reduced the target concentration of propofol until pre-BIS was reached. The pre-BIS was maintained and a remifentanil infusion was added during surgery. The courses of the BIS, heart rate and blood pressure were recorded and the total amounts of intra-operative propofol and remifentanil were determined. Assessment of implicit memory during anaesthesia was performed with an auditory implicit memory test consisting of item sequences. Administration of clonidine resulted in a decrease in the BIS from 45 (SD 4) to 40 (6) (P<0.001), which allowed a reduction of propofol target concentration from 3.3 (0.6) to 2.7 (0.7) microg ml(-1) (P<0.001) and measured propofol concentration from 2.9 (0.6) to 2.5 (0.7) kg ml(-1) (P=0.009) in order to maintain the pre-BIS value. During subsequent surgery, propofol requirements were reduced by 20% (P=0.002) in the clonidine group and a similar amount of remifentanil was used in each group. The increase in anaesthetic depth given by clonidine can therefore be measured with bispectral EEG analysis and allows reduction of the propofol dose to achieve a specific depth of anaesthesia.
PMID: 11575336, UI: 21459178
Br J Anaesth 2001 May;86(5):618-26
Department of Anesthesiology, University of California-Irvine Medical Center, Orange 92868, USA.
If the in vivo effects of anaesthesia are mediated through a specific receptor system, then a relationship could exist between the regional changes in brain metabolism caused by a particular agent and the underlying regional distribution of the specific receptors affected by that agent. Positron emission tomography data from volunteers studied while unconscious during propofol (n=8) or isoflurane (n=5) anaesthesia were used retrospectively to explore for evidence of relationships between regional anaesthetic effects on brain glucose metabolism and known (ex vivo) regional distribution patterns of human receptor binding sites. The regional metabolic reductions caused by propofol differed significantly from those of isoflurane. Propofol's reductions negatively correlated most significantly with the regional distribution of [3H]diazepam and [3H]flunitrazepam (benzodiazepine) binding site densities (r=-0.86, P<0.0005; r=-0.79, P<0.005, respectively) and less strongly with [3H]naloxone (opioid) binding density (r=-0.69, P<0.05). Isoflurane's reductions positively correlated only with muscarinic (acetylcholine) binding density (r=0.85, P<0.05). These findings are consistent with the hypothesis that some of propofol's in vivo anaesthetic effects may be mediated through a GABAergic mechanism and suggest some of isoflurane's in vivo effects might involve antagonism of central acetylcholine functioning.
PMID: 11575335, UI: 21459177
Br J Anaesth 2001 May;86(5):607-10
PMID: 11575332, UI: 21459174
Br J Anaesth 2001 Feb;86(2):280-2
Cardiothoracic Unit, Freeman Hospital, Newcastle upon Tyne, UK.
An association between intercostal nerve block and the development of a total spinal is rare. Usually, subarachnoid injection is considered to have followed intraneural placement or inadvertent entrance into a dural cuff extending beyond an intervertebral foramen. We report a patient that followed injection of local anaesthetic into a paravertebral catheter sited at surgery in the thoracic paravertebral space of a patient undergoing thoracotomy. This was a life-threatening event that occurred on two occasions before the definitive diagnosis was made. It is considered likely that the paravertebral catheter entered an intervertebral foramen and the tip perforated the dura.
PMID: 11573676, UI: 21457579
Br J Anaesth 2001 Feb;86(2):254-66
Department of Anaesthetics, Royal Prince Alfred Hospital, Camperdown NSW, Australia.
Sleep disordered breathing is a common problem affecting all age groups, particularly in association with certain other medical conditions and syndromes. The pathological consequences of the disorder may be severe, with significant implications for the perioperative management of sufferers. Research into the effects of surgery and anaesthesia on sleep is very much in its infancy. Understanding of the implications of sleep disturbance and sleep disordered breathing for perioperative morbidity and mortality is limited. While several observations have led to considerable speculation in the literature, evidence of a causal relationship is still largely lacking. Anaesthetists are ideally placed to screen large numbers of people for sleep disordered breathing, a source of considerable community morbidity. Recognizing the symptoms, signs and associations of the condition during the preoperative visit is important in planning management, as is recognition of the likelihood of OSA in patients who present difficulty with tracheal intubation or airway maintenance. Particular care is required in the perioperative management of patients with diagnosed or suspected sleep apnoea.
PMID: 11573670, UI: 21457573
Br J Anaesth 2001 Feb;86(2):245-8
Department of Anaesthesia, Western Infirmary, Glasgow, UK.
A prospective, randomized, double-blind study was performed to investigate whether altering the rate of injection of local anaesthetic through a Whitacre needle had any effect on the spinal block achieved. Twenty patients scheduled for elective urological surgery under spinal anaesthesia received an injection of 3 ml of 0.5% plain bupivacaine either by hand (fast) over 10 s (18 ml min(-1)) or by infusion pump (slow) over 3 min (1 ml min(-1)). All patients were in the sitting position both during insertion of the spinal needle and for 3 min after the start of spinal injection, and they then changed to the supine position. The slow injection group achieved peak sensory block earlier, after a median interval of 20 (95% confidence interval 12.5-30) min vs 30 (22.5-45) min (P<0.05) for the fast group. The level of peak sensory block was similar: T3.5 (T2-T4.5) vs T4 (T1.5-T6.5). The time to lowest mean arterial pressure occurred earlier in the slow group, at 10 (8 to 18) vs 20 (15-31) min (P<0.05). Duration of the motor block was shorter in the slow group: 180 (152-242) vs 270 (225-300). We conclude that a slow spinal injection of plain bupivacaine results in a block of more rapid onset and recovery.
PMID: 11573668, UI: 21457571
Br J Anaesth 2001 Feb;86(2):241-4
University Department of Anaesthesia, Ninewells Hospital and Medical School, Dundee, UK.
Forty patients undergoing spinal anaesthesia for a variety of surgical procedures were randomly allocated to receive 3 ml of ropivacaine 5 mg ml(-1) in glucose 10 mg ml(-1) or 50 mg ml(-1). Onset of sensory block to T10 was significantly faster (P=0.03) with the glucose 50 mg ml(-1) solution (median 5 min, range 2-20 min) than with the 10 mg ml(-1) solution (median 10 min, range 2-25 min). Maximum extent of cephalad spread was virtually the same in both groups (10 mg ml(-1) median T6/7, range T3-T10; 50 mg ml(-1) median T6, range T3-T10) with similar times to regression beyond S2 (10 mg ml(-1) median 210 min, range 150-330 min; 50 mg ml(-1) median 210 min, range 150-330 min). Complete motor block was produced in the majority of patients (10 mg ml(-1) 90%; 50 mg ml(-1) 85%) and the time to complete regression was the same in both groups (median 120 min, range 90-210 min). A block adequate for the projected surgery was achieved in all patients.
PMID: 11573667, UI: 21457570
Br J Anaesth 2001 Feb;86(2):230-5
Department of Anaesthesia and Intensive Care Medicine, St George's Hospital Medical School, London, UK.
It has been suggested that the incidence of early graft occlusion after arterial reconstructive surgery to the leg may be decreased by epidural analgesia. This effect may be mediated by the suppression of the usual cortisol response to surgery, which results in increased circulating plasminogen activator inhibitor-1 with consequent adverse effects on fibrinolysis. To investigate this and other potential mechanisms, 30 patients undergoing arterial reconstructive surgery to the leg were randomized to receive either general anaesthesia or general anaesthesia plus epidural analgesia. Post-operative analgesia was provided by morphine infusion or epidural analgesia, respectively. Blood samples were collected at 0, 2, 4, 6, 12 and 24 h, and 2, 3 and 5 days and analysed for cortisol, plasminogen activator inhibitor-1 antigen, interleukin-6 and beta thromboglobulin. The incidence of graft-related and systemic complications was recorded for 30 days. Only one patient developed early graft occlusion that required embolectomy and eventually amputation. There were no significant changes from control values in either group of patients in circulating cortisol, plasminogen activator inhibitor-1 and beta thrombogobulin (a marker for platelet degranulation). Interleukin-6 values increased significantly in both groups after 4 h and remained elevated until day 3. There were no significant differences between the groups in any variable measured. We conclude that any effect of epidural analgesia on early graft patency is unlikely to be mediated by fibrinolysis or platetlet degranulation.
PMID: 11573665, UI: 21457568
Br J Anaesth 2001 Feb;86(2):217-22
Department of Anaesthesia, University Children's Hospital of Basel, Switzerland.
Chin lift, jaw thrust and these manoeuvres combined with continuous positive airway pressure (CPAP) can be used to improve the patency of the upper airway during general anaesthesia. We used video endoscopy and measurement of stridor to compare the efficacy of these manoeuvres in 24 children (3-10 yr) with adenotonsillar hyperplasia. A bronchofibrescope was passed via the nose while the children were breathing spontaneously, to identify (i) the shortest transverse distance between the tonsils during inspiration and during expiration and (ii) the distance from the tip of the epiglottis to the posterior pharyngeal wall. Chin lift or jaw thrust lifted the epiglottis and, when combined with CPAP (10 cm H2O), there was a significant lateral displacement of the tonsils. Both chin lift plus CPAP and jaw thrust plus CPAP reduced stridor significantly compared with the unsupported condition. In conclusion, in spontaneously breathing children with large tonsils, chin lift plus CPAP is recommended, whereas jaw thrust plus CPAP is no better and may cause post-operative discomfort.
PMID: 11573663, UI: 21457566
Br J Anaesth 2001 Feb;86(2):209-12
Department of Anaesthesiology and Intensive Care, Centre Hospitalo-Universitaire Lyon-Sud, France.
This prospective study was designed to evaluate the correlation between the electroencephalographic bispectral index (BIS) and the hypnotic component of anaesthesia (CA) induced by sevoflurane in 27 children and 27 adult patients. BIS and CA were compared at loss of consciousness (LOC) and on recovery of consciousness (ROC). Mean (SD) BIS decreased significantly at LOC in children and adults from 94 (2.7) to 87.4 (4) and from 96.2 (2) to 86.7 (4.4), respectively, without any difference between groups. Correlation coefficients (p) between BIS and CA at LOC were -0.761 in children and -0.911 in adults. BIS increased significantly at ROC in children and adults from 74.1 (4.2) to 86.7 (2) and from 80.2 (5) to 90.7 (3), respectively, without any difference between groups. Correlation coefficients between BIS and CA in ROC were -0.876 in children and -0.837 in adults. BIS values at ROC were not different from those at LOC in either group. These data demonstrate that BIS correlates with the hypnotic component of anaesthesia induced by sevoflurane in children as well as in adults.
PMID: 11573661, UI: 21457564
Br J Anaesth 2001 Feb;86(2):203-8
Department of Anesthesiology, University of Heidelberg, Germany.
We compared psychomotor recovery after total intravenous anaesthesia (TIVA) with remifentanil/propofol and balanced anaesthesia (BAL) with etomidate/fentanyl/isoflurane in 40 patients, ASA I-III, aged > or =80 yr undergoing elective cataract surgery. Recovery times were recorded and psychomotor recovery was assessed according to simple reaction time, critical flicker fusion frequency (CFF) and short-term memory 30 min, 2 h and 1 day after surgery. Physical characteristics of patients in the two groups (19 in the TIVA group and 21 in the BAL group) were comparable. The TIVA group recovered significantly more quickly. Both groups showed a poorer psychomotor performance 30 min after surgery than at baseline assessment, but simple reaction time and short-term memory were close to baseline values 2 h after surgery. Only performance in the CFF test remained below baseline at this point. No deficits in psychomotor performance were noted on the first day after surgery. We conclude that there is only a minor deficit in psychomotor function in elderly patients 2 h after cataract surgery under general anaesthesia and that psychomotor function recovers completely by 24 h after surgery.
PMID: 11573660, UI: 21457563
Br J Anaesth 2001 Feb;86(2):196-202
Department of Anaesthesia, Hull Royal Infirmary, Kingston upon Hull, UK.
While using the isolated forearm technique, we wished to determine whether patients who did not respond to commands during general anaesthesia with a total intravenous technique (propofol and alfentanil with atracurium) had any evidence of post-operative explicit or implicit memory. Forty women undergoing major gynaecological surgery were randomized, in a double-blind design, to hear two different tapes during surgery. Psychological tests of explicit and implicit memory were conducted within 2 h of surgery. There was no evidence of implicit or explicit memory, nor any recall, in the seven women who responded to commands during surgery. We conclude that during total intravenous anaesthesia with propofol and alfentanil, there is no evidence that learning takes place when anaesthesia is adequate. Furthermore, with this anaesthetic technique, it would seem that--provided any period of patient responsiveness is short and that unconsciousness is induced rapidly again--there is no evidence of implicit or explicit memory.
PMID: 11573659, UI: 21457562
Br J Anaesth 2001 Apr;86(4):599-600
PMID: 11573648, UI: 21457551
Br J Anaesth 2001 Apr;86(4):595-6
PMID: 11573643, UI: 21457546
Br J Anaesth 2001 Apr;86(4):586-9
Department of Anaesthesia, Royal Hallamshire Hospital, Sheffield, UK.
We present an unusual case of hypercapnia and surgical emphysema during transanal endoscopic microsurgery, which led to delayed post-operative ventilatory failure. The hypercapnia and surgical emphysema were secondary to rectal insufflation with carbon dioxide used to facilitate visualization and resection of a rectal tumour. Despite a return to wakefulness after surgery, the patient's level of consciousness deteriorated in the recovery area as a result of hypercapnia. The PaCO2 rose to 16.8 kPa because of absorption of carbon dioxide from the surgical emphysema. On close examination, surgical emphysema was identified in unusual areas, including the anterior abdominal wall, both loins, both groins and the left thigh. Reventilation was required until these unusual carbon dioxide stores had dissipated. We discuss the need for prolonged post-operative vigilance in patients with surgical emphysema secondary to carbon dioxide insufflation, and the risk of delayed ventilatory failure.
PMID: 11573640, UI: 21457543
Br J Anaesth 2001 Apr;86(4):570-2
Department of Anaesthesia, Vancouver General Hospital, University of British Columbia, Vancouver, Canada.
A randomized controlled trial compared recovery characteristics after selective spinal anaesthesia (SSA) or propofol general anaesthesia (GA) for short-duration outpatient laparoscopic surgery. Forty women were randomized to receive either SSA (1% lidocaine 10 mg, sufentanil 10 microg and sterile water 1.8 ml) or GA (propofol and nitrous oxide 50% in oxygen). Compared with the GA group, times to leaving the operating room, performing a straight leg raise, performing deep knee-bends and achieving an Aldrete score >9 and the time in Phase II recovery were significantly shorter (P < 0.05) in the SSA group.
PMID: 11573635, UI: 21457538
Br J Anaesth 2001 Apr;86(4):567-9
Department of Anaesthesia, Northwick Park and St Marks NHS Trust, Harrow, Middlesex UK.
Sixty-two women requesting regional analgesia in labour were allocated to receive a 1.5 ml intrathecal injection as part of a combined spinal-epidural (CSE) analgesic technique. This contained either bupivacaine 2.5 mg plus fentanyl 25 microg (group F) or bupivacaine 2.5 mg plus diamorphine 250 microg (group D). Times of analgesic onset and offset were recorded, motor and proprioceptive assessments made and side-effects noted. Analgesic onset was not significantly different between the groups (group F, 8.0 min; group D, 9.5 min; P = 0.3) but time to first top-up request was significantly longer in the diamorphine group (group F, 73 min; group D, 101 min; P = 0.003). Motor loss, assessed by the modified Bromage score, was statistically but not clinically greater in the fentanyl group (P = 0.01). Maternal hypotension, pruritis, proprioceptive loss, nausea and fetal bradycardia were rare and not severe, and their incidences did not differ between groups. No respiratory depression was observed after CSE. This use of diamorphine was not associated with increased side-effects compared with fentanyl/bupivacaine, and it has a longer duration of action.
PMID: 11573634, UI: 21457537
Br J Anaesth 2001 Apr;86(4):555-64
The National Hospital for Neurology and Neurosurgery, London, UK.
The neurofibromatoses are autosomal dominant diseases that have widespread effects on ectodermal and mesodermal tissue. The commonest member of the group is neurofibromatosis type 1 (NF1) which varies in severity but which can affect all physiological systems. Neurofibromas are the characteristic lesions of the condition and not only occur in the neuraxis but may also be found in the oropharnyx and larynx; these may produce difficulties with laryngoscopy and tracheal intubation. Pulmonary pathology includes pulmonary fibrosis and cystic lung disease. The cardiovascular manifestations of NF1 include hypertension, which may be associated with phaeochromocytoma or renal artery stenosis. Neurofibromas may also affect the gastrointestinal tract and carcinoid tumours may be found in the duodenum. This review documents the aetiology and clinical manifestations of the neurofibromatoses and discusses their relevance to the anaesthetist.
PMID: 11573632, UI: 21457535
Br J Anaesth 2001 Apr;86(4):535-9
Abteilung fur Anasthesie und Intensivmedizin, Kreisklinik Langen, Germany.
We determined the incidence of persistent back pain (PBP) after non-obstetrical spinal anaesthesia (SPA) and investigated factors predisposing to such pain in a prospective 1 yr follow-up study in 245 patients undergoing elective general or trauma surgery (218 patients undergoing single SPA, 27 undergoing two to six SPAs). All patients received a first questionnaire 3 months after the last SPA, and those reporting PBP after 3 months were sent a second questionnaire I year after the operation. Variables were PBP before and within 5 days, at 3 months and I year after SPA, patient satisfaction with SPA, patient characteristics and technical data. Statistical analysis was by contingency tables with Fisher's exact test and an unpaired t-test with logistic regression (P < 0.001 after Bonferroni correction was taken as significant). The response rate in patients who had a single SPA was 56% (122/218). Twenty-three of these 122 patients (18.9%) complained of back pain before SPA compared with 12/122 (10.7%, P = 0.0015) within 5 days after SPA. After 3 months, 15/122 patients (12.3%) reported PBP with 14 complaining of PBP before SPA (P < 0.0001), corresponding to an incidence of new PBP of 1/122 (0.8%). Multiple logistic regression revealed that pre-existing back pain was the only variable associated with PBP after 3 months (P < 0.0001). Patient characteristics and technical factors were not associated with PBP. Nine of the 15 patients with PBP after 3 months returned the second questionnaire: four still reported PBP (three of these had suffered from PBP before SPA). Despite PBP after 3 months, 13/15 patients said they would opt for SPA again. The response rate and results in patients who had had multiple SPAs were similiar to those who had had a single SPA.
PMID: 11573628, UI: 21457531
Br J Anaesth 2001 Apr;86(4):523-7
Division of Anaesthesiology, Geneva University Hospitals, Switzerland.
The bispectral index (BIS) and a sedation score were used to determine and compare the effect of propofol in the presence of fentanyl, alfentanil, remifentanil and sufentanil. Seventy-five non-premedicated patients were assigned randomly into five groups (15 in each) to receive fentanyl, alfentanil, remifentanil, sufentanil or placebo. Opioids were administered using a target-con-trolled infusion device, to obtain the following predicted effect-site concentrations: fentanyl, 1.5 ng ml(-1); alfentanil, 100 ng ml(-1); remifentanil, 6 ng ml(-1); and sufentanil, 0.2 ng ml(-1). After this, a target-controlled infusion of propofol (Diprifusor) was started to increase concentration gradually, to achieve predicted effect-site concentrations of 1, 2, and 4 microg ml(-1). At baseline and at each successive target effect-site concentration of propofol, the BIS, sedation score and haemodynamic variables were recorded. At the moment of loss of consciousness (LOC), the BIS and the effect-site concentration of propofol were noted. The relationship between propofol effect-site concentration and BIS was preserved with or without opioids. In the presence of an opioid, LOC occurred at a lower effect-site concentration of propofol and at a higher BIS50 (i.e. the BIS value associated with 50% probability of LOC), compared with placebo. Although clinically the hypnotic effect of propofol is enhanced by analgesic concentrations of mu-agonist opioids, the BIS does not show this increased hypnotic effect.
PMID: 11573626, UI: 21457529
Br J Anaesth 2001 Apr;86(4):519-22
Department of Neurosurgery, Frenchay Hospital, Bristol, UK
Ocular microtremor (OMT) is a fine high frequency tremor of the eyes caused by extra-ocular muscle activity stimulated by impulses emanating in the brain stem. Several studies have shown that the frequency of this tremor is reduced in patients whose consciousness is reduced by anaesthesia or head injury. Therefore, OMT may possibly be used to determine depth of anaesthesia. Twenty-two unpre-medicated subjects undergoing surgery with general anaesthesia were studied. OMT activity was measured at admission using the open eye piezoelectric strain gauge technique. Anaesthesia was induced with propofol using a target controlled infusion delivery system (Diprifusor). OMT activity was then recorded at predicted plasma propofol concentrations of 1, 2, 3 and 5 microg ml(-1). The patient's level of consciousness (response to command or stimulation) was assessed after each OMT measurement. OMT activity was reduced progressively at predicted plasma concentrations of propofol of I and 2 microg ml(-1) and then plateaued between 3 and 5 microg ml(-1). There was a significant difference between the last awake OMT recording and the first recording at loss of consciousness (P < 0.001). OMT recording holds promise as a practical indicator of the depth of anaesthesia.
PMID: 11573625, UI: 21457528
Br J Anaesth 2001 Apr;86(4):513-8
Wessex Institute for Health Research and Development, University of Southampton, Bassett Crescent East, UK.
We investigated the relationship between the latency of the Nb wave of the auditory evoked response (AER) and periods of awareness during propofol anaesthesia. In the anaesthetic room before cardiac surgery the AER was recorded continuously in 14 patients. Awareness was measured by the ability of the patient to respond to command using the isolated forearm technique (IFT). The Nb latencies were shorter when the patients were able to respond than at loss of response (P<0.001). In six patients who repeated this transition from response to loss of response, there was a high and significant correlation between Nb latencies. None of the patients had any recollection of events after the initial induction of anaesthesia as measured by explicit and implicit memory tests. These results suggest that the Nb latency of the AER may represent an indication of awareness in individual patients, but wide inter-patient variability limits its practical usefulness. In addition, because no evidence of memory was demonstrated, even when patients were known to be awake, the relationship between AER and memory processing remains unclear.
PMID: 11573624, UI: 21457527
Br J Anaesth 2001 Apr;86(4):473-6
PMID: 11573619, UI: 21457522
Br J Anaesth 2001 Jun;86(6):900-1
PMID: 11573611, UI: 21457514
Br J Anaesth 2001 Jun;86(6):899
PMID: 11573609, UI: 21457512
Br J Anaesth 2001 Jun;86(6):893-5
Department of Neurosurgery, Sir Ganga Ram Hospital, Rajinder Nagar, New Delhi, India.
Intracranial subdural haematoma is an exceptionally rare complication of spinal anaesthesia. A 20-yr-old male underwent appendicectomy under partial spinal and subsequent general anaesthesia. A week later, he presented with severe headache and vomiting not responding to bed rest and analgesia. Magnetic resonance imaging showed a small acute subdural haematoma in the right temporo-occipital region. The patient improved without surgical decompression. The pathogenesis of headache and subdural haematoma formation after dural puncture is discussed and the literature briefly reviewed. Severe and prolonged post-dural puncture headache should be regarded as a warning sign of an intracranial complication.
PMID: 11573605, UI: 21457508
Br J Anaesth 2001 Jun;86(6):882-6
Department of Anaesthesiology, Erasmus Medical Centre Rotterdam, The Netherlands.
There are few reports on anaesthesia for patients with Eisenmenger's syndrome requiring non-cardiac surgery and none of the use of xenon. We describe the use of xenon with a closed-circuit system in a patient with Eisenmenger's syndrome having a laparoscopic cholecystectomy.
PMID: 11573602, UI: 21457505
Br J Anaesth 2001 Jun;86(6):876-8
Department of Anaesthesia, Bromley Hospital, Kent, UK.
We have compared the efficacy of adding varying concentrations of hyaluronidase to a standard mixture of 2% lidocaine and 1% ropivacaine to provide peribulbar anaesthesia for cataract surgery. We used (i) the time to adequate anaesthesia for surgery and (ii) ocular and eyelid movement scores at 8 min after block as clinical endpoints. Ninety patients were randomly allocated to receive 7-10 ml of equal volumes of 2% lidocaine and 1% ropivacaine without hyaluronidase or with hyaluronidase 15 IU ml(-1) or 150 IU ml(-1). Median time at which the block was adequate for surgery was 6 min in all groups (interquartile range 4-12 min). Median eyelid movement scores were similar in all groups, but the ocular movement scores at 8 min were significantly lower in the group which received hyaluronidase 150 IU ml(-1) than in the group not given hyaluronidase (P<0.03). There were no differences between groups in the incidence of minor complications. A high concentration of hyaluronidase resulted in a statistically significantly lower ocular movement score at 8 min; the clinical relevance of this finding is uncertain.
PMID: 11573600, UI: 21457503
Br J Anaesth 2001 Jun;86(6):805-7
The standard spinal preparation of bupivacaine contains a high concentration of glucose (80 mg ml(-1)). However, the addition of only a small amount of glucose (8 mg ml(-1)) to plain solutions of bupivacaine results in a solution which, although no more than marginally hyperbaric, produces a more predictable block when used for spinal anaesthesia in non-pregnant patients. However, bupivacaine 5 mg ml(-1) in glucose 8 mg ml(-1) has a density [1.00164 (SD 0.00008) at 37 degrees C] which is relatively greater than that of the cerebrospinal fluid (CSF) of the pregnant patient at term (1.0003 at 37 degrees C) because CSF density decreases during pregnancy. Therefore, a double-blind, randomized, controlled study was carried out to compare intrathecal bupivacaine (glucose 8 mg ml(-1)) with bupivacaine (glucose 80 mg ml(-1)) in 40 pregnant patients at term. Although there was no difference between groups in onset of sensory block, dose of ephedrine or patient satisfaction, patients receiving bupivacaine (5 mg ml(-1)) with glucose (8 mg ml(-1)) had persistently higher sensory blocks between 60 and 120 min after intrathecal injection, suggesting that the spread of spinal solutions in the pregnant patient at term is not dependent on density.
PMID: 11573587, UI: 21457490
Br J Anaesth 2001 Jun;86(6):794-7
Department of Anaesthesiology, University Hospitals, Katholieke Universiteit Leuven, U. Z. Gasthuisberg, Leuven, Belgium.
Oesophageal Doppler monitoring (ODM) has been advocated as a non-invasive means of measuring cardiac output (CO). However, its reliance upon blood flow measurement in the descending aorta to estimate CO is susceptible to error if blood flow is redistributed between the upper and lower body. We hypothesize that lumbar epidural anesthesia (LEA), which causes blood flow redistribution, causes errors in CO estimates. We compared ODM with thermodilution (TD) measurements in fourteen patients under general anaesthesia for radical prostatectomy, who had received an epidural catheter at the intervertebral level L2-L3. Coupled measurements of CO by means of the TD and ODM techniques were performed at baseline (general anaesthetic only) and after epidural administration of 10 ml of 0.25% bupivacaine. The two methods were compared using Bland-Altman analysis: before LEA there was a bias of -0.89 litre min(-1) with limits of agreement ranging between -2.67 and +0.88 litre min(-1). Following lumbar sympathetic block, bias became positive (+0.55 litre min(-1)) and limits of agreement increased to -3.21 and +4.30 litre min(-1). ODM measured a greater increase in CO after LEA (delta=+1.71 (1.19) litre min(-1) (mean (SD)) compared with TD (delta=+0.51 (0.70) litre min(-1)). We conclude that following LEA, measurements with the Oesophageal Doppler Monitor II overestimate CO and show unacceptably high variability. Blood flow redistribution may limit the value of ODM.
PMID: 11573585, UI: 21457488
Br J Anaesth 2001 Jun;86(6):789-93
Sir Humphry Davy Department of Anaesthesia, Bristol Royal Infirmary, UK.
Hypertension is the commonest avoidable medical indication for postponing anaesthesia and surgery. There are no universally accepted guidelines stating the arterial pressure values at which anaesthesia should be postponed. The aim of this study was to determine the extent of variation across the South-West region of the UK in the anaesthetic management of patients presenting with stage 2 or stage 3 hypertension. Each anaesthetist in the region was sent a questionnaire with five imaginary case histories of patients with stage 2 or stage 3 hypertension. They were asked if they would be prepared to provide anaesthesia for each patient. The response rate was 58%. We found great variability between anaesthetists as to which patients would be cancelled. Departmental protocols may aid general practitioners and surgeons in the preparation of patients for surgery, but such protocols may be difficult to agree in the light of such a wide variation in practice.
PMID: 11573584, UI: 21457487
Br J Anaesth 2001 Jun;86(6):777-88
Wellington School of Medicine, New Zealand.
We describe a simple model of cardioventilatory coupling in which a hypothetical inspiratory pacemaker is stimulated by a signal related to cardiac action. At suitable values for the control variables (cardiac signal magnitude, heart rate, inspiratory pacemaker rate and inspiratory rate variability), the model was found to: (1) replicate all clinically described patterns of coupling; (2) predict variations in these described patterns and new patterns which were subsequently found in clinical time series; (3) simulate variations in clinically observed breathing frequency variations associated with each coupling pattern; (4) simulate the clinically observed distribution of coupling patterns between heart rate and breathing frequency; (5) explain the invariability of coupling below a critical heart rate/breathing frequency ratio; and (6) simulate the changes in breathing frequency and transitions between coupling patterns from the heart rate time series of human subjects. Although cardioventilatory coupling causes complex breathing rate irregularities during anaesthesia, these are readily explained by three variables, heart rate, intrinsic breathing frequency, and the strength of their interaction. This simple model, along with clinical observations of cardioventilatory coupling may provide a useful non-invasive method to study the respiratory central pattern generator.
PMID: 11573583, UI: 21457486
Br J Anaesth 2001 Mar;86(3):458-9
PMID: 11573550, UI: 21457453
Br J Anaesth 2001 Mar;86(3):454-5
PMID: 11573544, UI: 21457447
Br J Anaesth 2001 Mar;86(3):435-7
Department of Anaesthesia, Sunderland Royal Hospital and Sunderland Eye Infirmary, UK.
A case study is described of a 7-day-old full term baby with bilateral congenital cataracts who underwent surgical removal of both cataracts 2 days apart. Problems with oxygen saturation during and after the first anaesthetic prompted further investigation that revealed a non-obstructive hypertrophic cardiomyopathy. The significance and possible causes of low oxygen saturation in a previously healthy neonate during anaesthesia are discussed. The likely diagnosis of Sengers syndrome, and the evaluation of asymptomatic babies with cardiac pathology are discussed.
PMID: 11573538, UI: 21457441
Br J Anaesth 2001 Mar;86(3):403-12
Department of Clinical Science, University of Umea, Sweden.
We have evaluated and compared the pharmacokinetic and pharmacodynamic properties of allopregnanolone and pregnanolone at induction of anaesthesia in male rats. A threshold method was used, and the first burst suppression period of 1 s or more in the EEG was selected as the end-point after fairly slow infusions. An optimal dose of 4.0 mg kg(-1) min(-1) was noted for both steroids. Brain concentrations were low at low infusion rates, indicating that acute tolerance was not occurring. Significant positive correlations were noted between dose rate and serum concentrations of allopregnanolone (r = 0.94, P<0.001) and pregnanolone (r = 0.88, P<0.001). Such correlations were also seen in striatum, cerebellum, cortex and muscle for both steroids (P<0.01). Despite changing infusion rates, the concentrations of both steroids in brainstem, hippocampus and fat remained stable. Because no correlation between infusion rate and steroid concentration was noted in the brainstem and hippocampus, these two brain areas may be regarded as primary sites of action for allopregnanolone and pregnanolone. Pregnanolone concentrations in the brainstem and hippocampus were significantly higher than those of allopregnanolone, suggesting that allopregnanolone was more potent than pregnanolone in inducing anaesthesia.
PMID: 11573532, UI: 21457435
Br J Anaesth 2001 Mar;86(3):395-402
Department of Anesthesiology, Nara Medical University, Kashihara, Japan.
The effect of nitrous oxide on myogenic motor evoked potentials (MEPs) after multipulse stimulation is controversial. We investigated the effects of propofol in this paradigm. MEPs were elicited electrically by a single pulse and by trains of three and five pulses in rabbits anaesthetized with ketamine and fentanyl. Nitrous oxide 30-70% was given and MEPs were recorded. After washout of nitrous oxide, propofol was given as a bolus of 10 mg kg(-1) followed by 0.8 (n=9) or 1.6 mg kg(-1) min(-1) (n=8) as a continuous infusion. Nitrous oxide was then re-administered and MEPs were recorded. Without propofol, nitrous oxide significantly reduced the amplitude of MEPs dose-dependently, but this effect was reversed by multipulse stimulation. Administration of low-dose propofol enhanced nitrous oxide-induced suppression, and this effect was reversed by five-pulse stimulation. However, high-dose propofol produced a greater increase in suppression, such that even five-pulse stimulation did not overcome the suppression. The results suggest that the degree of reversal of nitrous oxide-induced MEP suppression produced by multipulse stimulation is affected by the administration of propofol.
PMID: 11573531, UI: 21457434
Br J Anaesth 2001 Mar;86(3):388-94
Academic Unit of Anaesthesia and Intensive Care, University of Aberdeen, Foresterhill, UK.
We investigated the effects of anaesthesia on dynamic nitric oxide production, concentrations of tetrahydrobiopterin and the accumulation of cyclic GMP (cGMP) in the rat central nervous system (CNS). Rats were assigned to anaesthesia with halothane, isoflurane, pentobarbital, diazepam, ketamine or xenon (n=6 per group). After 30 min, [14C]L-arginine (i.v.) was given and, after a further 60 min of anaesthesia, rats were killed and exposed immediately to focused microwave radiation. After removal of the brain and spinal cord, nitric oxide production from radiolabelled arginine (and hence nitric oxide synthase activity during anaesthesia) was measured as [14C]L-citrulline by scintillation counting. cGMP was determined by enzyme immunoassay and tetrahydrobiopterin by fluorescence HPLC, in brain regions and the spinal cord. Nitric oxide synthase activity was similar in all brain regions but was lower in the spinal cord, and was unaffected by anaesthesia. cGMP was similar in all areas of the CNS and was significantly decreased in rats anaesthetized with halothane. Isoflurane produced similar effects. In contrast, ketamine and xenon anaesthesia increased cGMP in the spinal cord, brainstem and hippocampus. Diazepam and pentobarbital had no effect. Tetrahydrobiopterin concentrations were similar in all areas of the CNS and were increased in the cortex and hippocampus after anaesthesia. We have shown profound differential effects of anaesthesia on the nitric oxide pathway in the rat CNS.
PMID: 11573530, UI: 21457433
Br J Anaesth 2001 Mar;86(3):382-7
Departement d'Anaesthesie, CHU d'Angers, France.
This study details all incidents involving medical devices used in anaesthesia and intensive care reported to the relevant authorities in France in 1998. There were 1004 reports during that year. Incidents were classified as serious (harmful to patients) in 11% of cases; death resulted in 2% of cases. Equipment for ventilation and infusion, and monitors of all kinds, accounted for most of the reports, representing 37%, 30% and 12%, respectively, of all reports. The leading causes of failure varied according to the category of device. User errors, quality control problems during production of the device and design faults were the three main causes. The problems identified during the study period enabled the faulty medical devices to be improved in 12-44% of cases. We conclude that post-marketing vigilance is a useful way of improving the quality of medical devices.
PMID: 11573529, UI: 21457432
Br J Anaesth 2001 Mar;86(3):372-6
University Department of Anaesthesia, University Hospitals of Leicester NHS Trust, Leicester General Hospital, UK.
Pre-emptive intramuscular (i.m.) vasopressors were evaluated in 108 patients undergoing elective Caesarean section under spinal anaesthesia, assigned to four groups in a randomized, double-blind, placebo-controlled study. Group 1 received pre-emptive phenylephrine 4 mg i.m., group 2 received phenylephrine 2 mg i.m., group 3 received ephedrine 45 mg i.m., while controls received an i.m. injection of saline, all given immediately after induction of spinal anaesthesia. Hypotension was defined as a 25% decrease in mean arterial pressure (MAP). Rescue intravenous (i.v.) boluses of ephedrine were given if the patient was hypotensive or reported nausea, vomiting or dizziness. The incidence of hypotension was 33% in the phenylephrine 4 mg group compared with 70% in the control and phenylephrine 2 mg groups (P=0.03), and 48% in the ephedrine 45 mg group. The phenylephrine 4 mg and ephedrine 45 mg groups had a significantly lower percentage reduction in MAP (-21 (SD 14)% and -22 (14)%) compared with controls (-32 (18)%, P=0.04). They also had a lower total dose of rescue i.v. ephedrine (15.7 (15.7) mg and 15.8 (15.6) mg) compared with controls (28.8 (20.6) mg, P=0.02). We conclude that pre-emptive i.m. phenylephrine 4 mg and ephedrine 45 mg reduce the severity of hypotension and the total dose of rescue i.v. ephedrine during spinal anaesthesia for Caesarean section.
PMID: 11573527, UI: 21457430
Br J Anaesth 2001 Mar;86(3):366-71
Department of Anaesthesia, The Royal Hospital for Sick Children, Bristol, UK.
We prospectively studied the post-operative recovery profile of 28 ex-premature infants undergoing inguinal herniotomy. All infants had a post-conceptual age of less than 46 weeks at the time of surgery and were randomized to receive either sevoflurane (group 1, 14 patients) or spinal anaesthesia (group 2, 14 patients). All patients received supplemental caudal analgesia before skin incision. Cardiorespiratory function was continuously recorded in all patients before and after surgery. A blinded observer analysed each paired recording for predefined episodes of apnoea, hypoxaemia or bradycardia and the reports were used to compare the two groups. Spinal anaesthesia was attempted unsuccessfully in four patients in group 2. Five patients in group 1 demonstrated an 'excess' number of episodes (median 4, range 3-12) of clinically silent post-operative cardiorespiratory complications. ('Excess' in our study was defined as a 3-fold or greater increase in the number of post-operative episodes of bradycardia or apnoea relative to pre-operative occurrence). Three of these patients had pre-existing abnormal respiratory function and accounted for 80% of the episodes (26/32) of post-operative bradycardia and all five episodes of post-operative apnoea identified. All episodes of bradycardia and apnoea were temporally unrelated. None of the remaining patients in group 2 demonstrated an unacceptable number of post-operative cardiorespiratory complications. Our limited study suggests that general anaesthesia with an inhalational agent such as sevoflurane may induce or unmask abnormalities of cardiopulmonary function in predisposed infants. Spinal anaesthesia may be preferable but it is potentially stressful for the infant and associated with a clinically significant failure rate.
PMID: 11573526, UI: 21457429
Br J Anaesth 2001 Mar;86(3):361-5
Department of Anaesthetics and Intensive Care Medicine, The Queen's University of Belfast, UK.
We have examined the effects on recovery end-points of supplementation of a propofol-based anaesthetic with remifentanil. After induction of anaesthesia with propofol and remifentanil 1.0 microg kg(-1), 15 patients each were randomly allocated to target plasma propofol concentrations of 2, 3, 4 or 5 microg ml(-1) for maintenance of anaesthesia. Remifentanil was administered by infusion for supplementation in doses required for maintenance of adequate anaesthesia. All patients received 50% nitrous oxide in oxygen and ventilation was controlled. The total amount of drugs used and times to different recovery end-points were recorded. Cognitive function was also assessed using a Mini-Mental State questionnaire. The median dose of remifentanil for maintenance of adequate anaesthesia (excluding the initial bolus dose) in the four groups was 0.21, 0.15, 0.11 and 0.13 microg kg(-1) min(-1) respectively (P=0.0026). The median times to eye opening and orientation were shortest in the 2 microg ml(-1) group [6.0 and 6.5 min, 8.5 and 10.8 min, 13.4 and 15.8 min, and 14.2 and 19.5 min respectively in the propofol 2, 3, 4, and 5 microg ml(-1) groups respectively (P<0.001)]. The times to discharge from the recovery ward and the Mini-Mental State scores were not significantly different.
PMID: 11573525, UI: 21457428
Br J Anaesth 2001 Mar;86(3):338-44
Department of Anesthesiology, Fuwai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China.
Volatile anaesthetics are often used during cardiopulmonary bypass (CPB). To understand the kinetics of inhaled anaesthetics during CPB, anaesthetists should understand changes in blood solubility caused by fluid use. We set out to predict the solubility of three volatile anaesthetics, desflurane, isoflurane and halothane, during CPB by determining: (i) their solubility in fresh whole blood and eight CPB priming fluids at 37 degrees C; (ii) the effect of temperature on the solubility of these anaesthetics in lactated Ringer's, gelofusin, banked blood and plasma; (iii) their solubility in different mixtures of these four priming fluids at different temperatures; and (iv) their estimated and actual solubility in blood during hypothermic CPB. We calculated solubility using a concept of volume fraction partition coefficient and compared estimated and measured solubilities. For the three anaesthetics tested, solubilities are in the order: fresh whole blood approximately = plasma > banked blood > normal saline approximately = lactated Ringer's approximately = gelofusin approximately = Haemaccel approximately = hydroxyethyl starch > mannitol. The solubilities of the anaesthetics in all priming fluids increased logarithmically at lower temperatures (P<0.05). The volume-fraction estimates of the partition coefficients were within approximately +/-20% of the measured values for all values of solubility. The corresponding estimates of solubility for CPB blood samples were between -36% and +24% of the measured values. During normothermic CPB, blood solubility of volatile anaesthetics would be unchanged when using plasma, slightly reduced when using banked blood and markedly reduced when using crystalloids and colloids.
PMID: 11573521, UI: 21457424
Eur J Pharmacol 2001 Apr 20;418(1-2):95-104
Department of Physiology and Pharmacology, Division of Pharmacology, Karolinska Institute, S-17177, Stockholm, Sweden. rickard.malmstrom@fyfa.ki.se
The object of the present paper was to investigate the in vivo pharmacological profile of the dihydropyridine neuropeptide Y Y(1) receptor antagonist 1,4-Dihydro-4-[3-[[[[3-[spiro(indene-4,1'-piperidin-1-yl)]propyl]amino]carbonyl]amino]phenyl]-2,6-dimethyl-3,5-pyridine dicarboxylic acid, dimethylester (H 394/84). The renal vasoconstrictor response to neuropeptide Y in anaesthetized rats was dose-dependently antagonized by H 394/84 (ID(50) value=41+/-4 nmol/kg/min), whereas the renal vascular responses to noradrenaline and angiotensin II were only slightly affected by H 394/84 (500 nmol/kg/min). In pigs pretreated with reserpine and transection of sympathetic nerves (depleted of noradrenaline), H 394/84 dose-dependently antagonized renal and femoral vasoconstrictor responses evoked by sympathetic nerve activation (neuronally released neuropeptide Y) and exogenous neuropeptide Y. Significant inhibition was seen already at 1.0 nmol/kg/min, when plasma levels of the antagonist reached 29+/-4 nM. Around 70% of the antagonism remained 90 min after H 394/84 was given. The disposition of H 394/84 fits a biexponential model with initial and terminal half-lives of 2.6 and 48 min, respectively. H 394/84 (100 nmol/kg/min) did not inhibit vascular responses to neuropeptide Y Y(2) receptor-, alpha-adrenoceptor- or purinoceptor-activation in the pig in vivo. It is concluded that H 394/84 is a potent neuropeptide Y Y(1) receptor antagonist with rather long duration of action in vivo. The selectivity and specificity in vivo is more than 100-fold, and H 394/84 antagonizes vascular responses to exogenous and endogenous, neuronally released, neuropeptide Y with similar potency.
PMID: 11334870, UI: 21233249
J Cardiothorac Vasc Anesth 2001 Aug;15(4):477-9
Department of Anaesthesiology, G.B. Pant Hospital, New Delhi, India. tempedeepak@hotmail.com
PMID: 11505354, UI: 21396196
J Cardiothorac Vasc Anesth 2001 Aug;15(4):445-50
Department of Anesthesiology, Klinikum der Stadt Ludwigshafen, Ludwigshafen, Germany.
OBJECTIVE: To compare hemodynamics, time to extubation, and costs of target-controlled infusion (TCI) with manually controlled infusion (MCI) of propofol in high-risk cardiac surgery patients. DESIGN: Prospective, randomized. SETTING: Major community university-affiliated hospital. PARTICIPANTS: Twenty patients undergoing first-time implantation of a cardioverter-defibrillator with severely reduced left ventricular function (left ventricular ejection fraction <30%). INTERVENTIONS: Anesthesia was performed using remifentanil, 0.2 to 0.3 microg/kg/min, and propofol. Propofol was used as TCI (plasma target concentration, 2 to 3 microg x mL; n = 10) or MCI (2.5 to 3.5 mg/kg/hr; n = 10). MEASUREMENTS AND MAIN RESULTS: Hemodynamics were measured at 6 data points: T1, before anesthesia; T2, after intubation; T3, after skin incision; T4, after first defibrillation; T5, after third defibrillation; and T6, after extubation. There were no significant hemodynamic differences between the 2 groups. Dobutamine was required to maintain cardiac index >2 L/min/m(2) in significantly more patients of the TCI group than of the MCI group. Mean dose of propofol was higher in the TCI patients (6.0 +/- 1.0 mg/kg/hr) than in the MCI patients (3.0 +/- 0.4 mg/kg/hr) (p < 0.05), whereas doses of remifentanil did not differ. Time to extubation was significantly shorter in the MCI (11.9 +/- 2.4 min) versus the TCI group (15.6 +/- 6.8 min). Costs were significantly lower in MCI patients (34.73 dollars) than in TCI patients (44.76 dollars). CONCLUSIONS: In patients with severely reduced left ventricular function, TCI and MCI of propofol in combination with remifentanil showed similar hemodynamics. TCI patients needed inotropic support more often than MCI-treated patients. Although extubation time was longer in TCI patients and costs were higher, both anesthesia techniques can be recommended for early extubation after implantation of a cardioverter-defibrillator. Copyright 2001 by W.B. Saunders Company.
PMID: 11505347, UI: 21396189
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