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Impact of peripheral elimination on the concentration-effect relationship of remifentanil in anaesthetized dogs.
Kabbaj M, Vachon P, Varin F.
Faculte de Pharmacie and Faculte de Medecine Veterinaire, Universite de Montreal, Montreal, Quebec, Canada.
BACKGROUND: This study elucidates the impact of sampling site when estimating pharmacokinetic-pharmacodynamic (PK-PD) parameters of drugs such as remifentanil that undergo tissue extraction in the biophase. The interrelationship between the concentrations of remifentanil predicted for the effect compartment and those measured in arterial, venous, and cerebrospinal fluid were investigated under steady-state conditions. METHODS: Following induction of anaesthesia with pentobarbital, an arterial cannula (femoral) and two venous catheters (jugular and femoral) were inserted. Electrodes were placed for EEG recording of theta wave activity. Each dog received two consecutive 5-min infusions for the PK-PD study and a bolus followed by a 60-min infusion was started for the steady-state study. Cerebrospinal fluid, arterial and venous blood samples were drawn simultaneously after 30, 40, and 50 min. At the end of the infusion, arterial blood samples were collected for pharmacokinetic analysis. RESULTS: Remifentanil PK-PD parameters based on theta wave activity were as follows: apparent volume of distribution at steady-state (V(ss)) (231+/-37 ml kg(-1)), total body clearance (Cl) (63+/-16 ml min(-1) kg(-1)), terminal elimination half-life (t(1/2beta)) (7.71 min), effect compartment concentration at 50% of maximal observed effect (EC(50)) (21+/-13 ng ml(-1)), and equilibration rate constant between plasma and effect compartment (k(e0)) (0.48+/-0.24 min). The mean steady-state cerebrospinal fluid concentration of 236 ng ml(-1) represented 52 and 74% of that in arterial and venous blood, respectively. CONCLUSIONS: Our study re-emphasizes the importance of a sampling site when performing PK-PD modelling for drugs undergoing elimination from the effect compartment. For a drug undergoing tissue elimination such as remifentanil, venous rather than arterial concentrations will reflect more exactly the effect compartment concentrations, under steady-state conditions.
PMID: 15653707 [PubMed - as supplied by publisher]
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Burns and tracheo-oesophageal-cutaneous fistula.
Eipe N, Pillai AD, Choudhrie R.
Department of Anaesthesia, Padhar Hospital, Betul, Madhya Pradesh-460005, India. neipe@yahoo.com
We report an unusual case of electric burns suffered by a 15-yr-old boy. The patient's neck had come in contact with a high voltage broken electric wire and by reflex he had pulled it away with his right hand. He presented with a tracheo-cutaneous fistula with a right-sided pneumothorax. Emergency airway management included insertion of a tracheostomy tube through the traumatic opening in the neck and insertion of an intercostal tube drain. When the diagnostic endoscopy revealed an externally communicating tracheo-oesophageal fistula, protecting the lower airways from gastrointestinal contamination became a priority. The patient was anaesthetized through the traumatic tracheostomy and a formal low tracheostomy was done below the level of the fistula. The patient then underwent oesophageal reconstruction with a stomach free flap. Tracheo-oesophageal-cutaneous fistula is a rare presentation of electric burns. The anaesthetic management of the emergency difficult airway in any penetrating neck injury can be extremely difficult requiring a carefully planned multi-disciplinary approach.
Publication Types:
PMID: 15516357 [PubMed - indexed for MEDLINE]
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Mortality analysis in hip fracture patients: implications for design of future outcome trials.
Foss NB, Kehlet H.
Department of Anaesthesia and Orthopaedic Surgery, Hvidovre University Hospital, Copenhagen DK-2650, Denmark. nicolai.bang.foss@hh.hosp.dk
INTRODUCTION: Patients with hip fractures are usually frail and elderly with a 30-day mortality in excess of 10% in European series. Perioperative morbidity is often multifactorial in nature, and unimodal interventions will not necessarily decrease mortality. The purpose of this prospective study was to analyse causes of mortality, and thereby the potential and limitations to decrease mortality after hip fracture surgery. METHODS: 300 consecutive, unselected hip fracture patients were treated in a multimodal rehabilitation programme with continuous perioperative epidural analgesia and anaesthesia, early surgery, standardized fluid and transfusion therapy, enforced oral nutrition and early mobilization and physiotherapy. All deaths within 30 days of surgery or during primary hospitalization were analysed and classified according to whether death was unavoidable, probably unavoidable, or potentially avoidable. RESULTS: Thirty-day mortality was 13.3% (40 patients) and the total perioperative mortality was 15.6% (47 patients). Death was definitely unavoidable in 28%, probably unavoidable in 15%, and in theory potentially avoidable in 57%. In the patients where death was potentially avoidable, active care was curtailed in 16 of 27 (59%) patients. CONCLUSION: About a quarter of the total mortality in hip fracture patients is definitely unavoidable, and death is probably only avoidable in about half of the unselected patients. These results have important implications for the design of future outcome studies, which should focus on other relevant outcomes than mortality per se.
PMID: 15516350 [PubMed - indexed for MEDLINE]
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Experience with the Arndt paediatric bronchial blocker.
Wald SH, Mahajan A, Kaplan MB, Atkinson JB.
Departments of Anesthesiology and Surgery at the David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA. swald@mednet.ucla.edu
Previously reported techniques for single lung ventilation in children have failed to provide consistent, single lung ventilation with relative ease and reliability. We report our experience with the use of a new device, the Arndt 5 French (Fr) paediatric endobronchial blocker, for single lung ventilation in a series of 24 children. We were able to achieve single lung ventilation in 23 of the 24 patients (aged 2-16 yr). Placement required approximately 5-15 min. Attempts at placement were aborted in one patient who was unable to tolerate even short periods of apnoea because of lung pathology. Although it has some limitations, our experience suggests that the paediatric bronchial blocker can be used as a consistent, safe method of single lung ventilation in most young children.
Publication Types:
PMID: 15486004 [PubMed - indexed for MEDLINE]
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Appropriate placement of intubation depth marks in a new cuffed paediatric tracheal tube.
Weiss M, Gerber AC, Dullenkopf A.
Department of Anaesthesia, University Children's Hospital Zurich, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland. markus.weiss@kispi.unizh.ch
BACKGROUND: The aim of this study was to evaluate the appropriateness of intubation depth marks on the new Microcuff paediatric tracheal tube. METHODS: With local Institutional Ethics Committee approval and informed parental consent, we included patients from birth (weighing > or =3 kg) to 16 yr who were undergoing general anaesthesia requiring orotracheal intubation. Tracheal intubation was performed using direct laryngoscopy, the intubation depth mark was placed between the vocal cords, and the tube was taped to the lateral corner of the mouth. The distance between the tube tip and the tracheal carina was assessed by flexible bronchoscopy with the patients in supine, and their head in neutral positions. Tube sizes were selected according to the formula: internal diameter (ID; mm)=(age/4)+3.5 in children > or =2 yr. In full-term newborns (> or =3 kg) to less than 1 yr ID 3.0 mm tubes were used and in children from 1 to less than 2 yr ID 3.5 mm tubes were used. Endoscopic examination was performed in 50 size ID 3.0 mm tubes, and in 25 tubes of each tube size from ID 3.5 to 7.0 mm. Tracheal length and percentage of the trachea to which the tube tip was advanced were calculated. RESULTS: 250 patients were studied (105 girls, 145 boys). The distance from the tube tip to the carina ranged from 1.4 cm in a 2-month-old infant (ID 3.0 mm) to 7.7 cm in a 14-yr-old boy (ID 7.0 mm). Mean tube insertion into the trachea was 53.2% (6.3) of tracheal length with a minimum of 40% and a maximum of 67.6%. CONCLUSIONS: The insertion depth marks of the new Microcuff paediatric tracheal tube allow adequate placing of the tracheal tube with a cuff-free subglottic zone and without the risk for endobronchial intubation in children from birth to adolescence.
Publication Types:
PMID: 15486002 [PubMed - indexed for MEDLINE]
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