Anesthesiology
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Comparative Study
Effect of Bay K 8644 on the magnitude of isoflurane and halothane contracture of skeletal muscle from patients susceptible to malignant hyperthermia.
Isoflurane has a lesser ability than halothane to induce contracture in malignant hyperthermia (MH) muscle in vitro. This does not necessarily imply that isoflurane is not as potent an MH trigger as halothane in vivo. A hypothesis was tested that in vitro treatment with Bay K 8644, an activator of both the dihydropyridine receptors as well as the sodium channels of the T-tubules, potentiates isoflurane-induced MH-susceptible skeletal muscle contracture. ⋯ Bay K 8644 did not induce muscle contracture on its own but consistently enhanced both the 0.5 MAC isoflurane and halothane to the same maximal isometric tension (1.09 +/- 0.35 g and 1.11 +/- 0.37 g, respectively). Such an effect was not observed in the MH-nonsusceptible group. Under the conditions of this in vitro study, 0.5 MAC isoflurane appears to be as potent as halothane in inducing muscle contracture in skeletal muscle bundles from individuals susceptible to MH.
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Human error is believed to contribute to the majority of negative anesthesia outcomes. Because retrospective analysis of critical incidents has several shortcomings and prospective studies are limited by the low frequency of critical incidents, an anesthesia simulator was used to evaluate the management of simulated emergency situations by ten anesthesia residents, ten faculty anesthesiologists, and ten anesthesiologists in private practice in order to identify specific patterns of errors in diagnosis and treatment. The simulator is a computer program that presents the patient, monitors, and management choices in a graphical display on an IBM or compatible personal computer. ⋯ Fixation errors or failure to revise a plan in the presence of inconsistent cues were made by 63% of subjects. The subjects that gathered more information during simulated anaphylaxis made the correct diagnosis more often and made fewer treatment errors. The time since the last ACLS training was found to be an important predictor of correct management of simulated cardiac arrest.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
Subhypnotic doses of propofol relieve pruritus induced by epidural and intrathecal morphine.
We investigated the efficacy of subhypnotic doses of propofol for spinal morphine-induced pruritus in a prospective, randomized, double-blind, placebo-controlled study. Fifty patients, ASA physical status 1-3, with spinal morphine-induced pruritus were allocated to receive either 1 ml propofol (10 mg) or 1 ml placebo (Intralipid) intravenously after gynecologic, orthopedic, thoracic, or gastrointestinal surgery. In the absence of a positive response, a second drug treatment was given 5 min later. ⋯ The beneficial effect of treatment was longer than 60 min in 85% of patients in the propofol group and in 100% of the controls (not significant). These results suggest that propofol in a subhypnotic dose is an efficient drug treatment for spinal morphine-induced pruritus. At the dose administered (10 mg), side effects were rare and minor.
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Randomized Controlled Trial Clinical Trial
Anesthesia for laparoscopic cholecystectomy. Is nitrous oxide contraindicated?
Since it has been suggested that the use of nitrous oxide (N2O) may contribute to bowel distention, we evaluated the effects of N2O on operating conditions during laparoscopic cholecystectomy in 50 healthy patients using a double-blind protocol design. All patients received the same preanesthetic medication (midazolam, 2 mg intravenously) and induction of anesthesia consisted of intravenously administered fentanyl 1.5 micrograms.kg-1, thiopental 4-6 mg.kg-1, and a nondepolarizing muscle relaxant. For maintenance of anesthesia, patients were randomly assigned to one of two treatment groups: group 1 (n = 26) received isoflurane with 70% N2O in oxygen (O2), whereas group 2 (n = 24) received isoflurane in an air/O2 mixture. ⋯ Finally, the incidence of postoperative nausea and vomiting was similar in both treatment groups. The surgeon was able to correctly determine that N2O had been administered only 44% of the time. Thus, N2O had no clinically apparent deleterious effects during laparoscopic cholecystectomy.
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Randomized Controlled Trial Clinical Trial
The use of oral mexiletine for the treatment of pain after peripheral nerve injury.
Neuropathic pain is often a difficult condition to treat. Clinical and laboratory studies using intravenously administered local anesthetics or antiarrhythmic agents support the use of these drugs for the treatment of neuropathic pain. The availability of the oral antiarrhythmic medication, mexiletine, has made it possible to study the effects of an orally administered medication on chronic neuropathic pain. ⋯ Median pain scores prior to mexiletine were 7, after placebo treatment 7, and while receiving mexiletine (750 mg/day) 4. Side effects were mild and well-tolerated. Mexiletine may be effective in reducing neuropathic pain for patients in whom alternative pain medications have been unsatisfactory.