Anesthesia and analgesia
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Vecuronium was studied in eight malignant hyperthermia (MH) susceptible pigs for its potential to either trigger or prevent MH. Two sets of experiments were performed in the same animals: 1-hr total neuromuscular blockade by vecuronium infusion with thiopental anesthesia in the absence of invasive monitoring and halothane; and 1-hr infusion of vecuronium with thiopental anesthesia with invasive monitoring in the absence of and then, followed by 30-min infusion in the presence of halothane, followed in turn by exposure to halothane alone. ⋯ In view of the results of control experiments, the development of MH during vecuronium neuromuscular blockade before exposure to halothane was attributed to surgical stress rather than to vecuronium itself. It is concluded that vecuronium is not a trigger to MH in susceptible pigs.
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Anesthesia and analgesia · May 1985
Acid and alkaline solutions of local anesthetics: duration of nerve block and tissue pH.
The effect of solution pH on the duration of rat infraorbital nerve blocks produced by 1% lidocaine or 0.25% bupivacaine at pH 5.0 and 7.4, with and without epinephrine was investigated in a double-blind study. The time course of tissue pH changes subsequent to infections into the infraorbital area or abdominal musculature of rats was measured with a tissue pH microelectrode. Injectable pH had little or no effect upon the duration of block. Tissue pH was minimally changed by the injection of solutions at pH 7.4, but decreased appreciably with injections of solutions at pH 5.0, or if the injectate contained epinephrine.
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Anesthesia and analgesia · Apr 1985
Vecuronium infusion dose requirements during fentanyl and halothane anesthesia in humans.
Steady-state infusion rate requirements of vecuronium were determined in 29 patients during either halothane-nitrous oxide or fentanyl-nitrous oxide anesthesia at different levels of neuromuscular block. During N2O-halothane anesthesia (end-tidal concentration, 0.5%), the infusion rate necessary for a steady-state (defined as unchanging twitch height and infusion rate for at least 20 min) 50% depression of twitch force was 28.8 +/- 5.4 (mean +/- SD) (n = 8) and 47.6 +/- 9.7 micrograms . kg-1 . hr-1 (n = 6) at 90% reduction of twitch force. ⋯ The variances of vecuronium steady-state infusion dose requirements were smaller in the halothane groups than in the fentanyl anesthesia groups. The steady-state vecuronium infusion dose requirements during fentanyl anesthesia were greater than the mean infusion dose requirements during halothane anesthesia at equivalent levels of twitch depression.
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The safety of etomidate for induction of anesthesia in malignant hyperthermia-susceptible (MHS) pigs was evaluated in a two-phase experiment. Two litters of Purebred Poland China pigs, one MHS (n = 4) and the other malignant hyperthermia-resistant (MHR) (n = 4) were used. Phase I compared MHS vs MHR animals in terms of cardiovascular, metabolic, and skeletal muscle rigidity responses to etomidate and fentanyl anesthesia and to a subsequent malignant hyperthermia (MH) challenge with halothane-succinylcholine. ⋯ Heart rate and bicarbonate levels were lower in MHS than in MHR pigs during etomidate infusion. With discontinuation of etomidate and a subsequent challenge with halothane-succinylcholine, all four pigs developed the MH syndrome within 15-30 min. Thiopental replacement of etomidate in the phase II experiment resulted in a twofold greater time (45-75 min) for halothane-succinylcholine to trigger MH in the susceptible pigs.(ABSTRACT TRUNCATED AT 250 WORDS)