Anesthesia and analgesia
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Anesthesia and analgesia · Apr 1981
Characteristics of succinylcholine-produced phase II neuromuscular block during enflurane, halothane, and fentanyl anesthesia.
The characteristics of phase II neuromuscular block following repeated intravenous injections of succinylcholine (SCh) were determined in 15 adult patients during enflurane, halothane, or fentanyl-nitrous oxide anesthesia. The onset of phase II block (train-of-four ratio (T4) equal to 0.5) occurred following a cumulative SCh dose of 4.4 +/- 0.3 (SEM) mg/kg of enflurane, 5.1 +/- 0.5 mg/kg of halothane, or 6.4 +/- 0.5 mg/kg of fentanyl. The cumulative SCh dose producing phase II block during fentanyl-nitrous oxide anesthesia was significantly greater than during enflurane (p less than 0.01) or halothane (p less than 0.05) anesthesia. ⋯ The transition phase was delayed during fentanyl-nitrous oxide anesthesia, occurring after a cumulative SCh dose of 4 to 7 mg/kg. Following this transition, tachyphylaxis (decreased time between SCh injections) was observed in each study group. The T4 ratio in all three study groups stabilized at 0.15 to 0.25 after 7 to 8 mg/kg.
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Sevoflurane, 3% and 4% in oxygen was administered to four dogs for 3 hours. Sevoflurane was metabolized to inorganic fluoride and hexafluoroisopropanol. Serum fluoride concentrations reached peak values during 2 to 3 hours into anesthesia and averaged 18.5 micrometer/L (n = 2) and 20.0 +/- 4.8 (mean +/- SD) micrometer/L (n = 4) following 3% and 4% sevoflurane exposure, respectively. ⋯ Immediately after anesthesia, observed mean (n = 6) serum fluoride concentrations were 2.9 +/- 0.5 micrometer/L and 2.5 +/- 0.6 micrometer/L, respectively. Hepatic microsomal enzyme induction produced by pretreatment with either phenobarbital or polychlorinated biphenyls (PCBs) resulted in an approximately 5-fold increase in serum fluoride concentrations following anesthesia with sevoflurane when compared to noninduced rats exposed to sevoflurane. A comparison of serum fluoride concentrations between the rat and dog indicates that the amount of sevoflurane metabolized is lower in the rat than in the dog, and the fluoride concentrations observed in both animal species during sevoflurane anesthesia are not expected to produce nephrotoxicity.
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Anesthesia and analgesia · Feb 1981
Randomized Controlled Trial Comparative Study Clinical TrialEarly extubation versus prophylactic ventilation in the high risk patient: a comparison of postoperative management in the prevention of respiratory complications.
To evaluate whether prophylactic ventilation during the early postoperative period diminishes pulmonary complications, 35 high risk, elderly patients undergoing major, elective abdominal aortic reconstruction were prospectively randomized into either an early extubation group or a prophylactic ventilation group. The 17 patients assigned to the prophylactic ventilation group received mechanical ventilation by assist/control mode until 8 a.m. of the first postoperative day. The 17 patients assigned to the early extubation group were extubated after the operation as soon as they could maintain a pH of 7.35, with a spontaneous respiratory rate of less than 30. ⋯ Intrapulmonary shunt and oxygen delivery were not significantly different between the groups at any time during the study period. There was no mortality or significant morbidity in either group. These findings suggest that in high risk surgical patients, prophylactic ventilation, per se, may not diminish respiratory complications or improve gas exchange.