Anesthesiology
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Comparative Study
Epidural anesthesia for cesarean section: a comparison of bupivacaine, chloroprocaine, and etidocaine.
The authors studied three groups of patients undergoing elective cesarean section during lumbar epidural anesthesia with bupivacaine, 0.75 per cent (15 patients), chloroprocaine, 3 per cent (15 patients) or etidocaine, 1 per cent (ten patients). Excellent sensory and motor block were obtained with chloroprocaine and bupivacaine; sensory anesthesia was inadequate with etidocaine in most patients. Onset of anesthesia, induction--delivery interval, and stay in the recovery room were all longer with bupivacaine when compared with chloroprocaine. ⋯ At delivery, fetal/maternal concentration ratio of bupivacaine was 0.31 and that of etidocaine, 0.25. The umbilical artery--umbilical vein blood concentration difference for etidocaine was significantly higher than that for bupivacaine. Excellent clinical results were obtained using either bupivacaine, 0.75 per cent, alone, or chloroprocaine, 3 per cent- for induction and maintenance of anesthesia, supplemented with bupivacaine, 0.25 per cent, before removal of the catheter.
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To determine the effect of nitrous oxide on the body's response to venous carbon dioxide (CO2) embolization, the authors compared changes in mean pulmonary arterial pressure (MPAP) following intravenous injections of CO2 in pentobarbital-anesthetized dogs breathing 100 per cent oxygen (O2) or nitrous oxide--oxygen, 79:21 per cent (N2O). When CO2 was infused intravenously in seven dogs at a rate of 3 ml/kg/min the volume of injected CO2 needed to increase MPAP to 40 per cent above control during breathing of O2 was approximately 5.5 times the volume necessary during inhalation of N2O. ⋯ The data suggest that breathing nitrous oxide intensifies and prolongs the effect of CO2 bubbles in blood. While the magnitude of insult following intravenous injection of CO2 is about 6.5 times less than that for a similar volume of air, avoidance of nitrous oxide should be considered in management of patients in whom CO2 embolism is possible.
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Biography Historical Article
Robert Hinckley's "The First Operation with Ether".