Anesthesia and analgesia
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Anesthesia and analgesia · Jun 1991
Randomized Controlled Trial Clinical TrialPrevention of postoperative nausea and vomiting using ondansetron, a new, selective, 5-HT3 receptor antagonist.
The effect of ondansetron, a 5-HT3 antagonist, in preventing postoperative nausea and vomiting was investigated in a randomized, double-blind, placebo-controlled study of 84 patients undergoing gynecologic operation and receiving the same general anesthetic. The patients received premedication with either 16 mg oral ondansetron, or a matching placebo. The same medication was given postoperatively 8 h after the first dose. ⋯ In the ondansetron group nausea and vomiting developed in 17% and 12%, respectively, values significantly different from those with placebos (P less than 0.005). Similar differences were observed throughout the entire 24-h period after recovery, the incidence of nausea and vomiting being 67% and 60%, respectively, in the placebo group and 29% and 26% in the ondansetron treatment group. Ondansetron appears to be a promising antiemetic for the prevention of postoperative nausea and vomiting.
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Anesthesia and analgesia · Jun 1991
Cerebral hemodynamics in neonates and infants undergoing cardiopulmonary bypass and profound hypothermic circulatory arrest: assessment by transcranial Doppler sonography.
Profound hypothermic circulatory arrest (PHCA) is followed by a transient period of increased intracranial pressure and a longer period of neurophysiologic dysfunction. To investigate the effect of cardiopulmonary bypass (CPB) with PHCA on cerebral hemodynamics, we used transcranial Doppler sonography to measure cerebral blood flow velocity in 10 neonates and infants before and after PHCA. ⋯ During normothermic CPB after PHCA, the modified cerebral vascular resistance (mm Hg.cm.s-1) was increased above values for normothermic CPB before PHCA (P less than 0.05). The results of this study suggest that the observed increase in intracranial pressure during PHCA is not caused by increased cerebral perfusion, but rather that cerebral perfusion is reduced in response to a decreased demand for cerebral metabolic oxygen.
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Anesthesia and analgesia · Jun 1991
Effect of pH of bupivacaine on duration of repeated sciatic nerve blocks in the albino rat. Local Anesthetics for Neuralgia Study Group.
Tachyphylaxis has been ascribed to tissue acidification after repeated injections of acidic local anesthetic solutions. We studied the effect of pH on the duration of action of bupivacaine to determine the validity of this proposed mechanism of tachyphylaxis by injecting bupivacaine solutions adjusted to pH 4.2 or 6.8 into a surgically implanted system created to permit in vivo irrigation of rat sciatic nerves with local anesthetic. Tachyphylaxis developed at both pH values. The results fail to support the acidification hypothesis as there was no statistically significant effect of a 400-fold difference in hydrogen ion concentration on the development of tachyphylaxis or the duration of motor dysfunction.