Anesthesia and analgesia
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Anesthesia and analgesia · Aug 1984
Comparative StudyContrasting effects of halothane, isoflurane, and enflurane on in vivo drug metabolism in the rat.
Inhalational anesthetics might affect perioperative drug elimination by alterations in distribution, hepatic blood flow, or metabolism. The purpose of our study was to investigate the effects of inhalational anesthetics on drug metabolism in vivo during the pre- and postanesthetic periods. The aminopyrine breath test was used as a sensitive non-invasive index of drug metabolism, when the rate of elimination of 14CO2 in the exhaled breath of rats was measured after the intravenous administration of (N-dimethyl-14C) aminopyrine. ⋯ Although isoflurane (1.3%) caused a slight prolongation (P less than 0.05) of aminopyrine half-life 2 hr after anesthesia, this effect had disappeared by 24 hr. Enflurane (1.8%) did not affect aminopyrine elimination. Our results imply that volatile anesthetics may reduce the elimination of drugs given in the perioperative period and that differences may exist among anesthetic agents.
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In order to evaluate the possible physiologic significance of intra- and postoperative hypotension, we monitored arterial blood pressure and heart rate continuously for 36 hr starting the night before and ending the morning after operation in 34 gynecologic patients. The lowest pressures that occurred during physiologic sleep were compared with the lowest arterial pressures that occurred during anesthesia without deliberate hypotension. ⋯ These physiologic nadirs in blood pressure are assumed to be tolerated well by the patient. Intraoperative pressures in elderly patients frequently drifted below sleep-associated levels of blood pressure and may, therefore, constitute physiologically significant hypotension.