Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1984
Halothane-epinephrine arrhythmias and adrenergic responsiveness after chronic imipramine administration in dogs.
The incidence of halothane-epinephrine arrhythmias increases after the short-term administration of imipramine, probably because of enhanced noradrenergic transmission. To determine whether this effect persists after long-term imipramine treatment, we have studied the arrhythmogenicity and adrenergic responsiveness in halothane anesthetized dogs after six weeks of imipramine administration, 150 mg X day-1, orally. The mean (+/- SD) arrhythmogenic dose of epinephrine (ADE) in nine dogs anesthetized with 1.2 MAC halothane was 2.57 (+/- 1.04) micrograms X kg-1 X min-1. ⋯ The dose of isoproterenol that increased heart rate by 75% (beta 75) was 309 +/- 180 ng X kg-1 X min-1. After imipramine treatment, the ADE (2.63 +/- 1.26), alpha 75 (5.16 +/- 2.05), and beta 75 (386 +/- 266) were not statistically different from the pre-imipramine values (P greater than 0.05), despite a fivefold increase in circulating norepinephrine. We conclude that chronic imipramine does not alter arrhythmogenicity and adrenergic responsiveness, since compensatory mechanisms, at the sympathetic nerve terminal, may revert the initial hyper-responsiveness to normal.
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Anesthesia and analgesia · Aug 1984
Continuous epidural infusion of morphine for treatment of pain after thoracic surgery: a new technique.
We evaluated postoperative pain relief and the incidence of side effects of three methods of thoracic epidural analgesia. Ninety patients, divided into three equal groups, received postoperative analgesia after thoracic surgery either as intermittent epidural injections of bupivacaine (25 mg/5 ml, 0.5% solution) as needed, or, intermittent epidural injections of morphine (5 mg/5 ml of normal saline, 0.1% solution) as needed, or continuous epidural infusion of morphine (0.1 mg, in 1 ml of normal saline) per hour supplemented with intravenous morphine (2 mg) upon request. Pain relief was evaluated by each patient on a pain scale visual analogue and by pain relief questionnaire for a period of 72 hr. ⋯ Intermittent epidural injection of morphine relieved pain for 5.8 +/- 2.3 hr/injection and was associated with urinary retention in all patients, with pruritus in 12 patients, and with central narcosis and respiratory depression in 8 patients. Continuous epidural infusion of morphine with occasional intravenous morphine (2 mg) supplementation also effectively relieved postoperative pain and was associated with minimal systemic side effects. One patient complained of pruritus, and two patients developed urinary retention.(ABSTRACT TRUNCATED AT 250 WORDS)
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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.