Anesthesia and analgesia
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Anesthesia and analgesia · Feb 2001
Blockage of one class of potassium channel alters the effectiveness of halothane in a brain circuit of Drosophila.
At concentrations comparable to those used in the clinic, halothane has profound effects on a neuronal pathway devoted to the escape reflex of the fruit fly, Drosophila melanogaster. We studied the influence of the potassium channel that is encoded by the Shaker gene on the halothane sensitivity of this circuit. Shaker channels were specifically inactivated either by genetic means, using strains with two different severe Shaker mutations, or by pharmacologic means, using ingestion of millimolar concentrations of 4-aminopyridine. ⋯ To ensure that the genetic alteration was specific, both mutations were studied as stocks that had been repeatedly backcrossed to a control strain. The specificity of the pharmacologic inhibition was demonstrated by the fact that 4-aminopyridine had no effect on halothane potency in a Shaker mutant. Quantitative differences in the effects of channel inhibition between males and females suggested a sexual dimorphism in the functional brain anatomy of the reflex circuit.
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Anesthesia and analgesia · Feb 2001
Randomized Controlled Trial Comparative Study Clinical TrialLarge-dose oral dextromethorphan as an adjunct to patient-controlled analgesia with morphine after knee surgery.
Dextromethorphan is a weak N-methyl-d-aspartate (NMDA) receptor antagonist that inhibits spinal cord sensitization in animal models of pain and also inhibits the development of cutaneous secondary hyperalgesia after tissue trauma. Perhaps coadministration of an NMDA antagonist with an opioid would lead to better pain relief, particularly with movement and an opioid-sparing effect. This has been shown for ketamine, but previous studies with dextromethorphan that have used small doses have shown only a modest reduction in morphine requirements with no or minimal changes in the postoperative pain experience. ⋯ Dextromethorphan treatment led to a significant but modest reduction in morphine requirements (29.3% P < 0.05) but no reduction in postoperative pain levels. We conclude that increasing orally administered dextromethorphan to near maximum tolerated doses does not provide greater morphine sparing than 20-40 mg given 6-8 hourly as in previous studies. Furthermore we conclude that dextromethorphan does not improve pain scores in a manner expected of a drug with NMDA antagonist properties.
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Anesthesia and analgesia · Feb 2001
Randomized Controlled Trial Clinical TrialTransient neurologic symptoms after spinal anesthesia with lidocaine in obstetric patients.
We investigated the relationship between intrathecal lidocaine and transient neurologic symptoms in the obstetric population because lidocaine spinal anesthetics are commonly used for various obstetric procedures, and little has been reported in this regard from within this population. In this study, 58 ASA physical status I patients presenting for postpartum bilateral tubal ligation under spinal anesthesia were randomized to receive either hyperbaric 5% lidocaine or 0.75% bupivacaine in a double-blinded manner. ⋯ The incidence of transient neurologic symptoms with lidocaine was 3% (95% confidence interval = 0.1%--17.8%) and that with bupivacaine was 7% (95% confidence interval = 0.9%--23.5%), (P = not significant). Symptoms consistent with this syndrome occurred within 24 h without any associated sensory or motor deficits or functional impairment, and resolved within 48 h without any intervention.
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Anesthesia and analgesia · Feb 2001
Randomized Controlled Trial Comparative Study Clinical TrialThe use of esmolol as an alternative to remifentanil during desflurane anesthesia for fast-track outpatient gynecologic laparoscopic surgery.
We compared esmolol and remifentanil infusions with respect to their effect on intraoperative hemodynamic stability and early recovery after outpatient laparoscopic surgery when administered as IV adjuvants during desflurane anesthesia. After premedication with midazolam 2 mg IV, anesthesia was induced with propofol 2 mg. kg(-1) IV in combination with either esmolol 1 mg. kg(-1) IV (n = 27) or remifentanil 1 microg. kg(-1) IV (n = 26) and succinylcholine 1 mg. kg(-1) IV according to a randomized, double-blinded protocol. Anesthesia was initially maintained with desflurane 2.5% (subsequently titrated to maintain an electroencephalogram-bispectral index value of 60) and nitrous oxide 65% in oxygen. ⋯ Both drugs were associated with frequent "postanesthesia care unit bypass" rates (78-81%), short times to "home readiness" (119-120 min), excellent patient satisfaction (81-85%), and rapid resumption of normal activities (2.6-3.2 d). Fast-tracked patients were ready for discharge home significantly earlier (112 +/- 46 vs 151 +/- 50 min). We concluded that esmolol infusion is an acceptable alternative to remifentanil infusion for maintaining hemodynamic stability during desflurane-based fast-track anesthesia for outpatient gynecologic laparoscopic surgery.