Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1992
Randomized Controlled Trial Comparative Study Clinical TrialA comparative study of 0.25% ropivacaine and 0.25% bupivacaine for brachial plexus block.
The present study compares the effectiveness of 0.25% ropivacaine and 0.25% bupivacaine in 44 patients receiving a subclavian perivascular brachial plexus block for upper extremity surgery. The patients were assigned to two equal groups in this randomized, double-blind study; one group received ropivacaine 0.25% (112.5 mg) and the other, bupivacaine 0.25% (112.5 mg), both without epinephrine. Onset times for analgesia and anesthesia in each of the C-5 through T-1 brachial plexus dermatomes did not differ significantly between the two groups. ⋯ The mean duration of analgesia ranged from 9.2 to 13.0 h, and the mean duration of anesthesia ranged from 5.0 to 10.2 h. Both groups required supplementation with peripheral nerve blocks or general anesthesia in a large number of cases, with 9 of the 22 patients in the bupivacaine group and 8 of the 22 patients in the ropivacaine group requiring supplementation to allow surgery to begin. In view of the frequent need for supplementation noted with both 0.25% ropivacaine and 0.25% bupivacaine, we do not recommend using the 0.25% concentrations of these local anesthetics to provide brachial plexus block.
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Desflurane causes dose-dependent decreases in cerebrovascular resistance and cerebral metabolic rate of oxygen consumption (CMRO2), suggesting that desflurane is a cerebral arteriolar dilator with global flow-metabolism coupling similar to halothane and isoflurane. Desflurane is also similar to isoflurane in that cerebrovascular responsivity to carbon dioxide appears to be maintained. In the dog, arterial hypotension to 40 mm Hg induced with 2.4 MAC desflurane resulted in global decreases in cerebral blood flow of 60% and CMRO2 of 20%. ⋯ The electroencephalographic effects of desflurane are similar to those of isoflurane in humans, and burst suppression is easily achieved. There are no data available concerning possible interactions between desflurane and the outcome of a cerebral ischemic event. Similar to other potent volatile agents, desflurane can cause cerebral vasodilation and may result in intracranial pressure changes in vulnerable patients, but if adequate hyperventilation and depth of anesthesia are maintained, it is probably safe to use desflurane in a manner similar to isoflurane in patients with decreased intracranial compliance.
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Anesthesia and analgesia · Oct 1992
Randomized Controlled Trial Clinical TrialA new approach to intravenous regional anesthesia.
In an attempt to reduce the dose of local anesthetic during intravenous (IV) regional anesthesia of the upper limb, we combined 100 mg of lidocaine with 0.05 mg of fentanyl and 0.5 mg of pancuronium. The study was designed in a randomized, double-blind fashion to determine the efficacy of this approach in providing analgesia and relaxation during surgery and to evaluate its safety after immediate deflation of the tourniquet following IV drug injection. Eighty unpremedicated patients, ASA physical status I or II, were assigned to the following groups: group A (n = 15) received 100 mg of lidocaine diluted in 40 mL of NaCl IV; groups B-D (n = 15 in each group) received 100 mg of lidocaine diluted in NaCl, with the addition of 0.05 mg of fentanyl (group B) or 0.5 mg of pancuronium (group C), or both (group D) to a total volume in all groups of 40 mL. ⋯ The analgesic effect was more profound in group D compared with groups A-C. In group D, 9 of 15 patients had excellent analgesia. In six patients, pain was experienced at the beginning of surgery, but 5 min thereafter patients remained pain free.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Oct 1992
Randomized Controlled Trial Clinical TrialVomiting after alfentanil anesthesia: effect of dosing method.
This double-blind study correlated the association of nausea and vomiting after alfentanil with its method of administration (bolus dose vs continuous infusion). Of 40 women undergoing lower abdominal gynecologic or laparoscopic surgery, 20 received an intravenous alfentanil (30 micrograms/kg) bolus dose for induction of anesthesia, with subsequent bolus doses of 10 micrograms/kg every 10 min, and 20 received the same induction dose delivered over 1 min, followed by an intravenous infusion at 1.0 micrograms.kg-1.min-1. ⋯ Laparoscopy and alfentanil infusion combined synergistically to worsen the incidence of nausea and vomiting. We conclude that alfentanil infusion for laparoscopic surgery entails a high risk for nausea and vomiting.
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Anesthesia and analgesia · Oct 1992
ReviewDesflurane animal and human pharmacology: aspects of kinetics, safety, and MAC.
Substitution of fluorine for the single chlorine atom in isoflurane produces the new anesthetic, desflurane. This seemingly small change produces several pharmacologic changes. The potency of desflurane (MAC equals 6.0% in middle-aged patients) is one-fifth that of isoflurane (1.15%), with MAC for each agent decreased by aging, hypothermia, or the addition of depressants such as midazolam, fentanyl, or nitrous oxide. ⋯ Of great importance, the substitution of fluorine for chlorine markedly decreases blood (desflurane blood-gas partition coefficient 0.42) and tissue solubility (e.g., brain-blood partition coefficient 1.3) relative to isoflurane (values 1.4 and 1.6, respectively). As a result, desflurane alveolar concentrations may be adjusted more rapidly and precisely; desflurane enters and leaves the lungs and tissues more rapidly; and recovery is quicker both for the short (first 10-20 min) and long (0.5-1.5 h) term. This greater precision of control and more rapid recovery are consistent with trends for new drug development in anesthesiology.