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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This prospective study was performed to determine whether anesthesia clinicians (i.e., both anesthesiologists and nurse anesthetists) can identify operating room alarms by their distinctive sounds and to identify factors related to alarm recognition accuracy. Nineteen alarms from 15 commonly used devices were recorded. These sounds were played, in a quiet room, to 44 anesthesia clinicians. ⋯ Complexity of the sound did not influence accuracy of recognition. Most errors were attributed to similarities in sound or function, or both, among alarms. We conclude that anesthetists cannot reliably identify current operating room alarms by their distinctive sounds.
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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.
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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
Aspects of mechanical ventilation affecting interatrial shunt flow during general anesthesia.
Intraoperative transesophageal echocardiography was used to study the incidence of flow-patent foramen ovale in 33 normal, healthy patients (ASA physical status I) undergoing general anesthesia in the supine position for nonthoracic surgical procedures. Echocardiographic contrast was injected intravenously during mechanical ventilation in the presence of 0, 5, 10, 15, or 19 cm H2O positive end-expiratory pressure (PEEP). A final test was performed during the release of 19 cm H2O PEEP. ⋯ In all three cases, the shunt flow was accentuated on the release of PEEP; however, no additional cases were detected using this respiratory maneuver. These cases represent the first demonstration of right-to-left interatrial shunting evoked as the result of the sustained application of PEEP. This study also revealed a lower than expected incidence of flow-patent foramen ovale (9%) when measured during general anesthesia and positive pressure ventilation with or without PEEP.