Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1999
Clinical TrialThe nature of spontaneous recovery from mivacurium-induced neuromuscular block.
The hypothesis of this study was that, in a given patient, recovery from a tracheal intubating dose of mivacurium would indicate the time course of spontaneous recovery after discontinuation of an infusion of mivacurium. Thirty-eight male patients consented to participate in the study. After induction of anesthesia and endotracheal intubation, the ulnar nerve was stimulated with train-of-four (TOF) stimuli at 12-s intervals. Patients received 0.3 mg/kg mivacurium in two evenly divided doses of 0.15 mg/kg each, separated by 30 s. Complete ablation of TOF responses occurred in most patients. Once the first twitch in the TOF (T ) had recovered to 25% of its baseline height, a mivacurium infusion was begun to maintain 95% suppression of T1. As surgery was nearing completion, the infusion was discontinued, and neuromuscular function was allowed to recover spontaneously. Data were analyzed for recovery intervals after the administration of the initial doses of mivacurium and after discontinuation of the infusion. Analysis of variance was used to determine the strength of correlation between the time from administration of the initial 0.3 mg/kg dose to 5% recovery of T1 and the times to recovery of TOF ratios of 70% and 90%. The 25%-75% recovery interval after discontinuation of the infusion ranged from 2.8 to 11.3 min. The time interval after administration of mivacurium 0.3 mg/kg to 5% recovery of T1 correlated with both the time to recovery of a TOF ratio of 70% and 90%. Recovery to a TOF of 90% after discontinuation of the infusion required approximately the same amount of time as recovery to 5% T1 after the administration of 0.3 mg/kg mivacurium. Each patient's recovery of neuromuscular function after discontinuation of a mivacurium infusion was related to his recovery after the administration of 0.3 mg/kg mivacurium. Therefore, the need for pharmacologic antagonism of block can be anticipated well before the end of an anesthetic. ⋯ Mivacurium (0.3 mg/kg) was administered to 38 patients. As they began to recover muscle strength, a mivacurium infusion was begun and later discontinued as surgery was nearing completion. Each patient's early recovery (administration to 5% recovery of T1) after the initial dose of mivacurium correlated well with more complete recovery of muscle strength after discontinuation of an infusion. This relationship enables early prediction of recovery speed after a mivacurium infusion.
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Anesthesia and analgesia · Mar 1999
The anesthetic and physiologic effects of an intravenous administration of a halothane lipid emulsion (5% vol/vol)
The i.v. administration of < or = 9 mL of nonvaporized liquid halothane causes significant pulmonary damage, cardiovascular decompensation, and death. To determine whether liquid halothane mixed in a lipid emulsion would alter these toxic effects, six swine were evaluated in a randomized cross-over study. The pulmonary, analgesic, hemodynamic, and histopathologic effects of liquid halothane (25 mL) mixed with a liquid carrier (475 mL, Liposyn III 20%) and administered by constant infusion were compared with halothane administered by a calibrated vaporizer. Three swine received the halothane lipid emulsion (HLE), followed by inhaled halothane. Three additional swine received inhaled halothane, followed by the HLE. There were no changes in pulmonary compliance or arterial blood gases during or after the administration of equivalent volumes of halothane (13.75 mL) either by infusion of HLE or by inhalation of halothane. The end-tidal halothane concentration for the minimum alveolar anesthetic concentration was 0.79% +/- 0.08% during HLE administration and 1.13% +/- 0.12% for inhaled halothane (P < 0.001). Hemodynamic variables and blood halothane levels by gas chromatography were measured at end-tidal concentrations of 0.6%, 1.2%, and 1.8%. Blood halothane levels (mg/mL) were significantly higher (P < 0.05) after the administration of HLE at end-tidal halothane concentrations of 1.2% (0.49 +/- 0.19 vs 0.82 +/- 0.18) and 1.8% (0.79 +/- 0.17 vs 1.29 +/- 0.34). When compared at equivalent blood levels, HLE caused fewer changes in the left ventricular end-diastolic pressure, mean arterial pressure, and dP/dt than inhaled halothane. There was no evidence of pulmonary histopathologic damage 4-8 h after the infusion of 500-700 mL of HLE. This novel method of delivery of a volatile anesthetic seems to lack the toxicity of direct i.v. administration of liquid halothane. It may be a useful alternative to traditional administration via a vaporizer. ⋯ Halothane causes pulmonary dysfunction and death when given i.v. in liquid form. Six swine received a halothane lipid emulsion i.v. to evaluate the anesthetic and physiologic effects. No pulmonary toxicity or deaths were associated with the halothane lipid emulsion. The anesthetic profile was similar to delivery of halothane via a vaporizer.
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Anesthesia and analgesia · Mar 1999
Rabbits treated with chronic isepamicin are resistant to mivacurium and rocuronium.
We compared the dose-response relationships and the neuromuscular blocking effects of mivacurium and rocuronium after chronic isepamicin therapy for 7 days in 56 anesthetized rabbits. Train-of-four stimuli were applied every 10 s to the common peroneal nerve, and the force of contraction of the tibialis anterior muscle was measured. Chronic isepamicin therapy is associated with a rightward shift of the mivacurium and rocuronium dose-response curves. The effective dose for 50% twitch depression of mivacurium and rocuronium increased significantly, from 16.9 +/- 4.8 and 56.5 +/- 5.3 microg/kg, respectively, with placebo to 30.6 +/- 5.3 and 75.6 +/- 4.7 microg/kg, respectively, during isepamicin therapy. The isepamicin rabbits receiving mivacurium 0.18 mg/kg or rocuronium 0.6 mg/kg had an accelerated recovery from neuromuscular blockade compared with those receiving placebo. The results of this study show that mivacurium and rocuronium have both a decreased effect and a shorter duration of action in rabbits when used during concurrent isepamicin therapy. ⋯ We studied the dose-response relationships and the neuromuscular blocking effects of mivacurium and rocuronium during chronic isepamicin therapy in rabbits. Mivacurium and rocuronium have both a decreased effect and a shorter duration of action during chronic aminoglycoside antibiotic therapy in rabbits.
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Anesthesia and analgesia · Mar 1999
The safety and efficacy of intrathecal opioid analgesia for acute postoperative pain: seven years' experience with 5969 surgical patients at Indiana University Hospital.
To assess the efficacy of the analgesic technique and the incidence of complications, we prospectively evaluated patients who received intrathecal opioid analgesia (ITOA) to manage postsurgical pain. Daily quality assurance data were collected on the first postoperative day and tabulated for 5969 adult patients who had received ITOA for major urologic, orthopedic, general/ vascular, thoracic, and nonobstetrical gynecologic surgery. A scale of 1-10 was used to quantify each patient's satisfaction with analgesia. The incidence of side effects, complications, and naloxone usage was also recorded and tabulated. The mean satisfaction score using a 10-point numeric rating scale was 8.51, with a score of 1 connoting "complete dissatisfaction" and 10 connoting "complete satisfaction." Side effects were minor and easily managed. Pruritus was the most common (37%). Respiratory depression was the least common (3%), easily detected by nursing observation, never life-threatening, and always responsive to treatment with naloxone. There were no deaths, nerve injuries, central nervous system infections, or naloxone-related complications. Postdural puncture headaches were rare (0.54%), as was the need for epidural blood patch (0.37%). ⋯ Over a 7-yr period, intrathecal opioid analgesia was used to control acute postoperative pain on nearly 6000 patients, resulting in a high degree of patient satisfaction and a low incidence of side effects and complications.
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Anesthesia and analgesia · Mar 1999
Minimum alveolar anesthetic concentration of volatile anesthetics in normal and cardiomyopathic hamsters.
Minimum alveolar anesthetic concentrations (MAC) values of volatile anesthetics in cardiovascular diseases remain unknown. We determined MAC values of volatile anesthetics in spontaneously breathing normal and cardiomyopathic hamsters exposed to increasing (0.1%-0.3% steps) concentrations of halothane, isoflurane, sevoflurane, or desflurane (n = 30 in each group) using the tail-clamp technique. MAC values and their 95% confidence interval were calculated using logistic regression. In normal hamsters, inspired MAC values were: halothane 1.15% (1.10%-1.20%), isoflurane 1.62% (1.54%-1.69%), sevoflurane 2.31% (2.22%-2.40%), and desflurane 7.48% (7.30%-7.67%). In cardiomyopathic hamsters, they were: halothane 0.89% (0.83%-0.95%), isoflurane 1.39% (1.30%-1.47%), sevoflurane 2.00% (1.85%-2.15%), and desflurane 6.97% (6.77%-7.17%). Thus, MAC values of halothane, isoflurane, sevoflurane, and desflurane were reduced by 23% (P < 0.05), 14% (P < 0.05), 13% (P < 0.05), and 7% (P < 0.05), respectively in cardiomyopathic hamsters. ⋯ Minimum alveolar anesthetic concentrations of volatile anesthetics were significantly lower in cardiomyopathic hamsters than in normal hamsters.