Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
A double-blind comparison of the efficacy of methadone and morphine in postoperative pain control.
This study reports the results of a double-blind, parallel-group comparison of intravenous methadone with morphine for the control of postoperative pain. Twenty patients (ASA Status 1 or 2) undergoing a surgical procedure involving an upper abdominal incision were randomly allocated to the methadone (n = 10) or morphine (n = 10) treatment groups. The patients were administered a 20-mg intraoperative opioid dose and 5-mg intravenous increments of opioid from precoded syringes in response to pain in the recovery and surgical wards. ⋯ Further, patients required significantly less (P less than 0.001) methadone (11.5 +/- 8.5 mg) than morphine (41 +/- 14.1 mg) in the surgical ward to provide adequate pain relief throughout the duration of the study (i.e., 60 h). There was a significant difference in visual analogue pain scores between the methoadone and morphine groups on postoperative days 1 and 2, suggesting the quality of pain relief was similar for both treatment groups. Blood opioid-concentration monitoring indicated that there was a relationship between blood opioid concentration and pain relief.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
The hemodynamic and cardiovascular effects of isoflurane and halothane anesthesia in children.
The hemodynamic and cardiovascular effects of isoflurane and halothane anesthesia were studied in 15 unpremedicated ASA I children using measurements of heart rate, blood pressure and M-mode echocardiography (echo). The children (ages 2 to 7.3 yr) were randomly assigned to receive either isoflurane (N = 8) or halothane (N = 7) with oxygen. End-tidal carbon dioxide concentrations (range 30-44 mmHg) were monitored throughout the study in each child. ⋯ Halothane was associated with a significant dose-dependent decrease in echo-measured left-ventricular shortening fraction and mean velocity of circumferential fiber shortening. These echo measurements were not significantly altered by isoflurane at either end-tidal anesthetic concentration. These alterations suggest halothane is associated with significant myocardial depression in normal children, while myocardial function is well preserved during isoflurane anesthesia.
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The authors determined the pharmacokinetics of fentanyl 100 micrograms X kg-1 iv in patients undergoing elective abdominal aortic surgery. The mean (+/- SD) age of the ten patients was 67.2 +/- 8.7 yr; their mean weight was 78.5 +/- 13.7 kg. Seven patients had aortic aneurysm repair, and the other three patients had aortobifemoral grafts. ⋯ In healthy volunteers or patients undergoing general surgery, other investigators report mean elimination half-times for fentanyl ranging from 1.7 to 4.4 h. The prolonged elimination half-time in patients having abdominal aortic surgery has important clinical implications. In particular, recovery from large doses will take much longer than would have been anticipated from previously published fentanyl pharmacokinetic data.
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A total of 305 timed-pregnant Sprague-Dawley rats were exposed for 6 h a day on each of three consecutive days in one of three periods, i.e., pregnancy days 14-16, 11-13, or 8-10, either to 0.55 times the minimum alveolar concentration (MAC) of nitrous oxide (75%) or to 0.75 MAC of halothane (0.8%), isoflurane (1.05%) or enflurane (1.65%); an additional 232 positive-control (retinoic acid) and air control rats were studied. Reproductive indices were determined, and the 5178 offspring delivered at cesarean section were examined for external, internal, and skeletal abnormalities. ⋯ Nitrous oxide exposure on days 14-16 resulted in a three-fold increase in fetal resorptions. The results suggest that the volatile anesthetics are not teratogenic and confirm that nitrous oxide may be associated with increased reproductive loss.