Anesthesia and analgesia
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Anesthesia and analgesia · Sep 2000
Randomized Controlled Trial Clinical TrialThe effect on intracuff pressure of various nitrous oxide concentrations used for inflating an endotracheal tube cuff.
We sought to determine the optimal concentration of nitrous oxide (N(2)O) for inflating endotracheal tube cuffs, to avoid overinflation and air leaks. Female patients undergoing endotracheal intubation (inner diameter 7.5 mm) during anesthesia with 67% N(2)O were randomly assigned to five groups of 25 subjects each, in which cuffs were inflated with 0% (Air), 30% (N30), 40% (N40), 50% (N50), or 67% (N67) N(2)O. The cuff pressure and the N(2)O concentration in the cuff were measured. In an additional 15 patients (N40-a group), pilot balloons were replaced with metal tubes, and the mouths and noses of the patients were wrapped with tape, to minimize N(2)O efflux into the air. Postoperative sore throats were evaluated in double-blinded interviews. Cuff pressures increased significantly in the Air and N30 groups but decreased in the N67 group. Cuff pressures were <22 mm Hg in the N40 and N50 groups, but the N50 group had air leaks. The N(2)O concentration in the cuff in the N40 group was significantly smaller than that in the N40-a group, suggesting N(2)O rediffusion. The incidence of sore throats (40% in the Air group) was reduced significantly in the N40 and N50 groups. Therefore, 40% N(2)O is optimal for filling the cuff during anesthesia with 67% N(2)O. ⋯ Nitrous oxide (N(2)O) diffuses into the cuff, equilibrating at a smaller concentration than the gas mixture with which patients are ventilated. Our data indicate that inflation of the cuff with 40% N(2)O is recommended to prevent both excessive endotracheal cuff pressure and air leaks during anesthesia with 67% N(2)O, reducing postoperative sore throats.
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Anesthesia and analgesia · Sep 2000
Randomized Controlled Trial Comparative Study Clinical TrialAdvantages of intrathecal nalbuphine, compared with intrathecal morphine, after cesarean delivery: an evaluation of postoperative analgesia and adverse effects.
We performed a prospective, randomized, double-blinded, multicenter study to compare the analgesic efficacy and adverse effects of intrathecal nalbuphine, at three different doses, and intrathecal morphine for postoperative pain relief after cesarean deliveries. Ninety healthy patients at full term who were scheduled for elective cesarean delivery with spinal anesthesia were enrolled in the study. They received 10 mg of hyperbaric bupivacaine 0.5% with either morphine 0.2 mg (Group 1), nalbuphine 0.2 mg (Group 2), nalbuphine 0. 8 mg (Group 3), or nalbuphine 1.6 mg (Group 4). Only patients in Groups 1 and 2 reported pain during surgery. Postoperative analgesia lasted significantly longer in the morphine group, compared with the nalbuphine groups (P: < 0.0001). In the nalbuphine groups, postoperative analgesia lasted longest with the 0.8-mg dose. The additional increase to 1.6 mg did not increase efficacy. The incidence of pruritus was significantly higher in Group 1 (11 of 22), compared with Group 2 (0 of 22, P: < 0.0002), Group 3 (0 of 23, P: < 0.0001), and Group 4 (3 of 20, P: < 0.02). Postoperative nausea and vomiting were more frequent in Group 1 (5 of 22), compared with Group 2 (0 of 22, P: < 0.05), Group 3 (0 of 23, P: < 0.05), and Group 4 (3 of 23, not significant). There was no maternal or newborn respiratory depression. Neonatal conditions (Apgar scores and umbilical vein and artery blood gas values) were similar for all groups. This study suggests that intrathecal nalbuphine 0.8 mg provides good intraoperative and early postoperative analgesia without side effects. However, only morphine provides long-lasting analgesia. ⋯ Small doses of intrathecal nalbuphine produce fewer adverse effects, such as pruritus and postoperative nausea and vomiting, compared with intrathecal morphine. This may allow earlier discharge of patients from the recovery room.
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Anesthesia and analgesia · Sep 2000
Randomized Controlled Trial Clinical TrialSpontaneous recovery profile of rapacuronium during desflurane, sevoflurane, or propofol anesthesia for outpatient laparoscopy.
We evaluated the spontaneous recovery characteristics of rapacuronium during desflurane-, sevoflurane-, or propofol-based anesthesia in 51 consenting women undergoing laparoscopic tubal ligation procedures. After the induction of the anesthesia with standardized doses of propofol and fentanyl, 1.5 mg/kg IV rapacuronium was administered to facilitate tracheal intubation. Patients were randomized to receive either 1 minimum alveolar anesthetic concentration of desflurane, 1 minimum alveolar concentration of sevoflurane, or 100 microg. kg(-1). min(-1) propofol infusion in combination with 66% nitrous oxide in oxygen for maintenance of anesthesia. Neuromuscular blockade was monitored at the wrist by using electromyography. The degree of maximum blockade and the times for first twitch recovery (T(1)) to 5%, 25%, 50%, 75%, and 90%, as well as the recovery index, were similar in all three anesthetic groups. However, recovery times for the train-of-four ratio to achieve 0.7 and 0.8 were significantly longer with desflurane (44.4 +/- 18.9 and 53.5 +/- 22.4 min) and sevoflurane (44.8 +/- 15.1 and 53.2 +/- 15.8 min) compared with propofol (31.8 +/- 5.3 and 36.5 +/- 6.5 min). Eight patients (16%) required a maintenance dose of 0.5 mg/kg rapacuronium and reversal of rapacuronium residual block occurred in three (6%) patients. We conclude that spontaneous recovery after an intubating dose of 1.5 mg/kg rapacuronium was significantly prolonged by both desflurane and sevoflurane compared with propofol-based anesthesia. Routine monitoring of neuromuscular activity is recommended even when a single bolus dose of rapacuronium is administered during ambulatory anesthesia. ⋯ When administered for laparoscopic surgery, the duration of action of an intubating dose of rapacuronium was prolonged 40%-50% by desflurane and sevoflurane, respectively, (versus propofol). Monitoring recovery of neuromuscular blockade produced by rapacuronium is particularly important when desflurane or sevoflurane is administered to ensure that an adequate recovery (train-of-four > or = 0.8) is achieved by the end of anesthesia.
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Anesthesia and analgesia · Sep 2000
Randomized Controlled Trial Comparative Study Clinical TrialThe anesthetic and recovery profile of two doses (60 and 80 mg) of plain mepivacaine for ambulatory spinal anesthesia.
Reports of transient neurological symptoms with the use of subarachnoid lidocaine has generated interest in alternate local anesthetics of intermediate duration, such as mepivacaine. This prospective randomized, double-blinded, dose-response study examined the anesthetic and recovery profiles of 60- and 80-mg doses of preservative-free plain mepivacaine for ambulatory spinal anesthesia. Sixty patients undergoing ambulatory anterior cruciate ligament repair of the knee under spinal anesthesia were randomized into two groups; Group 1 (29 patients) received 4 mL of 1.5% (60-mg dose) and Group 2 (31 patients) received 4 mL of 2% (80-mg dose) of plain mepivacaine. All patients received a combined spinal-epidural anesthetic technique. The epidural catheter was used only in the event the surgery outlasted the duration of surgical anesthesia with subarachnoid mepivacaine. Epidural supplementation was administered in three patients (12%) in Group 1 and one patient (3%) in Group 2 when the sensory block regressed to L-1 with surgery expected to last longer than 15 min. The cephalad dermatome level of the block and degree of motor block was comparable in the two groups. Times to two-segment and T-10 regression were comparable in the two groups (112 +/- 26 min in Group 1 versus 122 +/- 28 min in Group 2). Time to L-1 regression was significantly longer in Group 2 (146 +/- 28 min in Group 1 versus 159 +/- 19 min in Group 2). All of the ambulatory milestones were significantly faster in Group 1. Side effects, such as hypotension and emesis were negligible, severe bradycardia and urinary retention did not occur, and none of the patients in the two groups reported transient neurological symptoms over 24 h. In conclusion, plain mepivacaine in a 60- or 80-mg dose is a suitable local anesthetic choice for ambulatory spinal anesthesia with respect to anesthetic, as well as recovery profiles. ⋯ We evaluated the anesthetic and recovery profiles of 60- and 80-mg doses of plain mepivacaine for ambulatory spinal anesthesia. Both doses produced comparable sensory and motor block. Sensory and motor regression and ambulatory milestones were 20-30 min longer with the 80-mg dose. Side effects were negligible and transient neurological symptoms were not reported during a 24-h follow-up.