Anesthesia and analgesia
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Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialClonidine does not impair redistribution hypothermia after the induction of anesthesia.
Clonidine is commonly given for premedication, and it impairs normal thermoregulatory responses to warm and cold stimuli while depressing sympathetic tone. We studied the effect of premedication by clonidine on redistribution hypothermia induced by the induction of anesthesia. Sixteen ASA physical status I or II patients were randomly assigned to receive either clonidine 150 micrograms or a placebo. Anesthesia was induced 45 min later by thiopental, fentanyl, and vecuronium i.v. and was maintained by the administration of 0.6% isoflurane. We monitored central core (tympanic) temperature and skin surface temperatures at the forearm and the fingertip during the 2 h after the induction of anesthesia before surgery. We estimated skin blood flow at the level of the forearm by using laser Doppler during the same period. The core temperature decreased comparably in the two groups of patients, from 37.1 +/- 0.2 degrees C to 35.3 +/- 0.4 degrees C and from 37.1 +/- 0.2 degrees C to 35.5 +/- 0.3 degrees C in the clonidine and placebo groups, respectively. The forearm-fingertip surface temperature gradient decreased similarly in the two groups. There was no evidence of cutaneous vasoconstriction. The laser Doppler index at the fingertip increased similarly in the two groups, as did the forearm-fingertip temperature gradient. We conclude that premedication with clonidine does not significantly impair the profile of central hypothermia induced by heat redistribution after the induction of anesthesia. ⋯ The induction of general anesthesia is associated with redistribution hypothermia. This study shows that premedication with oral clonidine does not worsen the decrease in core temperature resulting from general anesthesia.
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Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialNurse-administered subcutaneous morphine is a satisfactory alternative to intravenous patient-controlled analgesia morphine after cardiac surgery.
There are no comparisons of i.v. patient controlled analgesia (i.v. PCA) versus nurse-administered subcutaneous (NA s.c.) morphine for acute postoperative pain. We undertook a prospective, randomized, controlled clinical trial of 80 cardiac surgical patients to compare i.v. PCA with NA s.c. morphine for postoperative pain control. Visual analog scale (VAS) pain scores at rest and with movement, daily verbal pain relief scores, and side effect profiles were not significantly different. Total morphine requirements in the two groups were not significantly different. A physiotherapist's evaluation of the effectiveness of analgesia for chest physiotherapy revealed no difference between the two groups. We conclude that NA s.c. morphine, administered as required (up to hourly), is a satisfactory alternative to i.v. PCA morphine after cardiac surgery. ⋯ In a prospective, randomized study, we have shown that nurse-administered subcutaneous morphine is a satisfactory alternative to i.v. patient-controlled analgesia after cardiac surgery.
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Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialPreoperative epidural ketamine does not have a postoperative opioid sparing effect.
Ketamine reduces nociception by binding noncompetitively to the N-methyl-D-aspartate receptor, the activation of which provokes hypersensitivity within the central nervous system. We studied the analgesic effect of extradural ketamine given before or after upper abdominal surgery. We sought to assess the effect of ketamine on preemptive analgesia. Ketamine 60 mg was injected epidurally through an indwelling catheter that was inserted at the T7-8 or T8-9 interspace in 98 patients. Patients were randomly allocated into one of the two groups, each consisting of 49 patients: ketamine was given before the induction of anesthesia (Group 1) and after the parietal peritoneum was closed (Group 2). Sample size was calculated using a two-tailed alpha = 0.05 and power of 95%. For postoperative analgesia, meperidine 25 mg was given epidurally whenever a patient complained of pain or the visual analog scale score was greater than 4. The first and the second day cumulative meperidine consumption was not different between the two groups. We conclude that preoperative epidural ketamine 60 mg does not have a preemptive analgesic effect. ⋯ In patients undergoing upper abdominal surgery, a single epidural injection of 60 mg of ketamine administered preoperatively was not associated with decreased postoperative analgesic demands. This findings does not contribute to one of the fundamental scientific objectives of preemptive analgesia that postoperative analgesia well beyond the duration of any single drug effect could be produced.
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Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialVisual evaluation of residual curarization in anesthetized patients using one hundred-hertz, five-second tetanic stimulation at the adductor pollicis muscle.
We were looking for a clinical test to indicate a train-of-four (TOF) ratio of approximately 0.9. We compared the adductor pollicis muscle (AP) visually evaluated response to ulnar nerve 100-Hz, 5-s tetanus (RF100 Hz) with the measured AP TOF ratio in 30 ASA physical status I or II adult anesthetized (propofol, sufentanil, N2O/O2) patients. After the induction of anesthesia, the left ulnar nerve was stimulated at the wrist (single twitch and TOF) and the resultant isometric force was measured. When TOF was assessed, the independent investigators, unaware of the left AP-measured TOF ratios, visually evaluated the presence or absence of AP fading elicited by right ulnar nerve 100-Hz, 5-s tetanus. The 30 patients were randomly allocated to receive either 0.5 mg/kg atracurium (n = 15) or 0.1 mg/kg vecuronium (n = 15). The neuromuscular blockade was allowed to resolve spontaneously. A multiple logistic regression analysis was performed by computing the 771 visual observations. The probabilities of success of 100-Hz, 5-s tetanus to detect TOF ratios of 0.8, 0.85, and 0.9 were 99%, 96%, and 67%, respectively. The sensitivity and specificity of 100-Hz, 5-s tetanus as an indicator of TOF ratios of 0.85 and 0.9 are 100% and 75%, 54% and 67%, respectively. We conclude that RF100 Hz visual assessment seems to be highly sensitive in evaluating residual paralysis, as the absence of RF100 Hz visual fading at the AP is compatible with a TOF ratio > 0.85. ⋯ After the administration of muscle relaxants, the absence of visual fading at the adductor pollicis, elicited in anesthetized patients by 100-Hz, 5-s tetanus, is compatible with a train-of four ratio > 0.85. Therefore, clinical observation of fading after 100-Hz, 5-s tetanus seems to be a highly sensitive test in evaluating residual paralysis.
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Anesthesia and analgesia · Jul 1998
Clinical TrialEpidural labor analgesia and the incidence of cesarean delivery for dystocia.
We performed this retrospective study to examine the changes in cesarean delivery rates associated with the establishment of a labor epidural service. In April 1993, St. Louis Regional Medical Center established an on-demand labor epidural service. We obtained demographic data for all patients and reviewed the operative records of all patients undergoing cesarean section who delivered 12 mo before and 16 mo after the start of the labor epidural service. We compared labor epidural rates and total and nulliparous dystocia cesarean delivery rates before and after the epidural service started and among patients who did and did not receive labor epidural analgesia when it was available. Included were 3195 patients who delivered before and 3733 patients who delivered after epidural analgesia became available. Labor epidural rates were 1.2% vs 29.4% for the Before group versus the After group (P < 0.001). Total (9.1% vs 9.7%) and nulliparous dystocia (5.7% vs 6.4%) cesarean delivery rates did not significantly change with the availability of epidural analgesia. However, the total (11.6% vs 8.8%; P = 0.009) and dystocia (8.0% vs 1.0%; P = 0.001) cesarean delivery rates were higher among patients who received epidural analgesia when it was available. We conclude that epidural labor analgesia is associated with, but does not cause, cesarean delivery for dystocia. ⋯ Increased epidural analgesia use did not change the overall dystocia cesarean delivery rate, although dystocia was more common among women who chose an epidural analgesia. Consequently, limiting epidural availability will not affect cesarean delivery rates. The evidence does not support advising patients that epidural labor analgesia increases the risk of cesarean delivery.