Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2003
Randomized Controlled Trial Clinical TrialModulation of remifentanil-induced analgesia, hyperalgesia, and tolerance by small-dose ketamine in humans.
Adding a small dose of ketamine to opioids may increase the analgesic effect and prevent opioid-induced hyperalgesia and acute tolerance to opioids. In this randomized, double-blinded, placebo-controlled crossover study, we investigated the effect of remifentanil combined with small concentrations of ketamine on different experimental pain models. Pain detection thresholds to single and repeated IM electrical stimulation and to repeated transcutaneous electrical stimulation, pressure pain tolerance threshold, and sedative, respiratory, and cardiovascular side effects were assessed in 14 healthy volunteers. Saline, remifentanil alone, and remifentanil combined with ketamine at target plasma concentrations of 50 or 100 ng/mL were administered in four study sessions. The ketamine infusion was started after baseline testing at a constant target concentration. Remifentanil was started after testing with ketamine alone at an initial target concentration of 1 ng/mL and then increased to 2 ng/mL and decreased to 1 ng/mL. The last test series were started 10 min after discontinuation of remifentanil. Acute remifentanil-induced hyperalgesia and tolerance were detected only by the pressure pain test and were not suppressed by ketamine. Remifentanil alone induced significant analgesia with all pain tests. Ketamine further increased the remifentanil effect only on IM electrical pain. Remifentanil at a 2 ng/mL target concentration induced a slight respiratory depression that was antagonized by ketamine. We conclude that ketamine effects on opioid analgesia are pain-modality specific. ⋯ Coadministration of ketamine and morphine for pain relief is still controversial. Our experimental pain study with volunteers showed that ketamine enhances opioid analgesia without increasing sedation and reduces respiratory depression. Opioid-induced hyperalgesia and tolerance were not affected by ketamine and depended on the type of nociceptive stimulus. This may explain the conflicting results on opioid tolerance in previous studies.
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Anesthesia and analgesia · Mar 2003
Randomized Controlled Trial Clinical TrialThe effect of spinal bupivacaine in combination with either epidural clonidine and/or 0.5% bupivacaine administered at the incision site on postoperative outcome in patients undergoing lumbar laminectomy.
Spinal anesthesia has numerous advantages over general anesthesia for patients undergoing lumbar laminectomy and microdisk surgery. In this study, we evaluated the addition of epidural clonidine and/or bupivacaine, injected at the incision site, on postoperative outcome variables in patients undergoing lower spine procedures using spinal anesthesia. One hundred twenty patients having lumbar spine surgery received bupivacaine spinal anesthesia supplemented by 150 microg of epidural clonidine with or without incisional bupivacaine, epidural placebo plus incisional bupivacaine, or placebo with incisional saline. Demographic data, intraoperative hemodynamics, blood loss, pain, nausea, urinary retention, hospital discharge, and other variables were compared by using either analysis of variance or chi(2) analysis. Demographics were similar. IV fluids, blood loss, incidence of intraoperative bradycardia, and hypotension were not different among groups. Postanesthesia care unit pain scores were lower and demand for analgesics was less in patients who received both the clonidine and subcutaneous bupivacaine. Patients who received epidural clonidine also had improved postoperative hemodynamics. Hospital discharge, urinary retention, and other variables were not different. We conclude that epidural clonidine as a supplement to spinal anesthesia produced no perioperative complications and improved postoperative pain and hemodynamic stability in patients undergoing lower spine procedures. ⋯ Spinal anesthesia with supplemental epidural clonidine in combination with incision site subcutaneous bupivacaine was evaluated both intra- and postoperatively and compared with spinal anesthesia alone for lower lumbar spine procedures. Both epidural clonidine and subcutaneous incisional bupivacaine, added to spinal anesthesia for lumbar spine surgery, improves pain relief and reduces the need for postoperative opioids with their associated side effects.
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Anesthesia and analgesia · Mar 2003
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of airway responses during desflurane and sevoflurane administration via a laryngeal mask airway for maintenance of anesthesia.
Although sevoflurane is less pungent than desflurane at larger concentrations, neither anesthetic seems to irritate the airway when administered at the smaller concentrations often used during maintenance of anesthesia. Both anesthetics may be delivered effectively via a laryngeal mask airway, with minimal evidence of airway irritation.
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Anesthesia and analgesia · Mar 2003
Randomized Controlled Trial Comparative Study Clinical TrialComparison of alpha-stat and pH-stat cardiopulmonary bypass in relation to jugular venous oxygen saturation and cerebral glucose-oxygen utilization.
Jugular venous oxygen saturation (SJVO(2)) reflects the balance between cerebral blood flow and metabolism. This study was designed to compare the effects of two different acid-base strategies on jugular venous desaturation (SJVO(2) <50%) and cerebral arteriovenous oxygen-glucose use. We performed a prospective, randomized study in 52 patients undergoing cardiopulmonary bypass (CPB) at 27 degrees C with either alpha-stat (n = 26) or pH-stat (n = 26) management. A retrograde internal jugular vein catheter was inserted, and blood samples were obtained at intervals during CPB. There were no differences in preoperative variables between the groups. SJVO(2) was significantly higher in the pH-stat group (at 30 min CPB: 86.2% +/- 6.1% versus 70.6% +/- 9.3%; P < 0.001). The differences in arteriovenous oxygen and glucose were smaller in the pH-stat group (at 30 min CPB: 1.9 +/- 0.82 mL/dL versus 3.98 +/- 1.12 mL/dL; P < 0.001; and 3.67 +/- 2.8 mL/dL versus 10.1 +/- 5.2 mL/dL; P < 0.001, respectively). All episodes of desaturation occurred during rewarming, and the difference in the incidence of desaturation between the two groups was not significant. All patients left the hospital in good condition. Compared with alpha-stat, the pH-stat strategy promotes an increase in SJVO(2) and a decrease in arteriovenous oxygen and arteriovenous glucose differences. These findings indicate an increased cerebral supply with pH-stat; however, this strategy does not eliminate jugular venous desaturation during CPB. ⋯ A prospective, randomized study in 52 patients during cardiopulmonary bypass revealed that pH-stat increased jugular venous oxygen saturation and decreased arteriovenous oxygen-glucose differences. There was no difference in the incidence of jugular venous desaturation. These findings suggest an increased cerebral blood flow with no protection against jugular venous desaturation during pH-stat.
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Anesthesia and analgesia · Mar 2003
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of vecuronium is enhanced by a large rather than a modest dose of gentamicin as compared with no preoperative gentamicin.
We compared the effect of two doses of gentamicin versus no gentamicin (NG) given before surgery on the neuromuscular relaxant effect of vecuronium. Seventy patients (intraabdominal procedures) were randomly allocated to receive preoperative large-dose (4 mg/kg) gentamicin (LD), a modest dose (1.2 mg/kg) of gentamicin (MD), or NG. No more than one dose of gentamicin was given before the vecuronium administration. Serum gentamicin levels, the time for 25% recovery of the first twitch in the train-of-four after a bolus of vecuronium, and the time from cessation of the vecuronium infusion to extubation of the trachea were estimated. Serum gentamicin levels were higher (P < 0.001) for LD than MD. The time for 25% recovery of the first twitch after the vecuronium bolus was slightly longer with LD than MD (P = 0.06) and longer in LD than NG (P = 0.001) (42.9 +/- 23.6 min versus 36.2 +/- 17 min and 27.4 +/- 9 min, respectively). The time to extubation was similar with LD and MD and longer for LD than NG (P = 0.008) (34.7 +/- 19.2 min versus 27.4 +/- 19.3 min and 19.4 +/- 10.1 min, respectively). The differences in these times were insignificant between MD and NG. Gentamicin administered as a LD rather than MD enhanced the neuromuscular blockade of vecuronium as compared with NG given before surgery. ⋯ We demonstrated that the neuromuscular relaxant effect of vecuronium is enhanced by a large (4 mg/kg) rather than a modest (1.2 mg/kg) dose of gentamicin as compared with no gentamicin given before surgery.