Anesthesia and analgesia
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Anesthesia and analgesia · May 2002
Comparative StudyThe hemodynamic effects of rapacuronium in patients with coronary artery disease: succinylcholine and vecuronium compared.
Rapacuronium is a nondepolarizing muscle relaxant similar in structure to pancuronium, rocuronium, and vecuronium. Rapacuronium has a mild to moderate effect on heart rate and arterial blood pressure in ASA physical status I and II patients. However, rapacuronium was often administered after, e.g., thiopental, an inhaled anesthetic, and fentanyl, thus modifying or masking the hemodynamic effects of rapacuronium. In this study, we investigated the hemodynamic effects of rapacuronium and compared its effects with those of vecuronium and succinylcholine. Sixty patients scheduled to undergo routine coronary artery bypass grafting were selected to receive rapacuronium 1.5 mg/kg, vecuronium 0.1 mg/kg, or succinylcholine 1 mg/kg. Heart rate, blood pressure, pulmonary artery pressures, and cardiac index were measured at 30- and 60-s intervals during the 2 min after the induction of anesthesia with diazepam and for a 3-min period after study drug administration. The Rapacuronium group exhibited significantly larger decreases in blood pressure and systemic vascular resistance than the Vecuronium or Succinylcholine groups. One patient in the Rapacuronium group experienced cutaneous flushing associated with a 33% decrease in blood pressure. ⋯ Rapacuronium is associated with a significantly larger decrease in blood pressure than succinylcholine or vecuronium, and this decrease should be considered when using rapacuronium in patients who cannot tolerate this decrease.
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Anesthesia and analgesia · May 2002
The neuropathologic effects in rats and neurometabolic effects in humans of large-dose remifentanil.
Given in clinically relevant large doses to rats, mu-opioids produce limbic system hypermetabolism and histopathology. This investigation extends these observations, in both rats and humans, for the short-acting drug remifentanil, which allows more precise control and assessment of the effects of duration of opioid exposure. We performed two series of experiments: one in rats for neuropathologic effects and the second in humans for neurometabolic effects. Fifty mechanically ventilated rats received saline solution or remifentanil 20-160 microg x kg(-1) x min(-1) for 3 h, followed by neuropathologic evaluation 7 days later. Four volunteers underwent induction of anesthesia and endotracheal intubation with propofol and rocuronium administration followed by remifentanil infusion at 1-3 microg x kg(-1) x min(-1) with positron emission tomography evaluation of cerebral metabolic rate for glucose. In rats, dose-related electroencephalogram activation was evident and 19 of 40 remifentanil-treated rats showed brain damage, primarily in the limbic system (P < 0.01). In humans, cerebral metabolic rate for glucose in the temporal lobe increased from 6.29 +/- 0.32 to 7.68 +/- 1.05 mg x 100 g(-1) x min(-1) (P < 0.05). These data indicate that prolonged large-dose remifentanil infusion is neurotoxic in rats with congruent metabolic effects with brief infusion in humans and suggest that some adverse effects reported in rats may be clinically relevant. ⋯ This study demonstrates dose-related remifentanil neurotoxicity in physiologically controlled rats with congruent brain metabolic effects in four humans undergoing positron emission tomography evaluation during brief large-dose remifentanil anesthesia. These data suggest that some adverse effects reported in rats may be clinically relevant.
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Anesthesia and analgesia · May 2002
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of remifentanil or fentanyl on postoperative vomiting and pain in children undergoing strabismus surgery.
Postoperative vomiting (POV) after strabismus surgery in children results in discomfort and prolonged hospital stays. Opioids increase the incidence of POV. Remifentanil has a context-sensitive half-life of 3 to 4 min, and how this short half-life influences POV in those patients is unknown. We conducted a prospective, double-blinded study in 81 ASA status I or II children from 2 to 12 yr of age undergoing elective strabismus surgery under general anesthesia. Patients were randomized to receive either remifentanil (bolus 1 microg/kg; infusion 0.1-0.2 microg x kg(-1) x min(-1)) or fentanyl (2 microg/kg, and 1 microg/kg every 45 min). POV episodes were recorded for 25 h. Pain scores were obtained by using an objective pain scale for 60 min during recovery. The number of patients who experienced POV did not differ significantly between groups (49% vs 48%). However, in the Remifentanil group, POV episodes were significantly less frequent (0.95 vs 2.2 episodes). In contrast, fentanyl was associated with lower pain scores during the first 30 min of recovery. We conclude that children undergoing strabismus surgery under balanced anesthesia with remifentanil, compared with fentanyl, showed less frequent POV. However, early postoperative analgesia was better with fentanyl. ⋯ Opioids increase the incidence of postoperative vomiting (POV). Remifentanil is characterized by the shortest half-life of all opioids used in anesthetic practice. Therefore, we studied the effect of remifentanil on POV compared with the longer-acting opioid fentanyl in children undergoing strabismus surgery.
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Anesthesia and analgesia · May 2002
Randomized Controlled Trial Clinical TrialThe absence of acute tolerance during remifentanil infusion in volunteers.
The development of acute opioid tolerance in humans remains controversial. We tested the hypothesis that continuous remifentanil infusion leads to rapid development of opioid tolerance. Twenty healthy male volunteers were enrolled onto a randomized, placebo-controlled, double-blinded, cross-over design study to receive a 3 h continuous infusion of remifentanil (0.08 microg x kg(-1) x min(-1)) or saline. Test procedures included determination of pain perception thresholds and pain tolerance thresholds to heat and cold and neuroselective sine wave constant current at 5 Hz and 250 Hz. Test procedures were performed at baseline and then repeated at 25, 55, 85, 115, and 160 min (heat/cold) and at 35, 65, 95, 125, and 170 min (electrical current) during infusion. No significant decrease of the pain threshold devolutions between 55 and 180 min after the start of infusion of remifentanil could be detected. In conclusion, no development of acute opioid tolerance was observed during constant remifentanil infusion of 3 h in volunteers. ⋯ The opioid remifentanil was applied to 20 volunteers at a constant concentration for 3 h while pain thresholds to temperature and current were repeatedly assessed. Our aim was to study whether thresholds decrease over time because of the rapid development of opioid tolerance. No development of rapid opioid tolerance was observed.