Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2001
Randomized Controlled Trial Multicenter Study Clinical TrialThe pharmacokinetics of remifentanil in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass.
Remifentanil is a potent opioid with a short duration of action. It has the potential for large-dose opioid anesthesia without an obligatory prolonged period of mechanical ventilation. However, because of high clearance and rapid tissue distribution, cardiopulmonary bypass (CPB) may influence its pharmacokinetics and alter drug requirements. We administered remifentanil by continuous infusion to 68 patients having coronary artery bypass graft surgery during CPB with hypothermia to describe the effects of these interventions on its pharmacokinetics. Remifentanil concentrations were measured before, during, and after CPB. Disposition was best described by a two-compartment model. The volume of distribution increased by 86% with institution of CPB and remained increased after CPB. Elimination clearance decreased by 6.37% for each degree Celsius decrease from 37 degrees C. ⋯ Remifentanil concentrations decrease with the institution of cardiopulmonary bypass because of an increase in the volume of distribution. The decrease in elimination clearance with hypothermia results in increased total remifentanil concentrations during cardiopulmonary bypass if the infusion rate is not altered. More constant blood remifentanil levels may be obtained by reducing remifentanil infusion rate by 30% for each 5 degrees C decrease in temperature.
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Anesthesia and analgesia · Nov 2001
Multicenter Study Comparative Study Clinical TrialThe recovery of Senegalese African blacks from intravenous anesthesia with propofol and remifentanil is slower than that of Caucasians.
Differences in sensitivity to anesthetic drugs have already been described among races. This study was designed to comparatively investigate the anesthetic requirements of two different ethnic groups: Caucasians and African blacks. Forty-five Caucasians from Italy and 45 African blacks from Senegal, who underwent general IV anesthesia with propofol and remifentanil, were comparatively evaluated for anesthetic depth and time lapsed before recovery. We used an electroencephalographic-derived index of depth of anesthesia, the bispectral index (BIS), and evaluation of clinical variables to assess the depth of anesthesia and the recovery trend. Mean BIS values from Caucasians after propofol discontinuation returned to baseline (92-100) in approximately 8 min, whereas in African blacks BIS values remained <80 for some 30 min. Time to eye opening was 10.6 +/- 4.8 min in Caucasians versus 16.9 +/- 8.8 min in African blacks (P < 0.001). Time to respond to loud verbal commands was 14.8 +/- 9.1 min in African blacks versus 9.1 +/- 4.2 min in Caucasians (P < 0.01). During anesthetic induction, the mean arterial pressure decreased by 20% in Caucasians and by only 10% in African blacks. We conclude that the recovery from general anesthesia with propofol was slower in African blacks compared with Caucasian patients. ⋯ This study demonstrates statistically significant differences between Caucasians and African blacks in the arousal time from IV anesthesia with propofol and remifentanil. The authors conclude that the recovery from general anesthesia was slower in African blacks compared with Caucasian patients.