Assessment of Depth of Anesthesia and Postoperative Respiratory Recovery after Remifentanil-versus Alfentanil-based Total Intravenous Anesthesia in Patients Undergoing Ear–Nose–Throat Surgery

Abstract

Background The authors investigated whether total intravenous anesthesia (TIVA) with precalculated equipotent infusion schemes for remifentanil and alfentanil would ensure appropriate analgesia and that remifentanil would result in better recovery characteristics. Methods Forty consenting patients (classified as American Society of Anesthesiologists physical status I-III) scheduled for microlaryngoscopy were randomized to receive, in a double-blind manner, either remifentanil (loading dose 1 microg/kg; maintenance infusion, 0.25 microg x kg(-1) x min-1) or alfentanil (loading dose, 50 microg/kg; maintenance infusion, 1 microg x kg(-1) x min-1) as the analgesic component of TIVA. They were combined with propofol (loading dose, 2 mg/kg; maintenance infusion, 100 microg x kg(-1) min(-1)). To insure an equal state of anesthesia, the opioids were titrated to maintain heart rate and mean arterial pressure within 20% of baseline, and propofol was titrated to keep the bispectral index (BIS) less than 60. Neuromuscular blockade was achieved with succinylcholine. Drug dosages and the times from cessation of anesthesia to extubation, verbal response, recovery of ventilation, and neuropsychological testing, orientation, and discharge readiness were recorded. Results Demographics, duration of surgery, and anesthesia were similar between the two groups. Both groups received similar propofol doses. There were no difference in BIS values preoperatively (mean, 96), intraoperatively (mean, 55), and postoperatively (mean, 96). Recovery of BIS and times for verbal response did not differ. At 20, 30, and 40 min after terminating the opioid infusion, the peripheral oxygen saturation and respiratory rate were significantly higher in the remifentanil group compared with the alfentanil group. Conclusions When both the hypnotic and analgesic components of a TIVA-based anesthetic are administered in equipotent doses, remifentanil provides a more rapid respiratory recovery, even after brief surgical procedures, compared with alfentanil.