Assessment of depth of anesthesia and postoperative respiratory recovery after remifentanil- versus alfentanil-based total intravenous anesthesia in patients undergoing ear-nose-throat surgery

Background: The authors investigated whether total intravenous anesthesia ( TIVA) with precalculated equipotent infusion schemes for remifentanil and a lfentanil would ensure appropriate analgesia and that remifentanil would re sult in better recovery characteristics. Methods: forty consenting patients (classified as American Society of Anest hesiologists physical status I-III) scheduled for microlaryngoscopy were ra ndomized to receive, in a double-blind manner, either remifentanil (loading dose 1 mug/kg; maintenance infusion, 0.25 mug.kg(-1).min(-1)) or alfentani l (loading dose, 50 mug/kg; maintenance infusion, 1 mug.kg(-1).min(-1)) as the analgesic component of TIVA. They were combined with propofol (loading dose, 2 mg/kg; maintenance infusion, 100 mug.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 titrat ed to keep the bispectral index (BIS) less than 60. Neuromuscular blockade was achieved with succinylcholine. Drug dosages and the times from cessatio n of anesthesia to extubation, verbal response, recovery of ventilation, an d neuropsychological testing, orientation, and discharge readiness were rec orded. Results: Demographics, duration of surgery, and anesthesia were similar bem een the two groups. Both groups received similar propofol doses. There wer e no difference in BIS values preoperatively (mean, 96), intraoperatively ( mean, 55), and postoperatively (mean, 96). Recovery of BIS and times for ve rbal response did not differ. At 20, 30, and 40 min after terminating the o pioid 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-base d anesthetic are administered in equipotent doses, remifentanil provides a more rapid respiratory recovery, even after brief surgical procedures, comp ared with alfentanil.