Preoperative paracetamol infusion reduces sevoflurane consumption during thyroidectomy under general anesthesia with spectral entropy monitoring

Background: Intravenous (IV) paracetamol has a significant opioid-sparing effect. We investigated the effect of paracetamol infusion on sevoflurane consumption during entropy monitored general anesthesia. Methods: Sixty-two ASA I and II patients undergoing thyroidectomy under general anesthesia were included in a prospective, randomized, double-blind and placebo controlled study. The patients were randomized to receive a slow infusion of either 1 g paracetamol (paracetamol group, n = 31) or saline (control group, n=31) just before induction of anesthesia. Sevoflurane concentration was titrated to keep the state entropy value between 40 and 50. End-tidal sevoflurane concentration, sevoflurane consumption, recovery characteristics, time to first analgesic request and meperidine consumption during the first 6 postoperative hours were recorded. Results: The mean +/- SD estimated sevoflurane consumption was significantly lower in the paracetamol treated patients (36.2 +/- 15 vs 44.9 +/- 13.9 ml, in the control group; p=0.021). Patients receiving paracetamol had a faster post-anesthetic recovery profile (extubation time, time to eye opening to command and time to state name and mention his/her home address) than the other group (p < 0.05). Mean +/- SD time to first analgesic request was significantly prolonged in paracetamol group compared to control group (48.4 +/- 14.0 vs 40.7 +/- 11.5 min, respectively; p = 0.021). Meperidine consumption was higher in control group than in paracetamol group (28.7 +/- 10.2 vs 23.1 +/- 9.0 mg, respectively; p=0.025). Conclusion: Preoperative IV paracetamol infusion improved consumption and emergence from entropy monitored sevoflurane anesthesia with enhancement of the early postoperative analgesia. (C) 2014 Production and hosting by Elsevier B.V. on behalf of Egyptian Society of Anesthesiologists. Open access under CC BY-NC-ND license.