Effect of nitrous oxide and dexmedetomidine on the consumption of propofol during general anesthesia in adult patients

Background: Use of both nitrous oxide and dexmedetomidine as anesthetic adjuvants has shown to reduce the consumption of propofol required for the maintenance of anesthesia. The present study evaluated these two agents for their propofol sparing effect which has not been compared so far. Materials and Methods: Sixty adult patients undergoing elective surgery were enrolled and randomly divided into three groups. Patients in group P received propofol started at 166 μg/kg/min and then titrated to maintain the Bi-Spectral Index (BIS) value between 40 and 60, while patients in group N and in group D received nitrous oxide as carrier gas and infusion of dexmedetomidine (1 μg/kg over 10 min followed by 0.5 μg/kg/h) respectively, in addition to propofol. Primary outcome of the study was total consumption of propofol. Secondary outcomes measured were intraoperative hemodynamics, recovery profile, residual sedation, rescue analgesic requirements, and relevant side effects. Results: Total consumption of propofol was significantly higher in group P (139.02 ± 65.24 μg) compared to group N (94.72 ± 48.04 μg) and group D (98.31 ± 39.45 μg) (mean difference [95% confidence interval] group P and N 44.3 [17.9–44.7]; group P and D 40.71 [26.0–52.8]; group N and D 3.59 [−5.3–21.5]) ( P = 0.015). Although the recovery parameters (time to extubation, time to achieve BIS of 90, and time to verbal commands) were significantly prolonged in group D ( P < 0.001), time to discharge from postanesthesia care unit (PACU) was comparable among all groups ( P = 0.65). When arrived in PACU, patients in group D were significantly more sedated ( P = 0.0005) however, the 30 min in PACU the difference was nonsignificant. None of the patients in group D had nausea and vomiting and did not require additional analgesics. Conclusion: Both nitrous oxide and dexmedetomidine significantly decreased the total consumption of propofol. Hence, both these agents can be used as potential anesthetic adjuvants to decrease the side effects associated with propofol infusion. Due to the lack of any reported environmental and long-term side effects, dexmedetomidine can be a safer and better alternative to nitrous oxide.