Impact of a preoperative conversational hypnotic session on propofol consumption using closed-loop anesthetic induction guided by the bispectral index: A randomized controlled trial

OBJECTIVE: The automated administration of propofol in a closed loop could be used to objectively evaluate the nonpharmacological anesthetic action of hypnotherapy. The objective of this study was to evaluate the impact of a conversational hypnosis session on the consumption of propofol for anesthetic induction. DESIGN: A randomized, usual care-controlled, single-center, patient-blind trial. SETTING: Tertiary care center in France from November 2012 to December 2013. PARTICIPANTS: Adult patients scheduled for a surgical procedure under general anesthesia. INTERVENTIONS: Before surgery, patients were randomized with a computer-generated random list for a preoperative conversational hypnosis session or for usual care. The conversational hypnosis session was conducted and individualized by the therapist with an academic degree in hypnosis in a quiet environment. Anesthetic induction was automatically performed by propofol without opioids and was assisted by the bispectral index in a closed loop. OUTCOME: Primary endpoint was the propofol dose required for anesthesia induction, defined as a Bispectral index less than 60 for at least 30 seconds. RESULTS: The study included 48 patients in the hypnosis group and 49 patients in the control group. No difference in propofol consumption to obtain anesthesia induction was observed between the groups (total dose: 138.6 [67.5] and 130 [47.9] mg, P = .47; adjusted dose: 2.15 [1.09] and 1.95 [0.66] mg/kg, P = .28, for the hypnosis and control groups, respectively). Hetero-evaluation of arm movement during propofol injection (no reaction: 98% and 74%; P = .004, in the hypnosis and control groups, respectively) and face reaction at venous access placement (no reaction 59% and 30%; P = .017, in the hypnosis and control groups, respectively) were lower in the hypnosis group. No adverse event was reported. CONCLUSIONS: No difference in propofol consumption was observed in this study designed to evaluate the effect of a hypnotic conversational session on anesthesia induction using an automated tool for propofol administration.