IMMEDIATE RECOVERY OF PSYCHOMOTOR FUNCTION AFTER PATIENT-ADMINISTEREDNITROUS OXIDE OXYGEN INHALATION FOR COLONOSCOPY/

Background and Study Aims: Previous studies have shown that patients i nhaling self-administered nitrous oxide/oxygen as a sedative/analgesic medication for colonoscopy were ready to leave the endoscopy unit on average sooner than those given conventional intravenous premedication , The aim of this study was to define the time course of recovery afte r nitrous oxide/oxygen sedation or intravenous opiate/benzodiazepine p remedication for colonoscopy. Patients and Methods: Consecutive colono scopy patients were randomized to receive either a 50% nitrous oxide/o xygen mixture (n=12), or pethidine 25-50 mg and midazolam 2.5 mg (n=15 ), or no sedation (n=10), Psychomotor function was assessed by multipl e-choice reaction time, hand-eye co-ordination, and letter deletion te sts before and at 15-minute intervals after colonoscopy, with the asse ssment carried out by an observer blinded to the sedation regime. Resu lts: The mean duration and tolerance of the procedure were similar in the three study groups. Patients receiving nitrous oxide/oxygen mixtur e were judged (by clinical observation) to recover more quickly than t hose given conventional sedation (median 8 min, range 3-25 min, vs, me dian 16 min, range 3-50 min), Recovery, as judged by a return to basel ine in psychomotor function tests, was complete within 30 minutes in a ll patients receiving the nitrous oxide/oxygen mixture, compared to 50 minutes in those given conventional intravenous sedation. Conclusions : The rapid recovery observed with nitrous oxide/oxygen sedation for c olonoscopy suggests that it is safe for patients to travel unescorted after the procedure, Driving may also be safe soon after nitrous oxide /oxygen sedation, but this requires further clarification.