Abstract
Background and Study Aims: Previous studies have shown that patients inhaling 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 after nitrous oxide/oxygen
sedation or intravenous opiate/benzodiazepine premedication for colonoscopy.
Patients and Methods: Consecutive colonoscopy patients were randomized to receive either a 50 % nitrous
oxide/oxygen 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 multiple-choice reaction
time, hand-eye co-ordination, and letter deletion tests before and at 15-minute intervals
after colonoscopy, with the assessment carried out by an observer blinded to the sedation
regime.
Results: The mean duration and tolerance of the procedure were similar in the three study
groups. Patients receiving nitrous oxide/oxygen mixture were judged (by clinical observation)
to recover more quickly than those given conventional sedation (median 8 min, range
3-25 min, vs. median 16 min, range 3-50 min). Recovery, as judged by a return to baseline
in psychomotor function tests, was complete within 30 minutes in all 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 colonoscopy 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.
