title: Immediate recovery of psychomotor function after patient-administered nitrous oxide/oxygen inhalation for colonoscopy.
abstract: OBJECTIVE
  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.
  
  
  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.
authors.affiliation: Dept. of Endoscopy, St. Mark's Hospital, London, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Trojan
authors.forename: B P
authors.initials: BP
authors.lastname: Saunders
authors.forename: M
authors.initials: M
authors.lastname: Woloshynowych
authors.forename: H S
authors.initials: HS
authors.lastname: Debinsky
authors.forename: C B
authors.initials: CB
authors.lastname: Williams
mesh_terms: D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage; D003113:Colonoscopy; D016292:Procedural Sedation; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D008297:Male; D008614:Meperidine / Q000008:administration & dosage; D008874:Midazolam / Q000008:administration & dosage; D008875:Middle Aged; D009609:Nitrous Oxide / Q000008:administration & dosage*; D010100:Oxygen / Q000008:administration & dosage*; D011292:Premedication; D011597:Psychomotor Performance / Q000187:drug effects*; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D006993:Hypnotics and Sedatives; D008614:Meperidine; D009609:Nitrous Oxide; D008874:Midazolam; D010100:Oxygen