Nitrous oxide for colonoscopy: a randomized controlled study

• Published in: Gastrointestinal endoscopy 2000-03, Vol.51 (3), p.271-277
• Main Authors: Forbes, Geoffrey M., Collins, Brendan J.
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Ambulatory Care; Analgesics, Non-Narcotic - administration & dosage; Analgesics, Opioid - administration & dosage; Anesthesia Recovery Period; Attitude of Health Personnel; Biological and medical sciences; Colonoscopy - adverse effects; Colonoscopy - psychology; Digestive system. Abdomen; Endoscopy; Female; Humans; Hypnotics and Sedatives - administration & dosage; Injections, Intravenous; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Meperidine - administration & dosage; Midazolam - administration & dosage; Middle Aged; Nitrous Oxide - administration & dosage; Patient Satisfaction; Tropical medicine
• ISSN: 0016-5107; 1097-6779
• DOI: 10.1016/S0016-5107(00)70354-3

Background: Intravenous sedation/analgesia for colonoscopy is accompanied with certain risks and postprocedure drowsiness. We sought to determine whether inhaled nitrous oxide (Entonox: 50% nitrous oxide, 50% oxygen) provides adequate analgesia for colonoscopy and the impact of this agent on recovery. Methods: All patients undergoing outpatient colonoscopy were considered for the study (n = 248) except those with previous colonic resection. Data for patients unsuitable for randomization (n = 58) and those who declined to participate (n = 88) were also analyzed. Results: One hundred two patients were randomized to receive inhaled Entonox alone (n = 56) or intravenous midazolam and meperidine (n = 46). Forty-nine (88%) patients randomized to Entonox underwent complete colonoscopy without conversion to intravenous medications. Entonox patients reported more pain ( p < 0.0001), tolerated colonoscopy less well ( p < 0.0001), were less satisfied ( p = 0.01), and less willing to undergo colonoscopy again under the same circumstances ( p = 0.04). Of patients receiving intravenous medication, 91% found colonoscopy less unpleasant and 9% as unpleasant as anticipated; this compares with 52% and 21% Entonox patients, respectively, and an additional 27% Entonox patients who found colonoscopy more unpleasant than anticipated. Recovery was faster among Entonox patients (median 30 versus 60 minutes, p < 0.0001). Conclusion: Entonox is less effective than midazolam with meperidine for colonoscopy but is acceptable in many patients and allows faster recovery. (Gastrointest Endosc 2000;51:271-7.)