title: A randomized controlled trial comparing continuous and as-required nitrous oxide use during screening colonoscopy.
abstract: OBJECTIVE
  Entonox is a 50 : 50 combination of nitrous oxide and oxygen, which may be used to manage pain during colonoscopy. The optimal mode of Entonox administration is unknown. The aim of this study was therefore to compare continuous and as-required Entonox use.
  
  
  METHODS
  Patients attending for screening colonoscopy at a single centre were randomized to continuous or as-required Entonox use. The primary outcome measure was the patient's overall pain rating at the time of discharge (verbally administered numerical ratings scale, 0=no pain and 10=extreme pain). Secondary outcome measures included the patients' experience of pain during the colonoscopy (rated every 2 min), side effects and the need for rescue intravenous medications.
  
  
  RESULTS
  A total of 108 patients were randomized, and 100 completed the study (46 continuous, 54 as required). The overall pain scores at discharge did not differ between those who used Entonox continuously and as required (mean=2.4 vs. 3.2, P=0.08). There were also no differences in the experience of pain during colonoscopy (mean=1.8 vs. 2.2, P=0.28; peak=4.2 vs. 4.8, P=0.26; and area under curve=23 vs. 30, P=0.24). Patients with high anxiety had greater overall pain scores (mean=3.7 vs. 2.4, P=0.03). Light headedness occurred more often with continuous Entonox use (48 vs. 21%, P=0.009).
  
  
  CONCLUSIONS
  Among patients attending for screening colonoscopy, comfort ratings were similar in those using Entonox continuously and as required, but light headedness was more common with continuous use (NCT identifier: 01865721).
authors: aDepartment of Gastroenterology, Northern General Hospital bSouth Yorkshire and Bassetlaw Bowel Cancer Screening Centre, Sheffield Teaching Hospitals cDepartment of Oncology, University of Sheffield, Medical School, Sheffield, UK.
authors: Alex J
authors: AJ
authors: Ball
authors: Said
authors: S
authors: Din
authors: Mark
authors: M
authors: Donnelly
authors: Stuart A
authors: SA
authors: Riley
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage* / Q000009:adverse effects; D003113:Colonoscopy / Q000009:adverse effects / Q000379:methods*; D004334:Drug Administration Schedule; D055088:Early Detection of Cancer / Q000009:adverse effects / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000008:administration & dosage* / Q000009:adverse effects; D015588:Observer Variation; D010100:Oxygen / Q000008:administration & dosage* / Q000009:adverse effects; D010146:Pain / Q000209:etiology / Q000517:prevention & control; D010147:Pain Measurement / Q000379:methods
chemical_list: D018712:Analgesics, Non-Narcotic; C001147:Entonox; D009609:Nitrous Oxide; D010100:Oxygen