title: Hypoxemia during outpatient gastrointestinal endoscopy: the effects of sedation and supplemental oxygen.
abstract: OBJECTIVE
  To compare the effects on oxygen saturation as measured by pulse oximetry (SpO2) and ECG changes of endoscopy alone, sedation followed by endoscopy, and sedation followed by endoscopy with supplemental oxygen (O2) during upper gastrointestinal (GI) endoscopy.
  
  
  METHODS
  Randomized trial.
  
  
  METHODS
  Outpatient gastroenterology clinic at a university medical center.
  
  
  METHODS
  58 healthy patients scheduled for outpatient upper GI endoscopy, with no clinical evidence of respiratory disease.
  
  
  METHODS
  Patients were randomly allocated to three groups: Group 1 received no benzodiazepines before endoscopy and breathed room air throughout (n = 18), Group 2 received midazolam intravenously (i.v.) before endoscopy and breathed room air throughout (n = 20), and Group 3 received i.v. midazolam and 2 L/min O2 through nasal cannulae during endoscopy (Group 3; n = 20).
  
  
  RESULTS
  Data collection, which included heart rate, cardiac rhythm, and SpO2 were recorded at seven intervals: baseline, topical anesthesia of the oropharynx, mouth gag insertion, endoscope insertion, biopsy, endoscope removal, and five minutes postendoscopy. In Group 2, mean SpO2 decreased after midazolam was administered and remained depressed during endoscopy (p < 0.05). After midazolam was given, Group 2 patients differed significantly from patients in Groups 1 and 3 (p < 0.05).
  
  
  CONCLUSIONS
  The use of hypnotic doses of benzodiazepines is the primary factor responsible for the reduced oxygenation seen during endoscopy. Neither the presence of the endoscope alone nor the use of midazolam with supplemental O2 caused a decreased oxygenation. This study also suggests that the routine use of benzodiazepines is unnecessary when the endoscopy is of short duration, and the endoscopist employs good topicalization of the oropharynx. In patients who require sedation for endoscopy, O2 administration prevents hypoxemia.
authors.affiliation: Department of Anaesthesia, St. James's Hospital, Dublin, Ireland.
authors.forename: K W
authors.initials: KW
authors.lastname: Patterson
authors.forename: N
authors.initials: N
authors.lastname: Noonan
authors.forename: N W
authors.initials: NW
authors.lastname: Keeling
authors.forename: R
authors.initials: R
authors.lastname: Kirkham
authors.forename: D F
authors.initials: DF
authors.lastname: Hogan
mesh_terms: D004562:Electrocardiography / Q000187:drug effects; D016099:Endoscopy, Gastrointestinal; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000139:chemically induced / Q000517:prevention & control*; D007275:Injections, Intravenous; D008297:Male; D008874:Midazolam / Q000008:administration & dosage / Q000009:adverse effects*; D008875:Middle Aged; D010092:Oximetry; D010102:Oxygen Inhalation Therapy; D011292:Premedication
chemical_list: D008874:Midazolam