The utility of supplemental oxygen during emergency department procedural sedation and analgesia with midazolam and fentanyl: a randomized, controlled trial

Ann Emerg Med. 2007 Jan;49(1):1-8. doi: 10.1016/j.annemergmed.2006.06.013. Epub 2006 Sep 15.


Study objective: To determine whether supplemental oxygen reduces the incidence of hypoxia by 20% in study patients receiving midazolam and fentanyl for emergency department procedural sedation and analgesia.

Methods: Patients were randomized to receive either supplemental oxygen or compressed air by nasal cannula at 2 L per minute. Physicians were blinded to the gas used and end-tidal carbon dioxide (ETCO2) data. Respiratory depression was defined a priori as oxygen saturation less than 90%, ETCO2 level greater than 50 mm Hg, an absolute change from baseline of 10 mm Hg, or loss of the ETCO2 waveform.

Results: Of the 80 patients analyzed, 44 received supplemental oxygen and 36 received compressed air. Twenty supplemental oxygen patients and 19 compressed air patients met at least 1 criterion for respiratory depression. Six supplemental oxygen patients and 5 compressed air patients experienced hypoxia (P=.97; effect size 0%; 95% confidence interval -15% to +15%). Fourteen patients in each group met ETCO2 criteria for respiratory depression but were not hypoxic. Physicians identified respiratory depression in 8 of 11 patients who became hypoxic and 0 of 28 patients who met ETCO2 criteria for respiratory depression but who did not become hypoxic. There were no adverse events.

Conclusion: Supplemental oxygen did not reduce (or trend toward reducing) the incidence of hypoxia in patients moderately sedated with midazolam and fentanyl. However, our lower-than-expected rate of hypoxia limits the power of this comparison. Blinded capnography frequently identified respiratory depression undetected by the treating physicians.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Analgesia
  • Analgesics, Opioid
  • Capnography
  • Child
  • Child, Preschool
  • Conscious Sedation*
  • Double-Blind Method
  • Emergency Service, Hospital
  • Female
  • Fentanyl*
  • Humans
  • Hypnotics and Sedatives*
  • Hypoxia / diagnosis
  • Hypoxia / prevention & control*
  • Male
  • Midazolam*
  • Middle Aged
  • Oxygen / blood
  • Oxygen Inhalation Therapy*
  • Prospective Studies
  • Research Design
  • Respiratory Insufficiency / diagnosis
  • Respiratory Insufficiency / epidemiology
  • Respiratory Insufficiency / etiology


  • Analgesics, Opioid
  • Hypnotics and Sedatives
  • Midazolam
  • Oxygen
  • Fentanyl