Conservative versus Liberal Oxygenation Targets for Mechanically Ventilated Patients. A Pilot Multicenter Randomized Controlled Trial

Am J Respir Crit Care Med. 2016 Jan 1;193(1):43-51. doi: 10.1164/rccm.201505-1019OC.


Rationale: There are no randomized controlled trials comparing different oxygenation targets for intensive care unit (ICU) patients.

Objectives: To determine whether a conservative oxygenation strategy is a feasible alternative to a liberal oxygenation strategy among ICU patients requiring invasive mechanical ventilation (IMV).

Methods: At four multidisciplinary ICUs, 103 adult patients deemed likely to require IMV for greater than or equal to 24 hours were randomly allocated to either a conservative oxygenation strategy with target oxygen saturation as measured by pulse oximetry (SpO2) of 88-92% (n = 52) or a liberal oxygenation strategy with target SpO2 of greater than or equal to 96% (n = 51).

Measurements and main results: The mean area under the curve and 95% confidence interval (CI) for SpO2 (93.4% [92.9-93.9%] vs. 97% [96.5-97.5%]), SaO2 (93.5% [93.1-94%] vs. 96.8% [96.3-97.3%]), PaO2 (70 [68-73] mm Hg vs. 92 [89-96] mm Hg), and FiO2 (0.26 [0.25-0.28] vs. 0.36 [0.34-0.39) in the conservative versus liberal oxygenation arm were significantly different (P < 0.0001 for all). There were no significant between-group differences in any measures of new organ dysfunction, or ICU or 90-day mortality. The percentage time spent with SpO2 less than 88% in conservative versus liberal arm was 1% versus 0.3% (P = 0.03), and percentage time spent with SpO2 greater than 98% in conservative versus liberal arm was 4% versus 22% (P < 0.001). The adjusted hazard ratio for 90-day mortality in the conservative arm was 0.77 (95% CI, 0.40-1.50; P = 0.44) overall and 0.49 (95% CI, 0.20-1.17; P = 0.10) in the prespecified subgroup of patients with a baseline PaO2/FiO2 less than 300.

Conclusions: Our study supports the feasibility of a conservative oxygenation strategy in patients receiving IMV. Larger randomized controlled trials of this intervention appear justified. Clinical trial registered with Australian New Zealand Clinical Trials Registry (ACTRN 12613000505707).

Keywords: critical illness; intensive care; mechanical ventilation; oxygen inhalation therapy; targets.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Female
  • Humans
  • Intensive Care Units
  • Male
  • Middle Aged
  • Oximetry
  • Oxygen / blood*
  • Oxygen Inhalation Therapy / methods*
  • Pilot Projects
  • Respiration, Artificial / methods*


  • Oxygen

Associated data

  • ANZCTR/ACTRN12613000505707