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

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 (Sp(O2)) of 88-92% (n = 52) or a liberal oxygenation strategy with target Sp(O2) 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 Sp(O2) (93.4% [92.9-93.9%] vs. 97% [96.5-97.5%]), Sp(O2) (93.5% [93.1-94%] vs. 96.8% [96.3-97.3%]), Pa-O2 (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 Sp(O2) less than 88% in conservative versus liberal arm was 1% versus 0.3% (P = 0.03), and percentage time spent with Sp(O2) 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 Pa-O2/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.