Panwar R, Hardie M, Bellomo R, Barrot L, Eastwood GM, Young PJ, Capellier G, Harrigan PW, Bailey M; CLOSE study investigators and the ANZICS Clinical Trials Group..; Am J Respir Crit Care Med. 2015 Sep 3. [Epub ahead of print]

RATIONALE: There are no randomized controlled trials (RCTs) 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 ≥24 hours were randomly allocated to either a conservative oxygenation strategy with target SpO2 of 88-92% (n=52) or a liberal oxygenation strategy with target SpO2 of ≥96% (n=51).

MEASUREMENTS AND MAIN RESULTS: The mean area-under-curve and 95% confidence interval (CI) for SpO2 [93.4% (92.9-93.9%) versus 97% (96.5-97.5%)], SaO2 [93.5% (93.1-94%) versus 96.8% (96.3-97.3%)], PaO2 [70 (68-73) mmHg versus 92 (89-96) mmHg] and FiO2 [0.26 (0.25-0.28) versus 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 <88% in conservative versus liberal arm was 1% versus 0.3% (p=0.03), and percentage time spent with SpO2 >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 pre-specified subgroup of patients with a baseline PaO2/FiO2 <300.

CONCLUSIONS: Our study supports the feasibility of a conservative oxygenation strategy in patients receiving IMV. Larger RCTs of this intervention appear justified.

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