Oxygen is vital during critical illness, but hyperoxia may harm patients. Our aim was to systematically evaluate the methodology and findings of cohort studies investigating the effects of hyperoxia in critically ill adults.
A meta-analysis and meta-regression analysis of cohort studies published between 2008 and 2015 was conducted. Electronic databases of MEDLINE, EMBASE, and Web of Science were systematically searched for the keywords hyperoxia and mortality or outcome.
Publications assessing the effect of arterial hyperoxia on outcome in critically ill adults (≥ 18 yr) admitted to critical care units were eligible. We excluded studies in patients with chronic obstructive pulmonary disease, extracorporeal life support or hyperbaric oxygen therapy, and animal studies. Due to a lack of data, no studies dedicated to patients with acute lung injury, sepsis, shock, or multiple trauma could be included.
Studies were included independent of admission diagnosis and definition of hyperoxia. The primary outcome measure was in-hospital mortality, and results were stratified for relevant subgroups (cardiac arrest, traumatic brain injury, stroke, post–cardiac surgery, and any mechanical ventilation). The effects of arterial oxygenation on functional outcome, long-term mortality, and discharge variables were studied as secondary outcomes.
Twenty-four studies were included of which five studies were only for a subset of the analyses. Nineteen studies were pooled for meta-analyses and showed that arterial hyperoxia during admission increases hospital mortality: adjusted odds ratio, 1.21 (95% CI, 1.08–1.37) (p = 0.001). Functional outcome measures were diverse and generally showed a more favorable outcome for normoxia.
In various subsets of critically ill patients, arterial hyperoxia was associated with poor hospital outcome. Considering the substantial heterogeneity of included studies and the lack of a clinical definition, more evidence is needed to provide optimal oxygen targets to critical care physicians.
1Department of Intensive Care Medicine, Leiden University Medical Center, Leiden, The Netherlands.
2Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands.
3Department of Medical Informatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
* See also p. 1547.
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