The association between early arterial oxygenation and mortality in ventilated patients with acute ischaemic stroke.

BackgroundThere are conflicting data that suggest that hyperoxia may be associated with either worse or better outcomes in patients suffering a stroke.ObjectivesTo investigate the association between PaO(2) in the first 24 hours in the intensive care unit and mortality among ventilated patients with acute ischaemic stroke.DesignRetrospective cohort study.SettingData were extracted from the Australian and New Zealand Intensive Care Society Adult Patient Database.ParticipantsAdults ventilated for ischaemic stroke in 129 ICUs in Australia and New Zealand, 2000-2009.Main outcome measuresThe primary outcome was the odds ratio for in hospital mortality associated with "worst" PaO(2) considered as a categorical variable, with data divided into deciles and compared with the mortality of the 10th decile. For patients on an FiO(2) of _50% at any time in the first 24 hours, "worst" PaO(2) was defined as the PaO(2) associated with the highest alveolar-arterial (A-a) gradient. For patients on an FiO(2) of <50%, it was defined as the lowest PaO(2). Secondary outcomes were ICU and hospital length of stay and the proportion of patients in each decile discharged home.ResultsOf the 2643 patients eligible for study inclusion, 1507 (57%) died in hospital. The median "worst" PaO(2) was 117mmHg (interquartile range, 87-196mmHg). There was no association between worst PaO(2) and mortality, length of stay or likelihood of discharge home.ConclusionsWe found no association between worst arterial oxygen tension in the first 24 hours in ICU and outcome in ventilated patients with ischaemic stroke.