Hyperoxia and unfavourable outcome in patients with non-traumatic subarachnoid haemorrhage: A systematic review and meta-analysis

Abstract

Background

It is common practice to administer oxygen to neurocritical patients in the Intensive Care Unit (ICU). Consequent hyperoxia has been associated with unfavourable outcomes including in patients with brain injury, after cardiac arrest, sepsis, and traumatic brain injury. The aim of this systematic review was to explore the association between hyperoxia exposure and unfavourable outcome in patients following a non-traumatic subarachnoid haemorrhage (SAH).

Methods

Systematic searches of Medline, Embase, Emcare, CINAHL and PubMed were performed in February 2024 using key words for SAH and hyperoxia. Non-human studies, articles in languages other than English, studies that did not measure blood oxygenation levels via pulse oximetry or arterial blood gas analyses, and studies exploring traumatic SAH were excluded. The Newcastle-Ottawa Risk of Bias tool (NOS) was used to assess the quality of included manuscripts. The primary outcome was a composite outcome combining mortality or poor functional neurological outcome. Secondary outcomes included mortality, poor functional neurological outcome, and development of delayed cerebral ischaemia (DCI).

Results

The literature search yielded 1,219 non-duplicate articles published after 1 January 2000, of which 21 articles were reviewed as full-texts and nine were included in this review. All included studies were rated good/high quality using the NOS. Hyperoxia exposure was associated with increased risk of adverse composite outcome of death or unfavourable functional neurological outcome (odds ratio (OR) 1.61, 95% confidence interval (CI) 1.19–2.16), poor functional neurological outcome alone (OR 1.79, 95% CI 1.33–2.42) and development of DCI (OR 2.63, 95% CI 1.79–3.85). The association of hyperoxia and hospital mortality alone was not statistically significant (OR 1.42, 95% CI 0.98–2.04).

Conclusion

Hyperoxia may contribute to unfavourable outcomes and the development of DCI after an non-traumatic SAH. Trials using restrictive oxygen therapy among patients with SAH are indicated.