Effects of hyperoxemia on aneurysmal subarachnoid hemorrhage outcomes: a systematic review and meta-analysis

Abstract

OBJECTIVE In recent years, hyperoxemia in the intensive care unit has received attention as potentially contributing to negative outcomes in the setting of cardiac arrest, ischemic stroke, and traumatic brain injury. The authors sought to evaluate whether hyperoxemia contributes to worse outcomes in the setting of aneurysmal subarachnoid hemorrhage (aSAH) and to summarize suggested pathophysiological mechanisms. METHODS A systematic literature review was conducted without date restrictions on the PubMed and Web of Science databases on September 15, 2021. All studies that assessed the relationship between patients treated for aSAH and hyperoxemia were eligible independent of the criteria used to define hyperoxemia. All nonclinical studies and studies that did not report outcome data specific to patients with aSAH were excluded. A total of 102 records were found and screened, resulting in assessment of 10 full-text studies, of which 7 met eligibility criteria. Risk of bias was assessed using the Downs and Black checklist. A meta-analysis on the pooled 2602 patients was performed, and forest plots were constructed. Additionally, a review of the literature was performed to summarize available data regarding the pathophysiology of hyperoxemia. RESULTS The included studies demonstrated an association between hyperoxemia and increased morbidity and mortality following aSAH. The criteria used to determine hyperoxemia varied among studies. Pooling of univariate data showed hyperoxemia to be associated with poor neurological outcome (OR 2.26, 95% CI 1.66–3.07; p < 0.001), delayed cerebral ischemia (DCI) (OR 1.91, 95% CI 1.31–2.78; p < 0.001), and increased incidence of poor neurological outcome or mortality as a combined endpoint (OR 2.36, 95% CI 1.87–2.97; p < 0.001). Pooling of multivariable effect sizes showed the same relationship for poor neurological outcome (OR 1.28, 95% CI 1.07–1.55; p = 0.01) and poor neurological outcome and mortality as a combined endpoint (OR 1.17, 95% CI 1.11–1.23; p < 0.001). Additionally, review of preclinical studies underlined the contribution of oxidative stress due to hyperoxemia to acute secondary brain injury and DCI. CONCLUSIONS Reported outcomes from the available studies have indicated that hyperoxemia is associated with worse neurological outcome, mortality, and DCI. These findings provide a general guideline toward avoiding hyperoxemia in the acute setting of aSAH. Further studies are needed to determine the optimal ventilation and oxygenation parameters for acute management of this patient population.

Hyperoxia is Dose-Dependently Associated with an Increase of Unfavorable Outcomes in Ventilated Patients with Aneurysmal Subarachnoid Hemorrhage: A Retrospective Cohort Study

“…However, no hyperoxia threshold or optimum oxygen target range could be established so far. With our study, we identified a range in which a potential hyperoxia threshold and an optimum oxygen target range may be situated, and we deem prospective confirmatory studies necessary, as has been suggested by other authors as well [ 22 ]. For example, comparing a target range of 75–85 mm Hg vs. 95–105 mm Hg approximating our quartiles 2 and 4 would require approximately 400 patients to detect a 14% difference in favorable outcome at 3 months.…”

“…When we reviewed the available data on oxygen targets in patients with SAH, no benefit could be shown for hyperoxia, and some studies could even show harm [ 22 ]. However, no hyperoxia threshold or optimum oxygen target range could be established so far.…”

Association between SpO2 and the risk of death in elderly T2DM patients with cerebral infarction: a retrospective cohort study

“…High oxygen saturation was linked to neurological adverse outcomes in adult patients with acute diseases, especially subarachnoid hemorrhage and cerebral infarction ( 31 ). In the case of aneurysmal subarachnoid hemorrhage, elevated oxygen saturation was correlated with poor neurological outcomes, increased mortality, and a higher incidence of DCI ( 32 ).…”

Exposure to hyperoxemia worsens survival and neurological outcome in patients supported by veno-arterial extracorporeal membrane oxygenation: a meta-analysis

“…Hence, even if our results are not derived from randomized controlled trials (RCTs), the ndings are supported by the correction for possible confounders and the large sample size. To randomize patients for different levels of oxygenation, including manifest hyperoxemia, would be certainly unethical considering that a not negligible body of literature suggests harmful effects of hyperoxemia in critically ill patients [40][41][42][43][44][45][46].…”