Association between high arterial oxygen tension and long-term survival after intracerebral hemorrhage

Introduction

Liberal use of oxygen after brain insults remains controversial [1, 2]. We studied whether high arterial oxygen tension (PaO₂) is associated with decreased long-term survival in patients with spontaneous intracerebral hemorrhage (ICH) treated in the ICU.

Methods

Data on primary admissions for adult patients (>18 years) treated for ICH in Finnish ICUs between 2003 and 2012 were collected from a nationwide ICU database. Patients were divided into three groups according to the PaO₂ value associated with the lowest measured PaO₂/ FIO₂ ratio during the first 24 hours after ICU admission. High arterial oxygen tension was defined as PaO₂ >19.9 kPa; intermediate as PaO₂ 13 to 19.9 kPa; and low as PaO₂ <13 kPa. The primary outcome was 6-month mortality.

Results

Of the 3,033 patients, 63% (n = 1,923) had low PaO₂, 29% (n = 892) intermediate PaO₂, and 7% (n = 218) high PaO₂. Forty-nine percent of the patients died during the 6-month follow-up. Of these, 75% died before discharge from hospital. Univariate analysis showed that 6-month mortality was higher in the high PaO₂ group (61%) compared with the intermediate and low PaO₂ groups (52% and 46% respectively, P < 0.001). Multivariate analysis, however, showed no statistically significant correlation between high PaO₂ and mortality (with the low PaO₂ group as the reference category, odds ratio for death (OR) for high PaO₂ = 1.10, 95% confidence interval (CI) = 0.76 to 1.58 and for intermediate PaO₂ = 0.96, 95% CI = 0.78 to 1.17).

Conclusion

High PaO₂ is not predictive of 6-month mortality in patients treated for spontaneous ICH in the ICU. Therefore, targeting higher PaO₂ values appears to be a safe approach in order to avoid hypoxemia.