Association Between Early Hyperoxia Exposure After Resuscitation from Cardiac Arrest and Neurological Disability: A Prospective Multi-Center Protocol-Directed Cohort Study
Background—Studies examining the association between hyperoxia exposure after resuscitation from cardiac arrest and clinical outcomes have reported conflicting results. Our objective was to test the hypothesis that early post-resuscitation hyperoxia is associated with poor neurological outcome.
Methods—Multi-center, prospective cohort study. We included adult, cardiac arrest patients who were mechanically ventilated and received targeted temperature management after return of spontaneous circulation (ROSC). We excluded patients with cardiac arrest due to trauma or sepsis. Per protocol, partial pressure of arterial oxygen (PaO2) was measured at one and six hours after ROSC. Hyperoxia was defined as a PaO2 > 300 mmHg during the initial six hours after ROSC. The primary outcome was poor neurological function at hospital discharge, defined as a modified Rankin Scale > 3. Multivariable generalized linear regression with a log link was used to test the association between PaO2 and poor neurological outcome. To assess if there was an association between other supranormal PaO2 levels and poor neurological outcome, we used other PaO2 cut points to define hyperoxia (i.e. 100, 150, 200, 250, 350, 400 mmHg).
Results—Of the 280 patients included, 105 (38%) had exposure to hyperoxia. Poor neurological function at hospital discharge occurred in 70% of patients in the entire cohort, and 77% vs. 65% among patients with and without exposure to hyperoxia respectively [absolute risk difference 12% (95% CI 1% - 23%)]. Hyperoxia was independently associated with poor neurological function, relative risk 1.23 (95% CI 1.11 - 1.35). On multivariable analysis, a one-hour longer duration of hyperoxia exposure was associated with a 3% increase in risk of poor neurological outcome [relative risk 1.03 (95% CI 1.02 - 1.05)]. We found the association with poor neurological outcome began at 300 mmHg or higher.
Conclusions—Early hyperoxia exposure after resuscitation from cardiac arrest was independently associated with poor neurological function at hospital discharge.
- Received October 3, 2017.
- Revision received December 20, 2017.
- Accepted January 4, 2018.