Abstract 41: Initial Hyperoxia Is Associated with Survival in Postarrest Patients Enrolled in the PATH Database

Abstract

Introduction: During and after resuscitation from cardiac arrest, patients often receive supplemental oxygen with high FiO 2 . Recent human data suggest that arterial hyperoxia within hours after resuscitation is associated with worse outcomes. We hypothesized that neurologically intact survivors would more likely be normoxic rather than hyperoxic or hypoxic. Methods: Retrospective chart review of post-arrest patients treated with therapeutic hypothermia (TH) in the Penn Alliance for Therapeutic Hypothermia (PATH) database from 11 institutions. Demographic variables were analyzed using chi-square tests. Data were collected at first arterial blood gas (ABG), and 12 hrs, 24 hrs, 36 hrs, and 48 hrs post arrest. Logistic regression was performed to assess the relationship between initial hypoxia (PaO 2 300 mmHg), mortality, and neurologic outcome. Results: We enrolled 179 patients with mean age 59.6 ± 16.4 yrs, 54% male, and 31% of initial rhythms were VF/VT. Sixty-six (37%) survived to discharge; and 50/66 (76%) had good neurologic outcome (cerebral performance category 1 or 2). An increasing percentage of PaO 2 values were in the optimal range at consecutive times (51% 0 hr; 82% 12 hrs; 90% 24 hrs; 93% 36 hrs; 92% 48 hrs). Survivors had significantly higher initial PaO 2 values than non-survivors (242 vs. 187 mmHg; p=0.03). When controlling for initial rhythm and gender, initial hyperoxia (> 300 mmHg) was associated with improved survival relative to normoxia (OR 2.07, 95% CI 0.98-4.36, p=0.055) while initial hypoxia did not affect outcomes (OR 0.63, 95% CI 0.23-1.70, p=ns). Thirty percent (54/179) were hyperoxic at time 0 and 39% (21/54) of them survived with good neurologic outcome. No significant association was found between oxygen status and neurologic outcomes (hyperoxia (OR 1.89, 95% CI 0.83-4.32, p=ns); hypoxia (OR 0.91, 95% CI 0.30-2.77, p=ns). Conclusions: Increasing percentages of patients had arterial oxygen levels optimized after ROSC. Increased survival was shown in patients with hyperoxic initial PaO 2 values when compared to normoxic values. There was no relationship between the arterial oxygen values and neurologic outcomes post-arrest.