Hyperoxia in pediatric severe traumatic brain injury (TBI): a comparison of patient classification by cutoff versus cumulative (area-under-the-curve) analysis.

OBJECTIVE: Hyperoxia is associated with adverse outcome in severe traumatic brain injury (TBI). This study explored differences in patient classification of oxygen exposure by PaO2 cutoff and cumulative area-under-the-curve (AUC) analysis. METHODS: Retrospective, explorative study including children (<18 years) with accidental severe TBI (2002-2015). Oxygen exposure analysis used three PaO2 cutoff values and four PaO2 AUC categories during the first 24 hours of Pediatric Intensive Care Unit (PICU) admission. RESULTS: Seventy-one patients were included (median age 8.9 years [IQR 4.6-12.9]), mortality 18.3% (n = 13). Patient hyperoxia classification differed depending on PaO2 cutoff vs AUC analysis: 52% vs. 26%, respectively, were classified in the highest hyperoxia category. Eleven patients (17%) classified as 'intermediate oxygen exposure' based on cumulative PaO2 analysis whereby they did not exceed the 200 mmHg PaO2 cutoff threshold. Patient classification variability was reflected by Pearson correlation coefficient of 0.40 (p-value 0.001). CONCLUSIONS: Hyperoxia classification in pediatric severe TBI during the first 24 hours of PICU admission differed depending on PaO2 cutoff or cumulative AUC analysis. We consider PaO2 cumulative (AUC) better approximates (patho-)physiological circumstances due to its time- and dose-dependent approach. Prospective studies exploring the association between cumulative PaO2, physiological parameters (e.g. ICP, PbtO2) and outcome are warranted as different patient classifications of oxygen exposure influences how its relationship to outcome is interpreted.