Brain Hypoxia is Associated with Short-Term Outcome After Severe Traumatic Brain Injury Independent of Intracranial Hypertension and Low Cerebral Perfusion Pressure
Ahead of Print: Brain Hypoxia is Associated with Short-Term Outcome After Severe Traumatic Brain Injury Independent of Intracranial Hypertension and Low Cerebral Perfusion Pressure
BACKGROUND: Brain hypoxia (BH) can aggravate outcome after severe traumatic brain injury (TBI). Whether BH or reduced brain oxygen (PbtO2) is an independent outcome predictor or a marker of disease severity is not fully elucidated.
OBJECTIVE: To analyze the relationship between PbtO2, ICP, and cerebral perfusion pressure (CPP) and examine whether BH correlates with worse outcome independently from ICP and CPP.
METHODS: We studied 103 patients monitored with ICP and PbtO2 for > 24 hours. Durations of BH (PbtO2 20 mm Hg and CPP < 60 mm Hg were calculated with linear interpolation and their association with outcome within 30 days was analyzed.
RESULTS: Duration of BH was longer in patients with unfavorable (Glasgow Outcome Score [GOS] 1-3) than those with favorable (GOS 4-5) outcome (8.3 +/- 15.9 vs. 1.7 +/- 3.7 hours, P<0.01). In patients with intracranial hypertension, those with BH had fewer favorable outcomes (46%) than those without (81%, p<0.01); similarly, patients with low CPP and BH were less likely to have favorable outcome than those with low CPP but normal PbtO2 (39% vs. 83%, p<0.01). After controlling for ICP, CPP, age, GCS, Marshall CT grade, and APACHE II score, BH was independently associated with poor prognosis (adjusted OR for favorable outcome 0.89 per hour of BH, 95% CI 0.79-0.99, p=0.04).
CONCLUSION: Brain hypoxia is associated with poor short-term outcome after severe TBI, independently from elevated ICP, low CPP and injury severity. PbtO2 may be an important therapeutic target after severe TBI.