Is there a relationship between optimal cerebral perfusion pressure-guided management and PaO2/FiO2 ratio after severe traumatic brain injury?

Abstract

Objective: Severe traumatic brain injury (TBI) management has been associated with adult respiratory distress syndrome (ARDS) in previous literature. We aimed to investigate the relationships between optimal CPP-guided management, ventilation parameters over time and outcome after severe TBI. Materials and methods: We performed retrospective analysis of recorded data from 38 patients admitted to the NCCU after severe TBI, managed with optimal cerebral perfusion pressure (CPPopt)-guided therapy, calculated using pressure reactivity index (PRx). All patients were sedated and ventilated with lung protective criteria (Peep > 5, tidal volume 6–8 ml/kg and airway pressure < 30 cmH2O). Results: Daily mean CPPopt varied between a minimum of 84 mmHg and a maximum of 91 mmHg with an all period mean value of 88 mmHg. The mean value for the difference between CPP and CPPopt was −1.9 mmHg. Daily mean P/F ratio decreased and varied between 253 and 387 with an all-period mean of 294 mmHg. During the 10 days of recording data, five patients (13%) developed criteria of severe ARDS, but only two patients died due to severe ARDS (5%). PaO2/FiO2 (P/F) ratio did not correlate with CPPopt, but showed a strong correlation with tidal volume (p = 0.000) and driving pressure (p = 0.000). Conclusions: Although CPPopt-guided therapy may induce a decrease in P/F ratio over time during the first 10 days, we could not find an association with worst outcome, which may be influenced by lung protective ventilation strategies and preservation of cerebral autoregulation.