Impact of Prehospital Blood Pressure Profile on Functional Outcome After Traumatic Brain Injury

Background/Objectives: Prehospital management after traumatic brain injury (TBI) focuses on the avoidance of secondary injuries such as derangement of blood pressure. Recent guidelines specify an updated optimal systolic blood pressure (SBP) target of 110-149 mmHg. We aim to characterise the prehospital blood pressure profile of patients including the SBP range and variability after TBI, amongst other prehospital parameters, to determine associations with the outcome. Methods: We performed a retrospective cohort study of adult patients admitted to the intensive care unit at University Hospital Zurich. The first recorded SBP, SBP variability, and average range during two-thirds of the prehospital time were analysed along with other prehospital parameters for survival and GOSE at hospital discharge using univariate and multivariable logistic regression analyses. Results: In total, 680 patients were included, of whom 76% had moderate to severe head injury and 117 patients died. Among the sample, 51% of patients were in the target range of 110-149 on initial assessment and 50% remained in this range during 2/3 of the prehospital time. The initial SBP, SBP variability, and SBP range were significant for survival in the univariate analysis, but they lost statistical significance in the multivariable model. This may indicate a reduced effect of the analysed SBP parameters on the outcome once controlling for confounding factors. In the multivariable analysis, catecholamine administration reduced the odds of an unfavourable GOSE at hospital discharge (OR 1.84 [1.20-2.81], p = 0.005), which may point towards a benefit of early haemodynamic stabilisation after injury. A younger age (OR 0.95 [95% CI 0.93-0.97], p < 0.001), lower AIS Head/Neck (OR 0.45 [0.29-0.70], p < 0.001), higher initial GCS (OR 1.24 [1.15-1.35], p < 0.001), and higher first haemoglobin (OR 1.24 [1.04-1.46], p = 0.014) were independent predictors of survival. Conclusions: Haemodynamic instability in the prehospital phase is common after TBI and represents a potentially modifiable factor. Catecholamine administration was associated with improved functional recovery, suggesting a possible role of prehospital haemodynamic management, although causality cannot be inferred.