Associations of Blood Pressure and Serum Lactate Levels Upon Admission with One-week Mortality in Patients with Severe Traumatic Brain Injury: A Multi-Center Retrospective Study.

Aim: To explore interrelationships between serum lactate (Lac) levels and other hemodynamic parameters, including diastolic blood pressure (DBP) and mean arterial pressure (MAP) and acute-phase mortality in severe traumatic brain injury (sTBI).

Material and methods: Clinical data for sTBI patients (Glasgow Coma Scale (GCS) score ?8 on admission) were collected from different hospitals from 2013 to 2024. One-week mortality was the endpoint. The associations of all blood pressure (BP) indices and Lac levels with one-week mortality were investigated using mixed effects logistic regression models, and the diagnostic value of mortality analysis based on the Lac levels was evaluated via receiver operating characteristic (ROC) curves and areas under the curve (AUCs). In addition, the relationships between the BP indices and Lac levels were assessed by linear regression analysis.

Results: A total of 1270 sTBI patients were analyzed in this study. Bivariate analysis revealed smooth U-shaped associations of different BP indices upon admission with one-week mortality, and extreme values of the BP indices were found to be associated with increased mortality, with no obvious threshold effect revealed. After adjustments were made for confounding factors, the likelihood of death clearly increased with a SBP < 100 mmHg, a DBP < 70 mmHg, a MAP < 80 mmHg and a Lac > 4.5. Furthermore, all three BP indices were significantly negatively correlated with Lac levels. Moreover, MAP has the strongest ability to predict oneweek mortality in sTBI patients, and it also has the strongest negative correlation with Lac levels.

Conclusion: In the development of guidelines for managing sTBI patients, the definition of hypotension should be reconsidered, and all three BP indices and serum Lac levels should be used as references instead of a single hypotension index of SBP < 90 mmHg to improve the survival rate.