A comparison of initial lactate and initial base deficit as predictors of mortality after severe blunt trauma

Abstract

Background: After injury, base deficit (BD) and lactate are common measures of shock. Lactate directly measures anaerobic byproducts, whereas BD is calculated and multifactorial. Although recent studies suggest superiority for lactate in predicting mortality, most were small or analyzed populations with heterogeneous injury severity. Our objective was to compare initial BD with lactate as predictors of inhospital mortality in a large cohort of blunt trauma patients all presenting with hemorrhagic shock.

Materials and methods: The Glue Grant multicenter prospective cohort database was queried; demographic, injury, and physiologic parameters were compiled. Survivors, early deaths (≤24 h), and late deaths were compared. Profound shock (lactate ≥ 4 mmol/L) and severe traumatic brain injury subgroups were identified a priori. Chi-square, t-test, and analysis of variance were used as appropriate for analysis. Multivariable logistic regression and area under the receiver operating characteristic curve analysis assessed survival predictors. P < 0.05 was significant.

Results: A total of 1829 patients met inclusion; 289 (15.8%) died. Both BD and lactate were higher for nonsurvivors (P < 0.00001). After multivariable regression, both lactate (odds ratio [OR] 1.17; 95% confidence interval [CI]: 1.12-1.23; P < 0.00001) and BD (OR 1.04; 95% CI: 1.01-1.07; P < 0.005) predicted overall mortality. However, when excluding early deaths (n = 77), only lactate (OR 1.12 95% CI: 1.06-1.19; P < 0.0001) remained predictive but not BD (OR 1.00 95% CI: 0.97-1.04; P = 0.89). For the shock subgroup, (n = 915), results were similar with lactate, but not BD, predicting both early and late deaths. Findings also appear independent of traumatic brain injury severity.

Conclusions: After severe blunt trauma, initial lactate better predicts inhospital mortality than initial BD. Initial BD does not predict mortality for patients who survive >24 h.

Keywords: Base deficit; Blunt trauma; Lactate; Metabolic acidosis; Resuscitation; Shock.