75.10 Lactate Clearance as a Predictor of Mortality in Trauma Patients with and without TBI

S. E. Dekker¹, H. M. de Vries¹, W. D. Lubbers¹, P. M. Van De Ven², A. Toor³, F. W. Bloemers⁴, L. M. Geeraedts⁴, P. Schober¹, C. Boer^{1 1}VU University Medical Center,Anesthesiology,Amsterdam, NH, Netherlands ²VU University Medical Center,Epidemiology And Biostatistics,Amsterdam, NH, Netherlands ³VU University Medical Center,Center For Acute Care, VU Medical Center Region,Amsterdam, NH, Netherlands ⁴VU University Medical Center,Surgery,Amsterdam, NH, Netherlands

Introduction: Impaired lactate clearance is predictive of mortality in general trauma patients. The relationship between this biomarker and outcome in traumatic brain injury (TBI) patients, however, is still unknown. This retrospective study examined the association between lactate clearance and mortality in trauma patients with and without TBI.

Methods: Lactate values of trauma patients admitted to the emergency department between 2010-2014 were retrieved from patient files. Patients without initial lactate drawn within 30 minutes after admission, or without a second lactate measurement within 8 hours after admission, were excluded. Lactate clearance was calculated based on modified methods described by Odom et al. (2013) [(Lactate_initial – Lactate_delayed) / Lactate_initial × 100%]; Régnier et al. (2012) [(Lactate_initial – Lactate_delayed) / Lactate_initial × 100% × Delay⁻¹]; and Billeter et al. (2009) [four groups: (1) always below 2.5mmol/L, (2) decreasing below 2.5mmol/L, (3) increasing above 2.5mmol/L, and (4) always above 2.5mmol/L]. We studied the association between lactate clearance and in-hospital mortality in patients with isolated TBI, TBI combined with extracerebral injuries, and trauma patients without TBI.

Results: Of the 3000 admitted trauma patients, 818 (27.2%) had an initial lactate measurement. 367 patients (12.2%) were eligible for lactate clearance calculations. A high initial lactate was associated with a higher in-hospital mortality [OR = 1.20, 95% CI: (1.13 – 1.27), P<0.001]. We found a significant relationship between the lactate clearance method of Billeter et al. and in-hospital mortality (Wald chi-square = 14.614, P=0.002). Post-hoc pairwise comparisons only revealed a significant difference between groups 1 and 4 [Bonferroni corrected P=0.002, OR = 3.59, 95% CI: (1.86 – 6.93)]. There was no association between lactate clearance and in-hospital mortality using the methods of Odom et al. and Régnier et al. Initial lactate value and Billeter’s lactate clearance method did not differ in their ability to predict in-hospital mortality [AUC 0.64, 95% CI: (0.56 – 0.71) vs. AUC 0.64, 95% CI: (0.57 – 0.71), P=0.71]. Neither initial lactate nor lactate clearance differed between isolated TBI, polytrauma + TBI, and general trauma without TBI patients.

Conclusion: This is the first study to investigate the relationship between lactate clearance and outcome in TBI patients, and the first to compare three previously described lactate clearance metrics. In contrast to the available literature for the general trauma patient, only lactate clearance using the method of Billeter et al. predicted mortality in trauma patients with and without TBI. However, in our patient population we found no clinical advantage of using Billeter’s lactate clearance method, as the initial lactate value was equally effective in its ability to predict in-hospital mortality.