Use of point-of-care lactate in the prehospital aeromedical environment

Abstract

Introduction: Lactate measurement has been used to identify critical medical illness and initiate early treatment strategies. The prehospital environment offers an opportunity for very early identification of critical illness and commencement of care.

Hypothesis: The investigators hypothesized that point-of-care lactate measurement in the prehospital aeromedical environment would: (1) identify medical patients with high mortality; (2) influence fluid, transfusion, and intubation; and (3) increase early central venous catheter (CVC) placement.

Methods: Critically ill, medical, nontrauma patients who were transported from September 2007 through February 2009 by University of Massachusetts (UMass) Memorial LifeFlight, a university-based emergency medical helicopter service, were eligible for enrollment. Patients were prospectively randomized to receive a fingerstick whole-blood lactate measurement on an alternate-day schedule. Flight crews were not blinded to results. Flight crews were asked to inform the receiving attending physician of the results. The primary endpoint was the ability of a high, prehospital lactate value [> 4 millimoles per liter (mmol/L)] to identify mortality. Secondary endpoints included differences in post-transport fluid, transfusion, and intubation, and decrease in time to central venous catheter (CVC) placement. Categorical variables were compared between groups by Fisher's Exact Test, and continuous variables were compared by t-test.

Results: Patients (N = 59) were well matched for age, gender, and acuity. In the lactate cohort (n = 20), mean lactate was 7 mmol/L [Standard error of the mean, SEM = 1]. Initial analysis revealed that prehospital lactate levels of ≥ 4 mmol/L did show a trend toward higher mortality with an odds ratio of 2.1 (95% CI, 0.3-13.8). Secondary endpoints did not show a statistically significant change in management between the lactate and non lactate groups. There was a trend toward decreased time to post-transport CVC in the non lactate faction.

Conclusion: Prehospital aeromedical point-of-care lactate measurement levels ≥ 4 mmol/L may help stratify mortality. Further investigation is needed, as this is a small, limited study. The initial analysis did not find a significant change in post-transport management.