Correlation of Venous Lactate and Time of Death in Emergency Department Patients with Noncritical Lactate Levels and Mortality from Trauma.

BACKGROUND

Serum venous lactate (LAC) levels help guide emergency department (ED) resuscitation of patients with major trauma. Critical LAC level (CLAC, ≥4.0 mmol/L) is associated with increased disease severity and higher mortality in injured patients. The characteristics of injured patients with non-CLAC (NCLAC) (<4.0 mmol/L) and death have not been previously described.

OBJECTIVES

(1) To describe the characteristics of patients with venous NCLAC and death from trauma. (2) To assess the correlation of venous NCLAC with time of death.

METHODS

A retrospective cohort study at an urban teaching hospital between 9/2011 and 8/2014. Inclusion: All trauma patients (all ages) who presented to the ED with any injury and met all criteria: (1) Venous LAC drawn at the time of arrival that resulted in an NCLAC level; (2) were admitted to the hospital; (3) died during their hospitalization. Exclusion: CLAC. Outcome: Correlation of NCLAC and time of death. Data were extracted from an electronic medical record by trained data abstractors using a standardized protocol. Cross-checks were performed on 10% of data entries and inter-observer agreement was calculated. Data were explored using descriptive statistics and Kaplan-Meier curves were created to define survival estimates. Data are presented as percentages with 95% confidence interval (CI) for proportions and medians with quartiles for continuous variables. Kaplan-Meier curves with differences in time to events based on LAC are used to analyze the data.

RESULTS

A total of 60 patients met the inclusion criteria. The median age was 52 years (quartiles: 30, 75) and 73% were male (age range 2-92). The median LAC in the overall cohort was 1.9 mmol/L (quartiles: 1.5, 2.1). Sixteen patients (27%) died during the first 24 h with 5 (31%) due to intracranial hemorrhage. The median survival time was 5.6 days (134.4 h) (95% CI: 2.3-12.6).

CONCLUSIONS

In trauma patients with NCLAC who died during the index hospitalization, the median survival time was 5.6 days, approximately one-third of patients died within the first 24 h. These findings indicate that relying on a triage NCLAC level alone may result in underestimating injury severity and subsequent morbidity and mortality.