Lactic acid clearance in the emergency department prognosticates multisystem organ failure and death

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Background

Lactic acid (LA) indicates anaerobic metabolism (global tissue hypoxia). While single LA levels are helpful diagnostically and therapeutically; the change in LA levels over time (LA-clearance) has better prognostic value in predicting morbidity or multisystem organ failure (MSOF) and death in the intensive care unit (ICU).

Objective

To examine the relationship of LA-clearance in the Emergency Department (ED) and the development of multisystem organ failure and death.

Methods

This was a prospective case series of critically ill patients presenting to a large urban ED in shock (systolic blood pressure <90 mmHg for thirty min after a 40 cc/kg volume challenge) or a LA >2 mM/l on arrival. Patients presenting in hemorrhagic shock, trauma, requiring immediate surgery, do not resuscitate orders, seizures or end-stage disease not benefiting from ICU care were excluded. Patients were managed by ED physicians by standard ED management. LA and Multisystem Organ Dysfunction Scores (MODS) were obtained on ED arrival, discharge and every 12 h for 72 h. Patients were grouped by the lactic acid clearance during the ED stay: Group 1 (no clearance, <0 mM/l/h, actual increase in lactic acid), Group 2 (intermediate clearance, >0 and <1 mM/l/h), and Group 3 (high clearance, >1 mM/l/h). Student's T-test and ANOVA were used to compare the MODS score and LA over time, with Bonferroni correction for multiple comparisons.

Results

A total of 142 patients were studied. The mean age was 65.9± 17.2 years. The lactic acid clearances for groups 1, 2 and 3 were -0.45± 0.55, 0.48± 0.48, 1.44± 0.38 mM/l/h respectively P<0.0001. The mean MODS scores over 72 h were 8.63± 3.35, 6.16± 4.23, 5.12± 3.76 for groups 1, 2 and 3 respectively P<0.02. The in-hospital mortality was 50%, 23%, 12% in groups 1, 2 and 3 respectively P<0.045.

Conclusions

The duration of global tissue hypoxia or decreased LA clearance in the ED is associated with MSOF and death. This pathogenic link suggests that diagnostic and therapeutic intervention should begin immediately in the ED.