Background:

Lactate clearance and urinary output are affected during severe sepsis and septic shock. Persistence of these conditions is associated with increased mortality. In this study both factors are combined to determine mortality in patients.

Methods:

A convenience cohort was studied and 31 patients with severe sepsis and septic shock were included from March to September 2014 from a private intensive care unit from northeast Mexico.

Data analysis:

Patients were classified in two groups, those who had >10% lactate clearance in 6 hours and those who cleared <10% lactate in 6 hours. We calculated ANOVA to compare both groups and determine if there were significant differences in BMI, APACHE II, SOFA, serum lactate (basal, at 6, 12 and 24 hours), urine output (in 6, 12 and 24 hours) and serum creatinine (basal and at 24 hours). The patients were also classified by urine output, a group of oliguria (urine output <0.5 mL/Kg/h) and a group with normal diuresis, ANOVA formula was used likewise to compare these groups. Relative risk was calculated for mortality associated to lactate clearance and urine output.

Results:

On the lactate clearance groups, there was significant differences on age (p = 0.038), BMI (p = 0.0135), serum lactate clearance at 6 hours (p = 0.029) and urine output in 6 hours (p = 0.01). Mortality Odds Ratio (OR) for patients who do not clear >10% of lactate in 6 hours is 1.23 (CI 95% 0.70-2.16). When patients were classified by urine output, we found significant differences in APACHE II (p = 0.001), BMI (p = 0.001), basal serum lactate, at 6, 12 and 24 hours (p = 0.02, 0.002, 0.007, <0.001 respectively), urine output in 6, 12 and 24 hours (p = 0.009, < 0.001, < 0.001 respectively), and mortality (p = 0.02). Mortality OR was 1.65 (CI 95% 1.05-2.58).

Conclusions:

Lactate clearance and urinary output may be used as mortality makers in severe sepsis and septic shock.

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