Failure to Clear Intermediate Lactate Levels in Ward Patients With Admission Blood Cultures Did Not Increase the Risk of Intensive Care Unit Transfer or In-Hospital Mortality: A Retrospective Cohort Study

Abstract

Introduction A sepsis bundle instituted by the Centers for Medicare and Medicaid Services, known as SEP-1, mandates remeasuring lactate concentrations in patients with suspected sepsis who have an initial lactate level ≥ 2.0 mmol/L to identify those at risk of mortality or clinical deterioration. However, in the group with an intermediate lactate level (2.0-3.9 mmol/L), evidence for the predictive utility for such practice is lacking. The objective of this retrospective cohort study was to evaluate the potential utility of repeating the blood lactate measurement for the premonitory detection of clinical deterioration in patients admitted to a ward with a diagnosis of suspected sepsis and an initial intermediate lactate level. Methods Using electronic health records, we retrospectively evaluated all non-hospice adult patients admitted from the emergency department to a ward of an academic medical center between October 1, 2017, and November 30, 2019, in whom a blood culture was obtained on admission as part of their workup for suspected sepsis. Patient demographics, the times and values of lactate concentrations, the occurrence of subsequent intensive care unit (ICU) transfer during the admission, and hospital mortality were determined. We computed the relative risk of ICU transfer (i.e., clinical deterioration) and hospital mortality in patients whose initial lactate was in the intermediate range who failed to reduce their lactate concentration by at least 10% within six hours. We hypothesized that failure to clear the lactate would be associated with an increased risk of ICU transfer and hospital mortality. Results We studied 12,157 patients, of whom 25 hospice patients were excluded. Of the remaining 12,132 patients, 1,416 (11.7%) were initially admitted to an intensive care unit, and 10,716 (88.3%) were admitted to a ward. Repeat lactate determinations were performed in 10.7%, 77.1%, and 90.2% of the ward patients with initial normal (< 2.0 mmol/L), intermediate (2.0-3.99 mmol/L), and high (≥ 4.0 mmol/L) admission lactate concentrations, respectively. There was no increase in the relative risk of ICU transfer (relative risk [RR] = 0.90, 95% CI, 0.53-1.28, P = 0.55) or hospital mortality (RR = 1.23, 95% CI, 0.85-1.79, P = 0.27) within the intermediate lactate level group among those whose lactate remained within 10% of the initial value (i.e., no change) or increased by more than 10%, compared to those in whom the level decreased by more than 10%. Conclusions Failure to reduce lactate concentrations in ward patients admitted with possible sepsis and an intermediate lactate level was not associated with an increased risk of ICU transfer or mortality. These results call into question the mandate in SEP-1 to routinely repeat the lactate determination in patients presenting with an intermediate concentration.