Long-Term β-Blocker Therapy Decreases Blood Lactate Concentration in Severely Septic Patients

Abstract

Objectives: Measurement of blood lactate concentration in the early management of sepsis is an important step in severity assessment. High blood lactate levels in the early phase of sepsis have classically been thought to be related to tissue hypoxia, but other factors could intervene. We hypothesized that the activation of glycolysis through β-adrenergic stimulation by endogenous catecholamines plays an important role in lactate production and that long-term β-blocker therapy could affect the lactate concentration in patients with severe sepsis and septic shock.

Design: Retrospective cohort study.

Setting: Emergency department.

Patients: Two hundred sixty patients with severe sepsis or septic shock were included. Twenty-five percent were previously treated with β-blockers.

Interventions: None.

Measurements and main results: We recorded initial vital signs, the source of infection, mortality at 28 days, blood lactate concentration, and Predisposition Insult Response of Organ failure and Sequential Organ Failure Assessment scores using an electronic database. Blood lactate concentration was significantly lower in patients previously treated with β-blockers (3.9 ± 2.3 mmol/L vs 5.6 ± 3.6 mmol/L; p < 0.001). This difference was still significant after controlling for mortality (p < 0.005), for the level of the Predisposition Insult Response of Organ failure (p < 0.05) and Sequential Organ Failure Assessment (p < 0.05) scores, and for the source of infection (p < 0.05). Nearly four times more patients treated with β-blockers had normal blood lactate levels (p< 0.001). Only two factors were significantly and independently associated with normal blood lactate concentration during severe sepsis and septic shock: survival (p = 0.03) and β-blocker therapy (p = 0.01).

Conclusions: Long-term β-blocker therapy decreases blood lactate concentration of severely ill septic patients at presentation. We conclude that the use of blood lactate measurement as a triage tool in the initial assessment of septic patients with β-blocker therapy may underestimate the severity of the sepsis.