Impact of Lactate Clearance on Clinical and Neurological Outcomes of Patients With Out-of-Hospital Cardiac Arrest Treated With Extracorporeal Cardiopulmonary Resuscitation: A Secondary Data Analysis

Objectives: Serial evaluations of lactate concentration may be more useful in predicting outcomes in patients with out-of-hospital cardiac arrest (OHCA) than a single measurement. This study aimed to evaluate the impact of lactate clearance (LC) on clinical and neurologic outcomes in patients with OHCA who underwent extracorporeal cardiopulmonary resuscitation (ECPR). Design: Retrospective multicenter observational study. Setting: Patients with OHCA receiving ECPR at 36 hospitals in Japan between January 1, 2013, and December 31, 2018. Patients: This study evaluated 1227 patients, with lactate initial assessed upon emergency department admission and lactate second measured subsequently. To adjust for the disparity in the time between lactate measurements, the modified 6-hour LC was defined as follows: ([lactate initial –lactate second ]/lactate initial ) × 100 × (6/the duration between the initial and second measurements [hr]). The patients were divided into four groups according to the modified 6-hour LC with an equivalent number of patients among LC quartiles: Q1 (LC < 18.8), Q2 (18.8 < LC < 59.9), Q3 (60.0 < LC < 101.2), and Q4 (101.2 < LC). Interventions: None. Measurements and Main Results: The 30-day survival rates increased as the 6-hour LC increased (Q1, 21.2%; Q2, 36.8%; Q3, 41.4%; Q4, 53.6%; p for trend < 0.001). In the multivariate analysis, the modified 6-hour LC was significantly associated with a 30-day survival rate (adjusted odds ratio [AOR], 1.003; 95% CI, 1.001–1.005; p < 0.001) and favorable neurologic outcome (AOR, 1.002; 95% CI, 1.000–1.004; p = 0.027). Conclusions: In patients with OHCA who underwent ECPR, an increase in the modified 6-hour LC was associated with favorable clinical and neurologic outcome. Thus, LC can be a criterion to assess whether ECPR should be continued.