Association of serum lactate and survival outcomes in patients undergoing therapeutic hypothermia after cardiac arrest

Abstract

Introduction: Recent studies have suggested that serum lactate may serve as a marker to predict mortality after resuscitation from cardiac arrest (CA). The relationship between serum lactate and CA outcomes requires further characterization, especially among patients treated with therapeutic hypothermia (TH) and agressive post-arrest care. Methods: A retrospective analysis of patients resuscitated from non-traumatic CA at three urban U.S. hospitals was performed using an established internet-based post-arrest registry. Adult (≥18 years) patients resuscitated from CA and receiving TH treatment were included. Logistic regression analysis was used to adjust for potential confounders to survival outcomes. Survival to discharge served as the primary endpoint. Results: A total of 199 post-CA patients treated with TH between 5/2005 and 11/2011 were included in this analysis. The mean age was 56.9 ± 16.5 years, 85/199 (42.7%) patients were female, and survival to discharge was attained in 84/199 (42.2%). While lower initial post-CA serum lactate levels were not associated with increased survival to discharge, subsequent lactate measurements were significantly associated with outcomes (24-h serum lactate levels in survivors vs. non-survivors, 2.7 ± 0.5 vs. 4.2 ± 0.4 mmol/L, p < 0.01). Multivariable logistic regression confirmed this relationship with survival to discharge (p < 0.01). Conclusion: Lower serum lactate levels at 12h and 24h, but not initially following cardiac arrest, are associated with survival to hospital discharge after resuscitation from CA and TH treatment. Prospective investigation of serum lactate as a potential prognostic tool in CA is needed.