PaRamEDIc assessment of laCTate in OHCA and survival to hospital (PREDICT protocol)

Cardiac arrest—defined as an abrupt cessation of spontaneous and effective ventilation and systemic circulatory perfusion (Niemann 1992)—is a major health epidemic. UK emergency medical services treat 30 000 out-of-hospital cardiac arrests (OHCA) annually (Perkins and Brace-McDonnell, 2015) but the survival rate remains persistently low. Cardiac arrest leads to an interruption of blood flow and is known to result in hyperlactatemia and metabolic acidosis (Atwood et al, 2005). Hyperlactatemia is commonly used in the context of evaluating shock in a range of medical emergencies and, in out-of-hospital practice, is commonly associated with the identification of mortality in sepsis, trauma, burns and overdose. Several studies have identified hyperlactatemia in arterial blood analysis as a prognostic of mortality in patients transported to the emergency department (ED) in a post-cardiac arrest state (Abramson et al, 1993; Kliegel et al, 2004). However, the association between blood lactate and a poor prognosis in OHCA remains controversial (Donnino et al, 2007; Yanagawa et al, 2009) and there exists a paucity of evidence to indicate if a venous blood lactate measurement, taken by a paramedic during an OHCA when cardiopulmonary resuscitation (CPR) is ongoing, is a good predictor of mortality.