Intensive care unit mortality after cardiac arrest: the relative contribution of shock and brain injury in a large cohort

Brain injury is well established as a cause of early mortality after out-of-hospital cardiac arrest (OHCA), but postresuscitation shock also contributes to these deaths. This study aims to describe the respective incidence, risk factors, and relation to mortality of post-cardiac arrest (CA) shock and brain injury. Retrospective analysis of an observational cohort. 24-bed medical intensive care unit (ICU) in a French university hospital. All consecutive patients admitted following OHCA were considered for analysis. Post-CA shock was defined as a need for infusion of vasoactive drugs after resuscitation. Death related to brain injury included brain death and care withdrawal for poor neurological evolution. None. Between 2000 and 2009, 1,152 patients were admitted after OHCA. Post-CA shock occurred in 789 (68 %) patients. Independent factors associated with its onset were high blood lactate and creatinine levels at ICU admission. During the ICU stay, 269 (34.8 %) patients died from post-CA shock and 499 (65.2 %) from neurological injury. Age, raised blood lactate and creatinine values, and time from collapse to restoration of spontaneous circulation increased the risk of ICU mortality from both shock and brain injury, whereas a shockable rhythm was associated with reduced risk of death from these causes. Finally, bystander cardiopulmonary resuscitation (CPR) decreased the risk of death from neurological injury. Brain injury accounts for the majority of deaths, but post-CA shock affects more than two-thirds of OHCA patients. Mortality from post-CA shock and brain injury share similar risk factors, which are related to the quality of the rescue process.