Improved cardiac arrest outcomes: as time goes by?

In a recent issue of Critical Care, Mally and colleagues reported outcomes from an observational study of out-of-hospital cardiac arrests in Slovenia. Multivariable analysis identified independent predictors for hospital discharge, including higher end-tidal carbon dioxide (ETCO2) levels, higher mean arterial pressure (MAP) and the recency (years) of the arrest. ETCO2 has been previously demonstrated to correlate with cardiac index, and predict successful resuscitation. Initial ETCO2 reflects the initial adequacy of resuscitation, and the ETCO2 on admission to hospital reflects a number of factors, including the adequacy of ventilation. During resuscitation, coronary perfusion pressure appears important for survival, but there are limited human data to guide hemodynamic management after cardiac arrest. A higher blood pressure could represent more vasoconstriction, less vasodilation, avoidance of hyperventilation, or a better cardiac output. Improved hospital discharge was also observed during the later years of the study. During this period a number of factors could have contributed to the improved outcome. These include new guidelines, the awareness of the importance of good CPR (including avoidance of hyperventilation), and better post-resuscitation care (including therapeutic hypothermia). It is hard to unravel the actual contribution of these factors to the final outcome, but the authors should be commended for their excellent overall results, and their thought provoking manuscript.