LAUSR

To The Editor: Recently in the Journal, De Graaf et al. (1), reported that survival from out-of-hospital cardiac arrest (OHCA) significantly decreases with increasing time to return of spontaneous circulation (ROSC) and that 8minutes was the optimal threshold for decision making of hospital transport. While the authors must be congratulated for this interesting study, we believe that their results interpretation require cautions. From a statistical point of view, logistic regression implies a linear relationship between the outcome and the covariates. For OHCA, previous studies reported the nonlinearity of the relationship: hope for survival with a favorable neurological prognosis is higher within the first minutes after OHCA occurrence. Moreover, the variables included in the multivariate analysis (age, sex, public location, bystander witnessed, bystander cardiopulmonary resuscitation, response time, and initial shockable rhythm) do not consider the in-hospital phase confounders for neurological outcome (2). Beyond this, we believe that more than ROSC obtainment, the main goal of cardiopulmonary resuscitation is to restore tissue perfusion in order to prevent endorgan damage, mainly irreversible neurological damage, pending cardiac arrest etiological treatment. Inhospital studies reported that post-ROSC hypotension is associated with worse neurologic outcome and increased mortality (3–7). The target is a systolic blood pressure > 90mmHg or mean arterial pressure > 65mmHg, although some studies suggest cerebral autoregulation impairment and advocate a mean arterial pressure of 80–100mmHg (8–10). In order to reach this goal, emergency medical services have various protocols including fluids and vasopressors (11). More than a blood pressure target, we believe that a bundle of care for post ROSC associated with to the classic chain of survival would be more efficient to increase OHCA survival (12). To date, it is unclear whether early recovery from OHCA because of shorter time to CPR or because of a healthier cardiovascular system is responsible for better OHCA neurologic outcome.