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Response to Letter to the Editor Dr. Mosesso

In the management of out-of-hospital cardiac arrest (OHCA) there are two competing “interests”: to spend time on scene to allow a patient to achieve return of spontaneous circulation (ROSC), (“stay and play”) and not losing time waiting for ROSC that will not occur on scene (“scoop and run”). At the start of resuscitation, it is not known if a patient will ever achieve ROSC or when. The study we now published addresses the question of the consequences for survival if ROSC occurs late vs. early after the start of resuscitation by EMS (1). This study should be viewed in relation to our earlier study (2) that showed that there is an association between longer time of on-scene resuscitation and lower 30day survival of patients that are transported without ROSC, with the highest survival of 8% in patients where the decision to transport was made within 20min after EMS arrival. The receiver operator characteristic (ROC) curve we describe in the study we now published, shows the increasing probability that longer stay and play may result in ROSC, but not in survival. The moment that ROSC occurs is interpreted as a positive test with survival as the outcome. By making the weight of sensitivity and specificity equal, the assumption was, that the opportunity lost with waiting for ROSC more than 8minutes is less than the opportunity gained from not waiting any longer in order to achieve ROSC and survival – either during transport or by advanced therapeutic measures that are only offered in the hospital. It is impossible to combine both studies into one because as soon as transportation is started without ROSC, the opportunity for ROSC to occur on scene is over. Transportation without ROSC may impair the quality of CPR but is potentially beneficial if treatment options can be applied that are generally unavailable in the pre-hospital setting, such as emergency coronary reperfusion (PCI) and/or extracorporeal cardiopulmonary resuscitation (ECPR). The paper of Grunau et al (that was published after our paper was submitted) studies this question using propensity score matching in a large populationbased cardiac arrest cohort (3). The paper concluded that any intra-arrest transport to the hospital was associated with a lower probability of survival to hospital discharge. Although no recommendations are linked to this conclusion, the conclusion appears contrary to a current trend to transportation to an ECMO capable facility, followed by emergency PCI. We like to question the robustness of their findings for two reasons. First, Figure 3 in the paper seems to contradict their conclusions: in the time-based epochs, a trend is clearly visible favoring on-scene resuscitation in the first 15minutes, but favoring intra-arrest transport after 20minutes. Second, the propensity score used in the study is based on factors of a known treatment-outcome relationship, which are also EMS factors considered for the decision to transport. In this study the precise reason for the decision for intra-arrest transport or ongoing resuscitation on-scene or termination was not documented, a selection mechanism could be present that may not be corrected for in the propensity score matching. The American Heart Association (AHA) guidelines recommend optimizing care on scene to achieve ROSC rather than transport with ongoing CPR and give no specific guidance when to transport to the hospital if ROSC is not achieved (4). Recently, we published a paper on decision making by EMS on-scene in patients without ROSC, using both quantitative and qualitative data (5). In this study known resuscitation outcome characteristics such as age, public location, bystander/EMS witnessed, and shockable initial rhythm were independently associated with transport with ongoing CPR. However, the proportion of variance explained by these characteristics was only 0.36. In our study, quantitative factors did not adequately describe the process of the decision to transport with ongoing CPR. The additional variance could be explained by other important qualitative themes: related to the patient and family, to local circumstances, to the paramedic himself, and Received September 1, 2021 from Candidate, Amsterdam Resuscitation Studies (ARREST), Department of Cardiology, Amsterdam UMC – Location AMC, The Netherlands (CDG); Director, Amsterdam Resuscitation Studies (ARREST), Department of Cardiology, Amsterdam UMC – Location AMC, The Netherlands (RWK). Accepted for publication September 5, 2021.