Early Echographic Asystole as a Predictive Factor of Absence of Spontaneous Circulatory Activity Recovery (SCAR) in Prehospital Cardio Respiratory Arrests (CRA) - ACE Study

Prehospital Cardio-Respiratory Arrests (CRA) represent a significant cause of mortality in France (between 30,000 and 50,000 cases per year) [1]. The prognosis is particularly pejorative, since only 5 to 6% of patients will leave the hospital alive with satisfying neurological condition [2,3]. Their management in France is part of a very singular Primary Care System, based on the medicalization of medical regulation (SAMU) and effectiveness (SMUR) and is based mainly on European recommendations (cardiac massage, ventilation and cardiac rhythm analysis) [4]). European 2015 recommendations advocate for the use of Cardiac Clinical Ultrasound (CCU) in Emergency Medicine, particularly to identify curable causes of CRA. Indeed, CCU is likely to reveal various curable etiologies as tamponade, massive pulmonary embolism, deep hypovolemia or suffocating pneumothorax[5]. Their identification allows the clinician to better adjust his therapeutic strategy and consequently improve patient prognosis.

But its predictive value on the absence of Spontaneous Circulatory Activity Recovery (SCAR) focus clinicians' interest due to its impact on extracorporeal circulation procedures, organ donation or resuscitation interruption guideline. Several studies support the predictive value associated with the absence of mechanical cardiac activity and resuscitation failure [5-10]. However, proof level remains very shaky and transposition to prehospital medicine is clearly impossible (delays, management and environment differ largely). As a corollary, the European Resuscitation Council (ERC) ruled in 2015 that the prognostic performances of ultrasound asystole had not been sufficiently finely measured to consider it as a rigorous criterion for resuscitation interruption, appealing for pivotal studies [4].

ACE French National Trial fits precisely into this bibliographic gap. Our objectives are multiple: assess prognostic value of Early CCU (ECCU; ie. <M12), alone or combined with other clinical parameters (composite prognostic tool combining myocardial and/or electrical activity, capnography, No/Low Flow duration, and clinical profile -sex, age-) on the absence of SCAR ; describe frequency and typology of curable etiologies in the context of CRA, and estimate the possible prognostic impact of early CCU on morbidity and mortality; finally, in case of validation of its prognostic performances, estimate theoretical time savings on ECMO (Extracorporeal Membrane Oxygenation) and organ donation processes.

Multicentric, based on rigorous methodology, high proof-level design and large sample (N=345), ACE wants to be resolutely pragmatic, by associating peripheric hospital and university hospital (Expertise), urban or rural environment (delays and intervention conditions), in order to answer definitely clinicians questioning of the emergency physicians. Continuing in the same vein, we aim a future validation study of a decision-making algorithm for pre-hospital management of CRAs to reduce morbidity and (Randomized Cluster Study in Stepped-Wedge integrating a medico-economic component).