Execution of Prehospital Transesophageal Echocardiography During Cardiopulmonary Resuscitation in Patients With Out-of-hospital Cardiac Arrest

Out-of-hospital cardiac arrest (OHCA) remains a major global public health challenge. Despite continuous advancements in resuscitation strategies, overall survival rates remain low. High-quality chest compressions are the cornerstone of cardiopulmonary resuscitation, and current guidelines recommend compressions over the lower half of the sternum. However, accumulating evidence suggests that compressions at this location may result in aortic valve compression in approximately half of patients, impairing valve opening and obstructing forward blood flow from the heart, thereby diminishing resuscitation effectiveness. Both animal and human studies have consistently demonstrated a significant inverse association between aortic valve compression and survival outcomes. Transesophageal echocardiography (TEE) enables real-time visualization of cardiac structures during ongoing chest compressions and can guide adjustment of the compression site to avoid aortic valve compression. The study team previously conducted an in-hospital randomized clinical trial of TEE-guided CPR (EXECT-CPR-1). Although improvements in physiologic indicators were observed, no statistically significant improvement in clinical outcomes was demonstrated. These findings support further investigation of whether earlier initiation of TEE-guided CPR in the prehospital setting can improve clinical outcomes. To evaluate this hypothesis, the present randomized clinical trial (EXECT-CPR-2) will leverage the nation's first prehospital physician rapid response system, in which physician-led teams are directly dispatched by the dispatch center to the scene of cardiac arrest. This approach aims to shift the initiation of TEE-guided intervention from the in-hospital to the prehospital phase. The study hypothesis, structured using the P-I-C-O framework, is that among patients with OHCA (P), those who receive prehospital TEE-guided chest compressions designed to avoid aortic valve compression (I), compared with conventional chest compressions over the lower half of the sternum (C), will achieve higher rates of return of spontaneous circulation (O), survival, and favorable neurological outcomes. A total of 204 patients will be enrolled over an estimated three-year period. This trial is expected to provide critical evidence to advance precision resuscitation medicine.

Inclusion Criteria Participants must meet all of the following criteria: 1. Age ≥18 years. 2. Suspected out-of-hospital cardiac arrest (OHCA) as determined by the EMS dispatch center. 3. Non-traumatic cause of cardiac arrest. 4. The physician response unit is dispatched by the EMS dispatch center to the resuscitation scene. Exclusion Criteria Participants meeting any of the following criteria will be excluded: 1. The patient is found not to have OHCA after arrival of the physician response unit. 2. The patient has obvious signs of irreversible death upon arrival of the physician response unit, including decapitation, rigor mortis, livor mortis, decomposition, or other apparent signs of death. 3. The family clearly expresses a wish not to attempt resuscitation, or the patient has a pre-existing Do Not Attempt Resuscitation order. 4. The patient has contraindications to TEE, including: * Failure to establish or confirm endotracheal intubation and adequate ventilation. * Massive active bleeding from the oral cavity, pharynx, esophagus, or stomach. * Anatomical abnormalities of the oral cavity, pharynx, esophagus, or stomach caused by disease, tumor, surgery, or trauma. 5. The scene condition may damage the device or endanger the rescue team, including but not limited to strong electromagnetic fields, such as high-voltage power facilities; extreme weather, such as heavy rain or snowstorm; hazardous environments, such as flooding, fire scenes, unstable buildings, major incident scenes, toxic chemical disasters, nuclear disasters, or any other scene judged unsafe by the on-scene EMS commander. 6. The TEE device is not functioning properly before randomization. 7. The physician assigned to the physician response unit has not been certified to perform prehospital TEE. 8. The patient receives or has extracorporeal cardiopulmonary resuscitation initiated before achieving the primary outcome. 9. The patient has been transported from the scene to the hospital before randomization. 10. The patient has already achieved the primary outcome, return of spontaneous circulation, before randomization.