Objectives: Out of Hospital Cardiac Arrest (OHCA) is a frequently encountered pathology with resultant poor outcomes in the majority of patients. Echocardiography has been utilized to help guide clinical decision making and monitor effectiveness of resuscitative efforts. Transthoracic echocardiography (TTE) the mainstay of point-of-care ultrasound (POCUS) real time resuscitative imaging has limitations, most notably is the disruption of closed chest compressions. Trans-esophageal echocardiography (TEE) is an emerging technology in emergency care and can potentially overcome these limitations but image quality and accuracy of use in the prehospital environment remains unknown. Our primary objective is to identify the accuracy of Emergency Medical Services (EMS) fellow physicians in performing TEE via the identification of key cardiac structures. Secondarily we assess image quality as well as accuracy on cardiac activity interpretation as compared to TEE-experienced cardiologists.
Methods: A pilot study using descriptive analysis of a retrospective case-series with specific focus on inter-rater reliability as well as pragmatic management alterations based on real-time image interpretation by EMS physicians. After focused education, 13 patients were eligible for prehospital TEE who suffering OHCA from July 2022-June 2023. Ultrasound (US) images were interpreted by EMS fellow physicians and over-read by cardiologists with specific focus on inter-rater reliability. After collection of patients presenting data and US images, analysis was performed.
Results: Of 13 patients initially screened, 10 patients were included in a study with a median age of 50 years old (41-70). Three patients were excluded due to equipment malfunction or insufficient image capture. An interrater reliability identified a kappa of 0.96 with respect to identification of cardiac structures and a kappa of 0.65 for identification of cardiac activity.
Conclusions: In this small study of prehospital TEE, EMS fellow physicians had high inter-rater reliability in image interpretation pertaining to anatomy and cardiac activity when compared with cardiologists. Further research is needed to determine its efficacy, safety, and widespread application in the prehospital setting.
Keywords: Resuscitation; cardiac arrest; echocardiography; ultrasound.