Use of transoesophageal echocardiography in the pre-hospital setting to determine compression position in out of hospital cardiac arrest

Background: A proportion of patients due to anatomical variation do not receive chest compressions over the left ventricle. Transoesophageal echocardiography (TOE) has the potential to impact survival rates by identifying the area of maximal compression (AMC), potentially improving forward flow and systemic perfusion in cardiac arrest. There is a paucity of data regarding the use of TOE during out of hospital cardiac arrest (OHCA) in the pre-hospital setting, with most data coming from studies performed in hospital. We therefore set out to retrospectively review patients who had received TOE as part of their resuscitation care by a pre-hospital medical team. Methods: A retrospective cohort study of OHCA patients treated by a specialist pre- hospital medical team who had received TOE as part of cardiac arrest management. Patients were identified over a 6-month period and their medical records reviewed. The primary outcome was to identify the proportion of patients in whom the AMC was not over the LV. The secondary outcomes were to describe the proportion of patients where information provided by the TOE clinically influenced patient management; to describe the temporal relationship between change in compression position and change in clinical findings including timing of ROSC or change in rhythm and to describe any associations between the AMC and physiological signs. Results: Nineteen patients were identified who had received TOE as part of cardiac arrest management over a 6 month period. Intra-arrest TOE identified 17 (89%) patients in whom compressions were not being performed over the left ventricle. Improved echocardiography evidence of left ventricular compression occurred in 13/17 (76%) patients, resulting in return of spontaneous circulation in 6 patients and change in rhythm in 10 patients. TOE was able to change management or confirm diagnosis in 17/19 (89%) patients. Conclusions: We present a retrospective cohort study of 19 patients who received pre- hospital intra-arrest TOE. Pre-hospital intra-arrest TOE is feasible and contributed significantly to optimising compression position to increase forward flow without interrupting chest compressions. Future studies are needed to correlate clinical findings with compression position as identified on TOE.