Prehospital transesophageal echocardiography during cardiac arrest: feasibility confirmed, but clinical interpretation must remain anchored to resuscitation fundamentals

We read with great interest the randomized controlled pilot study by Katzenschlager et al. evaluating the feasibility of prehospital transesophageal echocardiography (TEE) during out-of-hospital cardiac arrest (OHCA) [1]. In this randomized pilot trial, prehospital TEE was implemented without prolonging hands-off time or reducing chest compression fraction (CCF) within a highly resourced, physician-staffed emergency medical service system. Several methodological considerations are relevant when interpreting the reported physiological and process-related signals.

Hands-off time and CCF are inherently performance-sensitive endpoints. Given the unblinded nature of the intervention and the use of real-time image feedback, improvements in these metrics may reflect heightened situational awareness and team behavior rather than effects directly attributable to TEE guidance alone. In addition, the approximately 8.5-minute earlier arrival of the study team in the TEE group represents a clinically meaningful interval in the physiology of cardiac arrest, potentially corresponding to differences in metabolic state, tissue perfusion, and carbon dioxide (CO₂) clearance. Higher end-tidal CO₂ values observed in the TEE group may therefore, at least in part, reflect more favorable underlying physiology at the time of assessment.

Differences in case complexity further complicate the interpretation. A higher proportion of patients in the control group underwent evaluation for extracorporeal cardiopulmonary resuscitation, a process that introduces additional procedural preparation and cognitive load and may influence CPR process measures. Moreover, the study was conducted within a system characterized by substantial on-scene manpower and specialized physician-staffed teams—system-level factors that have independently been associated with improved resuscitation processes and are not intrinsic to TEE itself [2]. Taken together, these considerations do not detract from the validity of the trial but underscore that observed differences should be interpreted as context-dependent rather than readily generalizable.

From a clinical standpoint, a central concern is the potential for overinterpretation of feasibility data as justification for prioritizing additional procedures during the earliest phases of resuscitation. Demonstrating feasibility and procedural safety does not imply that prehospital TEE should be introduced early or routinely, as its role is best understood as a conditional adjunct rather than a time-critical component of initial resuscitation. The non-negotiable foundations of resuscitation remain high-quality chest compressions, timely defibrillation, effective ventilation, and secure airway management [3].

Although TEE theoretically allows continuous imaging during chest compressions, its safe deployment depends on prerequisites that were present in this study but may not be universally available, including a secured airway, sufficient personnel to permit parallel task execution, and operators with substantial experience in resuscitative echocardiography [4]. In settings where these conditions are not met, premature or poorly coordinated use of TEE risks diverting attention from compression quality, ventilation, or other time-critical interventions, echoing concerns previously reported with transthoracic and point-of-care ultrasound during cardiac arrest [5].

In conclusion, Katzenschlager et al. provide important evidence that prehospital TEE can be integrated into OHCA resuscitation without compromising CPR delivery in selected settings. The principal contribution of this study lies in confirming feasibility and procedural safety. For critical care clinicians, the enduring challenge remains balancing the acquisition of additional physiological information against the imperative to preserve the fundamentals of high-quality resuscitation.

Abbreviations

TEE

Transesophageal echocardiography

OHCA

Out-of-hospital cardiac arrest

CPR

Cardiopulmonary resuscitation

CCF

Chest compression fraction

CO₂

Carbon dioxide

Author contributions

MHH drafted the manuscript. All authors contributed to critical revision of the manuscript and approved the final version.

Funding

The authors received no specific funding for this work.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.