Proposed section structure
1. Clinical context and rationale
2. Why compression location may matter
3. EXECT-CPR trial design and methods
4. Main efficacy results
5. Physiologic and safety findings
6. Clinical interpretation and limitations
7. Implications for practice and future research
8. Funding, registration, and citation
Highlights
TEE-guided adjustment of chest compression position after emergency department arrival did not significantly improve sustained return of spontaneous circulation compared with guideline-based hand placement in adults with nontraumatic out-of-hospital cardiac arrest.
Secondary clinical outcomes, including any return of spontaneous circulation, survival to intensive care unit admission, survival to discharge, and favorable neurologic status at discharge, were also not significantly different between groups.
TEE-guided CPR was associated with higher end-tidal carbon dioxide during minutes 11 to 20 after arrival, suggesting a potential hemodynamic benefit despite the neutral patient-centered outcomes.
No meaningful increase in TEE- or CPR-related adverse events was observed, supporting procedural feasibility and short-term safety in a highly controlled emergency department setting.
Background
High-quality chest compressions remain the cornerstone of cardiopulmonary resuscitation, yet the optimal location for force application on the chest is still debated. Current CPR guidelines generally recommend compressions on the lower half of the sternum, a practical and standardized approach that works across a broad range of patients and settings. However, imaging-based studies have raised concern that this landmark may not consistently maximize left ventricular compression. In some patients, standard hand placement may preferentially compress the aortic root or aortic valve region rather than the left ventricle, potentially reducing forward blood flow during arrest.
This physiologic question is clinically important. During cardiac arrest, small differences in perfusion may affect return of spontaneous circulation, downstream organ injury, and eventual neurologic recovery. Point-of-care ultrasound has increasingly been used during resuscitation to evaluate reversible causes of arrest, but transthoracic imaging is often limited by active compressions, body habitus, and interruptions in CPR. Transesophageal echocardiography offers a distinct advantage: it can provide continuous real-time imaging without stopping compressions, allowing the team to visualize whether the left ventricle is actually being compressed and whether the aortic valve is being obstructed.
Against this background, the EXECT-CPR investigators tested a straightforward but potentially practice-changing hypothesis: if TEE is used to guide rescuers away from aortic valve compression and toward the left ventricle, would outcomes improve in adults arriving at the emergency department with ongoing CPR for nontraumatic out-of-hospital cardiac arrest?
Study design
The EXECT-CPR study was a cluster-randomized clinical trial conducted at a single tertiary medical center in Taiwan between June 26 and November 19, 2023. Adults presenting consecutively to the emergency department with nontraumatic out-of-hospital cardiac arrest and ongoing resuscitation were eligible. Key exclusions were prehospital return of spontaneous circulation, extracorporeal CPR, contraindications to TEE, prior do-not-resuscitate orders, and obvious signs of death.
A total of 132 patients were randomized, with 66 assigned to TEE-guided CPR and 66 to conventional CPR. The median age was 68 years, with an interquartile range of 55 to 74 years, and 66% were male. Complete blinding was not feasible given the nature of the intervention, but the allocation schedule was disclosed only to the principal investigator.
The intervention began after emergency department arrival. In the TEE-guided group, the compression site was adjusted using transesophageal echocardiographic imaging to avoid aortic valve compression and instead target the left ventricle. In the control group, chest compressions followed guideline-recommended placement at the lower half of the sternum. This distinction is important: the trial did not test TEE throughout the entire arrest timeline, but rather TEE-guided optimization after hospital arrival, when some ischemic injury and no-flow or low-flow time had already accrued.
The primary outcome was sustained return of spontaneous circulation, defined as spontaneous circulation lasting at least 20 minutes. Secondary outcomes included any return of spontaneous circulation, survival to intensive care unit admission, survival to hospital discharge, favorable neurologic outcome at discharge defined as a cerebral performance category of 2 or lower, and intra-CPR end-tidal carbon dioxide levels. End-tidal carbon dioxide was included because it functions as a useful bedside surrogate for pulmonary blood flow and, indirectly, cardiac output during CPR.
Why compression location may matter mechanistically
The physiologic premise of this trial is sound. Chest compressions produce blood flow through a combination of direct cardiac pump effects and thoracic pump mechanisms. If compressions are centered over the left ventricle, one might expect more effective ventricular emptying and improved systemic perfusion. By contrast, if the force vector compresses the left ventricular outflow tract or aortic valve region, forward flow could theoretically be impaired. TEE is uniquely capable of showing these relationships in real time.
Prior observational work has suggested that standard sternal landmarks frequently fail to align with the maximal left ventricular diameter. This has encouraged interest in individualized compression targeting. Yet physiologic plausibility does not always translate into improved patient-centered outcomes, especially in cardiac arrest, where outcome is influenced by many upstream and downstream factors including initial rhythm, arrest etiology, bystander CPR, time to advanced life support, defibrillation timing, post-arrest care, and baseline comorbidity.
Key results
The primary endpoint was neutral. Sustained return of spontaneous circulation occurred in 29 patients in the TEE-guided group (44%) and 26 patients in the conventional CPR group (39%). The cluster-adjusted odds ratio was 1.21, with a 95% confidence interval of 0.64 to 2.29. This confidence interval crosses 1 and is wide enough to include both a clinically meaningful benefit and no benefit, underscoring statistical imprecision.
Secondary clinical outcomes were also not significantly different between groups. The abstract reports no significant group differences in any return of spontaneous circulation, survival to ICU admission, survival to hospital discharge, or favorable neurologic outcome at discharge. In other words, although the intervention was designed to improve the mechanics of CPR, this did not translate into detectable gains in the outcomes that matter most to patients and clinicians.
The most notable positive signal emerged from the physiologic data. Intra-CPR end-tidal carbon dioxide levels were higher in the TEE-guided group during the 11th to 20th minutes after emergency department arrival. This finding suggests a possible improvement in perfusion during ongoing CPR, at least during that time window. Because end-tidal carbon dioxide often correlates with cardiac output during resuscitation, the result supports the idea that image-guided targeting may improve compression effectiveness even if the trial was unable to show a clear clinical benefit.
Safety findings were reassuring. Adverse event rates related to TEE and CPR were comparable between groups. This is clinically relevant because TEE insertion during active resuscitation may raise concern for esophageal trauma, airway interference, or procedural distraction. In this trial, those concerns did not appear to translate into a measurable excess in harm.
How should clinicians interpret the neutral result?
The central message is not that TEE-guided CPR is ineffective under all circumstances. Rather, this trial shows that in a single-center emergency department setting, adjusting the compression site after hospital arrival did not significantly improve major clinical outcomes compared with conventional CPR. The study therefore does not support routine adoption of TEE-guided compression targeting solely for the expectation of improved ROSC or survival based on current evidence.
At the same time, the neutral finding should not be overinterpreted as proof of no effect. The authors explicitly note that the trial was underpowered because the assumed effect size used in planning was overly optimistic. That matters. Cardiac arrest trials often require large sample sizes because outcomes are heterogeneous and absolute improvements are typically modest. With only 132 participants, EXECT-CPR may have been capable of detecting only a large treatment effect. If the true effect of TEE guidance is smaller but still clinically worthwhile, this study would have been unlikely to identify it with confidence.
Timing also likely influenced the result. The intervention began after emergency department arrival, not in the prehospital phase. By then, many determinants of outcome had already been set in motion, including arrest duration, time to first CPR, time to defibrillation, and cumulative ischemic burden. If image-guided compression optimization has value, it may be greater when applied earlier in the arrest course or in highly selected subgroups.
There is also the issue of implementation complexity. TEE-guided CPR requires equipment, operator expertise, procedural workflows, and a team comfortable integrating live imaging into an already crowded resuscitation environment. In a specialized center, this may be feasible. In most emergency departments or prehospital systems, it may be substantially harder to operationalize without delaying or distracting from other elements of high-quality resuscitation.
Strengths of the EXECT-CPR trial
The study has several notable strengths. First, it addressed an important mechanistic hypothesis using a randomized design rather than relying solely on observational imaging data. Second, it targeted a practical and modifiable intervention: where exactly compressions are delivered. Third, the use of TEE is clinically innovative because it allows continuous imaging without interrupting compressions. Fourth, the investigators evaluated both patient-centered and physiologic endpoints, which helps explain why a mechanistically promising strategy may or may not translate into outcome benefit.
The trial also provides useful safety information. For centers with established expertise, TEE during CPR appears feasible and did not produce a clear safety penalty in this study. That alone may support its continued role for diagnostic clarification during arrest, even if therapeutic compression-site guidance remains unproven.
Limitations and generalizability
The most important limitation is limited statistical power. The wide confidence interval around the primary endpoint leaves meaningful uncertainty. A second limitation is the single-center design, which may reduce generalizability to systems with different patient populations, EMS performance, arrest etiologies, or resuscitation resources.
Third, the cluster-randomized structure and the inability to blind clinicians introduce some possibility of performance differences beyond the intervention itself, although this is difficult to avoid in procedural resuscitation research. Fourth, the study focused on adult nontraumatic out-of-hospital cardiac arrest patients who arrived with ongoing CPR. The findings may not apply to in-hospital arrest, traumatic arrest, extracorporeal CPR candidates, or patients with early prehospital ROSC.
Fifth, the trial tested one specific use of TEE: adjusting compression location to avoid aortic valve compression and target the left ventricle. TEE may still be valuable during arrest for other reasons, such as identifying tamponade, pulmonary embolism, profound ventricular failure, right heart strain, intracardiac thrombus, or ineffective compressions from other causes. Thus, a neutral result for compression targeting should not be conflated with a lack of utility for TEE more broadly in advanced resuscitation.
Relation to current resuscitation practice
Current resuscitation guidelines emphasize immediate, high-quality chest compressions with minimal interruptions, appropriate depth and rate, full recoil, early defibrillation for shockable rhythms, and treatment of reversible causes. They do not recommend routine individualized imaging-guided alteration of compression location for all patients. EXECT-CPR is broadly consistent with that stance: the study does not provide sufficient evidence to replace standard landmark-based chest compression positioning in routine emergency department practice.
However, the physiologic signal seen in end-tidal carbon dioxide suggests that this research direction remains worth pursuing. A reasonable interpretation is that TEE may improve the mechanics of CPR without yet demonstrating a patient-centered advantage under the conditions tested. This is not unusual in critical care trials, where biologic improvement can be attenuated by treatment delays, competing risks, and small sample size.
What comes next?
Future research should focus on larger multicenter trials powered for clinically meaningful differences in sustained ROSC, survival, and neurologic outcomes. Studies should also examine whether benefits differ by arrest phenotype, such as shockable versus nonshockable rhythm, presumed cardiac versus noncardiac etiology, obesity, chest wall anatomy, or prolonged transport times. Another important question is whether earlier application, including prehospital physician-led systems, would produce a larger effect.
Investigators may also consider adaptive or enrichment designs that identify patients most likely to benefit from individualized compression targeting. Integration with mechanical CPR devices is another intriguing avenue, as TEE could potentially be used to optimize device position in a reproducible way. Finally, trials should incorporate workflow metrics to ensure that imaging guidance does not inadvertently delay other time-critical interventions.
Clinical bottom line
For emergency and critical care clinicians, EXECT-CPR offers a careful and important corrective to a compelling physiologic idea. In adults arriving at the emergency department with ongoing nontraumatic out-of-hospital cardiac arrest, TEE-guided chest compression targeting did not significantly improve sustained ROSC or other major clinical outcomes compared with conventional CPR. Nevertheless, the higher end-tidal carbon dioxide levels observed during later resuscitation and the absence of excess adverse events suggest that image-guided optimization may still have physiologic value.
The study should therefore be read as a neutral, not negative, trial. It does not justify routine implementation of TEE-guided compression-site adjustment for all such patients, but it also does not close the door on the concept. For now, standard evidence-based resuscitation priorities remain paramount, while TEE continues to hold promise as a diagnostic and potentially hemodynamic adjunct in expert hands.
Funding and ClinicalTrials.gov
Trial registration: ClinicalTrials.gov Identifier NCT05907460.
The abstract provided does not specify the funding source. Readers should consult the full JAMA Internal Medicine article for complete funding and conflict-of-interest disclosures.
References
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