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Published on: April 18, 2025
Bridging the gap: Hybrid cardiac echo in the critically ill
Jacob J Glaser1, Cassandra Cardarelli, Samuel Galvagno
1From the Division of Trauma and Surgical, Critical Care (J.J.G., T.M.S., S.B.M.), Department of Surgery, and Department of Anesthesiology (S.G.), University of Maryland School of Medicine, R Adams Cowley Shock Trauma Center, Baltimore; and Walter Reed National Military Medical Center (C.C.), Bethesda, Maryland.
Insights
The Focused Rapid Echocardiographic Examination (FREE) correlates well with standard transthoracic echocardiography (TTE) for assessing cardiac function. This hybrid ultrasound provides actionable data for critically ill patients, especially in resource-limited settings.
Area of Science:
- Point-of-care ultrasound
- Cardiac imaging
- Critical care medicine
Background:
- Point-of-care ultrasound (POCUS) is vital for critically ill patients but often lacks the quantitative detail of transthoracic echocardiography (TTE).
- The Focused Rapid Echocardiographic Examination (FREE) was developed as a hybrid POCUS tool emphasizing cardiac function over detailed anatomy.
- FREE aims to provide actionable clinical data comparable to TTE.
Purpose of the Study:
- To evaluate the correlation between quantitative measurements obtained from FREE and standard TTE.
- To determine if FREE provides clinically useful information for decision-making in critically ill patients.
Main Methods:
- A cohort of patients who underwent both FREE and TTE on the same day was identified.
- Quantitative cardiac function parameters, including ejection fraction, diastolic function, and right ventricular function, were measured using both FREE and TTE.
- Correlation analyses were performed to compare measurements between the two echocardiographic modalities.
Main Results:
- FREE demonstrated strong correlations with TTE for ejection fraction (r=0.89) and other key parameters like left ventricular internal dimension end diastole (r=0.94).
- Right ventricular function agreement was observed in 82% of patients, and pericardial effusion detection showed 94% concordance.
- FREE effectively assessed cardiac function without missing significant valvular anatomy.
Conclusions:
- The FREE examination provides a functional cardiac assessment that strongly correlates with TTE measurements.
- FREE offers significant clinical value for critically ill patients, particularly in remote or resource-limited environments.
- This hybrid ultrasound approach enhances clinical decision-making by offering rapid, actionable cardiac insights.
Background:
Point-of-care ultrasound often includes cardiac ultrasound. It is commonly used to evaluate cardiac function in critically ill patients but lacks the specific quantitative anatomic assessment afforded by standard transthoracic echocardiography (TTE). We developed the Focused Rapid Echocardiographic Examination (FREE), a hybrid between a cardiac ultrasound and TTE that places an emphasis on cardiac function rather than anatomy. We hypothesized that data obtained from FREE correlate well with TTE while providing actionable information for clinical decision making.
Methods:
FREE examinations evaluating cardiac function (left ventricular ejection fraction), diastolic dysfunction (including early mitral Doppler flow [E] and early mitral tissue Doppler [E']), right ventricular function, cardiac output, preload (left ventricular internal dimension end diastole), stroke volume, stroke volume variation, inferior vena cava diameter, and inferior vena cava collapse were performed. Patients who underwent both a TTE and FREE on the same day were identified as the cohort, and quantitative measurements were compared. Correlation analyses were performed to assess levels of agreement.
Results:
A total of 462 FREE examinations were performed, in which 69 patients had both a FREE and TTE. FREE ejection fraction was strongly correlated with TTE (r = 0.89, 95% confidence interval). Left ventricular outflow tract, left ventricular internal dimension end diastole, E, and lateral E' derived from FREE were also strongly correlated with TTE measurements (r = 0.83, r = 0.94, r = 0.77, and r = 0.88, respectively). In 82% of the patients, right ventricular function for FREE was the same as that reported for TTE; pericardial effusion was detected on both examinations in 94% of the cases. No significant valvular anatomy was missed with the FREE examination.
Conclusion:
Functionally rather than anatomically based hybrid ultrasound examinations, like the FREE, facilitate decision making for critically ill patients. The FREE's functional assessment correlates well with TTE measurements and may be of significant clinical value in critically ill patients, especially when used in remote operating environments where resources are limited.
Level Of Evidence:
Diagnostic test, level III.
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