Transthoracic Echocardiography feasible during prone-position ventilation

A few modifications in technique make it possible to perform transthoracic echocardiography (TTE) during prone position ventilation, researchers in Mexico report.

“The challenge in performing transthoracic echocardiography in these patients is the fact that being in the prone position, this limits the possibility of having an adequate transthoracic window; in addition, those who require this rescue maneuver are patients with very high mechanical-ventilation parameters, so the positive pressure applied to the lung affects the interface between the transducer and the heart,” Dr. Daniel Manzur-Sandoval of Instituto Nacional de Cardiologia Ignacio Chavez, in Mexico City, told Reuters Health by email.

Prone-position ventilation is increasingly used during the COVID-19 pandemic, but there is a lack of information on how to obtain TTE for cardiac and hemodynamic evaluation in this position.

Dr. Manzur-Sandoval and colleagues evaluated the feasibility of obtaining echocardiographic images to measure multiple parameters with TTE during prone-position ventilation of 15 consecutive patients with confirmed SARS-CoV-2 infection in their critical-care unit.

They modified their echocardiographic technique in several ways to overcome the challenges associated with prone-position ventilation. First, they raised the patient’s left arm and placed a pillow or folded sheet underneath the midthoracic wall to maintain the left hemithorax slightly elevated to allow for comfortable transducer manipulation.

Second, they obtained images with the right hand on the right side of the bed (on the patient’s left side), placing the probe in the fifth or sixth intercostal space at the midclavicular line (or at the point of maximal impulse, if palpable) and aiming it toward the patient’s back.

Finally, the operator tilted, slid and rocked the probe, as necessary, to optimize image resolution.

By employing this methodology, they were able to evaluate right ventricular, left ventricular and diastolic function, as well as abnormal flow patterns at mitral, tricuspid and/or aortic valves with color Doppler and searching for pericardial effusion, all in about 10 minutes. The main limitation of this approach is that the inferior vena cava cannot be evaluated, the authors note.

Adequate evaluation of these features was possible in all but one patient, in whom the right ventricular free wall could not be assessed, the team reports in the Journal of the American College of Emergency Physicians Open.

Interrater agreement was strong (kappa coefficient >0.8) for all categorical measurements.

“We consider this a great initial experience, since there is no extensive previous investigation in this regard, except for anecdotal reports, and the studies that have been carried out are in non-intubated patients,” Dr. Manzur-Sandoval said. “We show in our study the feasibility of obtaining apical four-chamber and five-chamber views to measure multiple echocardiographic parameters with this technique to perform a qualitative and quantitative evaluation in patients with mechanical ventilation in prone position.”

“Taking into account the severity of this illness and the unknown clinical course in patients with COVID-19 infection, we must begin to carry out the hemodynamic evaluation of these patients, particularly during the prone position,” he said.

“A larger series will be required to assess the correlation (of prone TTE) with the usual measurements in supine position and its impact in clinical decision-making and outcomes,” the authors note. Medscape