Nontraumatic aortic blood flow sensing by use of an ultrasonic esophageal probe

Abstract

The measurement of blood velocity fields, volume flow, and arterial wall motion in the descending thoracic aorta provides essential hemodynamic information for both research and clinical diagnosis. The close proximity of the esophagus to the aorta in the dog makes it possible to obtain such data nonsurgically using an ultrasonic esophageal probe; however, the accuracy of such a probe is limited if the angle between the sound beam and the flow axis, known as the Doppler angle, is not precisely known. By use of a pulsed Doppler velocity meter (PUDVM) and a triangulation procedure, accurate empirical measurement of the Doppler angle has been obtained, allowing quantification of blood velocity scans across the aorta. Volume flow is obtained by integration of blood velocity profiles and arterial wall motion is measured with an ultrasonic echo tracking device. Accuracy of the probe was substantiated by comparison with ultrasonic and electromagnetic implanted flow cuff measurements. Use of the probe in measurement of blood velocity, volume flow and arterial wall motion at various locations along the 8- and 10-cm length of the descending thoracic aorta in adult beagle dogs is detailed. The simplicity, accuracy, and nontraumatic aspect of the technique should allow increasing use of such a probe in numerous research and clinical applications.

Extravascular lung water measurements and hemodynamic monitoring in the critically ill: bedside alternatives to the pulmonary artery catheter

“…However, this approach was abandoned because the position of a handheld probe is difficult to stabilize and standardize, especially for repeat measurements, and because this location provides a relatively poor ultrasound window. Instead, with EDM, the aortic blood velocity measurements are obtained via a Doppler transducer secured to the tip of a probe placed in the middle esophagus, optimally at the level of the left atrium (23,95). The frequency of the Doppler pulsed wave depends on the probe manufacturer but is normally between 4 -5 MHz.…”

Utility of esophageal Doppler as a minimally invasive hemodynamic monitor: a review

“…E ED D: : t th he eo or re et ti ic ca al l c co on ns si id de er ra at ti io on ns s ED was first proposed as a minimally invasive hemodynamic measure in the 1970's and it has undergone significant technological advancement and clinical evaluation since. 9,10 Initially, suprasternal transthoracic ultrasound/Doppler probes were used for determining CO but they were not widely adopted because probe position instability limited their use for repeated measures over extended periods of time. 11 Esophageal probes were recognized to have two significant advantages over suprasternal probes.…”

Measuring 3D velocity vectors using the Transverse Oscillation method

“…Several ultrasound methods have been proposed for measuring three-dimensional (3D) velocities over the past decades. These includes cross-beam methods [5], [6], [7], speckle [8] or feature tracking methods [9], transverse Doppler methods using the spectral broadening effect [10], [11], decorrelation based techniques [12],cross-correlation of beams [13], [14], [15], or particle imaging velocimetry [16], [17], [18]. However, the various techniques have individual limitations such as limited field of view, high computational demands, or the need for contrast agents.…”