Evaluation of Transesophageal Doppler Detection of Air Embolism in Dogs

Abstract

The use of a cylindrical sensor which transceives (transmits and receives) ultrasound in a 360.degree. arc mounted on a standard esophageal stethoscope catheter to detect air embolism in dogs was assessed. Electronic circuitry developed specifically to provide a continuous analog recording of high frequency Doppler energy as well as an audible signal was used. The esophageal Doppler sensor apparently was easy to position. In 25 of 30 dogs, the system distinguished Doppler sounds of venous air emboli, present either in the superior vena cava, right atrium, right ventricle or pulmonary artery, from normal cardiovascular sounds. In the remaining 5 animals, Doppler heart and air emboli sounds were initially of poor quality, but improved with aspiration of air from the esophagus. In another 5 dogs, arterial air emboli produced by left venticular injections also were detected. The esophageal sensor was sensitive to both venous and arterial air emboli ranging from 0.05-0.2 ml of air, and repeated i.v. injections of air were consistently detected throughout a 5-h time period. Optimal position of the sensor for detection of venous air emboli was at the level of superior vena cava above its junction with the right atrium. Optimal position to detect arterial air emboli introduced via a left ventricular catheter was at the level of the aortic arch. Tissue analysis of the esophagus revealed no morphologic damage due to the sensor or transmitted energy.