Objectives: The aim of this study was to compare the sensitivity of a newly applied transoesophageal ultrasonic Doppler sensor for detection of air with the traditional precordial ultrasonic Doppler sensor in clinical use.
Methods: We studied 16 patients undergoing neurosurgical procedures in a sitting position. Two ultrasonic Doppler devices were compared as to their ability to detect venous air embolisms (VAE): transoesophageal (ODM II, co. Abbott) versus a precordial ultrasonic Doppler sensor (Parks Medical Electronics Inc.). After establishing general anaesthesia and endotracheal intubation, we applied an ultrasonic Doppler sensor to the right sternal border of the patient's chest and inserted an ultrasonic Doppler probe into the oesophagus. With the patient in the sitting position, microparticularly d-galactose was injected to verify the efficacy of both ultrasonic Doppler devices.
Results: Using ODM II by positioning the probe toward the azygos vein, a dosage of 1 ml microparticularly d-galactose was detected in every patient. When adjusting the ODM II-probe on the right myocardial wall or using the precordial ultrasonic Doppler sensor, the administration of microparticularly d-galactose was detected by the devices in only 11 patients.
Conclusions: This study demonstrates that a transoesophageal ultrasonic Doppler sensor (ODM II) is more efficient than the precordial ultrasonic Doppler sensor for monitoring patients who are at risk of VAE by sonification of the azygos vein.