Detection of venous gas bubbles with computerized doppler ultrasound

Abstract

Venous Gas Embolism (VGE) may occur during the brain and neck surgery where the operative site is higher than the heart. Medium where the pressure changes significantly like diving, aviation and space missions also promote VGE. For this reason, early detection of VEG is very crucial. The Doppler Ultrasound Audio (DUA) signals recorded from two divers detectors are analyzed to detect the embolic waveforms. The optimal pass band characteristics of the embolic event are determined by an extensive bandpass filtering analsis and the optimum band is determined as 4.5-8 KHz. A nonlinear Teager operator and adaptive thresholding is also applied to the filtered DUA for automatic detection of the embolic events. As a last step, a software that can perform all the operations from digitizing the DUA recordings to detecting the embolic events is developed for off-line analysis.|Keywords: Doppler Ultrasound Audio, gas bubble, Teager energy operator, venous gas embolism, frequency band analysis.