Detecting the Change in Total Circulatory Flow with a Wireless, Wearable Doppler Ultrasound Patch: A Pilot Study.

Abstract

Prospective observational pilot study. Patients undergoing elective, on-pump coronary artery bypass grafting (CABG) surgery. Fourteen patients were referred for elective coronary artery bypass grafting surgery. Cardiopulmonary bypass (CPB) pump flow changes during surgery, as chosen by the perfusionist. A hands-free, wearable Doppler patch was used for CCA velocity measurements with the aim of preventing user errors in ultrasound measurements. Maximum CCA velocity was determined from the spectrogram acquired by the Doppler patch. CPB flow rates were recorded as displayed on the CPB console, and further measured from the peristaltic pulsation frequency visible on the recorded Doppler spectrograms. Changes in CCA maximum velocity tracked well with changes in CPB flow. On average, a 13.6% change in CCA maximum velocity was found to correspond to a 10% change in CPB flow rate. Changes in CCA velocity may be a useful surrogate for determining fluid responsiveness when user error can be mitigated.