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. 2023 May 5;5(5):e0914.
doi: 10.1097/CCE.0000000000000914. eCollection 2023 May.

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

Chelsea E Munding  1 , Jon-Émile S Kenny  1   2 , Zhen Yang  1 , Geoffrey Clarke  1   2 , Mai Elfarnawany  1 , Andrew M Eibl  1   2 , Joseph K Eibl  1   2   3 , Bhanu Nalla  2   3 , Rony Atoui  2   3
Affiliations

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

Chelsea E Munding et al. Crit Care Explor. .

Abstract

Measuring fluid responsiveness is important in the management of critically ill patients, with a 10-15% change in cardiac output typically being used to indicate "fluid responsiveness." Ideally, these changes would be measured noninvasively and peripherally. The aim of this study was to determine how the common carotid artery (CCA) maximum velocity changes with total circulatory flow when confounding factors are mitigated and determine a value for CCA maximum velocity corresponding to a 10% change in total circulatory flow.

Design: Prospective observational pilot study.

Setting: Patients undergoing elective, on-pump coronary artery bypass grafting (CABG) surgery.

Patients: Fourteen patients were referred for elective coronary artery bypass grafting surgery.

Interventions: Cardiopulmonary bypass (CPB) pump flow changes during surgery, as chosen by the perfusionist.

Measurements: 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.

Main results: 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.

Conclusions: Changes in CCA velocity may be a useful surrogate for determining fluid responsiveness when user error can be mitigated.

Keywords: Doppler ultrasound; Fluid responsiveness; cardiopulmonary bypass; carotid arteries; hemodynamic monitoring; wearable technology.

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Figures

Figure 1.
Figure 1.
Using the Doppler patch to compare changes in common carotid artery (CCA) velocity to changes in cardiopulmonary bypass (CPB) pump flow rate. A, CW Doppler patch in place over CCA. B, Displayed spectrogram during a change in flow rate, showing maximum CCA velocity trace (green line) and CPB pump pulsations (blue arrows). C, Dose-response curve (black line) fitted to changes in CPB pump flow and corresponding changes in CCA maximum velocity for a single subject. (i) Inferred point representing zero flow, (ii) negative CPB pump flow change, (iii) baseline CPB pump flow and baseline CCA maximum velocity, (iv) positive CPB pump flow change. The red points indicate the overall mean CCA velocity change for each of the time windows, while the black points show the variability of each 0.5 s segment of the corresponding windows. The change in CCA velocity corresponding to a 10% change in CPB pump flow was determined from the equation of the dose-response curve to be 8.5% with a 95% CI of (5.0–12.0%).
See this image and copyright information in PMC

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