A portable, flexible Doppler ultrasound machine continuously monitors the absolute speed of blood flow in deeply embedded arteries, according to study results published in Science Advances.
Developed by a research team in China, the device could potentially enable long-term monitoring of thrombosis and restenosis and improve the quality of care for patients after vascular reconstruction surgery.
To prevent thrombosis – which can occur within 72 hours – and restenosis complications after vascular reconstruction surgery, an hourly physical examination of capillary filling and skin color should be performed. However, patients who are admitted to the hospital are only assessed sporadically or sometimes not after discharge. The aim of the current study was to follow how a portable Doppler device can improve the quality of care after reconstruction operations.
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The researchers used a continuous wave Doppler in the handheld device that contained a transducer that continuously emitted a beam of ultrasound while an adjacent transducer received scattered blood-based echoes. According to the researchers, the skin-conforming device offered simple signal processing and functionality compared to pulse wave Doppler devices.
In design, they used an angled transducer array to develop opaque ultrasound beams that were used to determine the relative motion between the ultrasound beam and the scatterers. The researchers then determined the Doppler angle using a dual-beam ultrasound Doppler method. The transducer impulse and frequency responses were determined and found a stable center frequency of approximately 5 MHz.
Tests with the device were performed on a standard ultrasound phantom that was used to simulate tissue and blood fluid in humans. The device showed continuous changes in vascular resistance, which proved its value in detecting certain blood flow properties. Ultimately, the researchers found that several experimental studies on both ultrasound phantoms and human participants showed that the wearable device provided accurate measurements of flow velocity, demonstrating its potential as a non-invasive measurement of flow velocity in human arteries.
Based on their experiments, the researchers added that the device avoids the complex imaging common to clinical ultrasound machines and “does not require an experienced operator, applies much less pressure and thus helps with long-term monitoring” after vascular reconstruction.
reference
Wang F, Jin P, Feng Y, et al. Flexible Doppler ultrasound device for monitoring blood flow velocity. Sci Adv. Published online October 29, 2021. doi: 10.1126 / sciadv.abi9283
