Cross-sectional study of mechanism of arterial pulsation amplitude modulation under ultrasound probe compression: Similarities and differences compared with the oscillometric blood pressure measurement principle.

Arterial pulsation is used to differentiate arteries from veins on ultrasound imaging. However, the mechanism by which the arterial pulsation amplitude changes when an ultrasound probe compresses the artery has not been reported. Here, we aimed to investigate whether this mechanism resembles the oscillometric maximum amplitude algorithm. An automatic blood pressure cuff was placed on the upper left arm of 7 healthy participants (four men and 3 women; aged 27-46 years). An ultrasound probe attached to a force sensor was gradually applied to the distal brachial artery using an automated test stand until the lumen of the artery was completely occluded. Probe pressure and arterial pulsation data were recorded and analyzed during compression. Sequential ultrasound images and probe pressure measurements were obtained over time under 2 conditions: without cuff occlusion and with the cuff inflated above the systolic blood pressure. Without cuff inflation, ultrasonography-detected arterial pulsations and probe pressure oscillations were perfectly synchronized. The timing of the maximum amplitude occurrences in both signals coincided. Conversely, when pulsatile flow was stopped by cuff inflation above the systolic pressure, neither arterial pulsation nor probe pressure oscillations were observed. Pulsatile oscillations in the probe pressure persisted after local arterial occlusion by the probe. The mechanism underlying arterial pulsation generation under probe compression can be explained by the transmural pressure-volume relationship of the artery, in which pulsatile flow and reduced transmural pressure cause changes in arterial volume and produce observed probe pressure oscillations. These findings link ultrasound imaging and oscillometric blood pressure principles, providing a unique perspective for noninvasive arterial hemodynamic assessment.