Related Experiment Video
Updated: Jun 24, 2026

Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Published on: October 22, 2014
Impact of wall filter selection on the detection of vasomotor changes in the brachial artery: a pilot study
Michel J Johnson1, J Kevin Shoemaker
1Neurovascular Research Laboratory, University of Western Ontario, London, ON N6A3K7, Canada. michelj@nipissingu.ca
Abstract:
During Doppler ultrasound assessment of blood flow, a wall filter is used to reduce or eliminate high-amplitude, low-velocity signals from the vessel wall and the surrounding tissue. This study investigated the impact of a range of wall filters (22 Hz, 75 Hz, 128 Hz, and 252 Hz) on the accuracy of forearm blood flow monitoring during the sympathoexcitatory application of lower body negative pressure, when peripheral blood flow may decrease substantially. The 252 Hz filter eliminated diastolic flow in 4 of 10 participants. In the remaining participants, the 252 Hz filter minimized the sensitivity of the pulsatility index. The interpretation of physiological responses could ultimately be compromised by using filters beyond 128 Hz.
Related Concept Videos
Assessment of blood pressure in brachial artery(one-step method)
Prepare for the Procedure:
Assessment of blood pressure in brachial artery(two-step method)
Sites for measuring blood pressure
The Brachial Artery: Primary Site for Blood Pressure Measurement
Special considerations while measuring blood pressure
Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
Pre-Procedural Guidelines for Assessing Blood Pressure
Assessing Blood pressure using a doppler ultrasound
Pre-Procedural Guidelines for Doppler Ultrasound Blood Pressure Assessment:
Preparation of Equipment:

