|The Segmental Blood Pressure (SBP) tests require the placement of dedicated pressure cuffs on the various limb segments, which typically include the 2 brachial segments, the thighs (some protocols divide the thigh into 2 separate segments), the segment below the knees, the ankles and the toes. Additional segments can be measured, such as the digits for diagnosis of the Raynaud's Syndrome.
Prior to segmental cuff inflation, a reference signal is identified distal to the cuff location. This reference signal is typically a CW Doppler measurement or a PPG (Photo-Plethysmograph, used for the digits and toes).
Above is an example of a SBP measurement taken from
Viasonix FALCON/Pro system using 8 MHz CW Doppler probe.
When the cuff pressure exceeds the systolic pressure, the reference signal waveforms should disappear. Then, the cuff pressure is slowly deflated at constant bleeding rate, and the first occurrence of the return of the reference signal waveform marks the systolic pressure. The clinician is normally interested in the ratio of the ankle systolic pressure to the brachial pressure (ABI – Ankle Brachial Index), or in significant pressure differences either in sequential segments or side-to-side differences for the same segment.