Fig 1.
The principle of calibration-free cuffless local ΔP measurement from superficial arteries using arterial compliance probe.
Fig 2.
Experimental setup used for the phantom study to verify the proposed technique.
Fig 3.
In-vivo validation study protocol.
(A) In-vivo study setup; showing brachial BP measurement from the left hand. (B) The operator performing local ΔP measurement from the left carotid artery. (C) Subject performing stair-running exercise.
Fig 4.
Summary of phantom-based verification study results.
(A) Ultrasound echo frame from the carotid phantom. (B) A sample of continuous distension wave. (C) A sample of dual MPG waveform acquired along with the distension wave. (D) Correlation analysis between reference ΔP from catheter and ΔP estimated using the MPG-ultrasound arrangement. (E) Bland-Altman analysis showing the degree agreement between the reference and estimated ΔP.
Fig 5.
Sample waveforms recorded from human carotid artery using the arterial compliance probe.
(A) An ultrasound echo frame with proximal and distal arterial walls (B) A sample of arterial distention waveform, and (C) simultaneously acquired dual MPG waveforms.
Fig 6.
Simultaneously recorded beat-by-beat physiological parameters from the carotid artery.
(A) Local PWV, (B) arterial distension ΔD, and (C) end-diastolic diameter DD.
Fig 7.
Beat-to-beat variations in continuous physiological parameters.
Box-and-whisker diagrams showing beat-to-beat variation in the measured local PWV, ΔD, DD, and estimated carotid ΔP under physically relaxed condition (data pooled over all the subjects).
Fig 8.
Mean carotid local PWV and ΔD of each individual measured from both the physically relaxed and post-exercise conditions.
Fig 9.
Reference brachial ΔP versus estimated carotid ΔP.
(A) Box-and-whisker diagrams illustrating the brachial ΔP and carotid ΔP under physically relaxed and post-exercise conditions. (B) Correlation plot of brachial ΔP versus carotid ΔP.
Fig 10.
Correlation between measured brachial SBP and estimated carotid SBP (data pooled over all the subjects).