Raj Kiran V, Nabeel P M, Chandran Dinu, Sivaprakasam Mohanasankar, Joseph Jayaraj
Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, India.
Healthcare Technology Innovation Centre, IIT Madras, Chennai, India.
Blood Press. 2022 Dec;31(1):19-30. doi: 10.1080/08037051.2021.2022453. Epub 2022 Jan 11.
Existing technologies to measure central blood pressure (CBP) intrinsically depend on peripheral pressure or calibration models derived from it. Pharmacological or physiological interventions yielding different central and peripheral responses compromise the accuracy of such methods. We present a high-frame-rate ultrasound technology for cuffless and calibration-free evaluation of BP from the carotid artery. The system uses a pair of single-element ultrasound transducers to capture the arterial diameter and local pulse wave velocity (PWV) for the evaluation of beat-by-beat BP employing a novel biomechanical model.
System's functionality assessment was conducted on eight male subjects (26 ± 4 years, normotensive and no history of cardiovascular risks) by perturbing pressure short-term moderate lower body negative pressure (LBNP) intervention (-40 mmHg for 1 min). The ability of the system to capture dynamic responses of carotid pressure to LBNP was investigated and compared against the responses of peripheral pressure measured using a continuous BP monitor.
While the carotid pressure manifested trends similar to finger measurements during LBNP, the system also captured the differential carotid-to-peripheral pressure response, which corroborates the literature. The carotid diastolic and mean pressures agreed with the finger pressures (limits-of-agreement within ±7 mmHg) and exhibited acceptable uncertainty (mean absolute errors were 2.4 ± 3.5 and 2.6 ± 4.0 mmHg, respectively). Concurrent to the literature, the carotid systolic and pulse pressures (PPs) were significantly lower than those of the finger pressures by 11.1 ± 9.4 and 11.3 ± 8.2 mmHg, respectively ( < .0001).
The study demonstrated the method's potential for providing cuffless and calibration-free pressure measurements while reliably capturing the physiological aspects, such as PP amplification and dynamic pressure responses to intervention.
现有的测量中心血压（CBP）的技术本质上依赖于外周血压或由此得出的校准模型。产生不同中心和外周反应的药理或生理干预会损害这些方法的准确性。我们提出一种高帧率超声技术，用于从颈动脉进行无袖带且无需校准的血压评估。该系统使用一对单元素超声换能器来捕获动脉直径和局部脉搏波速度（PWV），以便采用一种新颖的生物力学模型逐搏评估血压。
通过短期适度下肢负压（LBNP）干预（-40 mmHg持续1分钟）对8名男性受试者（26±4岁，血压正常且无心血管疾病风险史）进行系统功能评估。研究了该系统捕获颈动脉压力对LBNP的动态反应的能力，并与使用连续血压监测仪测量的外周压力反应进行比较。
虽然在LBNP期间颈动脉压力呈现出与手指测量相似的趋势，但该系统还捕获了颈动脉与外周压力的差异反应，这与文献相符。颈动脉舒张压和平均压与手指压力一致（一致性界限在±7 mmHg内），并且表现出可接受的不确定性（平均绝对误差分别为2.4±3.5和2.6±4.0 mmHg）。与文献一致，颈动脉收缩压和脉压（PPs）分别比手指压力显著低11.1±9.4和11.3±8.2 mmHg（P<0.0001）。
该研究证明了该方法在提供无袖带且无需校准的压力测量方面的潜力，同时能够可靠地捕获生理方面的信息，如脉压放大和对干预的动态压力反应。
