PS-C08-6: COMPARING BLOOD PRESSURE MEASUREMENTS BETWEEN A NOVEL CUFF-LESS EARPHONE-TYPE DEVICE BASED ON GREEN REFLECTED PHOTOPLETHYSMOGRAPHY AND A STANDARD CUFF-BASED SPHYGMOMANOMETER

Abstract

Objective: Blood pressure (BP) measurement with conventional sphygmomanometers often causes discomfort and pain to the users due to arterial occlusion pressure caused by the inflatable cuff, making it difficult to perform continuous or frequent measurements for rigid blood pressure control. Developing unconstrained wearable electronics that can measure BP continuously would be useful in the healthcare field. We have developed a novel earphone-type device for cuff-less BP monitoring based on photoplethysmography with green light. In the present study, we compared the measured BP values between this novel cuff-less BP monitoring device and a conventional cuff-based sphygmomanometer. Design and Methods: From August 2020 to October 2021, 20 healthy subjects and 40 hypertensive patients (outpatients attending Yokohama City University Hospital and Yokohama Minami Kyosai Hospital, Yokohama, Japan) were recruited. Each participant's BP was measured using the novel cuff-less BP monitoring device as well as a standard cuff-based sphygmomanometer under four different conditions: static, BP rising and falling, and reproducible after the one-month interval. The results of measurements under the four conditions were integrated and analyzed. The BP measurements were determined to be comparable between the standard cuff-based sphygmomanometer and the novel cuff-less earphone-type device, if the mean absolute difference (MAD) of the measurements was within 7 mmHg. We also performed Bland-Altman agreement analyses. Results: The participants’ characteristics were as follows. Male to female ratio was approximately 50% in both groups. Age was 27.5 [interquartile (IQR) 24.5–33.0] years old for the healthy subjects and 65.0 [IQR 49.5–74.0] years old for the patients with hypertension (HTN). BMI was 21.2 [IQR 20.1–22.5] kg/m 2 and 23.8 [IQR 21.8–24.9] kg/ m 2, respectively. MAD between the novel cuff-less device and the reference using the standard cuff-based sphygmomanometer among the healthy subjects was 5.8 mmHg for systolic BP (SBP) and 5.3 mmHg for diastolic BP (DBP). MAD in the patients with HTN was 7.8 mmHg for SBP and 4.4 mmHg for DBP. In Bland-Altman agreement analyses, mean difference in the healthy subjects was 2.7 (95% confidence interval [CI] −13.4, 16.8) mmHg for SBP and 2.4 (95% CI −10.7, 15.5) mmHg for DBP. Mean difference in the patients with HTN was 0.9 (95% CI −20.0, 21.9) mmHg for SBP and 0.7 (95% CI −10.9, 12.3) mmHg for DBP. Conclusions: Our newly developed cuff-less earphone-type device based on green reflected photoplethysmography able to predict BP in healthy subjects, but it was difficult to predict SBP in the patients with HTN.