Detection of blood pressure changes induced by exercise and coldstress using cuffless technique

Objective: Single point calibration is commonly used in cuffless devices that estimate blood pressure (BP) based on pulse transit time. However, it is not established whether such devices can detect BP changes induced by physiological interventions. This pilot study investigates the ability of a clinically validated cuffless device (Maisense Freescan®), which measures electrocardiogram and radial pulse wave for BP estimation, in detecting acute BP changes. Methods: Six participants (age 22±7, mean±SD, 1 female) had their BP measured in triplicate after 5 minutes of seated rest and initial individualised calibration, each time with Freescan® first then with a clinically validated oscillometric device (OMRON® HEM-742). Participants then performed two minutes of stationary cycling. Three participants also underwent a cold pressor test (CPT). BP was measured first with Freescan®, followed by OMRON®, immediately at cessation of cycling and at two minutes of CPT. Results: At rest, systolic (SBP) and diastolic BP as measured by Freescan® differed by 6±7 mmHg and 7±6 mmHg, respectively, when compared to brachial measurements (P<0.001). After cycling, both Freescan® and OMRON® registered an increase (P<0.01) in SBP from baseline (36±16 mmHg and 20±10 mmHg, respectively). However, during CPT, the devices registered a different change in magnitude and direction (-4±8 mmHg and 12±8 mmHg, respectively). Conclusion: The directional change in BP during exercise was detected by Freescan® albeit with a larger magnitude. The BP increase during CPT was not detected. Further investigation is required to understand underlying causes for differences and implication for future development of cuffless BP measurement.