Evaluation of the Accuracy of a New Cuffless Magnetoplethysmography Blood Pressure Monitor in Hypertensive Patients.

OBJECTIVE: There is a growing demand for cuffless blood pressure (BP) measurement as an easy alternative to cuff-occlusion-based BP measurement. We assessed the accuracy of a new cuffless, watch-style BP monitor with a magnetoplethysmography (MPG) sensor compared to two standard auscultatory and oscillatory BP monitors. SUBJECTS AND METHODS: A total of 34 patients with uncontrolled hypertension (systolic BP ≥150 mm Hg or diastolic BP ≥95 mm Hg) were enrolled in the study. BP was measured by two conventional monitors and the new device during the pre-exercise phase, during isometric handgrip exercise, and during the recovery phase (5 min after exercise). The correlation between monitors was assessed using intraclass correlation coefficient (ICC) and Bland-Altman plots. RESULTS: Although two reference monitors produced highly correlated BP measurements, each was differentially correlated with BP measurements obtained by the new MPG monitor. During exercise, the mean difference between systolic BP obtained by the MPG and oscillatory monitors was >7 mm Hg with an ICC of 0.549 (95$ CI 0.264-0.746) in systole and 0.737 (95$ CI 0.534-0.859) in diastole. The ICC between the auscultatory monitor and the MPG monitor was 0.753 (95$ CI 0.559-0.868) in systole and 0.841 (95$ CI 0.706-0.918) in diastole after exercise. Bland-Altman plots also indicated that the performance of the new MPG device was very similar to that of the auscultatory monitor. CONCLUSION: Although the performance of the new MPG monitor was comparable to that of the reference monitors used in this study, improved stability and accuracy are necessary for accurate BP evaluation during dynamic activity.

Estimation of Circadian Body Temperature Rhythm Based on Heart Rate in Healthy, Ambulatory Subjects.

Core body temperature is a reliable marker for circadian rhythm. As characteristics of the circadian body temperature rhythm change during diverse health problems, such as sleep disorder and depression, body temperature monitoring is often used in clinical diagnosis and treatment. However, the use of current thermometers in circadian rhythm monitoring is impractical in daily life. As heart rate is a physiological signal relevant to thermoregulation, we investigated the feasibility of heart rate monitoring in estimating circadian body temperature rhythm. Various heart rate parameters and core body temperature were simultaneously acquired in 21 healthy, ambulatory subjects during their routine life. The performance of regression analysis and the extended Kalman filter on daily body temperature and circadian indicator (mesor, amplitude, and acrophase) estimation were evaluated. For daily body temperature estimation, mean R-R interval (RRI), mean heart rate (MHR), or normalized MHR provided a mean root mean square error of approximately 0.40 °C in both techniques. The mesor estimation regression analysis showed better performance than the extended Kalman filter. However, the extended Kalman filter, combined with RRI or MHR, provided better accuracy in terms of amplitude and acrophase estimation. We suggest that this noninvasive and convenient method for estimating the circadian body temperature rhythm could reduce discomfort during body temperature monitoring in daily life. This, in turn, could facilitate more clinical studies based on circadian body temperature rhythm.

Evaluation of performance of several established pitch detection algorithms in pathological voices.

Robust pitch estimation is important in many areas of speech processing. In voice pathology, diverse statistics extracted form pitch estimation were commonly used to test voice quality. In this study, we compared several established pitch detection algorithms (PDAs) for verification of adequacy of the PDAs. In the database of total pathological voices of 99 and normal voices of 30, an analysis of errors related with pitch detection was evaluated between pathological and normal voices, or among the types of pathological voices. Pitch errors of all PDAs used in this study more or less showed some changes between pathological and normal voices. According to the results of pitch errors, gross pitch error showed some increases in cases of pathological voices; especially excessive increase in PDA based on nonlinear time-series. In an analysis of types of pathological voices classified by aperiodicity and the degree of chaos, the more voice has aperiodic and chaotic, the more growth of pitch errors increased. Consequently, it is required to survey the severity of tested voice in order to obtain accurate pitch estimates.