Effects of measurement intervals on the values of repeated auscultatory blood pressure measurements.

Objective: For repeated measurements of blood pressure (BP) using the auscultatory method, current guidelines recommend intervals of 1-2 minutes; however, evidence to support this recommendation is insufficient. In the present study, the effects of intervals among repeated BP measurements using the auscultatory method were evaluated.Methods: Systolic and diastolic BPs were measured using the auscultatory method in 37 participants. The measurements were repeated 5 times each at intervals of 15, 30, 60, 90, and 120 seconds. The changes in the BP along with the increasing the number of repetitions were assessed at each measurement interval using a linear mixed model.Results: With an increasing number of measurements, the systolic and diastolic BPs showed significant progressive decrease and increase (p < 0.05), respectively, when the measurement interval was 15 seconds. However, the precision of BP measurements was not affected by performing the measurements at intervals of 30 seconds or longer.Conclusion: Repeated BP measurements using the auscultatory method need to have an interval of at least 30 seconds, which is shorter than the intervals recommended by the current guidelines.

Estimating metabolic equivalents for activities in daily life using acceleration and heart rate in wearable devices.

BACKGROUND: Herein, an algorithm that can be used in wearable health monitoring devices to estimate metabolic equivalents (METs) based on physical activity intensity data, particularly for certain activities in daily life that make MET estimation difficult. RESULTS: Energy expenditure data were obtained from 42 volunteers using indirect calorimetry, triaxial accelerations and heart rates. The proposed algorithm used the percentage of heart rate reserve (%HRR) and the acceleration signal from the wearable device to divide the data into a middle-intensity group and a high-intensity group (HIG). The two groups were defined in terms of estimated METs. Evaluation results revealed that the classification accuracy for both groups was higher than 91%. To further facilitate MET estimation, five multiple-regression models using different features were evaluated via leave-one-out cross-validation. Using this approach, all models showed significant improvements in mean absolute percentage error (MAPE) of METs in the HIG, which included stair ascent, and the maximum reduction in MAPE for HIG was 24% compared to the previous model (HJA-750), which demonstrated a 70.7% improvement ratio. The most suitable model for our purpose that utilized heart rate and filtered synthetic acceleration was selected and its estimation error trend was confirmed. CONCLUSION: For HIG, the MAPE recalculated by the most suitable model was 10.5%. The improvement ratio was 71.6% as compared to the previous model (HJA-750C). This result was almost identical to that obtained from leave-one-out cross-validation. This proposed algorithm revealed an improvement in estimation accuracy for activities in daily life; in particular, the results included estimated values associated with stair ascent, which has been a difficult activity to evaluate so far.

Effectiveness of a Self-monitoring Device for Urinary Sodium-to-Potassium Ratio on Dietary Improvement in Free-Living Adults: a Randomized Controlled Trial.

BACKGROUND: Reducing the urinary sodium-to-potassium ratio is important for reducing both blood pressure and risk of cardiovascular disease. Among free-living Japanese individuals, we carried out a randomized trial to clarify the effect of lifestyle modification for lowering urinary sodium-to-potassium ratio using a self-monitoring device. METHODS: This was an open, prospective, parallel randomized, controlled trial. Ninety-two individuals were recruited from Japanese volunteers. Participants were randomly allocated into intervention and control groups. A month-long dietary intervention on self-monitoring urinary sodium-to-potassium ratio was carried out using monitors (HEU-001F, OMRON Healthcare Co., Ltd., Kyoto, Japan). All participants had brief dietary education and received a leaflet as usual care. Monitors were handed out to the intervention group, but not to the control group. The intervention group was asked to measure at least one spot urine sodium-to-potassium ratio daily, and advised to lower their sodium-to-potassium ratio toward the target of less than 1. Outcomes included changes in 24-hour urinary sodium-to-potassium ratio, sodium excretion, potassium excretion, blood pressure, and body weight in both groups. RESULTS: Mean measurement frequency of monitoring was 2.8 times/day during the intervention. Changes in urinary sodium-to-potassium ratio were -0.55 in the intervention group and -0.06 in the control group (P = 0.088); respective sodium excretion changes were -18.5 mmol/24 hours and -8.7 mmol/24 hours (P = 0.528); and corresponding potassium excretion was 2.6 mmol/24 hours and -1.5 mmol/24 hours (P = 0.300). No significant reductions were observed in either blood pressure or body weight after the intervention. CONCLUSIONS: Providing the device to self-monitor a sodium-to-potassium ratio did not achieve the targeted reduction of the ratio in "pure self-management" settings, indicating further needs to study an effective method to enhance the synergetic effect of dietary programs and self-monitoring practice to achieve the reduction. However, we cannot deny the possibility of reducing sodium-to-potassium ratio using a self-monitoring device.

Development of beat-by-beat blood pressure monitoring device and nocturnal sec-surge detection algorithm.

The nocturnal blood pressure (BP) surge in seconds (sec-surge) is defined as a brief, acute transient BP elevation over several tens of seconds, triggered by obstructive sleep apnea (OSA) and sympathetic hyperactivity. Sec-surge imposes a significant strain on the cardiovascular system, potentially triggering cardiovascular events. Quantitative evaluation of sec-surge level could be valuable in assessing cardiovascular risks. To accurately measure the detailed sec-surge, including its shape as BP rises and falls, we developed a beat-by-beat (BbB) BP monitoring device using tonometry. In addition, we developed an automatic sec-surge detection algorithm to help identify sec-surge cases in the overnight BbB BP data. The device and algorithm successfully detected sec-surges in patients with OSA. Our results demonstrated that sec-surge was associated with left ventricular hypertrophy and arterial stiffness independently of nocturnal BP level or variability. Sec-surge would be worth monitoring for assessing cardiovascular risks, in addition to nocturnal BP level. Nocturnal blood pressure (BP) surge in seconds (sec-surge) places heavy load on the cardiovascular system and can trigger cardiovascular events. To identify sec-surges, we developed a beat-by-beat BP monitoring device and a sec-surge detection algorithm. Furthermore, sec-surge was more related to cardiovascular risks than conventional nocturnal BP parameters.

Nocturnal blood pressure surge in seconds is associated with arterial stiffness independently of conventional nocturnal blood pressure variability in suspected obstructive sleep apnea patients.

Nocturnal blood pressure (BP) surge in seconds (sec-surge), which is characterized as acute transient BP elevation over several tens of seconds is induced by obstructive sleep apnea (OSA) and OSA-related sympathetic hyperactivity. The authors assessed the relationship between sec-surge and arterial stiffness in 34 nocturnal hypertensive patients with suspected OSA (mean age 63.9 ± 12.6 years, 32.4% female). During the night, they had beat-by-beat (BbB) BP and cuff-oscillometric BP measurements, and brachial-ankle pulse wave velocity (baPWV) was assessed as an arterial stiffness index. Multiple linear regression analysis revealed that the upward duration (UD) of sec-surge was significantly associated with baPWV independently of nocturnal oscillometric systolic BP variability (ß = .365, p = .046). This study suggests that the UD of sec-surge, which can only be measured using a BbB BP monitoring device, may be worth monitoring in addition to nocturnal BP level.

Nocturnal blood pressure surge in seconds is a new determinant of left ventricular mass index.

Nocturnal blood pressure (BP) surge in seconds (sec-surge), which is characterized as acute transient BP elevation over several tens of seconds, could be a predictor of target organ damage. However, it is not clear that the severity of sec-surge is different between sec-surges induced by sleep apnea (SA) (apnea/hypopnea detected by polysomnography (PSG) or oxygen desaturation) and those induced by non-SA factors (rapid eye movement, micro arousal, etc.), and sec-surge variables associate with left ventricular hypertrophy (LVH) independently of conventional BP variables. The authors assessed these points with 41 patients (mean age 63.2±12.6 years, 29% female) who underwent full PSG, beat-by-beat (BbB) BP, and cuff-oscillometric BP measurement during the night. All patients were included for the analysis comparing sec-surge severity between inducing factors (SA and non-SA factors). There were no significant differences in the number of sec-surges/night between SA-related sec-surges and non-SA-related sec-surges (19.5±26.0 vs. 16.4±29.8 events/night). There were also no significant differences in the peak of sec-surges, defined as the maximum systolic BPs (SBPs) in each sec-surge, between SA-related sec-surges and non-SA-related sec-surges (148.2±18.5 vs. 149.3±19.2 mm Hg). Furthermore, as a result of multiple regression analysis (n = 18), the peak of sec-surge was significantly and strongly associated with the left ventricular mass index (standardized ß = 0.62, p = .02), compared with the mean nocturnal SBPs measured by oscillometric method (ß = -0.04, p = .87). This study suggests that peak of sec-surge could be a better predictor of LVH compared to parameters derived from regular nocturnal oscillometric SBP.

Reliability and validity of the Japanese version of the Behavior Problem Inventory-Short Form.

BACKGROUND: The Behavior Problems Inventory-Short Form (BPI-S), which assesses behavior problems in individuals with intellectual disabilities (ID), is a shorter version of the BPI-01. This study investigated the reliability and validity of the BPI-S Japanese version (BPI-S-J) for adolescents/adults with ID and behavior problems. METHODS: The test-retest reliability included participants with ID and behavioral problems who were enrolled in welfare services. For test-retest reliability, 42 caregivers independently responded to the BPI-S-J every two weeks. Inter-rater reliability was independently assessed using the BPI-S-J by two caregivers who were familiar with the 42 participants. The participants of the validity assessment were 227 students from special needs schools or patients with ID admitted to medical institutions. The total frequency total score was compared based on the degree of ID. To examine the criterion-related validity, we analyzed the total frequency score, the total score of the Criteria for Determining Severe Problem Behavior (CDSPB) and the total score of the Aberrant Behavior Checklist-Japanese version (ABC-J). RESULTS: The BPI-S-J of test-retest reliability was satisfactory (intra-class correlation; ICC) = 0.954), and the total score significantly (ICC = 0.721) represented good inter-rater reliability. For the validity, the BPI-S-J score of participants who had severe and profound ID was significantly higher than those who had mild and moderate ID. Significant correlations were observed between the BPI-S-J score and CDSPB score (r = 0.499), and the ABC-J score (r = 0.699), indicating adequate criterion-related validity. CONCLUSION: This study showed the utility of the BPI-S-J to assess behavior problems in the Japanese ID population.

Automatic detection algorithm for establishing standard to identify "surge blood pressure".

Blood pressure (BP) variability is one of the important risk factors of cardiovascular disease (CVD). "Surge BP," which represents short-term BP variability, is defined as pathological exaggerated BP increase capable of triggering cardiovascular events. Surge BP is effectively evaluated by our new BP monitoring device. To the best of our knowledge, we are the first to develop an algorithm for the automatic detection of surge BP from continuous "beat-by-beat" (BbB) BP measurements. It enables clinicians to save significant time identifying surge BP in big data from their patients' continuous BbB BP measurements. A total of 94 subjects (74 males and 20 females) participated in our study to develop the surge BP detection algorithm, resulting in a total of 3272 surges collected from the study subjects. The surge BP detection algorithm is a simple classification model based on supervised learning which formulates shape of surge BP as detection rules. Surge BP identified with our algorithm was evaluated against surge BP manually labeled by experts with 5-fold cross validation. The recall and precision of the algorithm were 0.90 and 0.64, respectively. Processing time on each subject was 11.0 ± 4.7 s. Our algorithm is adequate for use in clinical practice and will be helpful in efforts to better understand this unique aspect of the onset of CVD. Graphical abstract Surge blood pressure (surge BP) which is defined as pathological short-term (several tens of seconds) exaggerated BP increase capable of triggering cardiovascular events. We have already developed a wearable continuous beat-by-beat (bBb) BP monitoring device and observed surge BPs successfully in obstructive sleep apnea patients. In this, we developed an algorithm for the automatic detection of surge BP from continuous BbB BP measurements to save significant time identifying surge BP among > 30,000 BbB BP measurements. Our result shows this algorithm can correctly detect surge BPs with a recall of over 0.9.

Polysomnography-derived sleep parameters as a determinant of nocturnal blood pressure profile in patients with obstructive sleep apnea.

Obstructive sleep apnea causes blood pressure (BP) surges during sleep, which may lead to increased sleep-onset cardiovascular events. The authors recently developed an oxygen-triggered nocturnal BP monitoring system that initiates BP measurements when oxygen desaturation (SpO2 ) falls below a variable threshold. The association between nocturnal BP parameters obtained by nocturnal BP monitoring and simultaneously examined polysomnography-derived sleep parameters in 116 patients with obstructive sleep apnea (mean age 57.9 years, 85.3% men) was studied. In multivariable analysis with independent factors of age, body mass index, sex, and polysomnography-derived measures (apnea-hypopnea index, apnea index, arousal index, lowest SpO2 , and SpO2  < 90%), apnea-hypopnea index (ß = .26, P = .02) and lowest SpO2 (ß = -.34, P < .001) were independent determinants of hypoxia-peak systolic BP (SBP), defined as the maximum SBP value measured by nocturnal BP monitoring. Similarly, apnea-hypopnea index (ß = .21, P = .04) and lowest SpO2 (ß = -.49, P < .001) were independent determinants of nocturnal SBP surge, defined as the difference between the hypoxia-peak SBP and the average of the SBP values within 30 minutes before and after the hypoxia-peak SBP, measured by the fixed-interval function in the manner of conventional ambulatory BP monitoring. In conclusion, in polysomnography-derived parameters, lowest SpO2 , defined as the minimum SpO2 value during sleep, is the strongest independent determinant of hypoxia-peak SBP and nocturnal SBP surge measured by nocturnal BP monitoring. Our findings suggest that the severity of the decrease in SpO2 and the frequency of such decreases would be important indicators to identify high-risk patients who are likely to develop cardiovascular events specifically during sleep.

A longitudinal large-scale objective sleep data analysis revealed a seasonal sleep variation in the Japanese population.

In the contemporary era, when life habits are largely determined by social needs and individual preferences, sleep is nevertheless affected by seasonal environmental changes. Japan has large seasonal and geographical alterations of photoperiod and climate. Japan does not adopt the daylight saving time (DST) system, making it a suitable country for the study of seasonal variations in natural human sleep. The aim of this study was to analyze the seasonal changes in the sleep properties (timing and quality) and identify their relationship with environmental changes. Here, we report an analysis of objective sleep data of 691 161 nights collected from 1856 Japanese participants (age 20-79 years, male 91%, female 9%) for 3 years using contactless biomotion sensors. Sleep onset time did not show clear seasonal variation, but sleep offset time showed a seasonal change with a single latest peak in winter. Seasonal variation was larger during weekends than during weekdays. Sleep offset time well correlated with sunrise time but was different in spring and autumn even when the sunrise time was same, suggesting the role of temperature difference. Sleep quality, estimated by wake time after sleep onset and sleep efficiency, showed seasonal changes with the lowest trough around mid-summer. In conclusion, despite profound social influences, the timing and quality of sleep showed seasonal fluctuation indicating that they were influenced by climate factors even in the developed country.

Seasonal variation in home blood pressure: findings from nationwide web-based monitoring in Japan.

OBJECTIVES: Our aim was to assess seasonal variation in home blood pressure (BP) among free-living nationwide participants using home BP values accumulated from a web-based healthcare platform established in Japan. SETTINGS: An observational study. OMRON Healthcare Co., Ltd. has been developing web-based personal healthcare record systems in Japan since November 2010; over two million voluntary participants had joined this platform in September 2015. Nationwide home BP measurements made by oscillometric-type electronic sphygmomanometers from over 110 000 voluntary participants have been transmitted to the system from devices. PARTICIPANTS: Seasonal variation in home BP was evaluated among 64 536 (51 335 men, 13 201 women; mean age 52.9 years) free-living nationwide users for whom data were automatically and simultaneously transmitted to the system from devices. PRIMARY OUTCOME MEASURES: Mean monthly and weekly home BP. RESULTS: In multiple regression analysis, the relationship between BP and temperature was a significant inverse association, independent of age, gender and geological locations. Highest and lowest BP was observed in December and July, respectively. Substantial seasonal differences in the mean values of morning and evening home systolic BP between summer and winter were 6.2 mmHg and 5.5 mmHg in men, and 7.3 mmHg and 6.5 mmHg in women. Seasonal variation was a little greater in older (7.3 mmHg in men, 8.7 mmHg in women) than in younger individuals (5.8 mmHg in men, 6.5 mmHg in women). BP from February to July was approximately 1.5 mmHg lower than the value from August to December. CONCLUSIONS: A web-based healthcare platform has enabled easier monitoring of population-wide BP. Tighter BP control is necessary in winter than in summer, and especially in a colder climate toward winter than toward summer. New technologies using web-based self-monitoring systems for health-related indexes are expected to initiate a new phase of cardiovascular disease prevention and public health promotion.

Novel Triggered Nocturnal Blood Pressure Monitoring for Sleep Apnea Syndrome: Distribution and Reproducibility of Hypoxia-Triggered Nocturnal Blood Pressure Measurements.

Obstructive sleep apnea (OSA) causes blood pressure (BP) surges during sleep, which may lead to increased sleep-onset cardiovascular events. The authors recently developed a triggered nocturnal BP monitoring system that initiates BP measurements when oxygen desaturation falls below a variable threshold. The distribution and reproducibility of hypoxia-triggered nocturnal BP parameters compared with those of fixed-interval nocturnal BP parameters for two consecutive nights in 147 OSA patients (mean age 59.4 years, 86.4% men) were evaluated. The mean and distribution (standard deviation [SD]) of the hypoxia-peak systolic BP (SBP) were significantly greater than that of the mean nocturnal SBP (mean±SD: 148.8±20.5 vs 123.4±14.2 mm Hg, P<.001). The repeatability coefficient (expressed as %MV) of hypoxia-peak SBP between night 1 and night 2 was comparable to that of mean nocturnal SBP (43% vs 32%). In conclusion, hypoxia-peak nocturnal BP was much higher than mean nocturnal BP, and it was as reproducible as mean nocturnal BP.

Validation of a new snoring detection device based on a hysteresis extraction algorithm.

OBJECTIVE: This paper aims to introduce and validate our newly developed snoring detection device to automatically identify the incidence and amplitude of snores using the hysteresis extraction method. METHODS: Thirty patients (16 males and 14 females) with a history of snoring were included in this study. Each patient underwent a conventional polysomnography (PSG). Natural overnight snoring was recorded from each subject using our original snore detection device and an integrated circuit (IC) recorder while the patient slept during PSG. A new algorithm based on hysteresis extraction was used to detect snores and qualify the level of each event at 30-s intervals (one epoch). The automated and subjective assessment concordance was evaluated by comparing a total of 27,295 epochs, and sensitivity, specificity, and accuracy were calculated. RESULTS: Study population analysis revealed a mean rate of snore time against the total sleep time of 14.1±7.9%. Further, validation of the automatic snore detection revealed the following: sensitivity, 71.2%; specificity, 93.1%; positive predictive value, 77.7%; negative predictive value, 94.6%; and accuracy, 90.7%. CONCLUSIONS: This study revealed the efficacy of our newly developed snoring detection device and indicated that it may serve as a useful method in further snoring analysis via objective medical assessment. However, the sample size of 30 subjects was relatively small; therefore, further research is needed to evaluate this device.

A Wearable Healthcare System With a 13.7 µA Noise Tolerant ECG Processor.

To prevent lifestyle diseases, wearable bio-signal monitoring systems for daily life monitoring have attracted attention. Wearable systems have strict size and weight constraints, which impose significant limitations of the battery capacity and the signal-to-noise ratio of bio-signals. This report describes an electrocardiograph (ECG) processor for use with a wearable healthcare system. It comprises an analog front end, a 12-bit ADC, a robust Instantaneous Heart Rate (IHR) monitor, a 32-bit Cortex-M0 core, and 64 Kbyte Ferroelectric Random Access Memory (FeRAM). The IHR monitor uses a short-term autocorrelation (STAC) algorithm to improve the heart-rate detection accuracy despite its use in noisy conditions. The ECG processor chip consumes 13.7 µA for heart rate logging application.

Normally Off ECG SoC With Non-Volatile MCU and Noise Tolerant Heartbeat Detector.

This paper describes an electrocardiograph (ECG) monitoring SoC using a non-volatile MCU (NVMCU) and a noise-tolerant instantaneous heartbeat detector. The novelty of this work is the combination of the non-volatile MCU for normally off computing and a noise-tolerant-QRS (heartbeat) detector to achieve both low-power and noise tolerance. To minimize the stand-by current of MCU, a non-volatile flip-flop and a 6T-4C NVRAM are used. Proposed plate-line charge-share and bit-line non-precharge techniques also contribute to mitigate the active power overhead of 6T-4C NVRAM. The proposed accurate heartbeat detector uses coarse-fine autocorrelation and a template matching technique. Accurate heartbeat detection also contributes system-level power reduction because the active ratio of ADC and digital block can be reduced using heartbeat prediction. Measurement results show that the fully integrated ECG-SoC consumes 6.14 µ A including 1.28- µA non-volatile MCU and 0.7- µA heartbeat detector.

Six random specimens of daytime casual urine on different days are sufficient to estimate daily sodium/potassium ratio in comparison to 7-day 24-h urine collections.

The objective of this study was to determine the optimal number and type of casual (spot) urine specimens required to estimate an individual's urinary sodium/potassium (Na/K) ratio. A total of 48 participants, 25 men and 23 women, aged between 25 and 59 years, was recruited from healthy volunteers. The Na/K ratio in each casual urine and 7-day 24-h urine sample was measured. Correlation analysis and the quality of agreement by the Bland and Altman method between casual urine and 24-h urine were analyzed. The mean Na/K ratio of 7-day 24-h urine was 4.3. The mean Na/K ratio of six random specimens of daytime (collected between 09 and 17 hours) casual urine correlated most strongly with the Na/K ratio of 7-day 24-h urine (r=0.87). The bias for the mean Na/K ratio between 7-day 24-h urine and daytime casual urine was almost negligible (0.03), and the quality of agreement for the mean of the six random, daytime casual urine specimens on different days was similar to that of the 2-day 24-h urine samples for estimating 7-day 24-h values. Our findings show that the mean Na/K ratio of six random daytime casual urine specimens on different days was a good substitute for the 2-day 24-h urine Na/K ratio.

Neuromuscular electrical stimulation and an ottoman-type seat effectively improve popliteal venous flow in a sitting position.

The aim of this study was to examine the effects of the sitting posture on the lower limb venous flow and to explore the beneficial effects of neuromuscular electrical stimulation (NMES) and an ottoman-type seat on the venous flow. Healthy adult volunteers without a history of lower limb surgery or thromboembolism were recruited, and the flow velocity, cross-sectional area, and flow volume of the popliteal vein were measured using Doppler ultrasound. A posture change from the prone position to the sitting position on the ottoman-type seat decreased the flow velocity and increased the cross-sectional area of the popliteal vein, and the flow volume was not altered over 120 min. The flow velocity was further decreased, and the cross-sectional area was further increased by subjects sitting on a regular driving seat when compared with the values obtained with an ottoman-type seat. The popliteal flow velocity in the NMES leg was significantly higher than in the non-NMES leg throughout the 120-min testing in the sitting position, but no difference in the cross-sectional area was found between the NMES and the non-NMES legs. Thus lower limb venous stasis elicited by the sitting posture was improved by the ottoman-type seat and NMES.