Reference Blood Pressure Research Articles

PULSE ARRIVAL TIME CAN TRACK CHANGES IN SYSTOLIC BLOOD PRESSURE

Objective: Automated cuff-based blood pressure (BP) monitoring is limited to intermittent measurements vulnerable to movement. Pulse arrival time (PAT), calculated using electrocardiography (ECG) and photo plethysmography (PPG), has shown promise for non-invasive, continuous BP monitoring. The precise relationship between BP parameters and PAT under varying conditions remains to be fully understood. This study aimed to investigate the correlation between PAT and BP under different exercise modalities. Design and method: Data was analyzed on 33 volunteers aged 18 years or older with and without hypertension. The test protocol consisted of isometric leg exercise, an incremental ergometer bicycle test and seated periods of rest before, in-between and after. PAT was measured with an easy-to-use chest belt consisting of a 1-channel ECG and PPG sensor. PAT was calculated and averaged using a gliding average over 200 cycles from the R-wave in the ECG signal to the foot of the PPG waveform. Reference BP was measured every minute manually with an aneroid sphygmomanometer. Systolic- and diastolic BP was recorded to the nearest second for optimal synchronicity. Results: Subjects were aged 42.3 ± 13.3 years, ranging from 18–70. 48.5% were males, 18.2% had a prior diagnosis of hypertension and 15.2 % used antihypertensive medication. Systolic- and diastolic BP at inclusion were 123.6 ± 16.1 and 76.4 ± 8.4 mmHg with ranges from 98–168 and 66–100 mmHg respectively. Pearson's correlation between systolic BP and PAT was -0.86 ± 0.08, -0.84 ± 0.14 and -0.81 ± 0.14 for the full protocol, isometric exercise and dynamic exercise respectively. Corresponding correlation for diastolic BP was 0.43 ± 0.31, -0.75 ± 0.20 and 0.39 ± 0.35. For diastolic BP, correlation with PAT was positive in most subjects for the full protocol (94%) and dynamic exercise (79%), and negative in all subjects for isometric exercise. Systolic BP showed negative correlation inn all subjects for all analyses. Figure 1 shows test protocol and results for one subject. Conclusions: The results suggest that pulse arrival time can track changes in systolic blood pressure. The relationships between diastolic blood pressure and pulse arrival time varied between exercise modalities and remains to be further elucidated.

VALIDATION OF THE INBODY BPBIO750 OSCILLOMETRIC BLOOD PRESSURE MONITOR FOR PUBLIC SPACES (KIOSK) ACCORDING TO THE AAMI/ESH/ISO UNIVERSAL STANDARD

Objective: To evaluate the accuracy of the upper-arm cuff oscillometric blood pressure (BP) monitor InBody BPBIO750 developed for self-measurement by adults in public spaces (kiosk) in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018). Design and method: Subjects were recruited to fulfil the age, gender, BP and cuff distribution criteria of the AAMI/ESH/ISO Universal Standard in general population using the same arm sequential BP measurement method. The device has a fixed hole to insert the user's arm with a single implanted upper-arm cuff. Results: A total of 102 subjects were recruited and 85 were analyzed (mean age 56.7 ± 15.4 [SD] years, 40 men, arm circumference 32.3 ± 5.3 cm, range 22–42 cm). For validation Criterion 1, the mean ± SD of the differences between the test device and reference BP readings (N = 255) was 2.2 ± 6.1/-2.2 ± 5.2 mmHg (systolic/diastolic). For Criterion 2, the SD of the averaged BP differences between the test device and reference BP per individual (N = 85) was 5.00/4.63 mmHg (systolic/diastolic). Conclusions: The InBody BPBIO750 oscillometric device for BP measurement in public spaces fulfilled all the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018) in general population and can be recommended for clinical use in adults.

Validation of Omron HEM-7600T, a wearable device for monitoring blood pressure, according to the American National Standards Institute/Association for the Advancement of Medical Instrumentation/International Organization for Standardization 81060-2:2013 protocol in the general population without arrhythmias.

The present study aimed to evaluate the accuracy of the Omron HEM-7600T automated oscillometric upper-arm blood pressure (BP) monitor according to the American National Standards Institute/Association for the Advancement of Medical Instrumentation/International Organization for Standardization (ANSI/AAMI/ISO) 81060-2:2013 protocol. We recruited individuals until we obtained 86 eligible participants whose BP levels and ranges of arm circumference met the BP distribution requirements specified by the ANSI/AAMI/ISO. In each individual, we sequentially measured systolic and diastolic blood pressures (DBPs) using a mercury sphygmomanometer (two observers) and the HEM-7600T device (one supervisor) in the left upper arm. Data analysis was performed according to the ANSI/AAMI/ISO guidelines. A total of 101 individuals were recruited, and 86 were finally included in the analysis. For validation criterion 1, the mean ± SD of the differences between the test device and reference BP was -0.6 ± 6.6/1.0 ± 6.5 mmHg (systolic/diastolic). The data were in accordance with criterion 1 of the ANSI/AAMI/ISO 81060-2:2013 standard requirements (≤ 5 ± ≤ 8 mmHg). In addition, the mean device-observer difference in the 86 participants was -0.6 ± 5.65 mmHg for systolic blood pressure and 1.0 ± 5.96 mmHg for DBP, fulfilling criterion 2 with an SD of ≤6.91 mmHg for systolic blood pressure and ≤6.87 mmHg for DBP. The Omron HEM-7600T BP monitor fulfilled the requirements of the ANSI/AAMI/ISO validation protocol in adults and can be recommended for home BP measurements.

Validation of the single-cuff oscillometric blood pressure monitor InBody BPBIO750 for public spaces according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization Universal Standard.

The aim of this study was to evaluate the accuracy of the single upper-arm cuff oscillometric blood pressure (BP) monitor InBody BPBIO750 developed for self-measurement by adults in public spaces (kiosk) according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018). Subjects were recruited to fulfil the age, gender, BP and cuff distribution criteria of the AAMI/ESH/ISO Universal Standard in general population using the same arm sequential BP measurement method. A total of 102 subjects were recruited and 85 were analyzed [mean age 56.7 ± 15.4 (SD) years, 40 men, arm circumference 32.3 ± 5.3 cm, range 22-42 cm]. For validation criterion 1, the mean ± SD of the differences between the test device and reference BP readings was 2.2 ± 6.1/-2.2 ± 5.2 mmHg (systolic/diastolic). For criterion 2, the SD of the averaged BP differences between the test device and reference BP per subject was 5.00/4.63 mmHg (systolic/diastolic). The InBody BPBIO750 device fulfilled all the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018) in general population and can be recommended for clinical use in adults.

Automated blood pressure measurement in atrial fibrillation: validation process modification and evaluation of a novel professional device which detects atrial fibrillation and adapts its blood pressure measurement algorithm.

Blood pressure (BP) measurement in atrial fibrillation (AF) patients is problematic and automated monitors are regarded as inaccurate. The optimal procedure for validating BP monitors in AF is questionable. This study evaluated the accuracy of a novel professional oscillometric upper-arm cuff device (Microlife WatchBP Office), which has an algorithm for detecting AF and then applies an AF-specific BP measurement algorithm. BP variability, which is inherently increased in AF patients, was considered in the analysis. Subjects with sustained AF were included in a validation study using the same arm sequential measurement method of the Universal Standard (ISO 81060-2:2018) for special populations. Analysis was performed in all subjects and separately in those with and without high reference BP variability (>12/8 mmHg SBP/DBP). Thirty-five subjects with 105 paired test/reference BP measurements were included (mean age 76.3 ± 8.4 years, reference SBP/DBP 128.2 ± 19.5/72.5 ± 12.1 mmHg, pulse rate 68.3 ± 14.9 bpm). Validation Criterion 1 (mean difference ± SD) was 0.0 ± 7.7/0.2 ± 7.0 mmHg in all 105 BP pairs (threshold ≤5 ± 8 mmHg). Criterion 1 was 0.5 ± 6.1/-0.2 ± 6.8 mmHg in 18 subjects (54 BP pairs) with low reference BP variability and -0.6 ± 9.2/0.6 ± 7.3 mmHg in 17 (51 pairs) with high variability. Criterion 1 did not differ in pulse rate < 70 vs. ≥ 70 bpm Validation Criterion 2 (SD of differences for 35 individuals) was 5.38/6.20 mmHg (SBP/DBP; threshold ≤6.95/6.95). A technology which detects AF and activates an AF-specific BP measurement algorithm introduces a challenging solution for clinical practice. Validation of BP monitors in AF patients should not ignore their inherently high BP variability.

Unobtrusive Blood Pressure Estimation using Personalized Autoregressive Models.

Cuffless and continuous blood pressure (BP) measurement using wearable devices is of great clinical value and health monitoring importance. Pulse arrival time (PAT) based technique was considered as one of the most promising methods for this purpose. Considering the dynamic and nonlinear relationship between BP, PAT and other cardiovascular variables, this paper proposes for the first time to use nonlinear autoregressive models with extra inputs (ARX) for BP estimation. The models were first trained by the baseline data of all 25 subjects to determine the model structure and then trained by individual data to obtain the personalized model parameters. To assess the effects of the dynamic and nonlinear factors, the data during water drinking and the first 5 minutes of recovery after drinking were used to validate the four models: linear regression, linear ARX, nonlinear regression and nonlinear ARX. The reference BP, which were measured by Finometer, were increased by 36.7±10.5 mmHg for SBP and 28.4 ±7.7 mmHg for DBP. This BP changes were best modelled by the nonlinear ARX, with Mean ± SD differences of 5.6 ± 8.8 mmHg for SBP and 3.8 ±5.8 mmHg for DBP. The study also showed that nonlinear factor significantly reduced the root mean square error (RSME) by about 50%, i.e., from 20.4 to 10.7 mmHg for SBP and 13.3 to 7.3 mmHg for DBP during drinking. While the effects of dynamic factors were not as significant as nonlinear factors, especially after introducing nonlinear factors.

End-to-End Deep Learning Architecture for Continuous Blood Pressure Estimation Using Attention Mechanism.

Blood pressure (BP) is a vital sign that provides fundamental health information regarding patients. Continuous BP monitoring is important for patients with hypertension. Various studies have proposed cuff-less BP monitoring methods using pulse transit time. We propose an end-to-end deep learning architecture using only raw signals without the process of extracting features to improve the BP estimation performance using the attention mechanism. The proposed model consisted of a convolutional neural network, a bidirectional gated recurrent unit, and an attention mechanism. The model was trained by a calibration-based method, using the data of each subject. The performance of the model was compared to the model that used each combination of the three signals, and the model with the attention mechanism showed better performance than other state-of-the-art methods, including conventional linear regression method using pulse transit time (PTT). A total of 15 subjects were recruited, and electrocardiogram, ballistocardiogram, and photoplethysmogram levels were measured. The 95% confidence interval of the reference BP was [86.34, 143.74] and [51.28, 88.74] for systolic BP (SBP) and diastolic BP (DBP), respectively. The values were 0.52 and 0.49, and the mean-absolute-error values were 4.06 ± 4.04 and 3.33 ± 3.42 for SBP and DBP, respectively. In addition, the results complied with global standards. The results show the applicability of the proposed model as an analytical metric for BP estimation.

Validation of the InBody BPBIO250 oscillometric blood pressure monitor for professional office use in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization Universal Standard

The aim of this study was to evaluate the accuracy of the InBody BPBIO250 oscillometric upper-arm professional office blood pressure (BP) monitor in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018). Subjects were recruited to fulfil the age, gender, BP, and cuff distribution criteria of the AAMI/ESH/ISO Universal Standard in general population using the same arm sequential BP measurement method. Two cuffs of the test device were used for arm circumference 22-32 (medium) and 32-42 cm (large). Ninety-seven subjects were recruited and 88 were analyzed. For validation criterion 1, the mean ± SD of the differences between the test device and reference BP readings was 1.9 ± 5.9/0.9 ± 4.9 mmHg (systolic/diastolic). For criterion 2, the SD of the averaged BP differences between the test device and reference BP per subject was 4.78/4.31 mmHg (systolic/diastolic). The InBody BPBIO250 professional oscillometric device for office BP measurement fulfilled all the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018) in general population and can be recommended for clinical use.

Validation of an Automated and Adjustable Blood Pressure System for Use with a Public Health Station.

ObjectiveA new automated and adjustable blood pressure (BP) system has been developed to improve the accuracy of BP measurements on public-use health stations. This self-fitting BP system includes a mechanical cuff that wraps down to the user’s arm prior to bladder inflation. The purpose of this study was to validate the adaptable BP system (ABPS) using the current standards from the Association for the Advancement of Medical Instrumentation (AAMI).MethodsThe AAMI/ISO 81060:2013 standards for clinical validation of non-invasive automated arterial BP measurement devices were followed precisely using the same arm sequential method. For each participant, BP was measured over multiple trials by trained observers alternating a reference sphygmomanometer with the ABPS. All study requirements were met with 85 qualifying participants, each with 3 valid paired determinations.ResultsThe mean difference between ABPS BP and reference BP using all 255 paired determinations was −2.4 ± 7.7 mmHg for systolic and 1.7 ± 5.7 mmHg for diastolic. The standard deviation of the averaged paired determinations per participant was 6.3 mmHg for systolic and 5.2 mmHg for diastolic. Arm circumference measurements had a mean error of −2.1 ± 2.4 cm (R2 = 0.87). A new prediction model for arm circumference was validated using a holdout dataset (R2 = 0.94).ConclusionThe results of the study confirm that the ABPS met all benchmarks established by the AAMI. The device accurately measures BP across a wide range of arm circumferences (24–44 cm) and is suitable for use by individuals to self-monitor BP.

Accuracy testing of a new optical device for noninvasive estimation of systolic and diastolic blood pressure compared to intra-arterial measurements.

The objective of this study was to compare the systolic (S) and diastolic (D) blood pressure (BP) estimations from a new optical device at the wrist with invasive measurements performed on patients scheduled for radial arterial catheterization in the ICU. Optical signals were automatically processed by a library of algorithms from Aktiia SA (OBPM - optical blood pressure monitoring algorithms). A total of 31 participants from both sexes, aged 32-87 years, were enrolled in the study (NCT03837769). The measurement protocol consisted of the simultaneous recording of reflective photoplethysmographic signals (PPG) from the cuffless optical device and the reference BP values recorded by a contralateral radial arterial catheter. From the 31 participants, 23 subjects whose reference data quality requirements were adequate were retained for further analysis. The PPG signals from these patients were then automatically processed by the Aktiia OBPM library of algorithms, which generated uncalibrated estimates of SBP and DBP. After the automatic assessment of optical signal quality, 326 pairs of uncalibrated SBP and DBP determinations from 16 patients were available for analysis. These values were finally transformed into calibrated estimations (in mmHg) using arterial catheter SBP and DBP values, respectively. For SBP, a mean difference (±SD) of 0.0 ± 7.1 mmHg between the arterial catheter and the optical device values was found, with 95% limits of agreement in the Bland-Altman method of -11.9 to + 12.2 mmHg (correlation of r = 0.87, P < 0.001). For DBP, a mean difference (±SD) of 0.0 ± 2.9 mmHg between arterial catheter and the optical device values was found, with 95% limits of agreement in the Bland-Altman method of -4.8 to + 5.5 mmHg (correlation of r = 0.98, P < 0.001). SBP and DBP values obtained by radial artery catheterization and those obtained from optical measurements at the wrist were compared. The new optical technique appears to be capable of replacing more traditional methods of BP estimation.

Validation of the InBody BP170 oscillometric home blood pressure monitor in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization Universal Standard.

To evaluate the accuracy of the InBody BP170 oscillometric upper-arm home blood pressure (BP) monitor in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018). Subjects were recruited to fulfill the age, gender, BP and cuff distribution criteria of the AAMI/ESH/ISO Universal Standard in general population using the same arm sequential BP measurement method. Two cuffs of the test device were used for arm circumference 22-32 (medium) and 32-42 cm (large). One-hundred five subjects were recruited and 88 were analyzed. For validation Criterion 1, the mean ± SD of the differences between the test device and reference BP readings was 0.9 ± 6.9/0.5 ± 5.5 mmHg (systolic/diastolic). For Criterion 2, the SD of the averaged BP differences between the test device and reference BP per subject was 5.77/4.80 mmHg (systolic/diastolic). The InBody BP170 oscillometric home BP monitor fulfilled all the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018) in general population and can be recommended for clinical use.

Validation of the Omron HBP-9031C professional office blood pressure monitor in the general population according to the ANSI/AAMI/ISO 81060-2:2013 protocol.

The present study aimed to evaluate the accuracy of the Omron HBP-9031C automated oscillometric upper-arm blood pressure (BP) measurement device for professional office BP monitoring, according to the ANSI/AAMI/ISO 81060-2:2013 protocol (ANSI/AAMI/ISO) in the general population. The device was assessed by using it on 85 participants, who fulfilled our inclusion criteria involving the ranges of arm circumference and systolic and diastolic BP. The validation and data analysis were performed as per the protocol. In the ANSI/AAMI/ISO 81060-2:2013 validation procedure (criterion 1), the mean ± SD of the differences between the test device and reference BP was 1 ± 8/-2 ± 6 mmHg (systolic/diastolic). The mean differences between the two observers and the Omron HBP-9031C were 1 ± 7 mmHg for systolic BP and -2 ± 6 mmHg for diastolic BP, according to criterion 2. The two ANSI/AAMI/ISO criteria were fulfilled. The OMRON HBP-9031C professional BP monitor fulfilled the requirements of the ANSI/AAMI/ISO validation standard and can be recommended for clinical use.

Evaluating the Accuracy of the VitalWellness Device

Background Wellness devices for health tracking have gained popularity in recent years. Additionally, portable and readily accessible wellness devices have several advantages when compared to traditional medical devices found in clinical environments The VitalWellness device is a portable wellness device that can potentially aide vital sign measuring for those interested in tracking their health. Objective In this diagnostic accuracy study, we evaluated the performance of the VitalWellness device, a wireless, compact, non-invasive device that measures four vital signs (blood pressure (BP), heart rate (HR), respiratory rate (RR), and body temperature using the index finger and forehead. Methods Volunteers age ≥18 years were enrolled to provide blood pressure (BP), heart rate (HR), respiratory rate (RR), and body temperature. We recruited participants with vital signs that fell within and outside of the normal physiological range. A sub-group of eligible participants were asked to undergo an exercise test, aerobic step test and/or a paced breathing test to analyze the VitalWellness device’s performance on vital signs outside of the normal physiological ranges for HR and RR. Vital signs measurements were collected with the VitalWellness device and FDA-approved reference devices. Mean, standard deviation, mean difference, standard deviation of difference, standard error of mean difference, and correlation coefficients were calculated for measurements collected; these measurements were plotted on a scatter plot and a Bland-Altman plot. Sensitivity analyses were performed to evaluate the performance of the VitalWellness device by gender, skin color, finger size, and in the presence of artifacts. Results 265 volunteers enrolled in the study and 2 withdrew before study completion. Majority of the volunteers were female (62%), predominately white (63%), graduated from college or post college (67%), and employed (59%). There was a moderately strong linear relationship between VitalWellness BP and reference BP (r=0.7, P&lt;.05) and VitalWellness RR and reference RR measurements (r=0.7, P&lt;.05). The VitalWellness HR readings were significantly in line with the reference HR readings (r=0.9, P&lt;.05). There was a weaker linear relationship between VitalWellness temperature and reference temperature (r=0.3, P&lt;.05). There were no differences in performance of the VitalWellness device by gender, skin color or in the presence of artifacts. Finger size was associated with differential performance for RR. Conclusions Overall, the VitalWellness device performed well in taking BP, HR, and RR when compared to FDA-approved reference devices and has potential serve as a wellness device. To test adaptability and acceptability, future research may evaluate user’s interactions and experiences with the VitalWellness device at home. In addition, the next phase of the study will evaluate transmitting vital sign information from the VitalWellness device to an online secured database where information can be shared with HCPs within seconds of measurement.

Evaluating the Accuracy of an Integrated Vital Sign Measurement Wellness Device

Background Wellness devices for health tracking have gained popularity in recent years. Additionally, portable and readily accessible wellness devices have several advantages when compared to traditional medical devices found in clinical environments. Building tools for patients to manage their health independently may benefit their health in the long run by improving health care providers’ (HCPs) awareness of their patients’ health information outside of the clinic. Increased access to portable wellness devices that track vital signs may increase how patients and HCPs track and monitor chronic conditions which can improve health outcomes. The VitalWellness is a portable wellness device that can potentially aid vital sign measuring for those interested in tracking their health. Objective In this diagnostic accuracy study, we evaluated the clinical performance of the VitalWellness, a wireless, compact, non-invasive device that measures four vital signs using the index finger and forehead against reference vital signs devices used in the hospital setting. Methods Volunteers age ≥18 years were enrolled to provide blood pressure (BP), heart rate (HR), respiratory rate (RR), and body temperature. We recruited volunteers with vital signs that fell within and outside of the normal physiological range, depending on the measurements they consented to undergo. A subgroup of eligible volunteers were asked to undergo an exercise test, aerobic step test and/or a paced breathing test to analyze the VitalWellness device's performance on vital signs outside of the normal physiological ranges for HR and RR. Vital signs measurements were collected with the VitalWellness device and FDA-approved reference devices. Mean, standard deviation, mean difference, standard deviation of difference, standard error of mean difference, and correlation coefficients were calculated for measurements collected; these measurements were plotted on a scatter plot and a Bland-Altman plot. Sensitivity analyses were performed to evaluate the performance of the VitalWellness device by gender, skin color, finger size, and in the presence of artifacts. Results We enrolled 265 volunteers in the study and 2 withdrew before study completion. The majority of volunteers were female (62%), predominately white (63%), graduated from college or post college (67%), and employed (59%). There was a moderately strong linear relationship between VitalWellness BP and reference BP (r=0.7, P&lt;.05) and bewteen VitalWellness RR and reference RR measurements (r=0.7, P&lt;.05). The VitalWellness HR readings were significantly in line with the reference HR readings (r=0.9, P&lt;.05). There was a weaker linear relationship between VitalWellness temperature and reference temperature (r=0.3, P&lt;.05). There were no differences in performance of the VitalWellness device by gender, skin color or in the presence of artifacts. Finger size was associated with differential performance for RR. Conclusions Overall, the VitalWellness device performed well in taking BP, HR and RR when compared to FDA-approved reference devices and has potential serve as a wellness device. To test adaptability and acceptability, future research may evaluate user’s interactions and experiences with the VitalWellness device at home. In addition, the next phase of the study will evaluate transmitting vital sign information from the VitalWellness device to an online secured database where information can be shared with HCPs within seconds of measurement.

Continuous Tracking of Changes in Systolic Blood Pressure using BCG and ECG.

Blood pressure (BP) is an important physiological marker of human health. It is commonly measured by a cuff-based monitor via either auscultatory or oscillometric methods. Recently, significant research has been conducted to mathematically estimate BP from pulse transit time (PTT) to enable cuffless and continuous BP measurement. In this research, a new time reference, RJ interval, which is the time delay between electrocardiogram (ECG) R peak and ballistocardiogram (BCG) J peak was evaluated to determine if it can be used as a surrogate of PTT in cuffless BP estimation. Biomedical signals from ten healthy subjects were acquired by BCG, ECG and PPG sensors and the continuous reference BP data were collected by a cuff-based Finometer PRO BP monitor. An exponential model was employed to estimate systolic blood pressure (SBP) using RJ interval and PTT. RJ intervals extracted from ECG and BCG were shown to be useful in evaluating trends of SBP and can be the surrogate of PTT in cuffless SBP estimation.

Validation of an automatic device for the self-measurement of blood pressure in sitting and supine positions according to the ANSI/AAMI/ISO81060-2: 2013 guidelines: the Omron HEM-9700T.

We evaluated the performance of the Omron HEM-9700T, an automatic upper-arm-type device for the self-measurement of blood pressure (BP), in the sitting and supine positions according to the ANSI/AAMI/ISO81060-2:2013 guidelines. We screened 106 participants for the validation study in both positions. After excluding 21 participants, a total of 85 participants [38 (44.7%) men; 47 (55.3%) women] with mean±SD age of 54.5±12.2 years (range: 21-78 years) were included. Their arm circumference was 27.5±1.4cm (range: 17.9-40.8cm). The arm circumference distribution met the ANSI/AAMI/ISO81060-2:2013 requirement. The participants' BP measurements alternated between the use of a conventional mercury sphygmomanometer and the automatic device according to the ANSI/AAMI/ISO81060-2:2013 guidelines to measure their BP. The mean differences between reference BPs and HEM-9700T readings in the sitting and supine positions were -0.6±6.4/1.3±5.5 and -1.0±6.2/1.9±5.4mmHg for systolic BP/diastolic BP, respectively. The Omron HEM-9700T fulfilled the validation criteria of the ANSI/AAMI/ISO81060-2:2013 guidelines for both the sitting and supine positions.

Multimodal Wrist Biosensor for Wearable Cuff-less Blood Pressure Monitoring System

We propose a multimodal biosensor for use in continuous blood pressure (BP) monitoring system. Our proposed novel configuration measures photo-plethysmography (PPG) and impedance plethysmography (IPG) signals simultaneously from the subject wrist. The proposed biosensor system enables a fully non-intrusive system that is cuff-less, also utilize a single measurement site for maximum wearability and convenience of the patients. The efficacy of the proposed technique was evaluated on 10 young healthy subjects. Experimental results indicate that the pulse transit time (PTT)-based features calculated from an IPG peak and PPG maximum second derivative (f14) had a relatively high correlation coefficient (r) to the reference BP, with −0.81 ± 0.08 and −0.78 ± 0.09 for systolic BP (SBP) and diastolic BP (DBP), respectively. Moreover, here we proposed two BP estimation models that utilize six- and one-point calibration models. The six-point model is based on the PTT, whereas the one-point model is based on the combined PTT and radial impedance (Z). Thus, in both models, we observed an adequate root-mean-square-error estimation performance, with 4.20 ± 1.66 and 2.90 ± 0.90 for SBP and DBP, respectively, with the PTT BP model; and 6.86 ± 1.65 and 6.67 ± 1.75 for SBP and DBP, respectively, with the PTT-Z BP model. This study suggests the possibility of estimating a subject’s BP from only wrist bio-signals. Thus, the six- and one-point PTT-Z calibration models offer adequate performance for practical applications.

Accelerometric patch probe for cuffless blood pressure evaluation from carotid local pulse wave velocity: design, development, and in vivo experimental study

Objective: In this work, we demonstrate an accelerometric patch probe and associated measurement system for local pulse wave velocity (PWV) measurement and its application in cuffless blood pressure (BP) measurement. Approach: The proposed system consists of dual accelerometric patch probe to capture acceleration plethysmography (APG) signals from the carotid artery. The probe was integrated to an application-specific analog front-end circuitry with negligible inter-channel delay and a data acquisition module. Real-time signal processing and local PWV evaluation were performed using custom software. The functionality of the developed system and the relationship between local PWV and reference BP parameters were experimentally validated by multiple in vivo studies on a cohort of 26 subjects. Inter- and intra-subject BP-local pulse transit time (PTT) models were developed and used for cuffless BP measurement. Further, the reliability of the proposed method in long-term BP monitoring was validated by performing a study over a week. Main results: Reliability of the proposed novel approach for local PWV measurement using APG signals has been demonstrated. Measured baseline carotid local PWV values were in the range of 3–4.2 m s−1, with high reproducibility (R = 0.94) and with an inter-beat variation range of 2.61%–15.5%. Mean local PTT versus brachial systolic, diastolic, and mean arterial BP obtained from both sitting and standing posture correlated well with an R-value > 0.8. Beat-by-beat BP parameters and local PWV during the post-exercise recovery of each individual yielded statistically significant intra-subject trends. Cuffless BP estimation with intra-subject BP-local PTT models results in more reliable assessments of BP parameters than inter-subject models. The developed BP prediction models found to be reliable over a period of one week with a root-mean-square error ≤1.7 mmHg. Significance: A non-invasive cost-effective system for continuous monitoring central aortic BP parameters and local arterial stiffness indices.

Validation of two watch-type wearable blood pressure monitors according to the ANSI/AAMI/ISO81060-2:2013 guidelines: Omron HEM-6410T-ZM and HEM-6410T-ZL.

There is growing evidence of the clinical significance of daytime masked hypertension (MHT) and blood pressure (BP) variability (BPV). Recently, watch-type wearable devices for self-BP measurement have become available. Such devices might be promising tools to identify patients with daytime MHT or large BPV in their real-life conditions. The present study aimed to validate the accuracy of the Omron HEM-6410T-ZM and the Omron HEM-6410T-ZL, which are automatic watch-type wearable devices for self-BP measurement, according to the American National Standards Institute, Inc/Association for the Advancement of Medical Instrumentation/International Organization for Standardization (ANSI/AAMI/ISO) 81060-2:2013 guideline. Watches were held with the wrist at heart level. The mean differences between reference BPs and HEM-6410T-ZM readings were -0.9±7.6/-1.1±6.1mmHg for systolic BP (SBP)/diastolic BP (DBP) for criterion 1, and -0.9±6.8/-1.1±5.5mmHg for SBP/DBP for criterion 2. The mean differences between reference BPs and HEM-6410T-ZL readings were 2.4±7.3/0.7±7.0mmHg for SBP/DBP for criterion 1, and 2.4±6.5/0.7±6.5mmHg for SBP/DBP for criterion 2. The Omron HEM-6410T-ZM and the Omron HEM-6410T-ZL both fulfilled both validation criteria 1 and 2 of the ANSI/AAMI/ISO 81060-2:2013 guidelines.

Blood Pressure Estimation Using Photoplethysmography Only: Comparison between Different Machine Learning Approaches.

Introduction Blood pressure (BP) has been a potential risk factor for cardiovascular diseases. BP measurement is one of the most useful parameters for early diagnosis, prevention, and treatment of cardiovascular diseases. At present, BP measurement mainly relies on cuff-based techniques that cause inconvenience and discomfort to users. Although some of the present prototype cuffless BP measurement techniques are able to reach overall acceptable accuracies, they require an electrocardiogram (ECG) and a photoplethysmograph (PPG) that make them unsuitable for true wearable applications. Therefore, developing a single PPG-based cuffless BP estimation algorithm with enough accuracy would be clinically and practically useful. Methods The University of Queensland vital sign dataset (online database) was accessed to extract raw PPG signals and its corresponding reference BPs (systolic BP and diastolic BP). The online database consisted of PPG waveforms of 32 cases from whom 8133 (good quality) signal segments (5 s for each) were extracted, preprocessed, and normalised in both width and amplitude. Three most significant pulse features (pulse area, pulse rising time, and width 25%) with their corresponding reference BPs were used to train and test three machine learning algorithms (regression tree, multiple linear regression (MLR), and support vector machine (SVM)). A 10-fold cross-validation was applied to obtain overall BP estimation accuracy, separately for the three machine learning algorithms. Their estimation accuracies were further analysed separately for three clinical BP categories (normotensive, hypertensive, and hypotensive). Finally, they were compared with the ISO standard for noninvasive BP device validation (average difference no greater than 5 mmHg and SD no greater than 8 mmHg). Results In terms of overall estimation accuracy, the regression tree achieved the best overall accuracy for SBP (mean and SD of difference: −0.1 ± 6.5 mmHg) and DBP (mean and SD of difference: −0.6 ± 5.2 mmHg). MLR and SVM achieved the overall mean difference less than 5 mmHg for both SBP and DBP, but their SD of difference was >8 mmHg. Regarding the estimation accuracy in each BP categories, only the regression tree achieved acceptable ISO standard for SBP (−1.1 ± 5.7 mmHg) and DBP (−0.03 ± 5.6 mmHg) in the normotensive category. MLR and SVM did not achieve acceptable accuracies in any BP categories. Conclusion This study developed and compared three machine learning algorithms to estimate BPs using PPG only and revealed that the regression tree algorithm was the best approach with overall acceptable accuracy to ISO standard for BP device validation. Furthermore, this study demonstrated that the regression tree algorithm achieved acceptable measurement accuracy only in the normotensive category, suggesting that future algorithm development for BP estimation should be more specific for different BP categories.