Performance of the Aktiia optical blood pressure measurement device in the elderly: a comparison with double blinded auscultation in different body positions

BACKGROUND

Accurate blood pressure (BP) measurement is essential for the correct diagnosis and management of hypertension (HTN) especially in the elderly population. As with of all BP devices, the accuracy of cuffless devices must be verified. This study (NCT04027777) aimed to evaluate the performance of a wrist cuffless optical BP device in an elderly population cohort in different body positions with auscultation as the reference measurement.

DESIGN AND METHODS

Patients aged 65-85 years with different BP categories but without diabetes were recruited. After an initial calibration based on auscultatory measurements, BP estimation from the Aktiia Bracelet (Aktiia SA, Switzerland) were compared to reference double-blinded auscultatory measurements in sitting, standing and lying positions on four separate visits distributed over one month. In the absence of a universal standard for cuffless BP device at the time of the study, modified ISO81060-2 criteria were used for performance analysis.

RESULTS

Thirty-five participants were included in the analysis fulfilling the inclusion requirements of ISO 81060-2. A total of 469 paired measurements were obtained with overall 83% acceptance rate. Differences (mean ± SD)   between Aktiia Bracelet and auscultation for systolic BP were -0.26 ± 9.96 mmHg for all body positions aggregated (sitting 1.23 ± 7.88 mmHg, standing -1.81 ± 11.11 mmHg, lying -1.8 ± 9.96 mmHg). Similarly, differences for diastolic BP were -0.75 ± 7.0 mmHg (0.2 ± 5.55 mmHg, -5.35 ± 7.75 mmHg and -0.94 ± 7.47 mmHg, respectively). Standard deviation of the averaged differences per subject for systolic/diastolic BP was 3.8/2.5 mmHg in sitting and 4.4/3.7 mmHg for all body positions aggregated.

CONCLUSIONS

Overall, this study demonstrates a similar performance of the Aktiia Bracelet compared to auscultation in an elderly population in body positions representative of daily activities. The use of more comfortable, non-invasive, and non-occlusive BP monitors during long periods may facilitate e-health and may contribute to better management of HTN, including diagnosis and treatment of HTN, in the elderly.

A novel professional automated auscultatory blood pressure monitor with visual display of Korotkoff sounds: InBody BPBIO480KV validation according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization Universal Standard

OBJECTIVE

A novel automated auscultatory upper arm-cuff blood pressure (BP) monitor (InBody BPBIO480KV) for office use was developed. An electronic stethoscope embedded in the device cuff records the Korotkoff sounds, which are audible to the user and graphically displayed during cuff deflation. Automated BP measurements are provided, while allowing the user to assess the Korotkoff sounds. The device accuracy was tested using 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) and its Amendment 1.2020-01.

METHODS

Participants were recruited to fulfil the age, sex, BP, arm circumference and cuff distribution criteria of the Universal Standard in general population using the same arm sequential measurement method. Three cuffs of the test device were used for arm circumference 23-28, 28-35 and 33-42 cm.

RESULTS

Data from 85 individuals were analysed [mean age 57.3 ± 15.0 (SD) years, 53 men, arm circumference 23-42 cm]. For validation criterion 1, the mean ± SD of the differences between the test device and reference BP readings ( N  = 255) was 0.3 ± 5.5/0.6 ± 4.7 mmHg (systolic/diastolic; threshold ≤5 ± 8 mmHg). For criterion 2, the SD of the averaged BP differences per individual ( N  = 85) was 3.76/3.61 mmHg (systolic/diastolic; threshold ≤6.95/6.91 mmHg).

CONCLUSION

The InBody BPBIO480KV device for office use, which provides automated auscultatory measurements while reproducing and displaying the Korotkoff sounds, comfortably fulfilled the AAMI/ESH/ISO Universal Standard requirements in general population and can be recommended for clinical use. The assessment of Korotkoff sounds by healthcare professionals for evaluating the quality of automated measurements requires further evaluation.

To what extent can the chosen blood pressure measurement technique affect the outcomes of an observational survey?

Aim: We analyzed to what extent measurement protocol influenced individual blood pressure (BP) and achievement of treatment target in patients with coronary heart disease. Methods: In a subsample of Czech EUROASPIRE III-V survey participants (n = 913), we compared the per-protocol BP measurement (by automated oscillometric device OMRON at the beginning of survey procedure) with control auscultatory measurement (by physician during interview). Results: Per-protocol approach produced significantly (p < 0.0001) higher BP values (by 9/6 mmHg in median) than auscultatory measurements and led to markedly higher proportion of patients over target BP (less than 140/90 mmHg; 59.3 vs 34.9% [p < 0.0001], per-protocol vs auscultatory technique, respectively). Conclusion: Per-protocol oscillometric technique was not equivalent to conventional auscultatory measurement and seriously over-rated the real nonachievement of BP target in observational surveys.

Cardiac Murmurs in Children: A Challenge For The Primary Care Physician

Congenital heart disease is present in almost 1% of live births and despite current progress in prenatal screening a significant percentage has delayed diagnosis or remain undiagnosed. A cardiac murmur may be the first or unique clinical sign of congenital heart disease in childhood, however, less than 1% of auscultated murmurs are of an organic cause. Distinguishing between an innocent and a pathologic murmur can be challenging and the experience of the examiner is crucial for identifying the distinctive properties of an innocent murmur. Timely diagnosis of underlying cardiovascular pathology is of great significance so that prompt management is provided and morbidity or mortality are restricted. Of similar importance is the avoidance of unnecessary anxiety for the parents and unreasonable referrals to Paediatric Cardiologists. Indications for referral include a medical history suggestive of a cardiac abnormality, such as the presence of relevant symptoms, the identification of abnormal findings on clinical examination, auscultatory findings suggestive of an organic murmur, and very young patient age. ECG and a chest X-ray are not usually part of the diagnostic approach of a child with a cardiac murmur, as they do not increase the success rate of diagnosing heart disease, as compared to a detailed medical history accompanied by a thorough physical examination. In conclusion, the recognition of suspicious distinctive features of cardiac murmurs is crucial and requires skills based on sufficient training and experience.

A convenient method to verify the accuracy of oscillometric blood pressure monitors by the auscultatory method: A smartphone-based app

It is recommended that oscillometric devices be calibrated by auscultation when first used, but this is difficult in practice. Here, we introduce a smartphone-based technique to verify the accuracy of blood pressure monitors (BPMs). We enrolled 99 consecutive subjects and tested 6 brands of BPMs in this study. During measurements of electronic oscillometric BPMs, Korotkoff sounds were simultaneously collected using a stethoscope head beneath a cuff connected to a smartphone, and an app named Accutension Stetho could then yield an auscultatory BP reading as a reference. Next, differences in BP between the different BPMs and Accutension Stetho were determined. The percentage of BP differences falling within 5, 10, and 15 mm Hg; the mean (MD) value; and the standard deviation (SD) of BP differences and deflation errors were analyzed among all the BPMs. We found that the percentages of SBP differences falling within 5 mm Hg of the 6 BPMs were 80%, 79%, 77%, 72%, 68%, and 63%, in turn. The deflation rates among the 6 BPMs were 2.23, 3.48, 6.10, 2.44, 3.66, and 4.85 mm Hg/beat, respectively. Deflation errors, which were defined as deflation prior to the end of the Korotkoff sounds, existed in 4 BPMs. In conclusion, Accutension Stetho could detect BP differences between oscillometric BPM readings and simultaneous auscultatory readings. Diastolic BP was overestimated when the device deflated prior to the end of the Korotkoff sounds. Using the app, it is possible to evaluate the accuracy of BPMs among the same subjects.

An Assessment of the Accuracy of Home Blood Pressure Monitors When Used in Device Owners

OBJECTIVE

To examine the accuracy of home blood pressure (BP) devices, on their owners, compared to auscultatory reference standard BP measurements.

METHODS

Eighty-five consecutive consenting subjects ≥18 years of age, who owned an oscillometric home BP device (wrist or upper-arm device), with BP levels between 80-220/50-120 mm Hg, and with arm circumferences between 25-43 cm were studied. Pregnancy and atrial fibrillation were exclusion criteria. Device measurements from each subject's home BP device were compared to simultaneous 2-observer auscultation using a mercury sphygmomanometer. Between-group mean comparisons were conducted using paired t-tests. The proportion of patients with device-to-auscultatory differences of ≥5, 10, and 15 mm Hg were tabulated and predictors of systolic and diastolic BP differences were identified using linear regression.

RESULTS

Mean age was 66.4 ± 11.0 years, mean arm circumference was 32.7 ± 3.7 cm, 54% were female and 78% had hypertension. Mean BPs were 125.7 ± 14.0/73.9 ± 10.4 mm Hg for home BP devices vs. 129.0 ± 14.7/72.9 ± 9.3 for auscultation (difference of -3.3 ± 7.3/0.9 ± 6.1; P values <0.0001 for systolic and 0.17 for diastolic). The proportion of devices with systolic or diastolic BP differences from auscultation of ≥5, 10, and 15 mm Hg was 69%, 29%, and 7%, respectively. Increasing arm circumference was a statistically significant predictor of higher systolic (parameter estimate 0.61 per cm increase; P value 0.004) and diastolic (0.38; 0.03) BP.

CONCLUSIONS

Although mean differences from 2-observer auscultation were acceptable, when tested on their owners, most home BP devices were not accurate to within 5 mm Hg. Ensuring acceptable accuracy of the device-owner pairing should be prioritized.

Effect of Cuff Design on Auscultatory and Oscillometric Blood Pressure Measurements

BACKGROUND

Two-piece blood pressure (BP) cuffs are the historical cuff standard. Use of 1-piece cuffs is increasing. Substituting 1-piece for 2-piece cuffs has an unknown effect on measurement accuracy. We compared these cuff types in a 2-phase study using auscultatory and oscillometric techniques.

METHODS

Consenting subjects (aged ≥18 years) with BP levels between 80 and 220mm Hg/50 and 120mm Hg and arm circumferences between 25 and 43cm were studied using the International Standards Organization (ISO) 2013 protocol (modified). A Baum 2-piece cuff was used as the reference standard. A 1-piece Welch Allyn cuff was the comparator. In phase 1 (2-observer auscultation with a mercury sphygmomanometer), 88 subjects were required to obtain 255 paired BP determinations. In phase 2 (oscillometric measurement with a Spacelabs 90207 device), 85 subjects were studied. Each phase was analyzed separately using paired t-tests.

RESULTS

Phase 1 mean age was 54.2±20.5 years, mean arm circumference was 29.9±3.7cm, 60% were female, and 32% had hypertension. One-piece cuff mean BPs were lower than the 2-piece cuff means (115.5±15.5/66.4±9.3 vs. 117.8±15.2/67.9±9.2; difference of -2.4±3.6/-1.5±2.4; P values <0.0001 for systolic and diastolic comparisons). Phase 2 mean age was 52.8±20.8 years, mean arm circumference was 29.4±3.9cm, 67% were female, and 38% had hypertension. Mean BPs were lower for the 1-piece compared to the 2-piece cuff (116.5±12.8/67.1±8.1 vs. 120.8±13.5/70.4±8.5; difference of -4.4±3.6/-3.3±2.7; P values <0.0001 for both).

CONCLUSIONS

Mean BP is lower with 1-piece cuffs vs. 2-piece cuffs. Differences are greater with oscillometry. When performing validation studies and measurements for clinical purposes, cuff type should be taken into account.

Is one measurement enough to evaluate blood pressure among adolescents? A blood pressure screening experience in more than 9000 children with a subset comparison of auscultatory to mercury measurements

Evaluation of blood pressure is recommended in all children older than 3 years. Auscultatory devices are the recommended method to assess blood pressure in pediatrics, but automated oscillometric devices are increasingly common. A retrospective analysis of our school-based blood pressure screening was performed to determine if multiple oscillometric blood pressure measurements are needed to approach true blood pressure. All children had 4 oscillometric measurements of blood pressures and a random subset of 287 had an additional auscultatory measurement. Among 9870 participants, we observed a nonlinear decrease in blood pressure over time. The largest decrease in systolic blood pressure was between first and second (-3.8 mm Hg) and in diastolic from second to third (-3.3 mm Hg) measurement. For systolic blood pressure, the second oscillometric measurement, the average of second to third and the average of first to third were statistically similar to a single auscultatory measurement. We conclude that assessment of blood pressure using oscillometric devices should include at least 3 measurements in the same sitting to avoid inaccurate assessment.