Effect of overcuffing on the accuracy of oscillometric blood pressure measurements

Critical Bias in Critical Care Devices

Critical care data contain information about the most physiologically fragile patients in the hospital, who require a significant level of monitoring. However, medical devices used for patient monitoring suffer from measurement biases that have been largely underreported. This article explores sources of bias in commonly used clinical devices, including pulse oximeters, thermometers, and sphygmomanometers. Further, it provides a framework for mitigating these biases and key principles to achieve more equitable health care delivery.

Cuff Size Variation Across Manufacturers of Home Blood Pressure Devices: A Current Patient Dilemma

BACKGROUND

The American Heart Association (AHA) recommends cuff sizes of blood pressure (BP) monitoring devices based on patient arm circumference, which is critical for accurate BP measurement. This study aimed to assess cuff size variation across validated BP devices and to examine the degree of alignment with the AHA recommendations.

METHODS

Data on home BP devices were obtained from the US BP Validated Device Listing website and listed cuff sizes were compared against AHA recommendations: small adult (22-26 cm), adult (27-34 cm), large (35-44 cm), and extra-large (XL) (45-52 cm).

RESULTS

There were 42 home validated BP devices from 13 manufacturers, and none offered cuffs that were aligned with the AHA recommendations. Over half of the devices (22, 52.4%) were compatible with only a broad-range cuff, generally excluding arm sizes larger than 44 cm. Only 5 devices from 4 manufacturers offered a cuff labeled "XL," and of these, only 3 devices had sizes that covered the AHA XL range. Terminology lacked consistency with manufacturers using: different labels to describe the same-sized cuffs (e.g., 22-42 cm was labeled "integrated," "standard," "adult," "large," and "wide range"); the same labels to describe differently sized cuffs (e.g., cuffs labeled "large" were sized 22-42 cm, 32-38 cm, 32-42 cm, 36-45 cm).

CONCLUSIONS

Manufacturers of US home BP devices employ inconsistent terminologies and thresholds for cuff sizes, and sizes were not aligned with AHA recommendations. This lack of standardization could pose challenges for clinicians and patients attempting to select a properly sized cuff to support hypertension diagnosis and management.

Validation of the watch-type HUAWEI WATCH D oscillometric wrist blood pressure monitor in adult Chinese

OBJECTIVE

The aim of this study was to evaluate the accuracy of the watch-type automated oscillometric wrist blood pressure (BP) monitor HUAWEI WATCH D in the 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.

METHOD

Subjects were recruited to fulfill the age, sex, BP and cuff distributions of the AAMI/ESH/ISO Universal Standard in the general population using the same arm sequential BP measurement method. Two cuffs of the test device were used for wrist circumference of 13-16 cm (medium) and 16-20 cm (large), respectively.

RESULTS

One-hundred and nine subjects were recruited and 85 were analyzed. For validation criterion 1, the mean ± SD of the differences between the test device and reference BP readings was -1.4 ± 6.47/-0.2 ± 5.85 mmHg (systolic/diastolic). For criterion 2, the SD of the average BP differences between the test device and reference BP per subject was 5.66/5.48 mmHg (systolic/diastolic).

CONCLUSION

The HUAWEI WATCH D watch-type wrist BP monitor fulfilled all the requirements of the AAMI/ESH/ISO Universal Standard in the general population and can be recommended for self-measurement.

Self-reported practices of doctors and nurses for the measurement of blood pressure

BACKGROUND

Hypertension is one of the most common health problems worldwide and can be diagnosed with an accurate blood pressure measurement (BPM). We aim to evaluate the self-reported practices of family physicians and nurses for BPM.

METHODS

This study was conducted in the form of a survey administered through face-to-face interviews with 131 physicians and 371 nurses. The survey included questions about devices, patients, and BPM techniques.

RESULTS

The mean age was 31 ± 7.4 years. The most commonly used device was the aneroid model (47.8%). The majority of participants reported that they had sufficient technical knowledge about the devices (81.1%), and the devices were regularly calibrated (77.5%). Only 44.8% reported that they had asked patients about caffeine or nicotine use. About half of those in both groups (54%) performed BPM only once during a presentation. The most commonly used position during BPM was sitting. BPM was performed mostly on one arm without preference for any side (67.5%). Approximately half of the respondents reported that they performed BPM by actively supporting the arm at the heart level.

CONCLUSION

We found physicians and nurses had lack of adherence to proper techniques related to the use of appropriate positions and other relevant situations that should be considered during BPM. Accurate BPM is the most important factor for proper diagnosis and treatment of hypertension. Thus, BPM should be performed in accordance with the designated guidelines and can be performed with accurate results only as a result of repeated comprehensive training programs.

Validation of the Omron HEM-1040 Blood Pressure Monitor According to the American National Standards Institute/Association for the Advancement of Medical Instrumentation/International Organization for Standardization 81060-2:2013 Protocol

Objective

The accuracy of the Omron HEM-1040 automated oscillometric upper-arm blood pressure (BP) monitoring device, designed for home self-measurements in adult populations, was tested 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.

Methods

The requirements of this protocol were precisely followed with the recruitment of 85 individuals in whom sequential systolic BP (SBP) and diastolic BP (DBP) were measured in the same (left) arm and who fulfilled the inclusion criteria involving the ranges of arm circumference, SBP, and DBP.

Results

The mean device-observer difference in the 255 separate pairs of BP data was −2.7 ± 7.14 mmHg for SBP and −3.3 ± 5.70 mmHg for DBP. 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 85 participants was −2.7 ± 5.89 mmHg for SBP and −3.3 ± 4.99 mmHg for DBP, fulfilling criterion 2 with a standard deviation of ≤ 6.39 mmHg for SBP and ≤ 6.09 mmHg for DBP.

Conclusion

The OMRON HEM-1040 BP monitor fulfilled the requirements of the ANSI/AAMI/ISO validation standard.

The Effect of Cuff Size on Blood Pressure Measurement in Obese Surgical Patients: A Prospective Crossover Clinical Trial

Aim

This study aimed to determine the effect of a cuff properly sized for mid-upper arm circumference on blood pressure measurement in obese surgical patients.

Method

This prospective crossover clinical trial was conducted with 100 patients who had body mass index ≥30 kg/m² and mid-upper arm circumference ≥27 cm and were admitted to the general surgery unit of a medical faculty hospital in İstanbul, Turkey between January 1, 2015, and December 31, 2015. Blood pressure of the patients was measured using a small-sized adult cuff and a cuff properly sized for mid-upper arm circumference.

Results

Among the patients, 39% were morbidly obese and 67% had mid-upper arm circumference between 35 and 44 cm. Systolic blood pressure of the patients with a small adult cuff was 20.78 mmHg higher than that obtained with a cuff properly sized for mid-upper arm circumference, and their diastolic blood pressure was 10.15 mmHg higher on average (p<0.001). Only 6% of those with systolic hypertension according to the small adult cuff readings were found to have hypertension according to the cuff properly sized for mid-upper arm circumference (p<0.001).

Conclusion

The results showed that, in obese surgical patients, blood pressure is measured inaccurately and found to be falsely high when measurements are not performed using a cuff properly sized for mid-upper arm circumference.

Mean mid-arm circumference and blood pressure cuff sizes for US children, adolescents and adults: National Health and Nutrition Examination Survey, 2011-2016

BACKGROUND

Measuring blood pressure (BP) requires an appropriate BP cuff size given measured mid-arm circumference (mid-AC).

OBJECTIVE

To provide mid-AC means and percentiles for US population aged more than 3 years and examine the frequency distribution of mid-AC cuffed by Baum and Welch Allyn cuff systems.

PATIENTS AND METHODS

The 2011-2016 National Health and Nutrition Examination Survey, a cross-sectional survey, was used to estimate mean mid-AC (n=24 723).

RESULTS

Mean mid-AC did not differ from 2011 to 2016 (31.0 vs. 31.3 cm, P>0.05). During 2011-2016, mean mid-AC was greater for males than females (32.0 vs. 30.4 cm, P<0.001) and was largest among adults 40-49 years (34.0 cm). Non-Hispanic Black persons had the largest mean mid-AC (32.0 cm) and non-Hispanic Asian persons the smallest (28.4 cm). Increased BMI was associated with increased mean mid-AC for those 3-19 years (normal, 22.0 cm and obese, 31.5 cm, P<0.001) and more than 20 years (normal, 28.2 cm and obese, 37.8 cm, P<0.001). Among those aged 8-17 years, high BP status was associated with a larger mean mid-AC (normotensive 26.1 cm vs. high BP 28.2 cm, P=0.001). Among adults aged 18 years and older, hypertension status was associated with a larger mean mid-AC (normotensive 32.4 cm vs. hypertensive 34.2 cm, P<0.001). Among those aged 12-19 years, 13.0% required a Baum large cuff (35-46.9 cm mid-AC) and 21.7% required a Welch Allyn large cuff (32-39.9 cm mid-AC). Among those aged more than 20 years, 33.2% required a Baum large cuff, 48.2% required a Welch Allyn large cuff, 1.3% required a Baum extra-large cuff (44-66 cm mid-AC), and 9.5% required a Welch Allyn extra-large cuff (40-55 cm mid-AC).

CONCLUSION

Currently, BP is obtained in clinic, pharmacy, home, and ambulatory setting using single or multiple cuffs. National Health and Nutrition Examination Survey mid-AC data should be considered for accurate cuffing avoiding cuff hypertension or hypotension.

Dempster–Shafer Fusion Based on a Deep Boltzmann Machine for Blood Pressure Estimation

We propose a technique using Dempster–Shafer fusion based on a deep Boltzmann machine to classify and estimate systolic blood pressure and diastolic blood pressure categories using oscillometric blood pressure measurements. The deep Boltzmann machine is a state-of-the-art technology in which multiple restricted Boltzmann machines are accumulated. Unlike deep belief networks, each unit in the middle layer of the deep Boltzmann machine obtain information up and down to prevent uncertainty at the inference step. Dempster–Shafer fusion can be incorporated to enable combined independent estimation of the observations, and a confidence increase for a given deep Boltzmann machine estimate can be clearly observed. Our work provides an accurate blood pressure estimate, a blood pressure category with upper and lower bounds, and a solution that can reduce estimation uncertainty. This study is one of the first to use deep Boltzmann machine-based Dempster–Shafer fusion to classify and estimate blood pressure.

Systolic peak foot-to-apex time interval, a novel oscillometric technique for systolic blood pressure measurement

Background:

Noninvasive blood pressure (BP) measurement is essential for the study of human physiology but automatic oscillometric devices only estimate SBP and DBP using various, undisclosed algorithms, precluding standardization and interchangeability. We propose a novel approach by tracking, during pneumatic cuff deflation, the time interval from the foot to the apex of the systolic peak of the oscillometric signal, which reaches a maximum concomitant with the first Korotkoff sound.

Method:

In 145 study participants and patients (group 1), we measured the systolic brachial artery blood pressure by Korotkoff sound recording, conventional oscillometry, and our fully automated systolic peak foot-to-apex time interval (SFATI) technique. In 35 other patients (group 2), we compared SFATI with intra-arterial measurement.

Results:

In group 1, the concordance correlation coefficient was 0.989 and 0.984 between SFATI and Korotkoff sounds, 0.884 and 0.917 between oscillometry and Korotkoff sounds, and 0.882 and 0.919 between SFATI and oscillometry, respectively, on the left and right arm. In group 2, it was 0.72 between SFATI and intra-arterial measurement, 0.67 between oscillometry and intra-arterial measurement, and 0.92 between SFATI and Korotkoff sounds. In 40 study participants, the reproducibility study yielded a concordance coefficient of 0.95 for SFATI and 0.94 for Korotkoff sounds.

Conclusion:

SFATI BP measurement shows an excellent concordance with the auscultatory technique, offering a major improvement over current oscillometric techniques and allowing standardization.

The effect of back and feet support on oscillometric blood pressure measurements

BACKGROUND/OBJECTIVE

Recommendations to support the back and feet during blood pressure (BP) measurement are not always followed in clinical practice. Our objective was to determine to what extent back and feet support affects mean oscillometric BP measurements.

PARTICIPANTS AND METHODS

Eighty-five consecutive, consenting participants 18 years or older with systolic BP readings 80-220 mmHg and diastolic BP readings 50-120 mmHg and arm circumferences of 25-43 cm were recruited. BP was measured using an Omron HEM 907 oscillometric device. Back and feet support were examined independently. First, while the feet were supported, two sets of three BP readings were taken in random order: one with the back supported and one with the back unsupported. Next, with the back supported, two sets of three BP readings were taken in random order: one with the feet dangling and one with feet supported.

RESULTS

The mean age of the participants was 52.0±20.7 years and the mean arm circumference was 31.0±3.2 cm; 62% were women and 49% had hypertension. The mean BP levels with the back unsupported were slightly higher than those with the back supported (119.8±15.5/69.9±8.9 vs. 119.2±16.4/68.2±8.8 mmHg; difference of 0.7±4.9/1.8±3.0; P=0.21 for systolic and <0.0001 for diastolic comparisons). The mean BP levels with feet dangling were slightly lower than with feet supported (120.3±16.3/72.6±8.9 vs. 121.2±16.1/72.9±8.6 mmHg; difference of -0.9±4.1/-0.3±2.8; P=0.04 for systolic and <0.36 for diastolic comparisons). Systolic BP differences were greater than or equal to 5 mmHg in 34% (back phase) and 23% (feet phase) of the participants.

CONCLUSION

Provision of back and feet support has a small effect on the mean oscillometric BP. The magnitude of effect is greatest on diastolic BP when the back is unsupported.

Patient-Specific Oscillometric Blood Pressure Measurement: Validation for Accuracy and Repeatability

Oscillometric devices are widely used for automatic cuff blood pressure (BP) measurement. These devices estimate BP from the oscillometric cuff pressure waveform using population average methods. Hence, the devices may only be accurate over a limited BP range. The objective was to evaluate a new patient-specific method, which estimates BP by fitting a physiologic model to the same waveform. One-hundred and forty-five cardiac catheterization patients and normal adults were included for study. The oscillometric cuff pressure waveform was obtained with an office device, while reference BP was measured via brachial artery catheterization or auscultation, during baseline and/or nitroglycerin administration. Fifty-seven of the subject records were utilized for refining the patient-specific method, while the remaining 88 subject records were employed for evaluation. The precision errors for all BP levels of the patient-specific method ranged from 6.3 to 7.6 mmHg. These errors were significantly lower than those of the office device (by 29% on average) in subjects with high pulse pressure (>50 mmHg) while being comparable to those of the device in subjects with normal pulse pressure (<50 mmHg). The bias and precision of the differences in repeated estimates for all BP levels of the patient-specific method ranged from 0.1 to 1.1 and 2.1 to 5.9 mmHg, respectively. These precision differences were significantly lower than those of the office device (by 64% on average). The patient-specific method may afford more accurate automatic cuff BP measurement in patients with large artery stiffening while limiting the number of required cuff inflations/deflations per measurement.

Simultaneous validation of the Grandway MD2301 digital automatic blood pressure monitor by the British Hypertension Society and the Association for the Advancement of Medical Instrumentation/the International Organization for Standardization protocols

OBJECTIVE

The aim of this study was to determine the accuracy of the Grandway MD2301 digital automatic blood pressure monitor by the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI)/the International Organization for Standardization (ISO) protocols.

PARTICIPANTS AND METHODS

A total of 85 participants were included for evaluation based on the requirements of the BHS and the AAMI/ISO protocols. The validation procedure and data analysis followed the protocols precisely.

RESULTS

The device achieved A/A grading for the BHS protocol and maintained A/A grading throughout the low, medium and high blood pressure ranges. The device also fulfilled the requirement of the AAMI/ISO protocol with device-observer differences of -0.9±5.6 and 0.8±5.2 mmHg for systolic and diastolic blood pressure, respectively, for criterion 1, and -0.9±4.7 and 0.8±4.2 mmHg, respectively, for criterion 2.

CONCLUSION

The Grandway MD2301 digital automatic blood pressure monitor achieved A/A grade of the BHS protocol and passed the requirements of the AAMI/ISO protocol in adults.

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.

Validation of the RisingSun RS-651 Blood Pressure Monitor Based on Auscultation in Adults According to the ANSI/AAMI/ISO 81060-2:2013 Standard

This study validated the RisingSun RS‐651 blood pressure (BP) monitor based on auscultation in adults according to the American National Standards Institute/Association for the Advancement of Medical Instrumentation/International Organization for Standardization (ANSI/AAMI/ISO) 81060‐2:2013 standard. The RS‐651 device was evaluated in a study of 97 participants. The same arm simultaneous method, as defined in the ANSI/AAMI/ISO standard, was used. The mean differences±standard deviation for criterion 1 were 0.8±2.3 mm Hg for systolic BP (SBP) and −0.1±2.9 mm Hg for diastolic BP (DBP). Analysis for criterion 2 resulted in values of 0.8±1.5 mm Hg for SBP and −0.1±2.1 mm Hg for DBP. All of the data fulfilled the ANSI/AAMI/ISO 81060‐2:2013 standard requirements to pass the validation. The RisingSun RS‐651 device can be recommended for both clinical and self/home use in adults according to the ANSI/AAMI/ISO 81060‐2:2013 standard.