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.     

Cuff challenges in blood pressure measurement

The characteristics of the optimal cuff for blood pressure (BP) measurement are still the subject of much debate. The choice of the appropriate cuff in obese individuals depends not only on the arm circumference but also on its shape because a conically shaped arm makes it difficult to fit the cuff to the arm. When a large‐size cylindrical cuff is used in conical arms, an overestimation of the true BP is likely to occur with BP discrepancies that may be as large as 10 mm Hg. With the advent of automatic oscillometric devices, the choice of the appropriate cuff became even more controversial because with oscillometric BP measurement the reference point is not the artery occlusion but the oscillometric peak signal. To overcome the problem of miscuffing in obese individuals, special cuffs that can accommodate a wide range of arm sizes have been designed. Using these cuffs, accurate oscillometric BP measurements can be obtained over a wide range of arm circumferences using a unique software algorithm. These wide‐range cuffs coupled to oscillometric devices may represent a good option for BP measurement in very obese subjects. However, their reliability should be confirmed in larger populations and different settings.     

Single cuff comparison of two methods for indirect measurement of arterial blood pressure: standard auscultatory method versus automatic oscillometric method

Summary With the introduction of automatic oscillometric systems for indirect measurement of arterial blood pressure (e. g. DINAMAP), the problem of correspondence between that method and the standard auscultatory method arose. For an exact and valid comparison of two methods, for physiological and methodological reason, both measurements have to be performed simultaneously and using only one single cuff.Applying a methodological approach fulfilling these preconditions and offering in addition the advantage of a graphic documentation of the individual measurement cycles, we were able to investigate both methods in a sample of 216 comparative experiments.We found a mean difference (auscultatory method minus oscillometric method) between the methods (bias) of –0.82 mm Hg (–0.109 kPa) for systolic pressure, 1.25 mm Hg (0.166 kPa) for diastolic pressure and 1.00 mm Hg (0.133 kPa) for mean pressure. Except for systolic pressure, the differences were statistically significant (paired t-test and analysis of variance). We also obtained a significant negative correlation between the differences and the average of both pressure values (decreasing error with increasing pressure) and a significant negative correlation between differences and heart rate (decreasing differences with increasing heart rate).The conclusions drawn from the comparative study are that, although the oscillometric method exhibited a tendency to higher systolic and lower diastolic measurement values compared to the auscultatory method, both methods are well comparable and the differences are below the level of physiological and clinical significance.     

Arm position as a source of error in blood pressure measurement

The present study was designed to assess the value of correct positioning of a patient's arm when measuring blood pressure (BP). A total of 181 subjects were examined, 141 hypertensives on treatment, 25 untreated hypertensives, 15 normotensives. All the subjects underwent three BP measurements after a 5-min resting period in supine position. Then two BP readings were recorded in standing position with the arm either positioned by the patient's side or supported passively at patient's heart level. Average systolic BP (SBP) in standing position were 144.6 +/- 20.2 mmHg with the arm at the side and 136.4 +/- 21.1 mmHg with the arm at the heart level (p less than 0.001); average diastolic pressures were 99.0 +/- 12.0 mmHg and 90.2 +/- 12.3 mmHg (p less than 0.001), respectively. A fall in SBP greater than or equal to 20 mmHg from the supine to the upright position was detected in 18.2% of cases when measurement was performed at heart level; such a reduction was inapparent in two-thirds of cases when the arm was placed at the patient's body side. Incorrect positioning of a patient's arm during BP measurements in standing position leads to overestimation of BP values and masks the presence of postural hypotension.     

Body position and blood pressure measurement in patients with diabetes mellitus

AIMS: World Health Organization (WHO) guidelines recommend that the blood pressure (BP) should be routinely measured in sitting or supine followed by standing position, providing that the arm of the patient is placed at the level of the right atrium in each position. The aim of our study was to test the influence of body and arm position on BP measurement in diabetic patients. METHODS: In 142 patients with diabetes mellitus the BP was measured using a semiautomatic oscillometric device (Bosomat-R): (i) after 5 min of rest sitting on a chair with one arm supported at the right atrial level and with the other arm placed on the arm support of the chair, (ii) after 5 min of rest lying on a bed with both arms placed on a bed, and (iii) after 30 s and after 2 min of standing with one arm (the same as in sitting position) supported at the right atrial level and with the other arm vertical, parallel to the body. RESULTS: Both systolic (SBP) and diastolic (DBP) blood pressures were significantly lower in sitting position with the arm at the right atrial level than in supine position (by 7.4 and 6.6 mmHg, respectively, P < 0.01). In sitting and standing positions, SBP and DBP were higher when the arm was placed either on the arm support of the chair or vertical, parallel to the body, than when the arm was supported at the level of the right atrium (by 6-10 mmHg, P < 0.001). Duration of standing did not influence the estimation of orthostatic hypotension. CONCLUSIONS: The data of this study indicate that the WHO recommendation with regard to the equivalence of sitting and supine BP readings is incorrect at least in diabetic patients, as the sitting BP is lower than the supine BP when the arm was positioned at the right atrial level. In addition, incorrect positioning of the arm in standing position results in an underestimation of prevalence of orthostatic hypotension. We conclude that during BP measurement the arm should be placed at the right atrial level regardless of the body position.     

诊室噪声对血压测量值的影响

目的探讨诊室噪声对诊室血压测量值的影响。方法本研究为横断面研究,连续选取2015年1月至2016年6月于河南省人民医院心内科门诊就诊的、能提供近30 d内家庭自测血压数据、且符合入组标准的869例,按照就诊时诊室噪声是否符合《中华人民共和国国家标准声环境质量标准》(昼间≤55 dB)分为2组,比较诊室内血压值与家庭自测血压值的差异(|△SBP|),并采用有序多分类logistic回归分析相关影响因素。结果诊室噪声超标组(>55 dB)诊室收缩压及|△SBP|均明显高于诊室内噪声达标组(≤55 dB)[(144.04±21.58)mmHg比(140.06±18.11)mmHg,P=0.003;(13.44±14.67)mmHg比(9.52±12.19)mmHg,P<0.001],在校正了年龄、性别、体质指数、高血压病史、糖尿病病史、吸烟史、饮酒史后,logistic回归分析提示诊室噪声达标与|△SBP|相关(OR=0.648,95%CI:0.494~0.850)。结论诊室内噪声是否达标影响诊室内收缩压测量值与家庭自测收缩压值间的差异。     

Oscillometric blood pressure: a review for clinicians

Oscillometric devices for the non–invasive estimation of blood pressure (BP) have become the “clinical standard” because of training requirements for determination of BP by auscultation, cost, and the phasing–out/banning of mercury in many states and countries. Analysis of recent publications reveals a lack of understanding of the “meaning” of oscillometric blood pressure (OBP) measurements by authors, journal editors, and clinicians. We were invited to submit a review of OBP methodology written for clinicians. We hope that the material contained herein will clarify how clinicians should interpret OBP values for their patients.     

The optimal use of automated office blood pressure measurement in clinical practice

This evidence‐based article endorses the use of automated office blood pressure (AOBP). AOBP is the most favorable office blood pressure (BP) measuring technique as it provides accurate readings with 3‐15 mm Hg lower values than the casual conventional office measurements with auscultatory or semi‐automated oscillometric devices and relates closely to awake ABP readings. The AOBP technique seems to be superior to conventional office BP in predicting hypertension‐mediated organ damage and appears to be equally reliable to awake ABP in the prediction of cardiovascular (CV) disease. AOBP readings should be obtained either unattended, with the patient alone in the examination room, or attended with the presence of personnel in the room but with no talking to the patient, although this recommendation is not frequently followed in routine clinical practice. To optimize office BP readings, the type of device, the rest period before AOBP measurements (preceding rest), and the time intervals between measurements were evaluated. As AOBP readings have the advantage of removing many confounding factors, the authors propose to perform measurements with a preceding rest in all patients at the initial visit; if AOBP readings remain <130 mm Hg in subsequent visits, measurements could be accepted, otherwise, if are higher, patients should be evaluated by out‐of‐office BP measurements.     

预约就诊对诊室血压测量值的影响

目的 探讨预约就诊对诊室血压测量值的影响。方法 连续选取2015年1月至2016年6月间于郑州大学人民医院心内科门诊就诊的符合入组条件的患者869例,按照是否预约就诊分为2组,采用T检验比较诊室内血压值与家庭自测血压值组间的差异,并采用有序多分类Logistic回归分析进行相关影响因素分析。结果 1.诊室收缩压及舒张压测量值均高于家庭自测舒张压及收缩压测量值（141.97±19.94 mmHg vs 132.07±16.38 mmHg,P＜0.01;87.50±13.38mmHg vs 83.50±12.09mmHg,P＜0.01）;2.未预约就诊组患者诊室内收缩压（OSBP）及其与家庭自测收缩压（HSBP）的差值绝对值（|△SBP|）的平均值均明显高于预约就诊组（143.47±20.36mmHg vs 140.03±16.09mmHg,P＜0.01;13.54±13.87mmHg vs 8.52±12.06 mmHg,P＜0.01）。有序多分类Logistic回归分析提示,在校正年龄、性别、心率、BMI等因素后,预约就诊（OR=0.532,95%CI 0.403～0.704）与|△SBP|相关。结论 1.诊室收缩压及舒张压测量值均高于家庭自测值;2.预约就诊可减少OSBP测量值与HSBP的差异。     

The quest for accuracy of blood pressure measuring devices

The accuracy of blood pressure (BP) measuring devices is fundamental to good practice and scientific research. International guidelines on BP measurement are provided for clinicians who diagnose and treat patients with hypertension, clinical researchers who conduct trials on the efficacy of BP lowering drugs and interventional strategies, epidemiologists who conduct population surveys to determine the demographic consequences of hypertension on society, and researchers who perform meta‐analyses on published research to further influence the practice of medicine and the provision of resources. Although the outcomes of the endeavors of all these groups are dependent on the accuracy of BP measurements, the equipment is often of doubtful accuracy and the methodology of measurement is often poorly described and frequently not standardized. Thus, the fundamental element of hypertension evaluation has been largely ignored by both clinical practitioners and scientific researchers. Here, the authors briefly review the development of efforts to improve and validate the accuracy of BP measuring devices and highlight the deficiencies that persist. We conclude that, to protect the public from the serious consequences of inaccurate BP measurements, the following steps are required: (1) regulatory requirement for mandatory independent validation of all BP measuring devices using a universal protocol; (2) accreditation of laboratories for the performance of BP device validations; (3) online evaluation of validation studies with detection of protocol violations prior to publication of results; and (4) establishment of an independent scientific forum for the listing of accurate BP measuring devices.     

Assessment of blood pressure in patients with Type 2 diabetes: comparison between home blood pressure monitoring, clinic blood pressure measurement and 24-h ambulatory blood pressure monitoring.

AIMS: To compare a home blood pressure (BP) monitoring device and clinic BP measurement with 24-h ambulatory BP monitoring in patients with Type 2 diabetes mellitus (DM). METHODS: Fifty-five patients with type 2 DM had BP measured at three consecutive visits to the DM clinic by nurses using a stethoscope and mercury sphygmomanometer (CBP). Twenty-four-hour ambulatory BP was measured using a Spacelabs 90207 automatic cuff-oscillometric device (ABPM). Subjects were then instructed in how to use a Boots HEM 732B semiautomatic cuff-oscillometric home BP monitoring device and measured BP at home on three specified occasions on each of 4 consecutive days at varying times (HBPM). RESULTS: Correlations between HBPM and ABPM were r = 0.88, P < 0.001 for systolic BP and r = 0.76, P < 0.001 for diastolic BP, with correlations between CBP and ABPM being systolic r = 0.59, P < 0.001, diastolic r = 0.47, P < 0.001. HBPM agreed with ABPM more closely compared with CBP (CBP +10.9/+3.8 (95% confidence intervals (CI) 6.9, 14.8/1.6, 6.1) vs. HBPM +8.2/+3.7 (95% CI 6.0, 10.3/2.0, 5.4)). The sensitivity, specificity and positive predictive value of HBPM in detecting hypertension were 100%, 79% and 90%, respectively, compared with CBP (85%, 46% and 58%, respectively). CONCLUSIONS: In patients with Type 2 DM, home BP monitoring is superior to clinic BP measurement, when compared with 24-h ambulatory BP, and allows better detection of hypertension. It would be a rational addition to the annual review process. Diabet. Med. 18, 431-437 (2001)     

Comparison of EMT blood pressure measurements with an automated blood pressure monitor: on scene, during transport, and in the emergency department

Auscultation or palpation of blood pressure in critically ill patients by emergency medical technicians (EMTs) can be difficult, if not impossible, because of ambient noise, motion artifact, limited access to patients, or weak pulses. Automated blood pressure monitors (ABPMs) have been designed to overcome these problems during field emergencies and patient transport. Our study compared blood pressure measurements taken by EMTs with measurements provided by a Lifestat ABPM. Measurements in emergency patients on scene, during transport, in the emergency department (ED), and in a controlled environment were compared. Measurements in the various sites were obtained from 57 patients, and provision was made for two measurements at each site. Comparison of on-scene systolic blood pressures yielded a mean absolute systolic difference of 10.46 +/- 1.42 mm Hg and a mean absolute diastolic difference of 9.33 +/- 1.32 mm Hg. During transport systolic pressures showed a mean absolute difference of 11.50 +/- 1.72 mm Hg, and diastolic pressures showed a mean absolute difference of 7.59 +/- 1.16 mm Hg. Mean absolute differences in the ED were 11.23 +/- 1.49 mm Hg systolic and 8.37 +/- 1.25 mm Hg diastolic. Ninety comparison measurements in a controlled environment yielded a mean absolute systolic difference of 8.74 +/- 0.87 mm Hg and a mean absolute diastolic difference of 7.97 +/- 0.72 mm Hg. Comparison of mean diastolic pressure differences between EMT and ABPM measurements in various settings revealed some small, but statistically significant, discrepancies that were not considered clinically relevant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Non‐invasive measurement of reservoir pressure parameters from brachial‐cuff blood pressure waveforms

Reservoir pressure parameters [eg, reservoir pressure (RP) and excess pressure (XSP)] are biomarkers derived from blood pressure (BP) waveforms that have been shown to predict cardiovascular events independent of conventional cardiovascular risk markers. However, whether RP and XSP can be derived non‐invasively from operator‐independent cuff device measured brachial or central BP waveforms has never been examined. This study sought to achieve this by comparison of cuff reservoir pressure parameters with intra‐aortic reservoir pressure parameters. 162 participants (aged 61 ± 10 years, 72% male) undergoing coronary angiography had the simultaneous measurement of cuff BP waveforms (via SphygmoCor XCEL, AtCor Medical) and intra‐aortic BP waveforms (via fluid‐filled catheter). RP and XSP derived from cuff acquired brachial and central BP waveforms were compared with intra‐aortic measures. Concordance between brachial‐cuff and intra‐aortic measurement was moderate‐to‐good for RP peak (36 ± 11 vs 48 ± 14 mm Hg, P < 0.001; ICC 0.77, 95% CI: 0.71‐0.82), and poor‐to‐moderate for XSP peak (28 ± 10 vs 24 ± 9 mm Hg, P < 0.001; ICC 0.49, 95% CI: 0.35‐0.60). Concordance between central‐cuff and intra‐aortic measurement was moderate‐to‐good for RP peak (35 ± 9 vs 46 ± 14 mm Hg, P < 0.001; ICC 0.77, 95% CI: 0.70‐0.82), but poor for XSP peak (12 ± 3 vs 24 ± 9 mm Hg, P < 0.001; ICC 0.12, 95% CI: −0.13 to 0.31). In conclusion, both brachial‐cuff and central‐cuff methods can reasonably estimate intra‐aortic RP, whereas XSP can only be acceptably derived from brachial‐cuff BP waveforms. This should enable widespread application to determine the clinical significance, but there is significant room for refinement of the method.     

STRIDE BP international initiative for accurate blood pressure measurement: Systematic review of published validation studies of blood pressure measuring devices

Blood pressure (BP) is a vital sign, and its measurement is essential for diagnosing and treating hypertension. The accuracy of BP monitors is therefore essential, but unfortunately very few devices available on the market have been validated using an established protocol. STRIDE BP ( www.stridebp.org ) is an international nonprofit organization with the mission to improve the accuracy of BP measurement and the diagnosis of hypertension. It has a prestigious Scientific Advisory Board and operates in affiliation with the European Society of Hypertension, the International Society of Hypertension, and the World Hypertension League. STRIDE BP provides lists of accurate office, ambulatory, and home BP monitors. STRIDE BP performed a systematic review of 419 published validations (270 articles and 260 devices). In these publications, 50 (12%) of the validations were rejected compared with 129 (31%) rejected by STRIDE BP (P < .001). Of 79 validations approved in publications but rejected by STRIDE BP, 7 (9%) were rejected due to device inaccuracy and 72 (91%) due to inadequate study quality (execution, analysis, and reporting). Errors in conducting and reporting published validations must be avoided. Peer review must ascertain that a comprehensive checklist of all aspects of a validation study have been adhered to. The implementation of a Universal Standard for device validation and the global dissemination of information on accurate devices by STRIDE BP are expected to improve the quality and accuracy of BP measurement, which should have a positive impact on the diagnosis and management of hypertension globally.     

The effect of sleeved arms on oscillometric blood pressure measurement

The authors measured the blood pressures of 36 subjects who had bare and sleeved arms to determine the effect of wearing sleeves on automatic oscillometric blood pressure measurements. They found no statistically significant effect of sleeves on the measurement of either systolic or diastolic blood pressure (p>0.15). However, based on confidence intervals of possible sleeve effects, the authors recommend repeating blood pressure measurements on bared arms when the sleeved-arm oscillometric measurements are at least 86 mm Hg diastolic or 135 mm Hg systolic. Presented in part at the annual meeting of the Society of General Internal Medicine, Seattle, Washington, May 1–3, 1991.     

Principles and techniques of blood pressure measurement

Although the mercury sphygmomanometer is widely regarded as the gold standard for office blood pressure measurement, the ban on use of mercury devices continues to diminish their role in office and hospital settings. To date, mercury devices have largely been phased out in United States hospitals. This situation has led to the proliferation of nonmercury devices and has changed (probably forever) the preferable modality of blood pressure measurement in clinic and hospital settings. In this article, the basic techniques of blood pressure measurement and the technical issues associated with measurements in clinical practice are discussed. The devices currently available for hospital and clinic measurements and their important sources of error are presented. Practical advice is given on how the different devices and measurement techniques should be used. Blood pressure measurements in different circumstances and in special populations such as infants, children, pregnant women, elderly persons, and obese subjects are discussed.     

Comparison of exercise blood pressure measured by technician and an automated system

We evaluated the automated system Blood Pressure Measuring System (BPMS) developed by NASA on 277 adult males who elected to have a treadmill test as part of their annual physical. The BPMS uses acoustic transduction with a computer-assisted ECG gating to detect nonsynchronous noise. The BPMS readings were compared to pressures simultaneously measured by trained technicians. For all stages of work, BPMS readings were higher for systolic and lower for diastolic than technician readings. At peak stages of work, BPMS systolic pressures were about 20 mmHg higher than technician readings. Within each 3-min workstage, BPMS readings were found to be more inconsistent than technician readings. The standard errors of measurement for BPMS were from two to three times higher than technician values. These data showed automated blood pressure readings were significantly different than technician values and subject to more random fluctuations. These findings demonstrate the need to view exercise blood pressure measured by automated systems with caution.     

Comparison of awake ambulatory blood pressure and automated office blood pressure using linear regression analysis in untreated patients in routine clinical practice

The recent American hypertension guidelines recommended a threshold of 130/80 mmHg to define hypertension on the basis of office, home or ambulatory blood pressure (BP). Despite recognizing the potential advantages of automated office (AO)BP, the recommendations only considered conventional office BP, without providing supporting evidence and without taking into account the well documented difference between office BP recorded in research studies versus routine clinical practice, the latter being about 10/7 mmHg higher. Accordingly, we examined the relationship between AOBP and awake ambulatory BP, which the guidelines considered to be a better predictor of future cardiovascular risk than office BP. AOBP readings and 24‐hour ambulatory BP recordings were obtained in 514 untreated patients referred for ambulatory BP monitoring in routine clinical practice. The relationship between mean AOBP and mean awake ambulatory BP was examined using linear regression analysis with and without adjustment for age and sex. Special attention was given to the thresholds of 130/80 and 135/85 mmHg, the latter value being the recognized threshold for defining hypertension using awake ambulatory BP, home BP and AOBP in other guidelines. The mean adjusted AOBP of 130/80 and 135/85 mmHg corresponded to mean awake ambulatory BP values of 132.1/81.5 and 134.4/84.6 mmHg, respectively. These findings support the use of AOBP as the method of choice for determining office BP in routine clinical practice, regardless of which of the two thresholds are used for diagnosing hypertension, with an AOBP of 135/85 mmHg being somewhat closer to the corresponding value for awake ambulatory BP.