Is the accuracy of blood pressure measuring devices underestimated at increasing blood pressure levels?

Aortic Calcification is Associated With the Difference Between Invasive Central and Cuff-Measured Brachial Blood Pressure in Chronic Kidney Disease

BACKGROUND

Chronic kidney disease (CKD) is associated with accelerated vascular calcification and increased central systolic blood pressure when measured invasively (invCSBP) relative to cuff-based brachial systolic blood pressure (cuffSBP). The contribution of aortic wall calcification to this phenomenon has not been clarified. We, therefore, examined the effects of aortic calcification on cuffSBP and invCSBP in a cohort of patients representing all stages of CKD.

METHODS

During elective coronary angiography, invCSBP was measured in the ascending aorta with a fluid-filled catheter with simultaneous recording of cuffSBP using an oscillometric device. Furthermore, participants underwent a non-contrast computed tomography scan of the entire aorta with observer-blinded calcification scoring of the aortic wall ad modum Agatston.

RESULTS

We included 168 patients (mean age 67.0 ± 10.5, 38 females) of whom 38 had normal kidney function, while 30, 40, 28, and 32 had CKD stages 3a, 3b, 4, and 5, respectively. Agatston scores adjusted for body surface area ranged from 48 to 40,165. We found that invCSBP increased 3.6 (95% confidence interval 1.4-5.7) mm Hg relative to cuffSBP for every 10,000-increment in aortic Agatston score. This association remained significant after adjustment for age, diabetes, antihypertensive treatment, smoking, eGFR, and BP level. No such association was found for diastolic BP.

CONCLUSIONS

Patients with advanced aortic calcification have relatively higher invCSBP for the same cuffSBP as compared to patients with less calcification. Advanced aortic calcification in CKD may therefore result in hidden central hypertension despite apparently well-controlled cuffSBP. ClinicalTrials.gov identifier: NCT04114695.

An inaccurate automated device negatively impacts the diagnosis and treatment of gestational hypertension

OBJECTIVES

Automated blood pressure devices are frequently introduced in maternity care without prior validation for their accuracy in pregnancy. Our objectives were to, firstly, establish the accuracy in pregnancy of a locally used device (Welch Allyn 300) and, secondly, to audit its impact on the diagnosis and treatment of hypertension.

STUDY DESIGN

Validation study: The device was evaluated using the grading criteria of the European Society of Hypertension International Protocol (ESH-IP) (2010). Two observers took nine same-arm measurements alternating between the Welch Allyn and the mercury sphygmomanometer. Thirty-three women of any gestation were included. Clinical audit: One observer took three same-arm measurements alternating between the Welch Allyn and the mercury sphygmomanometer. One hundred women of any gestation referred with suspected hypertension were included. The main outcome measures were the proportion diagnosed with hypertension or commenced on anti-hypertensive treatment on the presenting visit when using either the manual or the automated device.

MAIN OUTCOME MEASURES

Grading criteria of the ESH-IP (2010) and proportion of women diagnosed with hypertension or commenced on antihypertensive therapy at the presenting visit when using either manual sphygmomanometry or the Welch Allyn device.

RESULTS

The Welch Allyn 300 series failed to meet the criteria of the ESH-IP (2010) for pregnancy. Compared to the mercury device, it under diagnosed hypertension by 48% and need for treatment by 80%.

CONCLUSIONS

The Welch Allyn 300 cannot be recommended for the measurement of blood pressure in pregnancy. Its use leads to the under-diagnosis and under-treatment of gestational hypertension.

Automated Versus Manual Blood Pressure Measurement: A Randomized Crossover Trial in the Emergency Department of a Tertiary Care Hospital in Karachi, Pakistan: Are Third World Countries Ready for the Change?

BACKGROUND

Hypertension has proven to be a strong liability with 13.5% of all mortality worldwide being attributed to elevated blood pressures in 2001. An accurate blood pressure measurement lies at the crux of an appropriate diagnosis. Despite the mercury sphygmomanometer being the gold standard, the ongoing deliberation as to whether mercury sphygmomanometers should be replaced with the automated oscillometric devices stems from the risk mercury poses to the environment.

AIM

This study was performed to check the validity of automated oscillometric blood pressure measurements as compared to the manual blood pressure measurements in Karachi, Pakistan.

MATERIAL AND METHODS

Blood pressure was recorded in 200 individuals aged 15 and above using both, an automated oscillometric blood pressure device (Dinamap Procare 100) and a manual mercury sphygmomanometer concomitantly. Two nurses were assigned to each patient and the device, arm for taking the reading and nurses were randomly determined. SPSS version 20 was used for analysis. Mean and standard deviation of the systolic and diastolic measurements from each modality were compared to each other and P values of 0.05 or less were considered to be significant. Validation criteria of British Hypertension Society (BHS) and the US Association for the Advancement of Medical Instrumentation (AAMI) were used.

RESULTS

Two hundred patients were included. The mean of the difference of systolic was 8.54 ± 9.38 while the mean of the difference of diastolic was 4.21 ± 7.88. Patients were further divided into three groups of different systolic blood pressure <= 120, > 120 to = 150 and > 150, their means were 6.27 ± 8.39 (p-value 0.175), 8.91 ± 8.96 (p-value 0.004) and 10.98 ± 10.49 (p-value 0.001) respectively. In our study 89 patients were previously diagnosed with hypertension; their difference of mean systolic was 9.43 ± 9.89 (p-value 0.000) and difference of mean diastolic was 4.26 ± 7.35 (p-value 0.000).

CONCLUSIONS

Systolic readings from a previously validated device are not reliable when used in the ER and they show a higher degree of incongruency and inaccuracy when they are used outside validation settings. Also, readings from the right arm tend to be more precise.

Blood Pressure Management Controversies in Neurocritical Care

Blood pressure (BP) management is essential in neurocritical care settings to ensure adequate cerebral perfusion and prevent secondary brain injury. Despite consensus on the importance of BP monitoring, significant practice variations persist regarding optimal methods for monitoring and treatment of BP values among patients with neurologic injuries. This article provides a summary of research investigating various approaches for BP management in neurocritical care. Evidence-based recommendations, areas for future research, and current technological advancements for BP management are discussed.

Blood pressure and the obese

With the prevalence of obesity escalating globally, an increasing number of patients who are obese are seeking elective or requiring emergency surgery. Certified registered nurse anesthetists are challenged to provide vigilant, safe care. The ability to provide supportive therapy and make anesthetic adjustments is often hindered with obesity. Although technological advancements may enhance patient care delivery, health care providers must question why and how specific tasks are performed. Health care providers should challenge themselves to acquire and evaluate current evidence that enables communication with colleagues, dissemination of findings to health care providers worldwide, and implementation of evidence-based practice.

Home Blood Pressure Monitoring

Hypertension is the most common preventable cause of cardiovascular disease. Home blood pressure monitoring (HBPM) is a self-monitoring tool that can be incorporated into the care for patients with hypertension and is recommended by major guidelines. A growing body of evidence supports the benefits of patient HBPM compared with office-based monitoring: these include improved control of BP, diagnosis of white-coat hypertension and prediction of cardiovascular risk. Furthermore, HBPM is cheaper and easier to perform than 24-hour ambulatory BP monitoring (ABPM). All HBPM devices require validation, however, as inaccurate readings have been found in a high proportion of monitors. New technology features a longer inflatable area within the cuff that wraps all the way round the arm, increasing the 'acceptable range' of placement and thus reducing the impact of cuff placement on reading accuracy, thereby overcoming the limitations of current devices.

The impact of central blood pressure levels on the relationship between oscillometric and central blood pressure measurements: a multicenter invasive study

The aim of this study was to investigate impact of central blood pressure (BP) levels and sex on the difference between central and upper arm oscillometric BP values. Oscillometric arterial BP measurements of 675 patients were simultaneously compared with values measured from the ascending aorta. The patients were divided into 3 groups according to systolic BP levels. The upper arm oscillometric device overestimated systolic BP (SBP) at low and medium BP levels but it underestimated SBP at high BP level. As for the effect of sex on differences in central and oscillometric BP, SBP was overestimated to a lesser degree in women than in men at low BP levels, but it was more highly underestimated in women than in men at high BP levels. The difference between oscillometric upper arm BP and aortic BP was directly affected by the patient's central BP level. In addition, the difference between central and oscillometric BP was also affected by sex factor.

The inaccuracy of automatic devices taking postural measurements in the emergency department

Automatic devices are used to take postural blood pressures in the emergency department despite research proving their inaccuracy in taking single blood pressures. This study assessed the accuracy of an automatic device compared with a manual aneroid reference standard for determining orthostatic hypotension and postural drops at triage. Supine and standing blood pressures were taken with an automatic and a manual device in a sequential and random order, and postural drops were calculated. The manual device indicated 10/150 emergency department patients had orthostatic hypotension (7%) and the automatic device detected this with a sensitivity of 30% and a specificity of 91%. The automatic-manual differences were clinically significant in 13% of systolic drops and 37% of diastolic drops. Findings suggest that automatic devices cannot reliably detect or rule out orthostatic hypotension, indicating that triage nurses need to use manual devices to take accurate postural blood pressures for optimal patient care.

A comparison of blood pressure and pulse pressure values obtained by oscillometric and central measurements in hypertensive patients

OBJECTIVE

Wide pulse pressure (PP) affects the accuracy of oscillometric blood pressure measurements (OBPM): however, the degree of this impact on different patient groups with wide PPs is unclear. This study will investigate the accuracy of OBPM in achieving target BP and PP in isolated systolic hypertension (ISH) group compared with mixed hypertension (MHT) group.

METHOD

A total of 115 patients (70 with ISH and 45 with MHT) were enrolled in the study. Upper arm and wrist OBPM, obtained by OmronM3 and OmronR6 devices respectively, were compared with the simultaneously measured values from the ascending aorta. The ISH was defined as a systolic blood pressure (SBP) > or =140 mmHg and a diastolic blood pressure (DBP) <90 mmHg. MHT was defined as a SBP> or =140 mmHg and a DBP> or =90 mmHg.

RESULTS

The mean central arterial blood pressure (BP) and central PP were higher in the ISH group than those in the MHT group. The upper arm OBPM underestimated the central SBP in two groups (-5 mmHg, -3 mmHg, p=0.5, respectively), but overestimated DBP in the ISH group compared with MHT patients (6.8 mmHg, 1 mmHg, p=0.04, respectively). Wrist OBPM similarly underestimated to the central SBP in each group (-16 mmHg, -19 mmHg, p=0.15), whereas the sum of overestimation of DBP was significantly higher in the ISH than in the MHT group (+6 mmHg, - 1 mmHg, p=0.001, respectively). Also, each of the devices underestimated the central PP in the ISH group (about 10 mmHg) as being higher than that of the MHT group.

CONCLUSION

Oscillometric devices may be used for self-BP measurement in patients with ISH without clinically important disadvantages compared with the patients with MHT. For PP measurement in patients with ISH, there were substantial differences between intra-arterial and indirect arm BP measurements.

Forearm and Upper-Arm Oscillometric Blood Pressure Comparison in Acutely III Adults

When patients’ upper arms are not accessible and/or when cuffs do not fit large upper arms, the forearm site is often used for blood pressure (BP) measurement. The purpose of this study is to compare forearm and upper-arm BPs in 70 acutely ill adults, admitted to a community hospital’s 14-bed ICU. Using Philips© oscillometric monitors, three repeated measures of forearm and upper-arm BPs are obtained with head of bed flat and with head of bed elevated at 30°. Arms are resting on the bed. Paired t tests show statistically significant differences in systolic BPs, diastolic BPs, and mean arterial pressures in the supine and head-elevated positions. Bland—Altman analyses indicate that forearm and upper-arm oscillometric BPs are not interchangeable in acutely ill adults.

Evaluation scale to assess the accuracy of cuff-less blood pressure measuring devices

OBJECTIVE

The call for early detection of hypertension and cardiac events creates a heavy demand for devices that can be used for blood pressure (BP) monitoring at home and in ambulatory settings. An emerging type of BP monitors without an occluding cuff has drawn great attentions for this application because it is comfortable and capable of providing continuous readings. For the development the cuff-less devices, it is crucial for the clinicians and engineers to joint efforts in establishing an evaluation standard.

METHODS

This study attempts to contribute to its initiation in two ways. First, a new distribution model for measurement differences between the test device and the reference was proposed. We verified the model using evaluation results from 40 devices, of which 80% of the American Association for the Advancement of Medical Instrumentation and British Hypertension Society reporting results were in agreement, as compared with 50%, if the original normal model was used. We further tested a cuff-less device on 85 patients for 999 datasets and found that the differences between the proposed distribution and that of the device were nonsignificant for systolic BP measurements (Kolmogorov-Smirnov = 0.036, P = 0.15). Second, some evaluation scales were studied for their capability to assess the accuracy of cuff-less devices. For mean absolute difference, a map was developed to relate it with the criteria of American Association for the Advancement of Medical Instrumentation, British Hypertension Society, and European Society of Hypertension protocols, on the basis of the proposed distribution model; for mean absolute percentage difference, it is prominent in evaluating devices that have measurement errors often increasing with BP, which is an issue has not been fully explored in existing standards.

CONCLUSION

This study focused on the statistical aspect of establishing standard to assess the accuracy of cuff-less BP measuring devices. The results of our study on the validation reports of various cuff-based devices and an experimental study on a cuff-less device showed that the t4 distribution is better than the normal distribution in portraying the underlying error distribution of both kinds of devices. Moreover, based on both the theoretical and experimental studies, mean absolute difference or mean absolute percentage difference is recommended as continuous scale to assess the accuracy of cuff-less devices for their own distinctive advantages.

Clinical applications of pulse transit time in paediatric critical care

A simple and non-invasive technique, termed pulse transit time (PTT), has shown its potential in long-term investigations such as respiratory sleep studies and cardiovascular studies. Based on these findings, the PTT technique shows relevance for continuous haemodynamic monitoring in critical care. The objective of this review is to understand the potential, applications and limitations of PTT in this clinical setting. Present non-invasive haemodynamic monitoring methods such as automated oscillometric blood pressure (BP) and auscultatory techniques have their known limitations. They tend to underestimate systolic BP while overestimating diastolic BP. Due to the periodic increase in cuff pressure cycles during data acquisition, these techniques may cause much discomfort in elderly geriatric patients, or lessen the cooperation of younger paediatric patients. Thus, there can be adverse effects on therapeutic decisions and possibly clinical outcomes. Documented evidences have indicated that changes observed in PTT are inversely correlated to the corresponding BP changes. In critical care, a simple and accommodating technique like PTT may be useful in providing better comfort for patients during extended monitoring. Being a semi-quantitative measure, blanket recommendations for its utility can then become possible. The basic instrumentations needed are often part of standard critical care monitoring system. Furthermore, PTT also has the potential to monitor the often tachypnoeic respiratory dependent BP changes seen in small infants during critical care.

Comparison of noninvasive blood pressure measurements in patients with atrial fibrillation

BACKGROUND AND RESEARCH OBJECTIVE

Limited research is available on the accuracy of automatic blood pressure (BP) measurement devices in patients with irregular rhythms. The purpose of this study was to examine the agreement between different methods for noninvasive BP measurement in patients with atrial fibrillation.

SUBJECTS AND METHODS

In a convenience sample of hospitalized patients with atrial fibrillation, a method-comparison study design was used to examine the agreement between 2 noninvasive devices for BP measurement (manual, automated). Blood pressure was obtained sequentially, with each device following manufacturer's directions and American Heart Association guidelines for BP determination and with BP order determined by random assignment. Heart rate and rhythm were determined from a continuous electrocardiographic monitoring. Heart rate was also recorded from the automated BP device. Differences and limits of agreement between the automated and reference standard (manual) BP devices were calculated and graphed according to the Bland-Altman method. Student t test was used to test differences in BP obtained with the 2 devices, as well as heart rate differences between the electrocardiographic monitor and automated BP device. The level of significance for all tests was set at 0.05.

RESULTS

53 participants were observed. Bland-Altman analysis found a bias plus/minus precision of -0.91 +/- 11.4 mm Hg for systolic BP and 3.3 +/- 6.9 mm Hg for diastolic BP. A significant difference was found for the diastolic BP obtained with the automated device and with that of the manual device (t52 = 3.51, P = .0009) and for heart rate differences between the automated BP device and the cardiac monitor (t52 = 2.4, P = .0217).

CONCLUSION

This study confirms that in the presence of irregular cardiac rhythms, diastolic BP and heart rate cannot reliably be measured with an automated BP device.

Comparison of noninvasive oscillometric and intra-arterial blood pressure measurements in hyperacute stroke

OBJECTIVES

This study aims to compare automatic oscillometric blood pressure recordings with simultaneous direct intra-arterial blood pressure measurements in hyperacute stroke patients to test the accuracy of oscillometric readings.

METHODS

A total of 51 first-ever stroke patients underwent simultaneous noninvasive automatic oscillometric and intra-arterial blood pressure monitoring within 3 h of ictus. Casual blood pressure was measured in both arms using a standard mercury sphygmomanometer on hospital admission. Patients who received antihypertensive medication during the blood pressure monitoring were excluded.

RESULTS

The estimation of systolic blood pressure (SBP) using oscillometric recordings underestimated direct radial artery SBP by 9.7 mmHg (95% confidence interval: 6.5-13.0, P<0.001). In contrast, an upward bias of 5.6 mmHg (95% confidence interval: 3.5-7.7, P<0.001) was documented when noninvasive diastolic blood pressure (DBP) recordings were compared with intra-arterial DBP recordings. For SBP and DBP, the Pearson correlation coefficients between noninvasive and intra-arterial recordings were 0.854 and 0.832, respectively. When the study population was stratified according to SBP bands (group A: SBP<or=160 mmHg; group B: SBP>160 mmHg and SBP<or=180 mmHg, group C: SBP>180 mmHg), higher mean DeltaSBP (intra-arterial SBP-oscillometric SBP) levels were documented in group C (+19.8 mmHg, 95% confidence intervals: 12.2-27.4) when compared with groups B (+8.5 mmHg, 95% confidence intervals: 2.7-14.5; P=0.025) and A (+5.9 mmHg, 95% confidence intervals: 1.8-9.9; P=0.002).

CONCLUSION

Noninvasive automatic oscillometric BP measurements underestimate direct SBP recordings and overestimate direct DBP readings in acute stroke. The magnitude of the discrepancy between intra-arterial and oscillometric SBP recordings is even more prominent in patients with critically elevated SBP levels.