Performance of the AM-5600 blood pressure monitor: comparison with ambulatory intra-arterial pressure

Identifying Isolated Systolic Hypertension From Upper-Arm Cuff Blood Pressure Compared With Invasive Measurements

Isolated systolic hypertension (ISH) is the most common form of hypertension and is highly prevalent in older people. We recently showed differences between upper-arm cuff and invasive blood pressure (BP) become greater with increasing age, which could influence correct identification of ISH. This study sought to determine the difference between identification of ISH by cuff BP compared with invasive BP. Cuff BP and invasive aortic BP were measured in 1695 subjects (median 64 years, interquartile range [55-72], 68% male) from the INSPECT (Invasive Blood Pressure Consortium) database. Data were recorded during coronary angiography among 29 studies, using 21 different cuff BP devices. ISH was defined as ≥130/<80 mm Hg using cuff BP compared with invasive aortic BP as the reference. The prevalence of ISH was 24% (n=407) according to cuff BP but 38% (n=642) according to invasive aortic BP. There was fair agreement (Cohen κ, 0.36) and 72% concordance between cuff and invasive aortic BP for identifying ISH. Among the 28% of subjects (n=471) with misclassification of ISH status by cuff BP, 20% (n=96) of the difference was due to lower cuff systolic BP compared with invasive aortic systolic BP (mean, -16.4 mm Hg [95% CI, -18.7 to -14.1]), whereas 49% (n=231) was from higher cuff diastolic BP compared with invasive aortic diastolic BP (+14.2 mm Hg [95% CI, 11.5-16.9]). In conclusion, compared with invasive BP, cuff BP fails to identify ISH in a sizeable portion of older people and demonstrates the need to improve cuff BP measurements.

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.

Accuracy of blood pressure monitoring devices: a critical need for improvement that could resolve discrepancy in hypertension guidelines

Hypertension is the most significant modifiable risk factor for cardiovascular disease and contributes to the highest global burden of disease. Blood pressure (BP) measurement is among the most important of all medical tests, and it is critical for BP monitoring devices to be accurate. Comprehensive new evidence from meta-analyses clearly shows that many BP monitoring devices (including oscillometric machines and "gold standard" mercury auscultation) do not accurately represent the BP within the arteries at the upper arm (brachial) or central aorta. Particular variability in the accuracy of BP devices compared with intra-arterial BP has been demonstrated in the cuff BP range from prehypertension to grade I hypertension (systolic BP 120-159 to diastolic BP 80-99 mmHg). This is within the BP range that is most common among people worldwide and, thus almost certainly, feeding confusion around optimal hypertension guideline thresholds. At the individual level, inaccurate BP devices have major potential consequences for best practice patient management, where underestimation of true BP is a missed opportunity to lower cardiovascular risk (with therapeutics or lifestyle) and overestimation of true BP could lead to overmedication. Each problem leads to increased cost from preventable cardiovascular events and unnecessary medications. Altogether, there is a critical need to improve the accuracy standards of BP monitoring devices. In the meantime, out-of-office BP (24 h of ambulatory BP and/or home BP monitoring) or automated, unobserved in-office BP monitoring that takes the average of multiple readings using validated devices are the best available options to determine BP control.

Comparison of Oscillometric and Intraarterial Systolic and Diastolic Blood Pressures in Lean, Overweight, and Obese Patients

To assess the effect of obesity on blood pressure measurement the authors obtained simultaneous oscillometric and intraarterial systolic and diastolic blood pressures on 188 lean, overweight, class I/II obese, and class III obese subjects. Oscillometric arm cuff/bladder size was selected in accordance with standard guidelines. Oscillometry significantly underestimated systolic and significantly overestimated diastolic blood pressures in each of the 4 weight groups studied. The differences between oscillometric and intraarterial systolic and diastolic pressures were not significantly different among lean, overweight, class I/II obese, and class III obese subjects. Thus, obesity per se does not influence the accuracy of blood pressure measurement. However, oscillometric blood pressure measurement is associated with significant error when compared to intraarterial blood pressure.