Measurement of central aortic pulse pressure: noninvasive brachial cuff-based estimation by a transfer function vs. A novel pulse wave analysis method.
The prognostic value of central aortic pulse pressure (PP-C) may have been underestimated due to its measurement inaccuracy. We aimed to investigate the accuracy of noninvasive brachial cuff-based estimation of PP-C by a generalized transfer function (GTF) or a novel pulse wave analysis (PWA) approach to directly estimate PP-C.Methods
Invasive high-fidelity right brachial and central aortic pressure tracings, and left brachial pulse volume plethysmography (PVP) waveforms from an oscillometric blood pressure (BP) monitor were all digitized simultaneously in 40 patients during cardiac catheterization. An aortic-to-brachial GTF and a PWA multivariate prediction model using the PVP waveforms calibrated to brachial cuff systolic BP (SBP) and diastolic BP(DBP) were constructed. Accuracy of the two methods was examined in another 100 patients against invasively measured PP-C.ResultsThe error of cuff PP in estimating PP-C was 1.8 ± 12.4 mm Hg. Application of the GTF on noninvasively calibrated PVP waveforms produced reconstructed aortic pressure waves and PP-C estimates with errors of -3.4 ± 11.6 mm Hg (PP-C = reconstructed aortic SBP - aortic DBP) and -2.3 ± 11.4 mm Hg (PP-C = reconstructed aortic SBP - cuff DBP), respectively. The observed systematic errors were proportional to the magnitudes of PP-C. In contrast, the error of the PWA prediction model was 3.0 ± 7.1 mm Hg without obvious proportional systematic error.Conclusions
Large random and systematic errors are introduced into the PP-C estimates when PP-C is calculated as the difference between the estimated central SBP and central or cuff DBP. The accuracy can be improved substantially with the novel PWA approach.American Journal of Hypertension 2012; doi:10.1038/ajh.2012.116.
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ABSTRACT: To study factors affecting the accuracy of oscillometric measurement. By means of a computer-based simulator, a variety of arterial pressure pulses of different shapes and amplitudes were composed as an input signal of the model, whereas cuff volume oscillations were obtained as an output signal. The shape of the artery-cuff pressure/volume relationship was modified. Thereafter, oscillation envelopes were drawn and an estimation of systolic and diastolic pressures was performed by implementing fixed characteristic ratios. The mean arterial pressure was estimated using the maximum oscillation criterion. Altogether, 32 combinations of four affecting factors were studied. For the studied range of affecting factors, the induced errors in systolic pressure, diastolic pressure, and mean arterial pressures were 15, 14, and 27 mmHg, respectively. Systolic readings moved toward underestimation and diastolic readings moved toward overestimation if pulse pressure increased. Arterial stiffening induced systematic overestimation of the systolic pressure and overestimation or underestimation of the diastolic pressure compared with a normal artery, with errors depending on the interaction of the symmetry and steepness indices of the artery-cuff pressure/volume curve. Errors of mean arterial pressure were proportional to pulse pressure, showing overestimation if stiffness increased and/or arterial pressure pulses became steeper. Oscillometric readings of systolic and diastolic pressures are strongly influenced by pulse pressure and the shape of the artery-cuff pressure/volume curve, whereas those of the mean arterial pressure are affected by pulse pressure and both the shape of the artery-cuff pressure/volume curve and the shape of the arterial pulse.Blood Pressure Monitoring 10/2011; 16(5):238-45. · 1.80 Impact Factor
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ABSTRACT: Determination of arterial compliance in vivo has long interested physiologists. Most current methods for estimating this parameter assume that compliance is constant, i.e., that arterial pressure-volume (P-V) relations are linear, and they also assume that diastolic aortic pressure decay is an exponential function of time. Both of these assumptions, however, are questionable. This study proposes improved methods of estimating compliance based on a Windkessel model of the arterial system but which utilize the area under the pressure tracing rather than the waveform itself. Formulations accounting for both linear and three hypothetical nonlinear arterial P-V relations (exponential, logarithmic, and parabolic) are presented. Data from patients with congestive heart failure and hypertension are used for illustration. Compliances assuming linear P-V relations are reasonably close to those assuming nonlinear P-V relations only at mean aortic pressure. At end-diastolic pressure the linear assumption underestimates and at peak systolic it overestimates the compliances obtained assuming nonlinear P-V relations. The simpler linear assumption still allows a first approximation to compliance, but we show that existing methods for obtaining compliance under this assumption have severe theoretical as well as practical shortcomings. Our proposed method avoids these shortcomings primarily because deviations from an exact exponential form of the pressure wave have less influence on these compliance estimates than currently used methods.The American journal of physiology 10/1986; 251(3 Pt 2):H588-600. · 3.28 Impact Factor
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ABSTRACT: This report, the third in a series on pulse pressure and pure systolic hypertension, examines the associations between blood pressure and the cardiovascular diseases and coronary heart disease, both cross-sectionally and prospectively, utilizing data from four Chicago epidemiologic studies, in an effort to determine whether or not a widened pulse pressure, or pure systolic hypertension, is an independent risk factor. In these analyses, blood pressure is divided into two components, one related to level and the other to pulse pressure, with pulse pressure redefined so that the association between pulse pressure and the prevalence of ECG abnormalities or mortality, indicates whether the endpoint is more strongly related to systolic or diastolic blood pressure. In these studies, blood pressure level is significantly related to both ECG abnormalities and mortality. In the cross-sectional analyses, pulse pressure is generally positively related to the prevalence of ECG abnormalities, indicating a stronger association for systolic blood pressure, and thus a possible association with pure systolic hypertension. However, in the prospective analyses, pulse pressure is generally not related to mortality, indicating an equal association with mortality for systolic and diastolic blood pressure in these studies. Thus, although the cross-sectional analyses generally support the hypothesis that a widened pulse pressure, or pure systolic hypertension, is an independent risk factor for the cardiovascular diseases and coronary heart disease, the prospective analyses do not.Journal of Chronic Diseases 02/1982; 35(4):283-94.