Arterial reservoir characteristics and central-to-peripheral blood pressure amplification in the human upper limb

Arterial Blood Pressure Features of Hypertensive Patients with Typical and Atypical 460 nm Skin Fluorescence Response to Transient Ischaemia

Flow-mediated skin fluorescence (FMSF) at 460 nm is a non-invasive method for assessing dynamic changes in the reduced form of nicotinamide adenine dinucleotide (NADH) and microcirculation in forearm skin under varying conditions of tissue perfusion. Typically, fluorescence increases during ischaemia, but atypical cases show a temporary signal decrease instead of a constant increase. This study aimed to explore the clinical implications of atypical FMSF patterns in patients with newly diagnosed untreated hypertension. NADH fluorescence and pulse wave analysis were performed on 65 patients. Differences in peripheral and arterial pulse pressure profiles were examined based on FMSF curve courses. Patients with atypical curve courses had significantly (p < 0.05 or lower for all) higher heart rate, peripheral and central diastolic pressure, tension time index, central rate pressure product, shorter diastole duration, and reservoir pressure-time integral. Hypertensive patients with atypical FMSF signals had less advantageous blood pressure profiles. Although the underlying factors causing these symptoms are unknown, the atypical FMSF pattern may reflect increased sympathetic stimulation and vascular resistance. The visual assessment of the FMSF curve may have important clinical implications that deserve further investigation.

Agreement between distal and forearm radial arterial pressures in patients undergoing prone spinal surgery: a prospective, self-controlled, observational study

OBJECTIVE

To test agreement and interchangeability between distal (dRA) and forearm radial arterial (RA) pressures (AP) during general anesthesia (GA) for prone spinal surgery.

METHODS

This prospective observational study involved 40 patients scheduled for GA spinal surgery. The right dRA and left forearm RA were cannulated in all patients to continuously measure invasive blood pressures (IBP). We compared the agreement and trending ability of systolic AP (SAP), diastolic AP (DAP), and mean AP (MAP) at each site 15 minutes after tracheal intubation, start of surgery, 30 and 60 minutes after the start of surgery, and after skin suturing.

RESULTS

Paired BP values (n = 184) (37 cases) were analyzed. The bias (standard deviation), limits of agreement, and percentage error were: SAP: 0.19 (3.03), -5.75 to 6.12, and 5.04%; DAP: -0.06 (1.75), -3.50 to 3.38, and 5.10%; and MAP: 0.08 (1.52), -2.90 to 3.05, and 3.54%, respectively. The linear regression coefficients of determination were 0.981, 0.982, and 0.988 for SAPs, DAPs, and MAPs, respectively; four-quadrant plot concordance rates were 95.11%, 92.03%, and 92.66%, respectively.

CONCLUSION

All arterial BPs showed good agreement and trending capabilities for both the dRA and RA. The dRA may be substituted for the RA in IBP monitoring.

Sex-specific associations of reservoir-excess pressure parameters with age and subclinical vascular remodeling

OBJECTIVE

Central artery reservoir pressure and excess pressure (XSP) are associated with cardiovascular disease (CVD) events and mortality. However, sex differences in the trajectory of central reservoir pressure and XSP with advancing age and their relations with vascular markers of subclinical CVD risk are incompletely understood. Therefore, we tested the hypothesis that central reservoir pressure and XSP would be positively associated with advancing age and vascular markers of subclinical CVD risk in men and women.

METHOD

Healthy adults ( n  = 398; aged 18-80 years, 60% female individuals) had central (carotid) artery pressure waveforms acquired by applanation tonometry. Reservoir pressure and XSP peaks and integrals were derived retrospectively from carotid pressure waveforms using custom written software. Carotid artery intimal-medial thickness (IMT) was measured by ultrasonography, and aortic stiffness was determined from carotid-femoral pulse wave velocity (cfPWV).

RESULTS

Reservoir pressure peak, reservoir pressure integral and XSP integral were higher with age in both men and women ( P  < 0.05), whereas XSP peak was lower with age in men ( P  < 0.05). In women, both reservoir pressure peak ( β  = 0.231, P  < 0.01) and reservoir pressure integral ( β  = 0.254, P  < 0.01) were associated with carotid artery IMT, and reservoir pressure peak was associated with cfPWV ( β  = 0.120, P  = 0.02) after adjusting for CVD risk factors.

CONCLUSION

Central artery reservoir pressure and XSP were higher with advancing age in men and women, and reservoir pressure peak was associated with both carotid artery wall thickness and aortic stiffness in women but not men. Central reservoir pressure peak may provide some insight into sex differences in vascular remodeling and subclinical CVD risk with advancing age in healthy adults.

Central blood pressure estimation in type 1 diabetes: impact and implications of peripheral calibration method

OBJECTIVE

Peripheral blood pressure (BP) waveforms are used for noninvasive central BP estimation. Central BP could assist in cardiovascular risk assessment in patients with type 1 diabetes mellitus (T1DM). However, correct calibration of peripheral BP waveforms is important to accurately estimate central BP. We examined differences in central BP estimated by radial artery tonometry depending on which brachial BP (SBP/DBP vs. MAP/DBP) is used for calibration of the radial waveforms, for the first time in T1DM.

METHODS

A cross-sectional study in T1DM patients without known cardiovascular disease. Radial artery BP waveforms were acquired using applanation tonometry ( SphygmoCor ) for the estimation of central SBP, central pulse pressure (PP) and central augmentation pressure, using either brachial SBP/DBP or MAP/DBP for the calibration of the radial pressure waveforms.

RESULTS

Fifty-four patients (age: 46 ± 9.5 years; T1DM duration: 27 ± 8.8 years) were evaluated. Central BP parameters were significantly higher when brachial MAP/DBP-calibration was used compared with brachial SBP/DBP-calibration (7.5 ± 5.04, 7.5 ± 5.04 and 1.5 ± 1.36 mmHg higher central SBP, central PP and central augmentation pressure, respectively, P  < 0.001).

CONCLUSION

In patients with T1DM, there are significant differences in central BP values estimated with radial artery tonometry, depending on the method used for calibration of the radial waveforms. Brachial MAP/DBP-calibration resulted in consistently higher central BP as compared to using brachial SBP/DBP, leading to patient re-stratification. Hence, the accuracy of noninvasive estimation of central BP by radial tonometry is dependent on calibration approach, and this problem must be resolved in validation studies using an invasive reference standard to determine which method best estimates true central BP.

Comparison between cuff-based and invasive systolic blood pressure amplification

OBJECTIVE

Accurate measurement of central blood pressure (BP) using upper arm cuff-based methods is associated with several factors, including determining the level of systolic BP (SBP) amplification. This study aimed to determine the agreement between cuff-based and invasively measured SBP amplification.

METHODS

Patients undergoing coronary angiography had invasive SBP amplification (brachial SBP - central SBP) measured simultaneously with cuff-based SBP amplification using a commercially available central BP device (device 1: Sphygmocor Xcel; n = 171, 70% men, 60 ± 10 years) and a now superseded model of a central BP device (device 2: Uscom BP+; n = 52, 83% men, 62 ± 10 years).

RESULTS

Mean difference (±2SD, limits of agreement) between cuff-based and invasive SBP amplification was 4 mmHg (-12, +20 mmHg, P < 0.001) for device 1 and -2 mmHg (-14, +10 mmHg, P = 0.10) for device 2. Both devices systematically overestimated SBP amplification at lower levels and underestimated at higher levels of invasive SBP amplification, but with stronger bias for device 1 (r = -0.68 vs. r = -0.52; Z = 2.72; P = 0.008). Concordance of cuff-based and invasive SBP amplification across quartiles of invasive SBP amplification was low, particularly in the lowest and highest quartiles. The root mean square errors from regression between cuff-based central SBP and brachial SBP were significantly lower (indicating less variability) than from invasive regression models (P < 0.001).

CONCLUSIONS

Irrespective of the difference from invasive measurements, cuff-based estimates of SBP amplification showed evidence of proportional systematic bias and had less individual variability. These observations could provide insights on how to improve the performance of cuff-based central BP.

Reservoir Pressure Integral Is Independently Associated With the Reduction in Renal Function in Older Adults

BACKGROUND

Arterial hemodynamic parameters derived from reservoir-excess pressure analysis exhibit prognostic utility. Reservoir-excess pressure analysis may provide useful information about an influence of altered hemodynamics on target organ such as the kidneys. We determined whether the parameters derived from the reservoir-excess pressure analysis were associated with the reduction in estimated glomerular filtration rate in 542 older adults (69.4±7.9 years, 194 females) at baseline and after 3 years.

METHODS

Reservoir-excess pressure parameters, including reservoir pressure integral, excess pressure integral, systolic, and diastolic rate constants, were obtained by radial artery tonometry.

RESULTS

After 3 years, and in a group of 94 individuals (72.4±7.6 years, 26 females), there was an estimated glomerular filtration rate reduction of >5% per year (median reduction of 20.5% over 3 years). A multivariable logistic regression analysis revealed that higher baseline reservoir pressure integral was independently associated with a smaller reduction in estimated glomerular filtration rate after accounting for conventional cardiovascular risk factors and study centers (odds ratio: 0.660 [95% CIs, 0.494-0.883]; P=0.005). The association remained unchanged after further adjustments for potential confounders and baseline renal function (odds ratio: 0.528 [95% CIs, 0.351-0.794]; P=0.002). No other reservoir-excess pressure parameters exhibited associations with the reduction in renal function.

CONCLUSIONS

This study demonstrates that baseline reservoir pressure integral was associated with the decline in renal function in older adults at 3-year follow-up, independently of conventional cardiovascular risk factors. This suggests that reservoir pressure integral may play a role in the functional decline of the kidneys.

Physiological and clinical insights from reservoir-excess pressure analysis

There is a growing body of evidence indicating that reservoir-excess pressure model parameters provide physiological and clinical insights above and beyond standard blood pressure (BP) and pulse waveform analysis. This information has never been collectively examined and was the aim of this review. Cardiovascular disease is the leading cause of mortality worldwide, with BP as the greatest cardiovascular disease risk factor. However, brachial systolic and diastolic BP provide limited information on the underlying BP waveform, missing important BP-related cardiovascular risk. A comprehensive analysis of the BP waveform is provided by parameters derived via the reservoir-excess pressure model, which include reservoir pressure, excess pressure, and systolic and diastolic rate constants and Pinfinity. These parameters, derived from the arterial BP waveform, provide information on the underlying arterial physiology and ventricular-arterial interactions otherwise missed by conventional BP and waveform indices. Application of the reservoir-excess pressure model in the clinical setting may facilitate a better understanding and earlier identification of cardiovascular dysfunction associated with disease. Indeed, reservoir-excess pressure parameters have been associated with sub-clinical markers of end-organ damage, cardiac and vascular dysfunction, and future cardiovascular events and mortality beyond conventional risk factors. In the future, greater understanding is needed on how the underlying physiology of the reservoir-excess pressure parameters informs cardiovascular disease risk prediction over conventional BP and waveform indices. Additional consideration should be given to the application of the reservoir-excess pressure model in clinical practice using new technologies embedded into conventional BP assessment methods.

Excess pressure as an analogue of blood flow velocity

INTRODUCTION

Derivation of blood flow velocity from a blood pressure waveform is a novel technique, which could have potential clinical importance. Excess pressure, calculated from the blood pressure waveform via the reservoir-excess pressure model, is purported to be an analogue of blood flow velocity but this has never been examined in detail, which was the aim of this study.

METHODS

Intra-arterial blood pressure was measured sequentially at the brachial and radial arteries via fluid-filled catheter simultaneously with blood flow velocity waveforms recorded via Doppler ultrasound on the contralateral arm (n = 98, aged 61 ± 10 years, 72% men). Excess pressure was derived from intra-arterial blood pressure waveforms using pressure-only reservoir-excess pressure analysis.

RESULTS

Brachial and radial blood flow velocity waveform morphology were closely approximated by excess pressure derived from their respective sites of measurement (median cross-correlation coefficient r = 0.96 and r = 0.95 for brachial and radial comparisons, respectively). In frequency analyses, coherence between blood flow velocity and excess pressure was similar for brachial and radial artery comparisons (brachial and radial median coherence = 0.93 and 0.92, respectively). Brachial and radial blood flow velocity pulse heights were correlated with their respective excess pressure pulse heights (r = 0.53, P < 0.001 and r = 0.43, P < 0.001, respectively).

CONCLUSION

Excess pressure is an analogue of blood flow velocity, thus affording the opportunity to derive potentially important information related to arterial blood flow using only the blood pressure waveform.

Brachial-cuff excess pressure is associated with carotid intima-media thickness among Australian children: a cross-sectional population study

Reservoir pressure parameters (i.e., reservoir pressure [RP] and excess pressure [XSP]) independently predict cardiovascular events in adults, but this has not been investigated in children. This study aimed to determine (1) the association of reservoir pressure parameters with carotid intima-media thickness (carotid IMT), a preclinical vascular phenotype, and (2) whether a multivariable regression model with or without reservoir pressure parameters fits better for estimating carotid IMT in children. Study participants were 11-12-year-old children (n = 1231, 50% male) from the Child Health CheckPoint study, a cross-sectional substudy of the population-based Longitudinal Study of Australian Children. RP and XSP were obtained using brachial-cuff oscillometry (SphygmoCor XCEL, AtCor, Sydney). Carotid IMT was quantified by vascular ultrasonography. XSP was associated with carotid IMT after adjusting for confounders including age, sex, BMI z-score, heart rate, pubertal stage, moderate-to-vigorous physical activity, and mean arterial pressure (β = 0.93 µm, 95% CI 0.30-1.56 for XSP peak and β = 0.04 µm, 95% CI 0.01-0.08 for XSP integral). The results of the likelihood ratio test indicated a trend that the model with XSP and the above confounders fit better than a similar model without XSP for estimating carotid IMT. Our findings indicate that brachial-cuff device-measured XSP is associated with carotid IMT independent of conventional cardiovascular risk factors, including standard BP. This implies that a clinically convenient cuff approach could provide meaningful information for the early assessment of cardiovascular risk among children.

Cuff Under Pressure for Greater Accuracy

PURPOSE OF REVIEW

To present the evidence that describes what is being measured by upper-arm cuff blood pressure (BP) and the level of accuracy compared with invasive central aortic and brachial BP. Potential causes of inaccuracy and emerging methods are also discussed.

RECENT FINDINGS

On average cuff systolic BP systematically underestimates invasive brachial systolic BP, although in a given individual it may substantially under- or over-estimate central aortic systolic BP. Such errors may affect individual health management outcomes and distort population level data on hypertension prevalence and control. Oscillometric cuff BP is particularly susceptible to inaccuracy in people with high arterial stiffness and with pathophysiological BP waveform shapes. Emerging cuff-less BP methods will be susceptible to inaccuracy if oscillometric cuff BP is used for calibration. The original purpose of cuff BP was to estimate central aortic BP. Recent evidence has shown substantial inaccuracy of oscillometric cuff BP exists for the measurement of invasive central aortic and brachial BP. Thus, development of more accurate BP methods, through better understanding of oscillometric and BP waveform morphology, is needed to improve health outcomes related to high BP.

Measurement, Analysis and Interpretation of Pressure/Flow Waves in Blood Vessels

The optimal performance of the cardiovascular system, as well as the break-down of this performance with disease, both involve complex biomechanical interactions between the heart, conduit vascular networks and microvascular beds. ‘Wave analysis’ refers to a group of techniques that provide valuable insight into these interactions by scrutinizing the shape of blood pressure and flow/velocity waveforms. The aim of this review paper is to provide a comprehensive introduction to wave analysis, with a focus on key concepts and practical application rather than mathematical derivations. We begin with an overview of invasive and non-invasive measurement techniques that can be used to obtain the signals required for wave analysis. We then review the most widely used wave analysis techniques—pulse wave analysis, wave separation and wave intensity analysis—and associated methods for estimating local wave speed or characteristic impedance that are required for decomposing waveforms into forward and backward wave components. This is followed by a discussion of the biomechanical phenomena that generate waves and the processes that modulate wave amplitude, both of which are critical for interpreting measured wave patterns. Finally, we provide a brief update on several emerging techniques/concepts in the wave analysis field, namely wave potential and the reservoir-excess pressure approach.

The modified arterial reservoir: An update with consideration of asymptotic pressure (P∞) and zero-flow pressure (Pzf)

This article describes the modified arterial reservoir in detail. The modified arterial reservoir makes explicit the wave nature of both reservoir (P_res) and excess pressure (P_xs). The mathematical derivation and methods for estimating P_res in the absence of flow velocity data are described. There is also discussion of zero-flow pressure (P_zf), the pressure at which flow through the circulation ceases; its relationship to asymptotic pressure (P_∞) estimated by the reservoir model; and the physiological interpretation of P_zf . A systematic review and meta-analysis provides evidence that P_zf differs from mean circulatory filling pressure.

Associations of Reservoir-Excess Pressure Parameters Derived From Central and Peripheral Arteries With Kidney Function

BACKGROUND

Central artery reservoir-excess pressure parameters are clinically important but impractical to record directly. However, diastolic waveform morphology is consistent across central and peripheral arteries. Therefore, peripheral artery reservoir-excess pressure parameters related to diastolic waveform morphology may be representative of central parameters and share clinically important associations with end-organ damage. This has never been determined and was the aim of this study.

METHODS

Intra-arterial blood pressure (BP) waveforms were measured sequentially at the aorta, brachial, and radial arteries among 220 individuals (aged 61 ± 10 years, 68% male). Customized software was used to derive reservoir-excess pressure parameters at each arterial site (reservoir and excess pressure, systolic and diastolic rate constants) and clinical relevance was determined by association with estimated glomerular filtration rate (eGFR).

RESULTS

Between the aorta and brachial artery, the mean difference in the diastolic rate constant and reservoir pressure integral was -0.162 S-1 (P = 0.08) and -0.772 mm Hg s (P = 0.23), respectively. The diastolic rate constant had the strongest and most consistent associations with eGFR across aortic and brachial sites (β = -0.20, P = 0.02; β = -0.20, P = 0.03, respectively; adjusted for traditional cardiovascular risk factors). Aortic, but not brachial peak reservoir pressure was associated with eGFR in adjusted models (aortic β = -0.48, P = 0.02).

CONCLUSIONS

The diastolic rate constant is the most consistent reservoir-excess pressure parameter, in both its absolute values and associations with kidney dysfunction, when derived from the aorta and brachial artery. Thus, the diastolic rate constant could be utilized in the clinical setting to improve BP risk stratification.

Intra-arterial analysis of the best calibration methods to estimate aortic blood pressure

OBJECTIVE

Estimation of aortic blood pressure (BP) requires peripheral BP waveform calibration. Mean arterial pressure (MAP)/DBP calibration is purported to estimate aortic BP more accurately than SBP/DBP calibration. However, this is based on inaccurate cuff calibration. Thus, direct comparisons of each calibration method using intra-arterial BP are required to confirm this, and was the aim of this study.

METHODS

Ascending aortic, brachial and radial artery intra-arterial BPs were measured among 107 patients (61.9 ± 10.0 years, 70% men) undergoing coronary angiography. Radial waveforms were calibrated with brachial SBP/DBP and brachial MAP/DBP to directly test the accuracy of estimated aortic SBP (derived using a commercial device) from each calibration compared with intra-arterial aortic SBP. Estimated aortic BP accuracy from aortic MAP/DBP, brachial and radial SBP/DBP calibrations of peripheral waveforms was also tested (six calibration methods in total; all using intra-arterial BP).

RESULTS

Estimated aortic SBP from brachial MAP/DBP calibration of radial waveforms had a significantly smaller mean difference than from brachial SBP/DBP calibration (-0.7 ± 7.5 mmHg versus -6.9 ± 7.3 mmHg, P < 0.0001 for difference). Of the other calibration methods, estimated aortic SBP was most accurate from aortic MAP/DBP calibration of radial waveforms (-1.8 ± 5.0 mmHg, P = 0.00023). However, for all calibration methods, aortic-to-brachial artery and/or brachial-to-radial artery SBP amplification had a major influence on estimated aortic SBP.

CONCLUSION

Brachial and aortic MAP/DBP were confirmed as the best calibration methods to estimate aortic SBP, but irrespective of calibration method, accuracy was significantly influenced by the level of SBP amplification. Thus, improved accuracy of estimated aortic SBP should be possible by closer consideration of SBP amplification or individual waveform characteristics that differ according to the level of SBP amplification.

Association of brachial-cuff excess pressure with carotid intima-media thickness in Australian adults: a cross-sectional study

OBJECTIVE

Reservoir pressure parameters [e.g. reservoir pressure (RP) and excess pressure (XSP)] measured using tonometry predict cardiovascular events beyond conventional risk factors. However, the operator dependency of tonometry impedes widespread use. An operator-independent cuff-based device can reasonably estimate the intra-aortic RP and XSP from brachial volumetric waveforms, but whether these estimates are clinically relevant to preclinical phenotypes of cardiovascular risk has not been investigated.

METHODS

The RP and XSP were derived from brachial volumetric waveforms measured using cuff oscillometry (SphygmoCor XCEL) in 1691 mid-life adults from the CheckPoint study (a population-based cross-sectional study nested in the Longitudinal Study of Australian Children). Carotid intima--media thickness (carotid IMT, n = 1447) and carotid--femoral pulse wave velocity (PWV, n = 1632) were measured as preclinical phenotypes of cardiovascular risk. Confounders were conventional risk factors that were correlated with both exposures and outcomes or considered as physiologically important.

RESULTS

There was a modest association between XSP and carotid IMT (β = 0.76 μm, 95% CI, 0.25-1.26 partial R = 0.8%) after adjusting for age, sex, BMI, heart rate, smoking, diabetes, high-density lipoprotein cholesterol and mean arterial pressure. Neither RP nor XSP were associated with PWV in the similarly adjusted models (β = -0.47 cm/s, 95% CI, -1.15 to 0.20, partial R = 0.2% for RP, and β = 0.04 cm/s, 95% CI, -0.59 to 0.67, partial R = 0.01% for XSP).

CONCLUSION

Cuff-based XSP associates with carotid IMT independent of conventional risk factors, including traditional BP, but the association was weak, indicating that further investigation is warranted to understand the clinical significance of reservoir pressure parameters.

Brachial and Radial Systolic Blood Pressure Are Not the Same

Radial intra-arterial blood pressure (BP) is sometimes used as the reference standard for validation of brachial cuff BP devices. Moreover, there is an emerging wearables market seeking to measure BP at the wrist. However, radial systolic BP may differ when compared with brachial; yet some authors have labeled these differences as a fictional Popeye phenomenon. Indeed, differences between brachial and radial systolic BP have never been accurately quantified, and this was the aim of this study. Intra-arterial BP was measured consecutively at the brachial and radial artery in 180 participants undergoing coronary angiography (aged 61±10 years; 69% men). On average, radial systolic BP was 5.5 mm Hg higher than brachial systolic BP. Only 43% of participants had radial systolic BP within ±5 mm Hg of brachial. Additionally, 46%, 19%, and 13% of participants had radial systolic BP >5, between 5 and 10, and between 10 and 15 mm Hg higher than brachial respectively. A further 14% of participants had radial systolic BP >15 mm Hg higher than brachial, representing the so-called Popeye phenomenon. Finally, 11% of participants had radial systolic BP >5 mm Hg lower than brachial. In conclusion, radial systolic BP is not representative of brachial systolic BP, with most participants having a radial systolic BP >5 mm Hg higher than brachial and many with differences >15 mm Hg. Therefore, validation testing of BP devices utilizing intra-arterial BP as the reference standard should use intra-arterial BP measured at the same site as the brachial cuff or wearable device.

Prognostic Value of Carotid and Radial Artery Reservoir-Wave Parameters in End-Stage Renal Disease

Background Reservoir-wave approach is an alternative model of arterial hemodynamics based on the assumption that measured arterial pressure is composed of volume-related (reservoir pressure) and wave-related components (excess pressure). However, the clinical utility of reservoir-wave approach remains debatable. Methods and Results In a single-center cohort of 260 dialysis patients, we examined whether carotid and radial reservoir-wave parameters were associated with all-cause and cardiovascular mortality. Central pulse pressure and augmentation index at 75 beats per minute were determined by radial arterial tonometry through generalized transfer function. Carotid and radial reservoir-wave analysis were performed to determine reservoir pressure and excess pressure integral. After a median follow-up of 32 months, 171 (66%) deaths and 88 (34%) cardiovascular deaths occurred. In Cox regression analysis, carotid excess pressure integral was associated with a hazard ratio of 1.33 (95% CI , 1.14-1.54; P<0.001 per 1 SD) for all-cause and 1.45 (95% CI : 1.18-1.75; P<0.001 per 1 SD) for cardiovascular mortality. After adjustments for age, heart rate, sex, clinical characteristics and carotid-femoral pulse wave velocity, carotid excess pressure integral was consistently associated with increased risk of all-cause (hazard ratio per 1 SD, 1.30; 95% CI : 1.08-1.54; P=0.004) and cardiovascular mortality (hazard ratio per 1 SD, 1.31; 95% CI : 1.04-1.63; P=0.019). Conversely, there were no significant associations between radial reservoir-wave parameters, central pulse pressure, augmentation index at 75 beats per minute, pressure forward, pressure backward and reflection magnitude, and all-cause or cardiovascular mortality after adjustment for comorbidities. Conclusions These observations support the clinical value of reservoir-wave approach parameters of large central elastic vessels in end-stage renal disease.

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.

Pulse Waveform Analysis: Is It Ready for Prime Time?

PURPOSE OF REVIEW

Arterial pulse waveform analysis has a long tradition but has not pervaded medical routine yet. This review aims to answer the question whether the methodology is ready for prime time use. The current methodological consensus is assessed, existing technologies for waveform measurement and pulse wave analysis are discussed, and further needs for a widespread use are proposed.

RECENT FINDINGS

A consensus document on the understanding and analysis of the pulse waveform was published recently. Although still some discrepancies remain, the analysis using both pressure and flow waves is favoured. However, devices which enable pulse wave measurement are limited, and the comparability between devices is not sufficiently given. Pulse waveform analysis has the potential for prime time. It is currently on a way towards broader use, but still needs to overcome challenges before settling its role in medical routine.