Reproducibility of derived central arterial waveforms in patients with chronic renal failure

Arterial stiffness potently predicts mortality in dialysis patients. Pulse-wave analysis permits the non-invasive assessment of indices of arterial stiffness and the central pressure waveform by applanation tonometry. The aim of this study was to assess the reproducibility of pulse-wave analysis in patients with chronic renal failure. A total of 188 subjects (23 healthy controls, along with 71 pre-dialysis, 67 dialysis and 27 transplant patients) took part. Duplicate measurements were recorded of brachial blood pressure using the semi-automated Omron 705 device and of the radial artery pressure waveform using applanation tonometry. The central pressure aortic waveform was then obtained by application of a transfer function incorporated into the SphygmoCor software. Central aortic mean blood pressure (MBP), indices of arterial stiffness [augmentation index (AIx) and time to reflection (TR)] and the subendocardial viability ratio (SEVR) were analysed for intra-observer, inter-observer and long-term reproducibility using Bland-Altman plots. The mean (+/-S.D.) intra-observer difference was 0+/-4% for AIx, 0+/-20 ms for TR, 0+/-3 mmHg for aortic MBP and 0+/-18% for the SEVR. Inter-observer mean differences were 0+/-3% for AIx, 1+/-7 ms for TR, 1+/-4 mmHg for aortic MBP and 1+/-9% for the SEVR. For the long-term study, the mean differences were -1+/-9% for AIx, -2+/-13 mmHg for aortic MBP, -2+/-12 ms for TR and 1+/-29% for the SEVR. Pulse-wave analysis showed excellent reproducibility in all the studies, and is therefore suitable for use in all patients with chronic renal failure. Further prospective and interventional studies are now required to assess whether AIx and TR are important prognostic indices of cardiovascular events, and therefore relevant surrogate indices of arterial stiffness in this susceptible population.