Renal dysfunction does not affect the peripheral-to-central arterial pressure transfer function

Arterial generalized transfer functions (GTFs) are increasingly used to estimate central pressure from peripheral measurements. Analysis of derived central waveforms may be valuable in the assessment of patients with chronic kidney disease. The aim of this study was to assess whether the GTF is affected by renal disease. Ninety-four subjects with varying degrees of renal function (Kidney Disease Outcomes Quality Initiative stages 1 to 5; 14 controls) had simultaneous measurements of carotid and radial waveforms made by applanation tonometry. GTFs were calculated by Fourier analysis for each subject group. Derived carotid waveforms were obtained by applying an independently generated GTF to the radial waveform. Glomerular filtration rate inversely correlated with central systolic (R = -0.42; P < 0.001), mean (R = -0.34; P < 0.01) and diastolic (R = --0.27, P < 0.01) blood pressures, as well as central augmentation index (R = -0.30; P< 0.01) and carotid-femoral pulse wave velocity (R = -0.33; P < 0.001). Derived waveforms were not significantly different from measured waveforms in terms of systolic blood pressure, augmentation index, maximum slope, or the delay between the incident and reflected waves, although the derived waveforms slightly underestimated the systolic ejection period (-4.4 ± 0.9 ms; P < 0.001). Overall root-mean-square error was 2.4 ± 0.1 mm Hg. No significant relationship existed between the degree of bias of any derived waveform measure and glomerular filtration rate or chronic kidney disease stage (P > 0.16). No significant differences between chronic kidney disease stages were observed in transfer function gain or phase (P > 0.05). We conclude that the peripheral-to-central GTF is not affected by degree of renal dysfunction and can be used with equivalence in patients with varying degrees of chronic kidney disease.