Noninvasive Blood Pressure Measurement in Maintenance Hemodialysis Patients: Comparison of Agreement between Oscillometric and Finger-Cuff Methods

Background: The Nexfin monitor is a device used for measuring arterial blood pressure (BP) continuously and noninvasively through finger-cuff technology. Since it was validated against the auscultatory method using a sphygmomanometer, the aim of this study was to test the ability of the Nexfin to evaluate brachial arterial pressure (BAP) in maintenance hemodialysis patients, quantifying accuracy and precision. Methods: Forty hemodynamically stable hemodialysis patients underwent serial measurements of Nexfix arterial pressure (NAP) and BAP, respectively, through Nexfin and oscillometric devices. All BP measurements were recorded before starting hemodialysis. Results: The mean age of the patients was 68.9 ± 14.9 years with 65% older than 65 years and 30% older than 75; eleven subjects (27%) were diabetic. Vascular calcification, evaluated from the aortic arch to the iliac bifurcation, was detected in 87.5% of patients. Bland-Altman analysis comparing NAP measurements with BAP revealed the following outcomes: a mean bias ± limits of agreements (LA) of 15.3 ± 34.8 mm Hg (29% error) for systolic BP, a mean bias ± LA of -0.9 ± 20.34 mm Hg (32% error) for diastolic BP and a mean bias ± LA of 4.5 ± 21.34 mm Hg (26% error) for mean arterial pressure (MAP). Nexfin had poor precision in the reconstruction of diastolic and mean BP and was extremely inaccurate when evaluating systolic BP. Diabetes mellitus, peripheral neuropathy, and increase in systolic BAP significantly predicted the disagreement in systolic pressure measurement between NAP and MAP, F (3.34) = 10.787, p < 0.005, R2 = 0.488. Conclusion: The Nexfin does not meet the criteria of interchangeability with oscillometric method in our hemodialysis patients. The negative influence of diabetes, neuropathy, and increase of systolic BAP on the reconstruction of systemic systolic pressure raises concerns about the feasibility of Nexfin in patients with a high prevalence of vasculopathy.