Uncontrolled blood pressure in hemodialysis patients and its relation to the flow volume and status of the arteriovenous fistula

Background Hypertension is highly prevalent among hemodialysis patients and often remains uncontrolled despite multidrug therapy. This may represent true-resistant hypertension or pseudoresistance due to volume overload, poor adherence. Increased arteriovenous fistula (AVF) flow, sympathetic overactivity, and endothelial dysfunction are among the proposed mechanisms contributing to resistant hypertension in this population. Patients and methods This cross-sectional study evaluated true versus pseudoresistant hypertension in 90 end-stage kidney disease patients on hemodialysis, divided into an uncontrolled hypertension group ( n =60) and a group with normal blood pressure (BP) as a control ( n =30). Assessments included clinical and laboratory evaluations, Doppler AVF analysis, inferior vena cava ultrasound for volume status, and treatment adherence measurement using the End-Stage Renal Disease-Adherence Questionnaire. Results Among the 60 uncontrolled patients, nine (15%) had pseudoresistant hypertension (linked to poor compliance or inadequate ultrafiltration), and 51 (85%) had true-resistant hypertension. Regarding the impact of the AVF, true-resistant patients had significantly higher AVF flow volumes than pseudoresistant patients and control cases ( P =0.012 and 0.001, respectively). Regarding the End-Stage Renal Disease-Adherence Questionnaire, patients with uncontrolled BP showed significantly poorer treatment adherence, though overall levels were satisfactory in both groups. Multivariate regression analysis identified the following as significant independent predictors of uncontrolled hypertension: previous fistula failure [odds ratio (OR)=2.91, 95% confidence interval (CI): 1.15–7.35, P =0.024], prior use of more than three central venous catheters (OR=2.67, 95% CI: 1.09–6.53, P =0.032), higher access flow rate (OR=1.24, 95% CI: 1.08–1.43, P <0.001), inferior vena cava collapsibility less than 50% (OR=3.78, 95% CI: 1.11–12.9, P =0.034), antihypertensive use (OR=17.15, 95% CI: 2.11–139.4, P =0.008), poor treatment adherence (OR=4.40, 95% CI: 1.31–14.8, P =0.017), larger infused normal saline volume during hemodialysis (OR=1.15, 95% CI: 1.32–4.55, P =0.005). Conclusion Uncontrolled hypertension in hemodialysis patients is frequently true-resistant hypertension, rather than pseudoresistant. High AVF flow rate is a major determinant of persistent hypertension in end-stage kidney disease patients on maintenance hemodialysis. Significant correlation exists between elevated AVF flow and increased systolic and diastolic BP across all dialysis phases.