Association between ultrafiltration volume and intradialytic hypertension in maintenance hemodialysis

Background and objectives Increase of blood pressure during hemodialysis (HD) is associated with adverse outcomes, while cause of the increase in blood pressure during HD is still under debate. It has been suggested that stimulation of RAAS by hypovolemia due to excessive ultrafiltration (UF) during HD is the main risk factor of IDH. We tested the hypothesis wether IDH is associated with measured UF volume during hemodialysis.MethodsForty eight stable patients who were on chronic HD were enrolled in a case-control cohort study. Thirty patients on maintenance HD without IDH (controls) and 18 with IDH (post HD systolic BP increase ≥10 mmHg than pre HD systolic BP on minimal four from six consecutive HD sessions). We have done a physical examination and past medical history review for all subjects. We also collected current monthly laboratory results. At each subsequent dialysis treatment from six consecutive HD sessions, we collect data of  ultrafiltrasion volume during HD, standardized BP measured (after 5 minutes of rest) were done by nurse pre-, during dialysis and postdialysis.Results We found 37.5% of subject had IDH. Between group we found predialytic systolic and diastolyc BP were similar, but average postdialysis systolic BP was higher on  IDH group. Mean of UF volume  is higher among IDH patients than controls (3.46±0.65Lvs 2.37±0.77L). Using logistic regression we found significant association between mean of UF volume and IDH (OR = 0.14 (95% CI 0.05-0.43 , p=0.001),  In IDH patients 88.9% had excessive UF (UF ≥ 3 L), but in control group only 13.3% had excesive UF. There was significant and strong correlation between excessive ultrafiltration and intradialytic hypertension (p=0.00), odds ratio 11.2 (95% CI : 2.8-43.3).Conclusions  Intradialytic hypertension is associated with excessive UF during hemodialysis.Â