The prevalence of persistent intradialytic hypertension in a hemodialysis population with extended follow-up.

BACKGROUND: Intradialytic hypertension, a phenomenon where blood pressure increases during hemodialysis, is associated with increased mortality in hemodialysis patients. The proportion of patients in which intradialytic hypertension persists over time is unknown.
METHODS: In a retrospective cohort study, we studied all patients from our outpatient hemodialysis units that received =1 month of treatments during the period from January to August 2010. We reviewed all pre- and post-hemodialysis blood pressure and weight measurements from 22,955 treatments during this study period. We defined intradialytic hypertension as an increase in systolic blood pressure =10 mmHg from pre- to post-hemodialysis. Individual patients were defined as having persistent intradialytic hypertension if the change in blood pressure from pre- to post-hemodialysis, when averaged throughout the study period, was =+10 mmHg. We calculated weight changes between and during hemodialysis and defined ultrafiltration rate per treatment as ultrafiltration volume divided by minutes on hemodialysis. We compared patients with and without persistent intradialytic hypertension using chi-square analysis and mixed linear models.
RESULTS: The prevalence of intradialytic hypertension was 21.3 per 100 treatments. The median percentage of intradialytic hypertension treatments per patient was 17.8% (9-31.3%, interquartile range). The prevalence of persistent intradialytic hypertension was 8 per 100 patients. Patients with persistent intradialytic hypertension had lower ultrafiltration rate compared to other patients (10.4 vs. 12.2 ml/min, p = 0.02).
CONCLUSIONS: Intradialytic hypertension is a persistent phenomenon in a subset of hemodialysis patients. Ultrafiltration rate was the only volume-related variable that differed between patients with and without persistent intradialytic hypertension.