title: Intradialytic hypertension during chronic haemodialysis and subclinical fluid overload assessed by bioimpedance spectroscopy.
abstract: BACKGROUND
  Intradialytic hypertension (IDH) increases morbidity and mortality. The prevalence in South Africa is unknown. The pathogenesis is unclear, but it has been suggested that IDH may be due to subclinical fluid overload. The objective of this study was to determine the prevalence of IDH and to evaluate its association with fluid overload using bioimpedance spectroscopy (BIS).
  
  
  METHODS
  A cross-sectional study involving 190 chronic haemodialysis patients in the Western Cape province of South Africa was conducted between January 2013 and May 2014. IDH was defined as a >10 mmHg increase in systolic blood pressure in at least four of six prior consecutive haemodialysis sessions.
  
  
  RESULTS
  The prevalence of IDH was 28.4% (n = 54). There was a trend towards pre-dialysis overhydration in the IDH group when compared with controls {2.6 L [95% confidence interval (CI) 1.7-3.4] versus 1.8 L [95% CI 1.4-2.1], respectively; P = 0.06} as measured by BIS, but no difference in mean ultrafiltration (UF) volume (2.4 versus 2.6 L; P = 0.30). A trend towards greater use of antihypertensive drugs was noted in the IDH group [2.5 drugs (95% CI 2.15-2.87) versus 2.1 (95% CI 1.82-2.30); P = 0.05]. More participants in the IDH group received calcium channel blockers (54 versus 36; P = 0.03).
  
  
  CONCLUSIONS
  The prevalence of IDH in our treatment centres is much higher than previously reported. Subclinical fluid overload may be a major contributing factor to the mechanism of this condition. The use of BIS identifies patients who may benefit from additional UF.
authors.affiliation: Department of Medicine, Division of General Medicine and Nephrology, Faculty of Medicine and Health Sciences , Stellenbosch University, and Tygerberg Academic Hospital , Francie van Zijl Drive, Parow Valley , Stellenbosch , Cape Town, South Africa.
authors.forename: Sajith
authors.initials: S
authors.lastname: Sebastian
authors.affiliation: Central University of Technology , Bloemfontein , South Africa.
authors.forename: Christelle
authors.initials: C
authors.lastname: Filmalter
authors.affiliation: Centre for Statistical Consultation, Stellenbosch University , Stellenbosch , South Africa.
authors.forename: Justin
authors.initials: J
authors.lastname: Harvey
authors.affiliation: Department of Medicine, Division of General Medicine and Nephrology, Faculty of Medicine and Health Sciences , Stellenbosch University, and Tygerberg Academic Hospital , Francie van Zijl Drive, Parow Valley , Stellenbosch , Cape Town, South Africa.
authors.forename: Mogamat-Yazied
authors.initials: MY
authors.lastname: Chothia
keywords: bioimpedance monitoring; haemodialysis; intradialytic hypertension