title: Ultrafiltration biofeedback guided by blood volume monitoring to reduce intradialytic hypotensive episodes in hemodialysis: study protocol for a randomized controlled trial.
abstract: BACKGROUND
  Fluid removal during dialysis, also known as ultrafiltration (UF), leads to intradialytic hypotension (IDH) in a significant number of patients treated with hemodialysis (HD) and is associated with an increase in morbidity and mortality. At present, there are no accepted standards of practice for the prevention or treatment of IDH. Relative blood volume monitoring (BVM) is based on the concept that the hematocrit increases with UF, relative to the patient's baseline hematocrit. The use of BVM biofeedback, whereby the HD machine automatically adjusts the rate of UF based on the relative blood volume, has been proposed for the prevention of IDH.
  
  
  METHODS
  This is a 22-week randomized crossover trial. Participants undergo a 4-week run-in phase to standardize medications and dialysis prescriptions. Subsequently, participants are randomized to standard HD or to BVM biofeedback for a period of 8 weeks followed by a 2-week washout phase before crossing over. The dialysis prescription remains identical for both arms. The primary outcome is the frequency of symptomatic IDH as defined by an abrupt drop in the systolic blood pressure of ≥ 20 mm Hg accompanied by headache, dizziness, loss of consciousness, thirst, dyspnea, angina, muscle cramps or vomiting. Secondary outcomes include the number of symptomatic IDH episodes and any reduction in IDH episodes, nursing interventions, dialysis adequacy, total body water, extra- and intracellular fluid volumes, brain natriuretic peptide and cardiac troponin levels, blood pressure, antihypertensive medication use, patient symptoms and quality of life.
  
  
  CONCLUSIONS
  Our study will determine the impact of using BVM biofeedback to prevent IDH and other serious adverse events in susceptible patients.
  
  
  BACKGROUND
  Clinicaltrials.gov NCT01988181 (6 November 2013).
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Canada. kcwleung@ucalgary.ca.
authors.forename: Kelvin C W
authors.initials: KC
authors.lastname: Leung
authors.forename: Robert R
authors.initials: RR
authors.lastname: Quinn
authors.forename: Pietro
authors.initials: P
authors.lastname: Ravani
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: MacRae
mesh_terms: D000416:Alberta; D001331:Automation; D001676:Biofeedback, Psychology / Q000295:instrumentation; D001810:Blood Volume; D001811:Blood Volume Determination; D002985:Clinical Protocols; D018592:Cross-Over Studies; D004867:Equipment Design; D006801:Humans; D007022:Hypotension / Q000175:diagnosis / Q000503:physiopathology / Q000517:prevention & control*; D011237:Predictive Value of Tests; D006435:Renal Dialysis / Q000009:adverse effects* / Q000295:instrumentation; D012107:Research Design; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome