title: The haemodynamic response to submaximal exercise during isovolaemic haemodialysis.
abstract: BACKGROUND
  Exercise during haemodialysis has potential benefits but may compromise cardiovascular stability. We studied its acute effects on relative blood volume (RBV) and other haemodynamic parameters.
  
  
  METHODS
  Two groups of 10 patients were exercised submaximally using a stationary cycle during isovolaemic dialysis whilst RBV was monitored continuously. In study 1, patients exercised for two 10 min periods separated by 10 min rest. Cardiac output (CO), peripheral vascular resistance (PVR), central blood volume (CBV) and stroke volume were measured using ultrasound dilution immediately before and after each exercise session. In study 2, haemoglobin, serum total protein and albumin levels were measured before and immediately after the exercise session and at the nadir of the RBV trace.
  
  
  RESULTS
  RBV fell immediately on exercise initiation, the maximum reduction being 2.0+/-1.1% (after 5.9+/-1.4 min of exercise 1: P<0.001) and 2.0+/-1.2% (after 4.7+/-2.3 min of exercise 2: P<0.001). CO increased significantly after both periods of exercise (4.5+/-0.96 and 5.1+/-1.1 to 7.2+/-2.1 and 7.9+/-2.4 l/min, P<0.001 in both). Stroke volume increased significantly and PVR fell significantly during exercise. CBV increased in absolute terms but fell as a proportion of CO. Mean haemoglobin level at the RBV nadir was significantly higher than baseline (12.3+/-1.8 vs 11.8+/-1.7 g/dl: P<0.05: mean change 4.4+/-2.3%), as was mean total protein concentration (66.0+/-6.9 vs 62.0+/-8.1 g/l: P = 0.001: mean change 6.8+/-5.9%) and mean serum albumin concentration (36.0+/-3.9 vs 34.1+/-3.9 g/l: P<0.001: mean change 5.8+/-3.5%).
  
  
  CONCLUSIONS
  The haemodynamic response to exercise during haemodialysis is comparable with that in normal individuals. The rapid reduction in RBV on exercise occurs in spite of a significant increase in CO, mainly as a consequence of fluid shifts from the microvasculature to the interstitium.
authors.affiliation: Renal Unit, Lister Hospital, Stevenage, Herts SG1 4AB, UK. ken.farrington@nhs.net
authors.forename: Anindya
authors.initials: A
authors.lastname: Banerjee
authors.forename: Chiew H
authors.initials: CH
authors.lastname: Kong
authors.forename: Ken
authors.initials: K
authors.lastname: Farrington
mesh_terms: D000328:Adult; D001794:Blood Pressure; D001810:Blood Volume; D002302:Cardiac Output; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D006435:Renal Dialysis; D013318:Stroke Volume; D014655:Vascular Resistance