title: Microvascular dilatation after haemodialysis is determined by the volume of fluid removed and fall in mean arterial pressure.
abstract: OBJECTIVE
  The effects of haemodialysis on the microcirculation are poorly understood. This study examined the changes in small vessel calibre.
  
  
  METHODS
  24 patients (including 12 males, median age 62.5 years, range 30-87) underwent digital retinal photography immediately before and after routine haemodialysis. Arteriolar and venular calibres were measured from the images by a trained grader using a highly reproducible, computer-assisted method.
  
  
  RESULTS
  Patients had an average 2.0 ± 0.3 litres of fluid removed with dialysis, and their mean arterial blood pressure fell by 6.8 mm Hg (CI 13.8-0.2, p = 0.06). Retinal arteriole calibre did not change (mean difference 2.3 µm, CI -1.1 to 5.7, p = 0.17) but the venules dilated (mean difference 12.7 µm, CI 7.3-18.3, p < 0.001). Calibre returned to baseline by 2 h. Venules dilated less in diabetics than non-diabetics (mean difference -6.2 µm, CI -9.6 to -2.9, p < 0.01). Retinal venular dilatation correlated positively with the volume of fluid removed per kilogramme body weight (5.9, CI 0.2-11.5, p = 0.04), and negatively with the fall in mean arterial pressure (-0.36, CI -0.72 to -0.01, p < 0.05) after adjusting for age, gender, diabetes and dyslipidaemia.
  
  
  CONCLUSIONS
  Haemodialysis is associated with systemic venular dilatation.
authors.affiliation: Department of Medicine (Northern Health), The University of Melbourne, Epping, Vic., Australia.
authors.forename: Foong Kien Newk-Fon Hey
authors.initials: FK
authors.lastname: Tow
authors.forename: Qi Lun
authors.initials: QL
authors.lastname: Ooi
authors.forename: Tien Y
authors.initials: TY
authors.lastname: Wong
authors.forename: Ryo
authors.initials: R
authors.lastname: Kawasaki
authors.forename: Deb
authors.initials: D
authors.lastname: Colville
authors.forename: Peter
authors.initials: P
authors.lastname: Mount
authors.forename: Judy
authors.initials: J
authors.lastname: Savige
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D062186:Arterial Pressure / Q000502:physiology*; D001810:Blood Volume / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D006435:Renal Dialysis / Q000639:trends*; D012171:Retinal Vessels / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*