title: Measurement of renovascular circulating volume during hypothermic organ perfusion.
abstract: BACKGROUND
  Kidney donation after cardiac death leads to vascular damage as a result of warm ischemia, affecting renovascular circulating volume. Novel ultrasound dilution techniques may be used to measure renovascular circulating volumes during hypothermic machine perfusion of donor kidneys.
  
  
  METHODS
  Renovascular circulating volumes of machine-perfused porcine kidneys were repeatedly measured by ultrasound dilution at different perfusion pressures (30, 40, 50, and 60 mm Hg), durations of perfusion (1 and 24 hr), and warm ischemia times (15 and 45 min). Validity of ultrasound dilution was assessed by comparing volume changes after clamping of renal artery branches.
  
  
  RESULTS
  Repeatability of ultrasound dilution measurements of renovascular circulating volumes was good (mean coefficient of variation, 7.6%). Renovascular circulating volumes significantly increased with higher perfusion pressures, remained constant over time, and significantly decreased with longer warm ischemia times. Changes in ultrasound dilution measurements after renal artery branch clamping did not correlate with changes in actual perfused volumes.
  
  
  CONCLUSIONS
  Ultrasound dilution is a reproducible method to assess renovascular circulating volumes in machine-perfused kidneys, which is susceptible to changes in warm ischemia times. Future studies should evaluate the value of renovascular volume in pretransplantation kidney viability testing.
authors.affiliation: Department of General Surgery, Maastricht University Medical Center, 6202 AZ Maastricht,The Netherlands. e.devries@maastrichtuniversity.com
authors.forename: Eva E
authors.initials: EE
authors.lastname: de Vries
authors.forename: Tim C
authors.initials: TC
authors.lastname: van Smaalen
authors.forename: Jorine
authors.initials: J
authors.lastname: Boer
authors.forename: E R Pieter
authors.initials: ER
authors.lastname: Hoogland
authors.forename: Nikolaj M
authors.initials: NM
authors.lastname: Krivitski
authors.forename: Maarten G J
authors.initials: MG
authors.lastname: Snoeijs
authors.forename: L W Ernest
authors.initials: LW
authors.lastname: van Heurn
mesh_terms: D000818:Animals; D007036:Hypothermia, Induced / Q000379:methods*; D007668:Kidney / Q000098:blood supply*; D009926:Organ Preservation / Q000379:methods*; D010477:Perfusion; D015203:Reproducibility of Results; D013552:Swine; D052096:Warm Ischemia