title: An ex-vivo evaluation of vascular catheters for continuous hemofiltration.
abstract: OBJECTIVE
  To measure outflow and inflow hydraulic resistance in double-lumen catheters used for hemofiltration under standardized laboratory conditions.
  
  
  METHODS
  ICU Laboratory of tertiary unit.
  
  
  METHODS
  Heparinized spent red cells diluted in polygeline solution to a constant hematocrit of 32% at 37 degrees C were pumped using a standard Prisma M60 circuit through several hemofiltration catheters. Blood pump speed was increased and decreased in steps of 30mL/min (30, 60, 90, 120, 150, and 180 mL/min) and catheter outflow and inflow pressures recorded and used to define the pressure flow relationship (line of hydraulic resistance) for each.
  
  
  RESULTS
  Double-lumen catheters posed different resistances to outflow or inflow. Among the < 15 cm long catheters, the 11.5 Fr Quinton-Mahurkar (0.56 mmHg/mL/min) catheter offered the least resistance to outflow, while the Medcomp 11.5 Fr catheter offered the least resistance to inflow (0.78 mmHg/mL/min). Among the >19 cm long catheters, the 13.5 Fr Vascath Niagara catheter showed the lowest blood flow resistance to both outflow (0.63 mmHg/ mL/min) and inflow (0.83 mmHg/mL/min). Longer catheters did not pose statistically greater resistance to both outflow and inflow. Resistance to inflow was consistently greater than resistance to outflow (p = 0.003). Overall, the Prisma M60 blood circuit alone accounted for 40% of the total extracorporeal circuit blood flow resistance.
  
  
  CONCLUSIONS
  Proprietary hemofiltration catheters have variable resistance to blood flow under standard ex-vivo conditions. This ex-vivo information might be useful to clinicians in guiding their choice of catheters for clinical use.
authors.affiliation: Department of Intensive Care, Austin and Repatriation Medical Centre, Studley Road, Heidelberg, Victoria 3084, Australia.
authors.forename: Han Khim
authors.initials: HK
authors.lastname: Tan
authors.forename: Nicholas
authors.initials: N
authors.lastname: Bridge
authors.forename: Ian
authors.initials: I
authors.lastname: Baldwin
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Bellomo
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002405:Catheterization, Central Venous / Q000379:methods*; D006440:Hemofiltration / Q000379:methods*; D018056:Hemorheology; D006801:Humans; D007674:Kidney Diseases / Q000503:physiopathology* / Q000628:therapy*; D008955:Models, Cardiovascular; D012079:Renal Circulation / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology*