An ex-vivo evaluation of vascular catheters for continuous hemofiltration.
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.
Tan
Han Khim
HK
Department of Intensive Care, Austin and Repatriation Medical Centre, Studley Road, Heidelberg, Victoria 3084, Australia.
Bridge
Nicholas
N
Baldwin
Ian
I
Bellomo
Rinaldo
R
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*