Vascular access for extracorporeal circulation. Resistance in double lumen cannulas.

Double lumen catheters (DLCs) currently are being used for vascular access with extracorporeal circulation. Blood flow studies were done on various DLCs connected to a circuit made of polyvinyl chloride tubing. Sheep's blood was used with all catheters at flows of 200 and 400 ml/min. The inlet and outlet pressures were measured and resistances calculated. Modified versions of the Shiley and Kendall catheters, also were tested. In both catheters, resistance was reduced with the use of perfusion adaptors. Flow through catheters, with a diameter that exceeded the Luer fitting dimension, was compromised. The modified Shiley and unmodified Kendall catheters had the lowest resistance to flow, and they thus are best suited for extracorporeal circulation.