Bare with me as this may be a simple question, I was just was wondering what is the commen practice for needle placement. Meaning when doing a access flow test with our Fresinius machine. should it matter if the venous and arterial needle go in the same direction UP. We often cannulate with both needles up and occasionally one up (venous) and one down (arterial) First is this proper cannulation for dialysis then is it okay for access flow monitoring. I know there are those access out there that require both needle up.
Needle direction depends on the direction of blood flow. The venous needle must always be placed in the direction of blood flow back to the heart. KDOQI opinion is that the arterial needle can be placed either way.
Although KDOQI currently suggests that the arterial needle can be placed in either direction, there is some evidence that placing the arterial needle towards the blood flow (aka down) can lead to formation of aneurysms and/or pseudoaneurysms. Difficult to explain without a picture, but basically when you insert a needle, small skin flap is created. When the needle is placed "up", the pressure exerted by the blood flow actually helps close the skin flap. When the arterial needle is placed "down", the blood continues to exert pressure in a manner that keeps the skin flap open. This pressure can theoretically contribute to prolonged bleeding, stenosis, and possible aneurysm formation.
With that said, to answer your actual question, yes, the direction of the needle CAN affect the blood flow measurement. However, if the direction of the needle does affect it, then the blood flow is low anyway, and the patient needs access intervention.
|Powered by Social Strata|