access flows

[GeauxNursing]

How do we interpret a negative access flow number? I know that for AVG and AVF we are looking for results greater than 400 and 600, sometimes we get a >2000 that we have to re- take. But a negative result, I am thinking that means the lines are backwards, am I right? Its a graft that we might just possibly be cannulating backwards.

[Chisca, RN]

Too many variables in play here and I'm not quite sure what you mean by "sometimes we get a >2000 that we have to retake". Establish which side of the fistula is arterial and which side is venous before you cannulate. Press on the middle of the fistula and the side with the strongest pulse is the arterial side. One of the variables affecting pressure will be the size of the needle. And at pump speeds above 200-225 ml minute it is largely needle resistance that the dialysis machine is measuring. A static reading on the venous side could give you a clue stenosis might be occuring but you would need multiple measurements over time to catch it. If the lines are backwards then you would suspect recirculation and have to do some sort of dilutional measurement or compare urea values pre and post treatment to confirm. Or get an ultrasound.