new in HD. need veterans' help

[dodoy, BSN, RN]

Good day nurses! I have a few questions to ask regarding hemodialysis. I'm fairly new to this field that's why. There's just so much to learn that I can't research them all by myself. Here it goes.

1. Why is it that tourniquet is not advisable to be used on grafts? I've been cannulating for months (though only once in a graft and I used one. Didn't know there were some issues regarding that, which I only read here)

2. Does changing the Na + concentration during intradialytic hypertension produce a great effect on the blood pressure? (e.g lowering the Na+ may cause decrease in BP and increasing Na+ during episodes of IDH may increase BP?). Could it cause a great effect on the patient's serum Sodium?

3. How about the dialysate temperature? I know lower temp. causes a natural response of vasoconstriction in the blood vessels, and heat causes vasodilation. Is it applicable in dialysate temperatures too? For example, for patients with IDH, can lowering the dialysate temp be of great effect in increasing the BP?

4. What are the factors that can affect the TMP? I usually see increase in TMP when the dialyzer has been used many times compared to the new. I also observed that clot formation, which causes increase in the venous and arterial pressures, is most of the time, accompanied by increase in TMP. Malfunctioning sensors too can display an increase in TMP. Are there other factors?

I have so much more to ask because I want to know much about this field before even shifting to other fields. However, as much as I would like to ask, I don't like any of you to feel that I'm letting you do a homework (which is not, afterall. This is not a homework). Anyways, thanks in advance to those who will respond. God bless.

[Dialysis RN1]

First off welcome to the world of dialysis. as you continue to learn and grow in your new position I am sure you will find it rewarding and satisfying. This will only come when you ask questions such as these for if you don't know the basics it can be frustrating and dawnting so good for you for reaching out. and remember the only stupid question is an unasked question. So here goes....

1. as for tourniquet use on a graft: first and foremost follow your unit policy. grafts are already large bored and placing a tourniquet wont tend to inflate them any more than they already are. Also they are not very elastic such as a fistula and any increase in pressure can actually cause a tear at the anastomosis.

2. Changing Na concentration does help with blood pressure but we tend to use Na to assist with shifting of fluids from the tissue to the vascular space. the draw back to the use of Na is that it will cause a patient to become thirsty and they will tend to drink much more fluid especially immediatly post dialysis treatment. I have used a hypertonic Na (23.4%) in 10ml doses to increase the movement of fluid from tissue to vasculature and have seen it very effective. the reason of course for the increase in B/P is due in part to the fact that the vascular volume is increased.

3. Yes dialysate temperature does a great deal for a blood pressure and for the reasons you listed above.

4. Trans Membrane Pressure (TMP) is effected by clotting, viscosity of blood traveling thru the membrane and the effort applied to removing fluid. If you have to remove 6Liters of fluid from a person who is hemoconcentrated meaning vascularly dry your TMP is going to move more towards 0 or even postive. remember you want a negative TMP. if you have to remove 6 liters from a patient who has the fluid to give up then the TMP shouldn't be to affected. Now if you have to remove 6 liters from a patient that has 4 liters to give up then you will notice towards the end of your run that the TMP starts to rise. and if you are using a dialyzer for the 25th time and it is only passing with a 92% you can assume that 8% of the fibers are clotted before you even get started so more blood has to travel thru less fibers and more fluid has to be removed at a higer rate at the dialyzer level causing a hemoconcentration at the dialyzer level thus an increased TMP. If your patient is septic..... well thats a whole nother conversation.

as for a malfunctioning sensor... you should NOT use equipment that has a malfunction period.

I hope this answers some of your questions and that you have a long and fruitfull employment in the dialysis world.

God Bless

[dodoy, BSN, RN]

Acute Dialysis RN

Thank you so much for your help! Things are much clearer now. I still have many questions, but I'll save them for the next time. Your help is very appreciated!

God bless