I currently have a clinic running all Fresenius H's (with acid/bicarb check valves installed)that are running on a Marcor bicarb distribution unit and a generic acid loop. The acid loop consists of storage tanks, a pump (nothing extravegant or overkill)and of course the loop. The regulator is pretty much wide open so there is not much pressure in the loop. The bicarb loop is set for 5 psi. At the wall stations, the pressure is about 2-4 psi for both acid and bicarb. From what I understand, the machine specs say 2 psi max. Is that with the check valves installed? If so, how dramatic an effect would it have if the port was putting out the pressure listed above? The reason I ask is that the clinic claims that while on jugs the machines are fine but when plugged into the wall the conductivity goes high. (All of them). There has been no problems with the loop up until yesterday. I, personally, think they are not mixing the bicarb correctly. Can someone give me some insight or opinions here??

Sounds as though you are on the right track, It's usaully the bicarb mix. One thing you can do to verify this is to check the conductivity at the machine (display and/or dialysate)on acid loop alone, the conductivity should stabilize between 9-10. However, if you have a hydrometer available, check the specific gravity of your bicarb mix it should be 1.060 � .003.

quote:

Originally posted by P.Rosales:
Sounds as though you are on the right track, It's usaully the bicarb mix. One thing you can do to verify this is to check the conductivity at the machine (display and/or dialysate)on acid loop alone, the conductivity should stabilize between 9-10. However, if you have a hydrometer available, check the specific gravity of your bicarb mix it should be 1.060 � .003.

The clinical staff claim that the bicarb is at 1.058 (if I remember correct) but I think there may be an accuracy problem with their hydrometer. Problem is, they don't have a back up hydrometer (go figure, eh?). Would you happen to know what the conductivity of the bicarb mix should be? (used to use that method with Fresenius and I DO happen to have a pHoenix meter). I haven't never checked the conductivity of bicarb used for a Cobe proportioning setup and I'm not sure what it should be. Thanks!

quote:

Originally posted by GTSCSS:
I currently have a clinic running all Fresenius H's (with acid/bicarb check valves installed)that are running on a Marcor bicarb distribution unit and a generic acid loop. The acid loop consists of storage tanks, a pump (nothing extravegant or overkill)and of course the loop. The regulator is pretty much wide open so there is not much pressure in the loop. The bicarb loop is set for 5 psi. At the wall stations, the pressure is about 2-4 psi for both acid and bicarb. From what I understand, the machine specs say 2 psi max. Is that with the check valves installed? If so, how dramatic an effect would it have if the port was putting out the pressure listed above? The reason I ask is that the clinic claims that while on jugs the machines are fine but when plugged into the wall the conductivity goes high. (All of them). There has been no problems with the loop up until yesterday. I, personally, think they are not mixing the bicarb correctly. Can someone give me some insight or opinions here??

I also run a clinic with both acid and bicarb central delivery. The unit I have is from Osmonics(Zyzatec). It is all gravity fed with a acid loop pressure running 4-5psi and a bicarb loop pressure of 3-4 psi. I also have H and K machines with the check valves located post acid and bicarb pump. I was told that if they are installed pre pump you could get conductivity problems.
I am also set to use Cobe formula. I use a Myron L meter for checking conductivity of the mixed bicarb. which is to be 50 mS +/- 2mS. I have never experienced a high conductivity as you describe but would suspect the bicarb. When we go to jugs to disenfect the bicarb loop, I do not have any conductivity problems.

Orc,

I know this system you speak of... the Zyzatech SDS system with the ceiling mounted distribution tanks that have acid/bicarb pumped to them from the mix tank/bulk storage acid tanks. I used one of those when I was with Fresenius. Nice unit, too! If I remember correctly, we never did put check valves on acid OR bicarb outlet tubing and we had OLC (which means two weak springs in the acid pump) and never had a problem either. For some reason, a coworker of mine is sure that's the problem. However, I went in when they opened this morning to watch them make the bicarb and test it to make sure they were doing it correctly. Furthermore, it was a different tech who opened the clinic. They followed the procedure as they were supposed to and guess what.... no problems. Go figure... I knew I wasn't crazy.... lol. Thanks for your input. I greatly appreciate it.

[This message has been edited by GTSCSS (edited 11-21-2003).]

Update- Same problem Monday morning... find a huge clump of bicarb on the plate in the bottom of the tank. I rinse the mix tank, make another batch and replace the bicarb in the distribution tank with bicarb that I made.... everything runs perfect. No problems. Imagine that.... INSERVICE TIME!!