What is the relationship between the dialysate pressure and dialysate flow?Let say what will happen to your dialysate pressure if you increase your dialysate flow. Does it affect your TMP too? Situation Goal is 2 kg. Time is 3.5 hours, Dialyzer kuf is 26 with 500 dialysate flow, no problem with 800 dialysate flow lots of problem. . Machine keeps on calibrating at 800 dialysate flow and will turn to UF control error.We are using Meridian by Baxter.

correction Dialyzer kuf is 36 not 26 thanks

Check the voltages and hertz on your inflow and outflow sensors. If voltages are low you my need to replace the LED cable or the exhaust housing. If the hertz are not running close to each other you may need to clean the rotor's or replace the rotor and jet ring.

been there thanks for the reply. I already checked the volume sensors . all four volume sensors were ok . I'm thingking if is it because the goal is too small for the dialyzer plus the dialysate flow.We tried to use 2 other machines and same result.

From the conditions that you describe above the machine should be well within parameters. If the goal and dialyzer coefficient were a problem than you would likely experience dialysate pressure alarms.

Check the condition of the pumps. Check the pressures and listen for noisy operation. The deaeration pump would be the first suspect but I have had worn dialysate pumps to cause UF alarms. Go to the info screen and view the sensors. Look for a rapid dip in frequency which will bounce back to normal quickly. This may take several minuets before it happens and may be a sign of a worn pumphead. The deaeration pump usually affects the In sensors and the dialysate pump the Out sensors.

If your seeing this on more then 1 machine my guess is the KUF of the dialyzer is too high for the amount of weight your pulling off. What are the art. and venous pressures running? If their high I'm surprised your not seeing a high dialysate pressure alarm. My suggestion would be to go with a lower KUF dialyzer and see if your problem disappears.

I have seen this problem several times on our Meridians. Mine were still under warranty, so went rounds with Baxter. We replaced all 4 volume sensors and a couple boards in the worst machine. It turned out to be the pumpheads, as Kim said. I replaced pumpheads on 5 warranty Meridians, then on 3 out-of-warranty machines. We have not had one single UF Control error since. On our worst day before replacing pumpheads, I had 6 of 11 machines fail in one morning. :-)
If in doubt, send your old ones to Flo-Tec and ask them to look at them and get back to you. The report they sent me was very helpful!!

thanks for all the reply . I really appreciate it. I have question , what is the dearation vacuum pressures at suction port and dearation vessel before and after you replace the headpump. Mine is still within parameters and as you know we are a small dialysis center so the budget is not that big and i want to make sure that it is the headpump that causing the problem.Machines is 15 month old and out of warranty. thanks

Actually, the pressures did not much change on any of my machines when I replaced the pumpheads. They were within specs all along, which is why it took so long to find the problem. I understand the budget-crunch! You could try swapping pumpheads from a "good" machine and a "bad" machine and see if the problem follows. I ran across the answer to the Meridian problem while working on a 1550 that just couldn't suck hard enough to get a dialysate pressure alarm. That pumphead was within specs, also, but Baxter told me to change it. When I applied the same logic to the Meridians, well, my life got a WHOLE lot easier!!

The pressures do not have to change that much. Just keep in mind in order for the machine to operate properly, the pressure at the dialysate pump should be 1 inHg greater than the pressure at the top of the deaeration vessel. In a perfect world the pressure at the top of the vessel would be 26 inHg but, we do not live in a perfect world. Over time this pressure will drop off. Also, if you are located in an area of high altitude this pressure may never be achieved. The machine will most likely work just fine at a pressure of 25 or even 24 inHg as long as the dialysate pump pressure is slightly higher.

Also, do not just turn on the machine and check the pressures. Let the machine operate for at least an hour before doing your checks and leave the gauge connected for several minuets. Sometimes the pressure will be fine initially, but after a while it may fluctuate just for a second or so which would cause UF errors and indicate a worn pumphead.The deaer pumphead usually is the problem because it does double duty by supplying both, vac. and press. If you encounter a worn pumphead, you can rebuild it at fraction of the cost of replacing the whole thing.

Have you spoke to Baxter Tech support? Have they given you any other suggestions other than a pumphead problem?

kim, they told me to check the 4 volume sensors, make sure to put the machine in 800 dialysate flow before priming the machine
(our default is 500 and we only change the dialysate flow according to doctors prescription)and also try to use other dialyzer with lower kuf.what i really don't understand is it's only happening with 800 dialysate flow (uf control error).

Ipdc, what UF fault codes are you experiencing? Are the sensor freqs. at the correct value ( around 350 at a D.F. rate of 800ml )? Sometimes I have had to match sensor freq. to correct a UF fault. For example, if the sensors are at the following values: In 1 352, In 2 344, Out 1 350, Out 2 342: swap In 2 and Out 1. Are the amplitudes 200 mv or greater at an 800ml D.F. rate?

This is a long shot, but have you recently replaced the deaer. vessel filter? If so, make sure that the tubing is correct at the bottom of the vessel.