|
|
Post by yellow2green on Jul 23, 2024 14:35:16 GMT
This has been on my mind since Machine Level 2/T.S. Class.
We are told to catch the amount leaving the the drain port (after prime) and measure it using a 100ml Graduated Cylinder and basically guess from there. I have 2 issues with it.
1. We cant get a graduated cylinder to measure 1/10th of a mL.
2. The amount of "dribble" from that flat section of the drain will skew your results.
Proposed solution.
I have found a buret that holds 100mL and is accurate to 1/10th of a mL. I use as short of hose as possible from the drain to the buret. And over prime that thing to ensure that ZERO air resides in the sections in and out of the machine. Then all you got to do is run the test.
Argument.
If this isnt acurate enough are we confident we are calibrating our UF pumps accurately? Do we really want Biomeds over/under stepping pumps to the bottom/top of the volume spec displayed on Debug 1, just to see that beautiful 13.5ms?
No question is rhetorical here. This is an idea I had, and I want it torn to bits so we can put it together the best/right way as possible.
|
|
|
|
Post by Chuck Weddle on Jul 23, 2024 14:41:13 GMT
Why not use a pocket gram scale?
The one I use for weighing cure ingredients has a 200g capacity and weighs to 0.01g.
|
|
|
|
Post by The Bluestar Whisperer on Jul 23, 2024 15:02:55 GMT
I was told in my Level 2 class that it was the absolute last resort to dialing in your conductivity, because, IT WILL WORK. From what I understand of it, the balancing chamber calibration has no idea how much dialysate is actually in the chambers. It relies on the CFS (Chamber Full Switch #9) to tell it that is it full. All the balancing chamber calibration does is adjust the pump steps on both acid and bicarb pumps (AAcd & ABic in jug mode on Debug 0). Ensuring that your UF pump is properly calibrated is paramount because it makes up the difference in the BC. As long as your 90XL is calibrated and your displayed conductivity is matching, how can it be wrong to "fudge the numbers"? Serious question.
|
|
|
|
Post by The Bluestar Whisperer on Jul 23, 2024 15:09:35 GMT
I actually had messed around with it a bit way before going to class so I had an idea of what it did and had questions regarding it.
For 2251 Granuflo running on jug/wall bicarb your numbers should be right around AAcd = 187 ABic =319 on Debug 0 to achieve 13.5 mS or what should be your TCD.
Edit: It should be noted that these numbers will change automatically with different baths and NA/Bicarb prescriptions. I use those numbers as my baseline with known concentrates.
|
|
|
|
Post by yellow2green on Jul 23, 2024 17:14:55 GMT
Just so everyone knows I'm always referring to the 2251 Granuflo. I've used premixed jugs of the same and different baths to confirm in the past. We are using 2251 Granuflo cause I'm sure thats what 92.789% of you guys are using when you test machines.
When you do the annual you verify those pumps are pumping within the tolerances stated on debug 1. As long as the pumps are within tolerance, its considered a pass. If we over/under step the pumps to the bottom/top of those tolerances to achieve the perfect conductivity, we are still maybe not following procedure but has the FMC standard applied.
I don't put too much stock in to AAcd and ABic because if someone smashes those screws in really tight with a drill on "Drill" setting when rebuilding it, those numbers will be different than a guy with his drill on 1. Because the 2 pumps have different volumes and have different number of steps to make volume goal. Not to mention aging membranes.
Although we are within tolerance, our journey to get there might feel...dirty? I mean your tricking the machine into thinking one thing and its really another. That and trying to teach a new person this? Brand new they are going to be asking "But thats not by the book?" I want to be able to give a person a machine and tell them to follow these procedures. Not have to wait a year plus to have a clinic with stable machines.
MR CHUCK If we use a scale we can get close, cause pure water is 1g/1mL. I would want it completely rinsed cause we are changing the weight of water when we add concentrates. But a scale to do that needs calibration and once again we have the "dribble dribble" during the test. Is this negligible? or is this the difference of 13.7ms and 13.5ms? Your experiences?
Ive always used the "Stock" number on the balancing chamber, on one exception. BCV was set to the Stock number 622. ACD was pinging 14.0-14.2ms. Settled (after testing) on a more conservative 609 and I was 13.5ms with both in middle of tolerance.
Arguments can go either way when we say how important. I just want to have the most accurate way to do it so the machine is set and ready to go, and it doesn't take a less experienced person an hour+ to calibrate these pumps.
|
|
|
|
Post by dave74 on Jul 23, 2024 20:28:51 GMT
This is from the Fresenius Technician's Manual.
According to the manual, Bluestar Wisperer is incorrect about the balance chambers. I have to go by what is in the manual. page II-1
Balancing Chamber
The most important component for volumetric dialysate fluid balancing. Guarantees accurate fluid balancing.
|
|
|
|
Post by 48yrshuntinbubbles on Jul 23, 2024 22:56:32 GMT
I've been going to fresenius machine classes since 1997. E, K, K², T, machine classes, the troubleshooting class twice, the electronics troubleshooting class. In all classes, I've been told never calibrate the balancing chamber. Use the number written on the balancing chamber as it was calibrated by an electronic buret in a lab. With that said, I have seen those who ca onl the chamber to adjust the conductivity to theoretical. Changing membranes does not affect the volume of the chamber. You can do what you want I'm just an old man.
|
|
|
|
Post by The Bluestar Whisperer on Jul 25, 2024 15:45:19 GMT
This is from the Fresenius Technician's Manual. According to the manual, Bluestar Wisperer is incorrect about the balance chambers. I have to go by what is in the manual. page II-1 Balancing Chamber The most important component for volumetric dialysate fluid balancing. Guarantees accurate fluid balancing. Where exactly was I incorrect? Does it say explicitly in "The Manual" that "Bluestar Whisperer is incorrect"? Just coming in and stating that "You're incorrect" because "The Manual" means nothing. Do you really think Big F is going to shout from the rooftops that they left a backdoor in the software which adjusts the concentrate pump steps directly affecting conductivity? Actually, everything I said is 100% true, from my own experimentation and observation in the field to the confirmation of my findings by my troubleshooting/Level 2 instructor (who is the same person). My instructor, a man who has 30+ years of working on, assisting with R & D, and instructing on every iteration of this machine. I would take his advice on these machines over anything else. These machines are not IBM Watson, my instructor likened them to an "Atari" because of how simplistic the electronics are (8-bit, only 256 possibilities for anything). Some may be giving the machines a little more credit than they deserve in the way of intelligence. They are quite simple when you break them into smaller sections. I'm not here to argue with anyone, nor was I ever saying that this was "THE WAY" to fix conductivity. I simply shared what I have noticed on my own and what was confirmed by my instructor. I really didn't expect a warm reception to the idea, but no one even took a stab at the question. Feels more like a Big F Groupthink Tank... |
|
pacnw
Full Member
Posts: 201
|
Post by pacnw on Jul 25, 2024 16:53:51 GMT
The argument can go may ways on this. I for one will not adjust the balance chamber volume to get my conductivity into range. I am not set up to properly measure(weigh) the correct balance chamber volume unless I am at my home clinic where i have a scale. I will always use the number written on the balance chamber. Just my two cents! Now our level 2 instructor says exactly what I am stating too. Don't adjust the chamber volume. You are masking the issue by doing this. Determine where the issue is and correct the conductivity following the normal process(ACID and BICARB volumes and Condo cell calibrations). Our goal is to provide our patients with the formula of dialysate that the MD provides. If we calibrate incorrectly or adjust volumes are we giving what the doctor requests? That is how our instructor explains it.
|
|
|
|
Post by The Bluestar Whisperer on Jul 25, 2024 17:22:55 GMT
The argument can go may ways on this. I for one will not adjust the balance chamber volume to get my conductivity into range. I am not set up to properly measure(weigh) the correct balance chamber volume unless I am at my home clinic where i have a scale. I will always use the number written on the balance chamber. Just my two cents! Now our level 2 instructor says exactly what I am stating too. Don't adjust the chamber volume. You are masking the issue by doing this. Determine where the issue is and correct the conductivity following the normal process(ACID and BICARB volumes and Condo cell calibrations). Our goal is to provide our patients with the formula of dialysate that the MD provides. If we calibrate incorrectly or adjust volumes are we giving what the doctor requests? That is how our instructor explains it. BUT, what if your displayed conductivity on the machine matches a calibrated 90XL, your estimated bicarb values come out perfect, and you are capturing the correct amount of dialysate over a given time after making the adjustments? The calibration adjusts both pumps simultaneously to keep with the 45X proportioning ratio, it DOES NOT just randomly put out numbers and it DOES NOT adjust how much dialysate is in the Balancing Chamber. I feel like there is a serious lack of understanding as to what I am saying here. Having said all of this, I still feel like I have to reiterate that, THIS IS NOT SOMETHING I DO TO FIX MACHINES!! I have used it once a couple of years ago to dial in a machine that was running 13.9mS and would not come down for anything. I monitored and tested that machine until I was confident that it was right. I will also say that patient safety is my NUMBER ONE priority, anyone who works with me knows this. I would NEVER, under any circumstances, let a machine out on the floor that I wouldn't let a family member dialyze on (should they ever need it). |
|
|
|
Post by Phillip-Ashley Ludlow on Jul 26, 2024 20:36:52 GMT
so, just for posterity, i'm gonna throw this out there: when i took my level 2 at HQ the guys and gals who actually wrote the 2008 series TS Manual were there. one of the key takeaways they put out was: NEVER [ censored] TOUCH THE BC VOLUME. EVER. DONT THINK ABOUT IT. JUST.DONT.DO.IT. even if you change the membraines, its not going to change the volume. dont mix parts from one bc to another, save for valves. Troubleshooting gets calls all the time for folks who think they know better than they do, and decide do do it their way, only to run into tons of issues. *jumps off soapbox* thank you all Friends ❤, Foes 🗡 and anyone who was dragged here against your will  . |
|
|
|
Post by Chuck Weddle on Jul 26, 2024 21:42:01 GMT
Just throwing this out for discussion.....
For years, people have been saying that Fresenius says not to calibrate the BC. If they say to never do it....why do they make it possible to along with a procedure to do it?(presumably).
|
|
|
|
Post by dave74 on Jul 26, 2024 22:39:18 GMT
Fresenius does say to only calibrate the balance chamber if the factory-measured volume has been lost or if the balance chamber has been repaired or replaced. "Repaired" is a rather vague term. The only balance chambers I can find in the parts book are assemblies with and without valves.
I can't help but think of the scene in the movie My Cousin Vinny. Fresenius calibrates those balance chambers to be dead on balls accurate. It's an industry term.
|
|
|
|
Post by yellow2green on Jul 29, 2024 20:34:35 GMT
The argument can go may ways on this. I for one will not adjust the balance chamber volume to get my conductivity into range. I am not set up to properly measure(weigh) the correct balance chamber volume unless I am at my home clinic where i have a scale. I will always use the number written on the balance chamber. Just my two cents! Now our level 2 instructor says exactly what I am stating too. Don't adjust the chamber volume. You are masking the issue by doing this. Determine where the issue is and correct the conductivity following the normal process(ACID and BICARB volumes and Condo cell calibrations). Our goal is to provide our patients with the formula of dialysate that the MD provides. If we calibrate incorrectly or adjust volumes are we giving what the doctor requests? That is how our instructor explains it. If I'm masking the issue, what is my issue if all components verify good (motors and heads, Membranes, regulators, Pdail , diasafe, cfs and all that Jazz) Dial flow is perfect at 500ml/min with zero variation and all concentrate pumps are within its limits using premixed, perfect 37.0C on all meters, and ACD is still +/- 0.5 to 0.7ms of TCD. and i mean EVERYTHING ruled out. Ask that question again, "Are we giving the patient what the doctor is ordering?" That machine sure as heck thinks so. But now were left here wondering if we are or not. Do we stop our investigation just because the Big F is telling you that you don't know any better? Do we over/under step our pumps (within tolerance) to bring it to TCD? What would you do pacnw? I hate to say it Phillip-Ashley Ludlow but i don't consider all of FMC Tech support to be the "experts" in this field. Some of them, HECK YEAH!! as many as they think there are?? HECK NO!!! And if they are measuring it so accurately why don't they tell us how they do it? Because if they do it exactly as policy (and wouldn't they have to? that's how they got the 2008t verified with the FDA) I don't believe its anywhere near as accurate as they claim. If FMC doesn't want me touching it, like turning off FORCED SELF TESTS or messing with the Ind Cond Cal (i am not saying i have or even can do this stuff. And i completely understand why they don't allow you to. Im using this as an example of stuff FMC keeps off limits and you dont have a choice about it), they wouldn't allow me to do it. SO, DO WE KEEP THE INVESTIGATION GOING??? I want to know how anyone else achieved what i am trying to do by physically measuring the amount coming through, and receiving a better ACD. Im not a fan of the scale/weight method, because of the lateral fitting that we get our measurment from (Little dribble dribble and now your over .5ml) and with uneven surfaces and calibrations... Were not here to debate if we should or shouldn't. Cause if we have ACD >0.2ms TCD and everything is ruled out we only have 2 choices, over/under step or BCV. Is one more right than another? |
|
|
|
Post by The Bluestar Whisperer on Jul 29, 2024 21:13:05 GMT
NOW, we are getting somewhere. I'm the type that if you "forbid" me to do anything I'm going to want to know why. If you really want to experiment and have actual lab results, pick a machine to make an adjustment to, then pull a dialysate sample and have a full test run on it. When I "fixed" that one a couple of years ago that's what I ended up doing so that I could sleep at night. It came back perfect, even the EBV was right on the prescribed 33. This is just my own personal experience and would still be just a theory had it not been confirmed by my instructor.
Lol, when our class inevitably made it around to the balancing chamber calibration discussion I added what I stated in my earlier posts about it adjusting the AAcd and ABic steps and his eyes got really big as he pointed at me, then he started shaking his head up and down fiercely, looking at the rest of the class as if I had just split the atom, and asked if everyone heard what I said. It was after that when he stated "it is the LAST RESORT" to dialing in your conductivity.
|
|
.