Hi,
I'm a patient and I'd like to learn about conductivity. A friend who does home hemo tells me that it is very important to have a stable conductivity throughout the tx and cond. must run high enough. I run on a Fresenius 2008H. The techs tell me that the cond. can run anywhere from 13 up. My friend tells me thats much too low..that cond. should run in the 14 and up range. I read where a patient said that when her machine is showing a low cond. she feels crampy. I had such a tx yesterday and when I looked at the machine to check the cond. it was only 13.2. My bp went haywire the last hour of tx going up and down by 20 points. Prior to this I had felt fine. I would start to decide to get some saline or cut back the goal, but the next bp would go up. I did not cramp or crash, but felt really strained and crampy and stayed crampy feeling later at home. I must of had low bp too as I couldnt stand up to prepare supper either (took me 4 tries and then I ate and crashed). I was strengthened when I awoke the next a.m., but it took me a whole day to recover. So, how could I rule out if this was related to cond.?

Our techs only measure cond. at the begining of the tx. There's the machine reading and they measure with a hand held meter. Can cond. drop during the tx? Thanks for any info.

i have worked with the Fresenius 2008H and according to the protocol here, average conductivity is 13.7. The machines will allow for some fluctuations in those numbers. I found this post that explains it very well. Thanks to Carol.


Carol Isaac MacKusick
Moderator

posted 02-22-2001 10:00 AM
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Conductivity is basically the measure of the electrical ions in the solution used for dialysis. If you have excessively diluted dialysate solution (too much water has been added) the conductivity is lower, and the patient can have electrolyte disturbances and hypernatremia. Elevated conductivity can result in hemolysis (rupture of the red blood cells) and hyponatremia. On most modern machines, conductivity is monitorred consistently throughout treatment, and verified by a second check prior to initiation of treatment.

The most common cause of increased conductivity in dialysate solutions is low water pressure feeding into the machine. This results in not enough water being fed to the dialysate solution. The most common cause of decreased conductivity is an empty concentrate bottle (someone forgot to change the acid or bicarb, for example), or something is wrong in the internal part of the dialysis machine.

Machines are now designed that when an inappropriate conductivity is registered to go automatically into 'bypass' so that the blood stream will not be exposed to inappropriate dialysate.

Dialysate solution is made from water, bicarbonate and acid, mixed together with a proportioning pump. This pump makes sure that you receive the correct amounts of each additive in your dialysate at all times.

Thank you for the help. With our tx a second check is done with a meter at the beginning of tx, but the cond. is not monitored the rest of the tx. The machine shows its inital reading and it stays the same for the remainder of the tx. Does this mean the cond. is not fluctuating the entire tx?

I have observed that the alarm comes on if the concentrate bottle runs out, but what is there to say the cond. is stable and not dropping too low?

I am wondering if I have had electrolyte disturbances. I will feel very jumpy inside almost like a buzzing feeling. What do they feel like?

[QUOTE]Originally posted by Reenie:
[B]Thank you for the help. With our tx a second check is done with a meter at the beginning of tx, but the cond. is not monitored the rest of the tx.
Actually it is. The machine's conductivity display is updated continuously. Any drop in conductivity is immediately reflected on the display.

The machine shows its inital reading and it stays the same for the remainder of the tx. Does this mean the cond. is not fluctuating the entire tx?
In a word, Yes. The machine is not showing an "initial reading", it is showing actual conductivity. Conductivity is monitored continuously.

I have observed that the alarm comes on if the concentrate bottle runs out, but what is there to say the cond. is stable and not dropping too low?
The machine has safety limits, minor fluctuations are to be expected and are not avoidable. When the concentrate container runs out, the machine will register a low conductivity momentarily until fresh concentrate is replaced.


I am wondering if I have had electrolyte disturbances. I will feel very jumpy inside almost like a buzzing feeling. What do they feel like?
You would be best advised to consult your MD about that. From what you have stated, I would have to say, in my opinion, that your conductivity is not fluctuating enough to cause problems. You have to understand that there are many different dialysate types, and your MD has chosen the best one for you. There is no "Ideal" conductivity, it actually depends on the Sodium content of the dialysate (among others).

TD

While conductivity is continously monitored and any alarm causes the machine to go into bypass (the dialysate is diverted to drain rather than go through the dialyzer) it is possible to manipulate the alarm limits so a low conductivity (lets say 13.3) would be within limits allowing the dialysate to go through the dialyzer. Some times patient care staff will lower the limits in order to clear alarms quickly so they can test the equipment. I have (unfortunately) even seen limits lowered so the equipment does not alarm (this should never be the case dialysate is a prescription item). You may want to "quiz" your care givers on correct conductivity. Also have them check the alarm limits (on front of 2008 get arrow by conductivity press SET button concentrate screen will appear and conductivity limits will be on lower left). There really is no excuse for the limits to be left lower than the prescribed conductivity, there are tolerances allowed (for small variations in pump calibrations and bicarb strength) however the conductivity should not be jumping around, if it is there is likely a problem with equipment or concentrate delivery. hope this helps.

Conductivity is measured by a device called a conductivity cell. The machine will pump bicarbonate and acid depending on what these conductivity cells are telling the machine. Pumps and conductivity cells can have intermitent problems. The conductivity alarm limits should warn you of any major fluctiations.

I know it is difficult being so dependant on a medical device. I would suggest that you log any thing you feel is significant so that the technician or technologist can remidy the problem. Make sure the technician or technologist is aware of the impact the problem has on you. Unfortunately not all of them have the training to be fully aware of patient impact. Read the users manual for the machine and try to learn as much as you can.
Dialysis machines are very good these days and very safe but remember it is just a machine. Many things can go wrong. The better you can communicate any perceived problems the better the machine and the technician can serve you.

Good luck, I hope further treatmnets are uneventful.

Thank you very, very much for all the instructive replies. I asked my charge nurse if my usual machine could be checked out after another patient had problmes with her tx (I was switcthed to a different machine where I had a problem-free tx and she was put on my machine for a tx). The machine I was switched to had a conductivity of 14.6. A biotech did check out my usual machine in the interim.

At my next tx, the cond was reading 13.8-13.9 insead of the 13.0 it was at when I was having the problems. I asked a RN why the difference in cond. rates? He told me it was because I am on a straight 140 that my cond. runs lower than patients who are on sodium modeling. He showed me on the machine how if the sodium is increased the cond. will rise. He felt that the reason the cond. was 14.6 the time I dialyzed on the other machine was because the tech forgot to lower the sodium to my rate of 140. But he could not explain why the cond. on my usual machine went from 13 to a 13.8-9 range. I suggested to him that the biotech must have adjusted the cond. cells. He disagreeded saying that cond. cells cant be calibrated. Now that the cond. rate is higher, I haven't had any more seriously uncomfortle txs. I can't say the problem of last hour crampiness is gone entirely, but its defintely better. I dialyzed on the other machine I spoke of an additional time. Both times the tx was more comfortable with the cond. being at 14.6. So, I am still watching the situation trying to determine why I feel better when the cond. is higher. My doctor said the cond. shoudn't have anything to do with the symptoms I described. I at leaste was glad that the charge nurse took me seriously and had the biotech check the machine out.

I have two things to add in response:
first off the conductivity will definitely have an effect on your well being, that is why we use sodium variation programs. The increased sodium will elevate blood pressure during dialysis so you won't become hypotensive. The staff especially doc should know this, higher conductivity higher sodium, basically if you get rid of the decimel you have the sodium level (14.0 condo is 140 sodium).
the second thing is that EVERY manufacturer as part of their pm (preventative maintenance) programs has the conductivity (and other displays) varified with a calibrated meter. This means that when maintenance is done a meter is hooked in line (where the dialyzer is during treatment) and the conductivity is verified, it should be within the specified limits and the meter should be within a tolerance of the display. If not the cell is calibrated or equipment repaired.
I suggest that you keep a journal of treatments, record pre bp, pre weight, conductivity, general feeling during treatment and post treatment, and all post treatment info. This way you can tell the staff what you do best on.
One last thought, if you are prescribed to run at a 140 sodium (14.0 conductivity) the conductivity should not vary more that plus/minus 5% (0.7) Anything below 13.3 or above 14.7 (unless sodium variation is used) and I would tell staff they need to replace the equipment. Hope this helps.

I have one patient who is able to sense small changes in his chemistries, specifically with him, his potassium. He is very sensitive to high potassium, and has various body sensations similar to what you describe. All other patients I've cared for don't seem to have the same degree of sensitivity to chemistry variations.

Perhaps the machine did indeed need a calibration, but was not altogether out of line. Perhaps you have the 'giftedness' of being sensitive to chemical variations, more so than others.

Our conductivity range is 13.2 to 14.2.

Increased sodium will indeed soothe your muscles. Be aware: increased sodium can cause increased thirst post treatment for several hours.

I agree you should chronicle your sensations, observations, etc to learn about your body and it's reactions to various subtle changes.