We have recently started sampling our electrolytes in the dialysate. I have a question about one of the results but first let me tell how the machine is set up

We Fresenius 2008H machines and use Rockwell acid and bicarb

The machine set up is as follows:
Bicarb 35
Sodium 140
K 2.0
Ca 2.5
Chloride 109
Magnesium 1.0
Acetic Acid 4.00
Dextrose 200
My question is about the CO2 reesult we are getting back. We are getting back a CO2 count of 39-42 is this correct?Or should I be getting a CO2 count back of or around 35mEg/L?

I have had it explained to me how this works two different ways. One says that with the machine set at 35 added with the 4 on the acetic acid side give it the 39 - 42. The other way says that I should be getting a CO2 of or around 35mEg/L.

Any help to shed some light on this matter would be great and thanks in advance.

quote:

Originally posted by mgunsolus:
We have recently started sampling our electrolytes in the dialysate. I have a question about one of the results but first let me tell how the machine is set up

We Fresenius 2008H machines and use Rockwell acid and bicarb

The machine set up is as follows:
Bicarb 35
Sodium 140
K 2.0
Ca 2.5
Chloride 109
Magnesium 1.0
Acetic Acid 4.00
Dextrose 200
My question is about the CO2 reesult we are getting back. We are getting back a CO2 count of 39-42 is this correct?Or should I be getting a CO2 count back of or around 35mEg/L?

I have had it explained to me how this works two different ways. One says that with the machine set at 35 added with the 4 on the acetic acid side give it the 39 - 42. The other way says that I should be getting a CO2 of or around 35mEg/L.

Any help to shed some light on this matter would be great and thanks in advance.

Are all of your machines getting these same results? In the past I was at a clinic that had the same problem. As it turned out the techs weren't calibrating the pHoenix meter properly (what we were using to test the bicarb after it was mixed) and the mS was off considerably. Once we corrected the problem and the bicarb was mixed properly the results came back better (35 +/- 1 mEq/L). Also, make sure it is set correctly in the conductivity screen as some PCT's may have accidentally (or purposely) changed it.

Are the dialysate samples taken with both acid and bicarbonate connected to the machine ? If bicarbonate is connected alone there are 4 mEq/l that will not be reactive with the Acetic Acid and therefore the CO2 result may be higher.

Yes there is bicarb connected to the machine. And as for the phoenix meters they are calibrated right I do them because of that very problem.

What type of acid and bicarb are you using? What conductivity are you mixing it to (the bicarb, that is).

[This message has been edited by GTSCSS (edited 02-20-2003).]

We are using Rockwell acid and bicarb. The expected conductivity should be 13.8 at the machine. The specific gravity for the bicarb is between 1.063-1.065 and the acid is 1.148-1.152.

The question I really have is what should I expect my co2 count to come back at if the machine is set to deliver a 35 bicarb. Because like I stated earlier I have heard two different things form 35 to 40.

quote:

Originally posted by mgunsolus:
We are using Rockwell acid and bicarb. The expected conductivity should be 13.8 at the machine. The specific gravity for the bicarb is between 1.063-1.065 and the acid is 1.148-1.152.

The question I really have is what should I expect my co2 count to come back at if the machine is set to deliver a 35 bicarb. Because like I stated earlier I have heard two different things form 35 to 40.

I use central delivery for acid and bicarb at my clinic and my supplier is Haemotec in Quebec Can. Since I do not do electrolytes on my dialysate regularly I was curious to find out what it would be.
I use a Cobe formula and I have 2008 H and K machines. My concentrate is Na 100 K 2 Ca 2.50 Mg 1.50 Acetate 4 Dextrose 100 Chloride 106.
I took a sample with the machine set at a Na of 140 and a bic. of 36. I was most interested in the C02 level so that is all I requested. I got a result of 37 mmol/L. Now, I don't know exactly how the concentrate can or does effect this vale but hear me out. About 3 months ago I was experiencing some high conductivity problems on all my machines about 0.3 above the TCD. When I sent some dialysate samples out for testing the results were rather interesting. The machines were all set to Na of 140 and a bic. of 36. When I received the results from the lab the thing that caught my I was that the only electrolyte that was out of whack was the sodium and the C02. One result showed that my sodium was 144 and my Co2 was 41. The second was a sodium of 143 and a Co2 of 39. Upon investigation with the manufacturer their sodium level in their concentrate was higher than our previous supplier although it was still within their specs. but in the upper range. Is there a connection? I don't know but maybe sone does. Also, you probably already checked this but what is your Co2 level in the mix tank? For the fun of it I took some bicarb from our previous supplier that comes premade and compared it to what i make. My Co2 from the mix tank was 860mmol/L . The premade solution 880mmol/L