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help...explain osmolarity of dialysis solution

My patient I will have later today is on CAPD, with a solution change every 6 hours. Of course, last night did all my research on the procedure, condition, drugs, etc. The one thing I can't figure out is about the osmolarity of the solution. My instructor wanted me to figure out what it meant.

The solution is Dianeal 4.25% with some cefazolin and heparin in it. I would assume that the higher the % of solution, the greater the osmolarity and concentration gradient, therefore the faster the dialysis? So, if the solution was a lower number, like 2.5%, it would take longer to dialysize (sp?) than the 4.25%.

It logically seems right, just wanting someone to confirm I guess. Thanks!

Aneroo, LPN

Specializes in Cath Lab, OR, CPHN/SN, ER.

I think you have the right concept. You wouldn't want the solution too high though (the percentage), because you run the risk of pulling fluids and lytes off too quickly. You might want to send this over to the renal/dialysis nursing page. I'm sure they've got tons of info! -Andrea

Thanks, I will post it over there!

I think you have the right concept. You wouldn't want the solution too high though (the percentage), because you run the risk of pulling fluids and lytes off too quickly. You might want to send this over to the renal/dialysis nursing page. I'm sure they've got tons of info! -Andrea

Aneroo, LPN

Specializes in Cath Lab, OR, CPHN/SN, ER.

yw

jnette, ASN, EMT-I

Specializes in Hemodialysis, Home Health. Has 10 years experience.

Just as in haemodialysis, peritoneal dialysis removes toxins from the blood... using the peritoneal membrane instead of a dialyzer.

You will be using a hypertonic dialyzing solution (dialysate) which moves excessive concentrations of electrolytes and uremic toxins across the membrane into the dailysate by DIFFUSION.

Next, by OSMOSIS, excessive water in the blood does the same.

Dialysate typically contains ow concentrations of sodium, potassium, calcium and magnesium cations and chloride anions... as well as high concentrations of acetate.. which the body readily converts to bicarbonate. Dialysate also contains glucose.

Because blood has higher concentrations of hydrogen ions and electrolytes than does dialysate, these solutions diffuse across the membrane (in your case the peritoneal membrane) into the dialysate.. which after a period of "dwell time" is then drained and discarded.

At the same time, dialysate solution has higher concentrations of glucose and acetate.. and so diffuses back across the membrane into the patient's blood.

All hemostasis. Excess water and toxins are removed, acidosis is reversed, electrolyte imbalances are amended.

Pretty neat, eh? :)

Remember that OSMOSIS removes excess FLUID VOLUME (water) in your patient.

The other (electrolytes, waste products, etc.) is removed through the process of DIFFUSION.

Hope that helps.

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