Monday, March 14, 2011

Fluid Retention

I focused more on fluid retention today because it turns out to be a critical issue. This info is from medical journal articles, Mayo Clinic, National Kidney Foundation, and dialysis textbooks. All agree that fluid retention is a major problem in kidney disease. Usually, this is because unhospitalized kidney patients eat too many salty foods, but Bill’s diet is completely controlled. The recommended amount of sodium for an advanced kidney disease patient is less than 5 grams daily. Bill’s tube feeding solution should follow this limit.

Excess fluid needs to be removed from the kidney patient’s body because it can harm the heart and lungs, leading to congestive heart failure or pulmonary edema. Typically, an unhospitalized person on dialysis will gain roughly 1.5 kg (a little over 3 pounds) of body fluid between each dialysis session. Dialysis should remove all of this excess fluid. If the body produces more than this amount between sessions while sodium and fluid intake are held constant, then something is wrong. Many factors could play a role, including blood pressure changes, effects of various medications, an abnormal reaction to increased calories, other medical problems—the list seemed endless.

Sometimes, people’s bodies produce normal amounts of fluid between dialysis sessions, but the dialysis itself does not remove enough of that fluid. It then builds up gradually. One potential cause of this is that the blood flow is not strong enough to be cleansed fully when it runs through the dialysis filtering membrane. There are a lot of common tests that can help tell the docs what’s going wrong. For example, they can draw Bill’s blood before and after dialysis, then compare blood urea nitrogen (BUN) levels to see whether the dialysis removes enough urea. They can compare tube feeding fluid intake to the amount of liquid removed. Creatinine levels will help. Sounds like they’re already doing many tests.

They can also compare his weight before and after dialysis to see how much fluid has been removed. This “dry weight” determination is most accurate if done repeatedly over several dialysis sessions. The National Kidney Foundation recommends keeping a log that shows wet weight, dry weight, blood pressure, blood volume, etc. for every session of dialysis.

All of the sources emphasize that fluid retention must be treated. There are several possible treatments:
  1. Diuretic drugs can be given, but they will lower blood pressure and Bill’s is already low. Apparently, many kidney patients are on diuretics, so he’s probably already taking these.
  2. If diuretics don’t work, ultrafiltration is needed in addition to regular dialysis. Ultrafiltration is a process of suctioning blood through the dialysis machine; the added pressure allows more excess fluid to be taken out of the blood. It’s done at the same time as regular dialysis. A 2009 study of 34,000 kidney patients says that “removal of fluid during the dialysis treatment, also known as ultrafiltration, is the cornerstone of volume management in advanced-stage chronic kidney disease… and offers a fast and effective alternative to medical [drug-based?] therapy.”
  3. Increasing the amount of time in each session of dialysis will clean the blood more thoroughly. This helps if blood is flowing from the body too slowly.
  4. The solution (“dialysate”) that is run through the dialysis machine can be altered by Bill’s physicians to match his needs, as shown in his blood tests.

Blood pressure is an obstacle. Fluid retention raises blood pressure, but Bill’s medications and dialysis treatments lower it, and ultrafiltration will lower it further. (We hear a lot about the dangers of high bp, but bp can be dangerously low, too.) Because Bill’s blood pressure is already low, his physicians will have to take care in deciding how aggressive to be. Maybe they can alter his blood pressure meds just enough to accommodate the additional decrease during ultrafiltration? I don't know. The National Kidney Foundation recommends monitoring blood pressure and blood volume during dialysis and using ultrafiltration with every dialysis treatment whenever fluid retention is an issue. Maybe Kaiser is already doing these things.    

Mushrooms tomorrow!
--Janet

Sources:
Textbook of Medical-Surgical Nursing, Smeltzer et al., p. 1333
Replacement of Renal Function by Dialysis, Maher, p. 793



1 comment:

  1. I think Janet's information is excellent, and she alludes to the question: What are the Kaiser
    docs doing to relieve the excess fluid now and do they keep the weight records as mentioned.

    ReplyDelete