Adequacy of dialysis
Adequacy is a measure of how well the dialysis is working. Looking at how well you are as well as looking at the results of the usual blood tests assesses this. However, special tests will also be carried out to make sure that enough water and waste products are being cleared from the blood, in order to keep you well.
What would be the symptoms if I was not getting enough dialysis?
- Tiredness, weakness
- Nausea or poor appetite
- Losing body weight
- Blood count is dropping because EPO does not work so well
By looking at adequacy it should be possible to alter the dialysis so that you feel better and lead a more active life.
You may hear the terms "creatinine clearance" and "urea kt/v" mentioned - these are the tests that the doctors and nurses will do. Also, remember when dialysis is started you may still produce some urine - this is known as "residual renal function" and the amount varies from person to person but tends to go down with time, more quickly with haemodialysis. Eventually in many patients this residual function declines completely and no more urine is produced.
How is adequacy measured?
The doctors and nurses need to be able to calculate this sum;
Residual renal function + dialysis clearance = total clearance
Therefore, two collections will be made - a 24 hour collection of urine plus collections to measure the dialysis. For haemodialysis that is simply a blood sample before and after dialysis. Peritoneal dialysis is measured by a blood sample and collecting the fluid which has been used for dialysis over a whole day - that sounds like a lot of fluid but there are special ways to do it!
The results are then analysed and often a computer plan can be used to suggest the best way of increasing the dialysis if needed. Studies have helped show how much dialysis is adequate but these levels will change as more information is gained over the years.
How can dialysis adequacy be improved?
The doctors and nurses will plan with you how the dialysis can be changed to improve the clearances and make you feel better as well as helping your body in the long term.
- Haemodialysis - Changes may include a change in the filter, increasing the pump speeds and increasing the length of each session or increasing the number of sessions. This may be a real problem, particularly if the time is increased - but it is worth thinking that the kidneys work 24 hours a day. Dialysis is less efficient than that and from studies of many patients it seems that patients getting good adequate dialysis do better in the long term than those getting inadequate dialysis.
- Peritoneal dialysis - a variety of changes may be suggested;
- Increase in fill volume
- Doing an extra CAPD exchange
- Altering the glucose strength of the PD bag or changing to icodextrin for the long dwell
- A change from CAPD to APD
- Increasing the time on APD or adding an extra daytime exchange
Sometimes, no matter what is tried it is not possible to achieve adequate levels, that may mean the best solution is to switch to haemodialysis.
What about fluid balance?
As well as assessing clearances of waste products it is also important to think about fluid balance. If the body is overloaded with fluid it causes high blood pressure, breathlessness as well as a strain on the heart. So changes in the dialysis prescription may be needed to remove more fluid. For peritoneal dialysis this may need a change in the exchange volumes and glucose strength or using icodextrin. For haemodialysis, this may need a longer time per session as removal of fluid over too short a time can make you feel ill as well as a strain on the heart.
We all know that nothing in this world stays the same, and that goes for dialysis as well! Adequacy results may change over time, particularly as residual renal function declines - so changes in the dialysis will be needed to compensate and keep you well.