Many times I have heard the phrase "that patient pulls fluid easily". In this age of volumetric machines why would one patient consistently pull 0.5 to 1 liter more (or less) fluid than any other patient on the same machine?

You're right, with volumetrics it doesn't make sense. Chances are either the pre weight is wrong or they may have gone to the bathroom after weighing in or before weighing out.

Chuck

It could also be where the fluid is located. Fluid in the tissues tends to come off easier than ascites fluid. Also, once the excess fluid in the bloodstream is removed, the shift of remaining excess fluids in the tissues to the bloodstream must occur before it can be removed.

Ascites is typically due to poor nutritional status evidenced by low serum albumin levels and builds up over time, not just from one treatment to the next. Albumin acts as an osmotic agent to pull fluid from all spaces back into circulation so that it can be removed. This is also the mechanism that an increased sodium or modeling uses to aid in ultrafiltration, the sodium increased the osmolality of the blood.

Chuck

Diabetic patient usually have poor refilling rate (unfortunately, most of the water is in the cells, and not where the dialysis process can take it, i.e. in the blood). As said above, to stimulate the water shift from cells to the vascular compartment, you need to "play" with sodium level in the dialysis fluid. So, for such patients, the best is a combination of sodium & UF profiling. Few machines have such an option, called Hemocontrol on some Gambro systems (in Canada, Europe)

I am a huge fan of Ultrafiltration Profiling for easier fluid removal. The Fresenius K machine has 4 profiles preloaded and is a mechanical means of getting to your dry weight. Talk to your dialysis professional about it. It makes allowances for refilling your vascular system that a flat ultrafiltration rate does not. Less fluid is removed at the end of your run when you have less to give. I believe it is a kinder and gentler way to dialyze.