Of the sources used to compile this resource, the most important was of course "Critical Care Nephrology" by Ronco Bellomo and Kellum (2009). Specifically, Chapter 221 by John K. Leypoldt ("Intermittent techniques for Acute Dialysis") and Chapter 232 by Lamiere et al ("Outcome of Intermittent Dialysis in Critically Ill Patients with Acute Renal Failure").
- This is what chronic dialysis patients have to do every 2-3 days.
- Every treatment lasts 3-4 hours
- Blood flow rate: ~ 200-400ml/min
- Dialysate flow rate: ~ 500-800ml/min
- Huge amounts of solute can be cleaned out of the patient, because of the high flow rate of blood. And it only takes a few hours.
- Usually anticoagulation is not necessary because of the high flow rate
- Rapid flow rates cause rapid removal of fluid, and this can cause hypotension by decreasing venous return to the heart.
- Thus, patients in ICU tend not to tolerate this very well, as they aren’t exactly the most hemodynamically stable population. Its fine for the outpatient group.
- There is also the issue of "disequilibrium syndrome" in patients with severe renal failure.
- The ICU patients typically have huge amounts of fluid sloshing around in their third space. This is bad: urea and various wastes are also dissolved in that fluid. Sure, if you clean out the wastes form the vascular compartment, the wastes out of the third space will equilibrate with the bloodstream, and the total amount of waste will be decreased, but you wont ever be able to wash the patient completely- they only get IHD for a few hours, and the time it takes for wastes to equilibrate could be days
- And of course the brain is full of these solutes also: which means if you suddenly clean the blood, the solvent will move into the brain and cause cerebral oedema. This is the unfortunate consequence of quick dialysis. People with relatively normal physiology and relatively low levels of urea will tolerate this pretty well; ICU patients with high urea probably wont.
This is the “dialysis disequilibrium syndrome. Those at greatest risk are hepatic encephalopathy patients and the head-injured population.