Monday, March 1, 2010

When Kidneys Fail: A Brief Glossary

One of my current projects centers on the rebuilding of the continuous renal replacement therapy (CRRT) program at Children’s Hospital and Medical Center in Omaha, NE. Last week I blogged from a CRRT meeting on Coronado Island, and more posts will include these topics as the project progresses. Definitions seem in order.

When kidneys fail, some form of dialysis must be performed to replace their function. Most people have heard about hemodialysis,HemoD illustrated in the photo, in which blood is pumped out of the body, run through an artificial kidney, and then returned to the circulation. Another form, peritoneal dialysis, uses the blood vessels that run through membranes in the bowels to filter blood. A tube inserted into the abdomen allows fluid to surround the bowels. After time for wastes to enter the fluid, it is drained and replaced.

CRRT is a continuous form of hemodialysis.  Some forms of CRRT use primarily hemofiltration to remove water and wastes from the body. Blood passes through the dialysis cartridge as in hemodialysis, but no dialysate passes around the blood filters. Instead, large amounts of filtrate are removed and then replaced with an appropriate sterile solution. In many cases, patients require both this type of clearance as well as dialysis to maintain appropriate biochemical balance; these therapies are collectively called hemodiafiltration.

CRRT removes fluid and wastes continuously, thus providing gentler shifts in balance than traditional hemodialysis. This therapy class most frequently benefits unstable intensive care patients who would not be able to tolerate hemodialysis and in whom peritoneal dialysis may not be feasible.

A pediatric CRRT program faces special challenges. First, virtually none of the devices have been FDA-approved for use in children; pediatric CRRT is not a huge market. Second, we are dealing with a much wider range of patient size than the adult market, with weights ranging from 5 to 300 pounds. Scalability becomes much more of an issue.

The process of rebuilding a program can be tedious, but we will develop state-of-the-art capabilities. Next step? Reviewing hardware.

Stay tuned!


  1. Made me a little squeamish. Good to know, and here's to hoping that we're all healthy enough to avoid dialysis in all its forms!

  2. Nice Blog! Interestingly I also attended the last yrs meeting at Del Coronado! It was wonderful!

    I am a Pediatric Nephrologist from India. Am putting a link of ur website on my site