Continuous Renal Replacement Therapy Information
Continuous renal replacement therapy (CRRT) is an increasingly popular way to treat acute renal failure in an intensive care setting. In many respects it is similar to standard hemodialysis (or dialysis), but there are some notable differences in methods. The main reason CRRT is chosen over hemodialysis is in ICU patients the hypertension caused by standard hemodialysis can have significant negative effects. In these pages you can learn the ins and outs of CRRT, everything you always wanted to know about CRRT from the basic to the complex.
The four most common types of CRRT treatments are:
- Slow continuous ultrafiltration (SCUF) - SCUF is generally used for fluid overloaded patients whose bodies have adjusted to diuretic drugs. See the SCUF page for more detailed information.(diagram right)
- Continuous veno-venous hemodialysis (CVVHD) - CVVHD is similar to standard dialysis, however, instead of the short (generally around 3 hour) intense treatment received under standard hemodialysis, CVVHD is performed continuously over a longer period of time, up to days. CVVHD is best at removing small molecules from the blood stream. See the CVVHD page for more detailed information.(diagram left)
- Continuous veno-venous hemofiltration (CVVHF) - CVVHF is similar to standard hemofiltration, however, instead of the short intense treatment received under standard hemodialysis, CVVHF is performed continuously over a longer period of time, up to days. CVVHF is best at removing middle molecules from the blood stream. See the CVVHF page for more detailed information.(diagram right)
- Continuous veno-venous hemodiafiltration (CVVHDF) - CVVHDF is probably the most common type of CRRT used, it combines aspects of both CVVHD and CVVHF. CVVHDF removes small and middle molecules from the blood stream. See the CVVHDF page for more detailed information.
CRRT is usually provided in a hospital intensive care setting. Performing CRRT requires special equipment consisting of a fluid control unit and a tubing set with hemofilter. CRRT is most commonly used to treat acute renal failure (ARF). The mortality rate of ARF is approximately 50-80% in the intensive care unit (ICU) populations. In a recent study approximately 1/3 of patients treated with CRRT died, while another 1/3 of patients left the ICU with improved renal function after a median of 4 days of treatment (REF). Clinical data suggest that CRRT should be strongly consideredfor patients with severe hyperphosphatemia or elevated intracranialpressure (ICP), and might also be a useful component of therapyfor lithium intoxication (22- 24).
The primary mode of access to the blood for CRRT is an intravenous catheter. The type of access is influenced by factors such as the expected
time course of a patient's renal failure and the condition of his or
her vasculature. SCUF treatment may use other modes of access, such as an arteriovenous (AV) fistula, or synthetic
graft, but this is rare.
Some additional resources:
CRRT Info, a blog covering the latest news and notes regarding CRRT.
CRRT Info at Critical Care Trauma Centre in London, Canada, this site includes detailed information including a number of slides straight from Gambro's Prisma presentation.
CRRT Online, a yearly CRRT conference in San Diego, CA.