CRRT: New Solutions to an Old Problem
By Suzan Miller-Hoover, DNP, RN, CCNS, CCRN
Continuous renal replacement therapy (CRRT) is an essential
tool for treating patients with acute kidney injury, acute renal failure, and
chronic renal failure when other treatment modalities are not enough.
A key concept of CCRT is to maintain therapy with minimal
periods of interruption (Ronco et al. 2015). Theoretically, the circuit should
only need to be changed every 72 hours. However, in septic patients,
ingestions, and pediatric patients it is often necessary to change the circuit
more frequently (Ronco et al. 2015).
With patients that are stable, stopping treatment to prime
and replace the old circuit every 72 hours does not interrupt treatment for an
extended period.However, patients that
are less stable may require more frequent circuit changes. This additional down time adds up and may result
in hemodynamic instability and less effective treatment.
The manufacturers of CRRT devices cannot support any other
process for changing the circuit due to the conditions of FDA approval.
Therefore, the manufacturer’s representatives/website cannot educate facilities
on alternative methods for changing circuits. Despite the manufacturer’s
inability to support alternative processes, there are processes that have been
developed and used successfully by institutions which care for a high-volume of
Two of these methods are circuit
to circuit (Eding, Jelsma, Metz, Steen, and Wincek, 2011) and circuit to patient, patient to circuit priming.
Circuit to patient, patient to circuit priming was first described during the
CRRT 2014 conference by Cincinnati Children’s Hospital. These processes were
developed to decrease the amount of exposure the patient receives from blood
bank blood and to reduce circuit downtime. Although circuit to circuit priming
has been around for several years, it is fraught with complications. The most
common complication occurs when the two machines are not in sync with each
other. This leads to multiple alarms and extended downtime; often resulting in
removing both circuits, loss of blood product, and additional supplies (Eding,
Jelsma, Metz, Steen, and Wincek, 2011).
In the circuit to circuit priming method, a second machine
is set up and primed in the usual manner. Then, the settings on the second
machine are matched to the settings on the original machine. At this point, the
original machine is shut off and the access line is disconnected from the
patient and hooked to a liter bag of saline. The access line of the second
circuit is then attached to the patient. The return line of the second circuit
is attached to an empty saline bag and the original return line remains
attached to the patient. When these connections are made, both machines are
turned on simultaneously. The result is the blood from the original circuit is
returned to the patient, while blood from the patient primes the second
circuit. The saline from the second circuit then fills the empty bag, and the
original circuit is flushed with the saline from the full bag. When the second
circuit is primed with the patient’s blood, the machines are shut off, the return
line from the original circuit is disconnected from the patient, then replaced
with the return line from the second circuit. Finally, the machine is turned on
and treatment resumes.
The entire process takes less than five minutes and has the
- Decreased treatment interruption time
- Decreased blood bank blood exposure
- Decreased hemodynamic instability risk
- Decreased infection risk
- Decreased risk of line clotting
As with any new process in your unit, it is essential that
you consider your patient population, your physician preferences, as well as
your policy and procedure.
While this process appears to be complicated, once the steps
are mastered it is a user-friendly process. This process may not be valuable to
the stable patient; however, for those patients who are hemodynamically
unstable this process could be lifesaving.
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Eding, D. M., Jelsma, L. R., Metz, C. J., Steen, V. S.,
& Wincek, J. M. (2011). Innovative techniques to decrease blood exposure
and minimize interruptions in pediatric continuous renal replacement therapy. Critical Care Nurse 31(1). doi:
Ronco, C., Ricci, Z., De Backer, D., Kellum, J. A., Taccone,
F. S., Joannidid, M., …Vincent, J. L. (2015). Renal replacement therapy in
acute kidney injury: Controversy and consensus. Critical Care 19 (146). doi: 10.1186/s13054-015-0850-8.