Clinical Parameters to Determine the Optimal Timing of CRRT in Critically Ill Patients with Acute Kidney Injury

Kim, Yong Chul; Hwang, Jin Ho; Cho, Eun Jin; Lee, Hajeong; Oh, Kook Hwan; Joo, Kwon Wook; Kim, Yon Su; Ahn, Curie; Han, Jin Suk; Kim, Suhnggwon; Kim, Dong Ki

Abstract

PURPOSE
The aim of this study was to evaluate the clinical parameters to determine the optimal time for continuous renal replacement therapy (CRRT) in critically ill patients with severe acute kidney injury (AKI).
METHODS
A single center retrospective study was performed using data from 166 AKI patients who received CRRT in intensive care unit (ICU) between October 2007 and January 2010. We compared mortality rate at 90 days after the initiation of CRRT, ICU-free and CRRT-free days between "early CRRT" and "late CRRT" groups stratified by blood urea nitrogen (BUN), serum creatinine, urine output and RIFLE criteria.
RESULTS
The 90-day mortality rate was significantly lower in the early group compared with the late group when stratified by median value of BUN at the start of CRRT and mean hourly urine output during 6 h, 12 h, and 24 h before CRRT. In addition, the 90-day mortality rate was also significantly lower in patients who received CRRT in the "injury" stage of RIFLE criteria compared with those in "failure" or "loss" stage. ICU-free and CRRT-free days during the first 28 days were significantly longer in the early group when stratified by median level of BUN. However, in terms of creatinine, ICU-free and CRRT-free days were significantly shorter in the early group compared with the late group. CRRT-free days during the first 28 days were also longer in early group stratified by median value of mean hourly urine output during 6 h, 12 h before CRRT. After adjusting for covariates, 90-day mortality was independently lower in the early group defined by median level of BUN (OR=1.65 (1.10-2.47), p=0.015) and mean hourly urine output during 12h before CRRT (OR=1.56 (1.05-2.33), p=0.027).
CONCLUSION
Our data suggest that early CRRT may have a survival benefit in critically ill patients with severe AKI, and BUN and urine output at the initiation of CRRT may be important parameters to determine the optimal time for CRRT.