Page 1362 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 98: Renal Replacement Therapy in the Intensive Care Unit 935

TABLE 98-2 Studies of RRT Initiation in AKI
Recovery of
Study Year Design # of Pts Early Initiation Criteria Late Initiation Criteria Renal Function Survival
Conger 3 1975 RCT 18 BUN <70 mg/dL BUN ≥150 mg/dL or SCr ≥10 mg/dL Early 64%
or SCr <5 mg/dL or clinical indication
Late 20%
Gillum et al 100 1986 RCT 34 Treatment goal BUN <60 mg/ Treatment goal BUN <100 mg/dL Early 41%
dL and SCr<5 mg/dL and SCr <9 mg/dL
Late 53%
Bouman et al 4 2002 RCT 106 <12 h after meeting definition BUN >112 mg/dL, K >6.5 mmol/L or Early high dose
for AKI requiring RRT severe cardiogenic pulmonary edema 74.3%
Early low dose 68.6%
Late low dose 75%
Gettings et al 5 1999 Retrospective Observational 100 BUN <60 mg/dL BUN >60 mg/dL Early 100% Early 39%
Late 91.6% Late 20%

Demirkilic et al 6 2004 Retrospective Observational 61 Urine output <100 mL × SCr >5 mg/dL or K >5.5 mEq/L Early 76.5%
8 hours despite diuretic
Late 45.5%

Elahi et al 7 2004 Retrospective Observational 64 Urine output 100 mL × Urea >84 mg/dL or Early 78%
8 hours despite diuretic
SCr >3.39 mg/dL or Late 57%
K >6 mEq/L
Wu et al 8 2007 Retrospective Observational 80 BUN <80 mg/dL BUN >80 mg/dL Early 39.2% Early 37%
Late 12% Late 15.4%

Liu KD et al 101 2006 Retrospective Observational 243 BUN ≤76mg/dL BUN >76 mg/dL Early 65%
Late 59%

with systemic hypotension. Since its initial inception, the use of CRRT more severely ill, the survival difference was eliminated. Specifically,
12
(initially CAVH and subsequently using continuous hemodialysis— when each tertile of APACHE III scores was examined and mortality
CAVHD) increased, and investigators worldwide reported its effective- was compared between IHD and CRRT, no difference was seen. The
16
ness at facilitating both solute clearance and volume removal in the importance of this study is that it highlighted that while a randomized
setting of AKI, especially in the critically ill. 13-15 Despite the widespread trial of modality of RRT could be executed, enrollment would remain
use, reported success, and improved fluid balance/solute clearance, limited by underlying illness. Approximately 21% of individuals who
experimental studies directly comparing the use of continuous versus were initially screened and underwent RRT were not included in the
intermittent RRT have been limited, and have not shown clear superior- study because they failed to meet the criteria for hemodynamic stability.
ity of CRRT over intermittent RRT in the majority of studies. Thus, while no benefit to CRRT was observed in the study, there were a
In 2001, the results of the first direct comparison trial of intermittent significant number of individuals who could not safely receive IHD. No
versus continuous RRT in the setting of AKI and critical illness was data were given on the outcome of these individuals and whether their
reported. This study of 166 critically ill adults with AKI was conducted ability to receive RRT ultimately influenced their outcomes is unknown.
at four US medical centers. AKI was defined as a BUN ≥40 mg/dL or The results of subsequent, randomized controlled trials have dem-
SCr ≥2 mg/dL for those without baseline values and an increase of onstrated similar outcomes. A single-center study conducted at the
≥1 mg/dL from a baseline for those with known prior serum creatinine Cleveland Clinic randomized 80 critically ill adults with AKI requiring
values. Subjects were randomized to receive IHD or CRRT (CAVHDF RRT to IHD or CVVHD. Importantly, the subjects were randomized
for the initial 2 years, and CVVHDF for the subsequent years of the according to severity of illness (high or low as determined by the
study). Importantly, individuals were required to have a mean arterial Cleveland Clinic Foundation severity of illness score). Furthermore,
pressures (MAP) >70 mm Hg (with or without vasopressor support) while exclusion criteria were similar to other studies (eg, individu-
to be eligible for randomization, so the population most likely to be als previously receiving dialysis were excluded), no individuals were
selected for CRRT in clinical practice were excluded from this trial. excluded for hemodynamic instability. Although the study failed to
The baseline characteristics of the subjects were generally similar, demonstrate a significant mortality benefit for either modality (67.5%
except individuals randomized to CRRT were more likely to have liver of patients died in the CVVHD group vs 70% of the patients in the IHD
failure and had higher mean APACHE III scores. Unadjusted mortal- group; p = NS), the study was inadequately powered for this end point.
ity was higher in the group randomized to CRRT: 59.5% versus 41.5%, However, the two groups did differ significantly in their hemodynamic
p < 0.02 at 28-day and 65.5% versus 47.6, p < 0.02 in-hospital. However, response to RRT, and in their achievement of fluid balance control. In
after adjusting for the fact that individuals randomized to CRRT were the 72 hours after initiation of RRT, MAP fell in the individuals receiving

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