Acute kidney injury in patients with acute lung injury: Impact of fluid accumulation on classification of acute kidney injury and associated outcomes*

Abstract

Objective It has been suggested that fluid accumulation may delay recognition of acute kidney injury (AKI). We sought to determine the impact of fluid balance on the incidence of non-dialysis requiring AKI in patients with acute lung injury and to describe associated outcomes, including mortality. Design Analysis of the Fluid and Catheter Treatment Trial, a factorial randomized clinical trial of conservative versus liberal fluid management and of management guided by a central venous versus pulmonary artery catheter. Setting and Patients 1000 patients at ARDS Network hospitals. Measurements and Main Results The incidence of AKI, defined as an absolute rise in creatinine of ≥ 0.3 mg/dL or a relative change of > 50% over 48 hours, was examined before and after adjustment of serum creatinine for fluid balance. The incidence of AKI before adjustment for fluid balance was greater in those managed with the conservative fluid protocol (57 versus 51%, p = 0.04). After adjustment for fluid balance, the incidence of AKI was greater in those managed with the liberal fluid protocol (66 versus 58%, p = 0.007). Patients who met AKI criteria after adjustment of creatinine for fluid balance (but not before) had a mortality rate that was significantly greater than those who did not meet AKI criteria both before and after adjustment for fluid balance (31 versus 12%, p < 0.001) and those who had AKI before but not after adjustment for fluid balance (31 versus 11%, p = 0.005). The mortality of those patients meeting AKI criteria after but not before adjustment for fluid balance was similar to patients with AKI both before and after adjustment for fluid balance (31% versus 38%, p = 0.18). Conclusions Fluid management influences serum creatinine and therefore the diagnosis of AKI using creatinine-based definitions. Patients with “unrecognized” AKI that is identified after adjusting for positive fluid balance have high mortality rates, and patients who have AKI before but not after adjusting for fluid balance have low mortality rates. Future studies of AKI should consider potential differences in serum creatinine caused by changes in fluid balance and the impact of these differences on diagnosis and prognosis.

Conservative fluid management or deresuscitation for patients with sepsis or acute respiratory distress syndrome following the resuscitation phase of critical illness: a systematic review and meta-analysis

“…The Newcastle-Ottawa score for observational studies is reported in Appendix 2. Secondary publications from included studies are reported along with the original study [13][14][15]. A summary of evidence is found in Table 2.…”

“…Along with posthoc analyses of the FACTT study showing a reduced incidence of AKI with a conservative fluid strategy [14] and a protective effect of diuretic use [15], this provide reassurance as to the safety of a conservative or deresuscitative approach to fluid management in terms of renal outcomes.…”

“…Hjortrup et al [26] reported a lower incidence of worsening of AKI in a conservative fluid group than with standard care (37% versus 54%, P=0.03). In separate post-hoc analyses of the FACTT study, Liu and colleagues showed that after correcting serum creatinine levels for fluid balance, AKI incidence was lower with a conservative than with a liberal fluid strategy [14]; and Grams et al reported that in patients with AKI, cumulative diuretic dose was independently associated with lower mortality [15].…”

Acute kidney disease and renal recovery: consensus report of the Acute Disease Quality Initiative (ADQI) 16 Workgroup

“…This approach has limitations, however, and loss of muscle mass, changes in volume of distribution, changes in renal reserve, and hyperfiltration can confound the assessment of functional recovery [54][55][56][57][58][59][60] . The limitations of using serum creatinine to assess recovery are supported by observational data indicating that AKI is associated with an increased risk of CKD, even when accompanied by an apparent complete return of serum creatinine to baseline levels 61,62 .…”

Urinary NGAL to define AKI in asphyxiated infants

“…As noted above, elevated NGAL may be a manifestation of a sub-clinical AKI portending worse systemic disease. While only speculative, we and others have shown that fluid overload may dilute SCr and mask SCr-based AKI detection [23,24]. One previous study used urinary NGAL-and not SCr-as the AKI definition in an AKI prevention study using fenoldopam versus placebo after cardiac surgery [25].…”