Relation of Positive Fluid Balance to the Severity of Renal Impairment and Recovery Among ST Elevation Myocardial Infarction Complicated by Cardiogenic Shock

Background:
Limited data is present regarding the relation of positive fluid balance and acute kidney injury (AKI). We analysed the relationship between a positive fluid balance and its persistence over time on AKI development and, severity and resolution among ST elevation myocardial infarction (STEMI) patients complicated by cardiogenic shock.

Methods:
We retrospectively studied the cumulative fluid balance intake and output at 96 hours following hospital admission in 84 consecutive adult patients with STEMI complicated by cardiogenic shock, all undergoing primary angioplasty.. The cohort was stratified into two groups, based on the presence or absence of positive fluid balance on day 4. Patients` records were assessed for the development of AKI, AKI severity and recovery.

Results:
Positive fluid balance was present in 44/84 patients (52%), and 51/84 (60%) developed AKI. Patients having positive fluid balance were more likely to develop a more severe AKI stage (52% vs. 13%; P<0.001) and were less likely to have recovery of their renal function (29% vs. 75%, p=0.001). Patients having positive fluid balance demonstrated positive correlation between the amount of fluid accumulated and the rise in serum creatinine (R² linear = 0.42, p = 0.004,). In a multivariate Cox regression model for the 51 patients with AKI, for every 1 liter increase in positive fluid balance, the adjusted possibility for recovery of renal function decreased by 21% (OR=0.796, 95% CI 0.67-0.93; P=0.006).

Conclusions:
A positive fluid balance was strongly associated with higher stage AKI and lower rate of AKI recovery in STEMI complicated by cardiogenic shock