B-Type Natriuretic Peptide, Aldosterone, and Fluid Management in ARDS

Area of Science:

• Critical Care Medicine
• Pulmonary Medicine
• Nephrology

Background:

• Conservative fluid management in acute respiratory distress syndrome (ARDS) increases ventilator-free days but does not affect overall mortality.
• B-type natriuretic peptide (BNP) and aldosterone levels may predict which ARDS patients benefit from specific fluid management strategies.

Purpose of the Study:

• To investigate whether plasma B-type natriuretic peptide (BNP) or aldosterone concentrations modify the effect of fluid management strategies on mortality in ARDS patients.
• To identify biomarkers that predict survival based on fluid management in ARDS.

Main Methods:

• Retrospective analysis of the Fluid and Catheter Treatment Trial (FACTT) involving 625 ARDS patients.
• Measurement of plasma B-type natriuretic peptide (BNP) and aldosterone concentrations using immunoassay.
• Multivariable analyses to examine the interaction between biomarker concentrations and fluid strategy (conservative vs. liberal) on 60-day in-hospital mortality.

Main Results:

• B-type natriuretic peptide (BNP) did not predict mortality, correlate with fluid balance, or alter the impact of fluid management on ARDS outcomes.
• Lower initial aldosterone concentrations were associated with increased ventilator-free days (17.1 vs. 12.5 days) and decreased mortality (19% vs. 30%) with conservative fluid management (P=0.01 for interaction).

Conclusions:

• B-type natriuretic peptide (BNP) does not appear to be a useful biomarker for guiding fluid management in ARDS.
• Lower baseline aldosterone levels identify ARDS patients for whom conservative fluid management may improve survival outcomes.