What proteins and albumins in bronchoalveolar lavage fluid and serum could tell us in COVID-19 and influenza acute respiratory distress syndrome on mechanical ventilation patient - A prospective double center study.

Summary

In a two-center prospective cohort (N=64), elevated BAL protein with low serum albumin predicted worse outcomes in viral ARDS, and serum albumin differed significantly across COVID-19, influenza, and controls. Early BAL (within 24 hours of ventilation) provided evidence of alveolocapillary membrane injury.

Key Findings

• Serum albumin levels differed significantly across COVID-19 ARDS, influenza ARDS, and control groups (ANOVA p<0.01).
• Low serum albumin (<35 g/L) combined with elevated BAL protein predicted poor outcomes in ARDS (ANOVA p<0.01).
• COVID-19 ARDS patients were older than influenza ARDS (median 72.5 vs 62 years; p<0.01), and early BAL sampling (within 24 hours of ventilation) captured alveolocapillary injury.

Clinical Implications

BAL protein fractions and serum albumin, measured early after intubation, may aid in prognostication and in identifying patients with severe barrier dysfunction who could benefit from targeted therapies.

Limitations

• Modest sample size with limited multivariable adjustment; potential confounding remains.
• Invasive BAL may limit generalizability; external validation is needed.

Future Directions

Validate thresholds for BAL protein and serum albumin in larger, multi-center cohorts; integrate with noninvasive biomarkers and imaging to refine risk stratification.