Cytokines in chest tube drainage after pediatric cardiac surgery - Is chylothorax the only phenotype?

Background: Chylothorax after pediatric cardiac surgery is associated with increased morbidity and mortality. Poor understanding exists regarding inflammation within the pleural fluid. Our aim was to determine the relationship between proinflammatory markers and chylothorax.

Methods: This is a single-center prospective observational cohort study. Pediatric patients after cardiac surgery with >20 mL/kg/day of chest tube output were included from January 2022 through January 2023. The pleural fluid was tested for 13 cytokine concentrations using a multiplexed immunoassay and for albumin and C-Reactive Protein (CRP) levels. Bivariable comparisons and Spearman's rank correlations were made.

Results: Out of 63 patients, chylothorax occurred in 20 (32 %), of which 10 (50 %) were neonates. Cytokine concentrations, CRP, and albumin levels were not different between chylothorax and non-chylothorax patients. Higher levels of four proinflammatory cytokines (IL-1β, IL-5, IL-8, IL-13) correlated with longer chest tube drainage (r = 0.29, 0.43, 0.28, 0.39 respectively). There were higher concentrations of IL-1β, IL-5, IL-8 and IL-13 in each progressively longer quartile of days to resolution. The longest quartile of days to resolution (12-50 days) showed the highest median cytokine levels.

Conclusions: The 13 cytokines tested were not associated with the diagnosis of chylothorax. However, higher IL-1β, IL-5, IL-8, and IL-13 concentrations were correlated with longer days to resolution. These findings demonstrate an inflammatory component to effusion resolution and may indicate an inflammatory phenotype that is distinct from chylothorax.