Chylothorax in critically ill children following cardiac surgery: a cohort study

Background Data on chylothorax after pediatric cardiac surgery are limited and high-quality evidence-based treatment strategies are lacking. Objectives We aimed to investigate the epidemiology, clinical characteristics, management and outcome of patients who developed chylothorax following cardiac surgery during pediatric intensive care unit (PICU) stay. Methods This was a retrospective cohort study performed between 01/2012 and 12/2022 at a tertiary-care hospital affiliated with the University of São Paulo. Results Over the study period, the incidence of chylothorax after cardiac surgery in our institution was 3.1%; 29 patients developed chylothorax during PICU stay. Their median age was 3 months, 41% had Down syndrome and 27.5% had intrathoracic deep vein thrombosis. Comparison of patients with low-output chylothorax (<20 ml/kg/day) ( n = 17) versus those with high-output chylothorax (≥20 ml/kg/day) ( n = 12) showed a prolonged duration of chest tube utilization, lower minimum number of lymphocytes in peripheral blood and increased PICU length of stay in patients with high-output chylothorax. All patients with low-output chylothorax were managed conservatively, whereas half of patients with high-output chylothorax underwent interventional treatment (pleurodesis and/or thoracic duct ligation). Eleven patients (37.9%) died; 55% of them had high output chylothorax. Cause of death was septic shock in all but one patient. The percentage of lymphocytes in pleural fluid was greater in patients who died compared to survivors, and among those who died of septic shock, the number of lymphocytes in peripheral blood was lower. Conclusions Chylothorax following pediatric cardiac surgery is associated with increased morbidity and mortality. Early resolution may contribute to outcome improvement.