O2082: Spontaneous Chylothorax in an Infant with Critical Pertussis

Introduction: Critical pertussis, defined as pertussis requiring pediatric intensive care admission and/or mechanical ventilation, is associated with a 34.2% increased risk of mortality. Chylothorax, the accumulation of lymphatic fluid rich in fat within the pleural space, is not a commonly recognized complication of pertussis. In this case, we describe a 5-week-old infant with critical pertussis on mechanical ventilation who developed chylothorax. To our knowledge, this complication has not been previously described in pediatric literature.

Case Description: A 5-week-old female infant, born at 35 weeks gestation to an unvaccinated household, was admitted to the PICU for acute hypoxemic respiratory failure in the setting of pertussis. She developed severe acute respiratory distress syndrome requiring mechanical ventilation with high frequency oscillatory ventilator (HFOV) and nitric oxide on hospital day (HD) 4. Her hospital course was complicated by recurrent complete left lung collapse when she was transitioned to conventional ventilation on HD 9. Her left lung collapse persisted for nine days despite aggressive pulmonary airway clearance including serial bronchoscopy. She required prolonged high pressure ventilatory support during this time. Chest x-ray on HD 21 revealed a right-sided pleural effusion, and pleural fluid studies via chest tube confirmed a chylous effusion. She was subsequently started on skimmed expressed breast milk (EBM) and Enfaport formula with improvement in chylous chest tube output. As respiratory status slowly improved and ventilatory support was de-escalated, she was transitioned back to regular EBM without re-accumulation of chylous effusion. The chest tube was subsequently removed, and she was slowly weaned to room air prior to discharge.

Discussion: Bordetella pertussis impairs normal respiratory ciliary function and interferes with pulmonary secretion clearance which can result in thick, inspissated mucus plugs. Chylothorax can either be traumatic or non-traumatic. Our patient did not have any concerns for common etiologies such as lymphatic malformation, obstruction, heart failure, or recent procedural injury. Meanwhile, in this infant with recurrent left lung collapse, high mean airway pressure (MAP) was necessary to maintain respiratory function. Positive pressure mechanical ventilation directly causes an increase in intrathoracic pressure, which increases central venous pressure (CVP). This can lead to increased hydrostatic pressure within the thoracic duct. We hypothesize the elevated MAP, in conjunction with a left lung collapse, resulted in an increased CVP and elevated hydrostatic pressure within the lymphatic duct. This in turn contributed to the development of right-sided chylothorax.

Conclusion: Given the recent rise in pertussis cases, it is crucial for clinicians to be aware of potential complications to enable early diagnosis and treatment. The co-occurrence of pertussis and chylothorax, as seen in this case, is extremely rare. However, clinicians should remain vigilant for the risk of chylothorax in this patient population, particularly in those requiring high-pressure ventilation settings who also exhibit lung collapse.