Hypercapnia as a Key Mechanism in the Development of Pulmonary Hypertension in Malignant Pertussis: A Case Report.

Malignant pertussis (MP) is a highly lethal complication of pertussis in young infants, typically associated with hyperleukocytosis, pulmonary hypertension (PHT), and multiorgan failure. Some authors suggest that structural pulmonary vascular damage explains the irreversibility and poor prognosis. In contrast, we present a well-documented case where sustained control of hypercapnia improved PHT. This case prompted a literature review. A 44-day-old male infant was admitted to our paediatric intensive care unit with confirmed pertussis and severe hypoxaemia. He required immediate intubation. The clinical course progressed to severe acute respiratory distress syndrome with PHT. Permissive hypercapnia was observed to worsen PHT, requiring progressive escalation of ventilatory and haemodynamic support. The use of a high-powered high-frequency oscillatory ventilator enabled effective carbon dioxide control and sustained clinical improvement. This case offers a novel perspective on a potentially modifiable pathophysiological mechanism in the management of MP.