USA Surgery Today

Persistent pulmonary hypertension (PPHN) affects more than 10,000 infants in the United States each year and can be defined as systemic hypoxemia, usually associated with evidence of extrapulmonary shunting and elevated pulmonary artery pressure (45:LASIX).

PPHN is associated with a wide variety of disease processes and can be categorized anatomically. Maladaptation with normal pulmonary vascular smooth muscle development can be seen in the clinical setting of birth asphyxia, sepsis, meconium aspiration, and pulmonary immaturity. Pulmonary hypertension in newborn infants has also been associated with excessive vascular muscle hypertrophy.

Pulmonary vascular smooth muscle may extend further out in the pulmonary arterial bed or the medial thickness of arterial resistance vessels may be increased, or both. Often irreversible, these anatomic changes have been seen in infants with chronic intrauterine hypoxemia and increased intrauterine blood flow. Underdevelopment of the pulmonary vascular bed with increased pulmonary vascular resistance and pulmonary hypertension may be associated with pulmonary hypoplasia, typically in the clinical setting of congenital diaphragmatic hernia or long-standing oligohydramnios (46:LASIX).

The choice of therapeutic interventions should be based on the physiology of the specific disease process. These interventions have included hyperventilation and hyperoxia, surfactant replacement therapy, high-frequency oscillation, nitric oxide, and extracorporeal membrane oxygenation (45,46).