The hemodynamic significance of massive pneumopericardium in preterm infants with respiratory distress syndrome. Clinical and experimental observations.

Radiographic and clinical data were evaluated in 12 preterm infants with pneumopericardium complicating ventilator therapy of respiratory distress syndrome. Eight infants had massive or tension pneumopericardium, reflected by bradycardia, hypotension, and cyanosis of abrupt onset; cardiac size decreased dramatically but returned to approximately the former size after aspiration of the pneumopericardium. In puppies, pneumopericardium large enought to reduce heart size by 32 +/- 3% caused decreased mean arterial pressure (-22 +/- 7%) and right ventricular peak systolic pressure (-11 +/- 2%) and increased right ventricular diastolic and intrapericardial pressures. These findings suggest that pneumopericardium per se causes severe hemodynamic compromise. When it is large enought to reduce heart size, drastic circulatory impairment is produced and pericardiocentesis should be performed immediately.