Neonatal pneumomediastinum with isolated mitral obstruction.

While mediastinal air accumulation in the ventilated newborn is usually a benign entity, tension pneumomediastinum can embarrass both respiratory and cardiac function. A case of isolated left ventricular inflow obstruction caused by a pneumomediastinum in a premature infant is described that resolved with high frequency ventilation. The development of pneumomediastinum and haemodynamic compromise in a premature infant warrants echocardiographic examination.