Source:http://linkedlifedata.com/resource/umls/id/C0032319
MSH: Presence of air or gas in the space between the heart and the PERICARDIUM. The degree of respiratory distress depends on the amount of trapped air and circulation blocked in the systemic and pulmonary veins.,NCI: The presence of air in the pericardial cavity. Causes include chest injury in adults, and respiratory distress syndrome in infants.