hydrocephalus Chest CT scan Intra/extrathoracic anomaly, mass, abscess, diaphragmatic hernia Abdomen CT scan Obstruction, mass, appendicitis Pulmonary and cardiac US Pleural or pericardial effusion, tamponade Electrocardiogram Cardiac anomaly, failure, pericarditis Echocardiogram Structural, functional cardiac abnormality Thoracentesis, Infection, inflammation, pericardiocentesis oncologic process cytology, biochemical, cx involving chest, heart, lymphatics Barium swallow Tracheoesophageal fistula, vascular ring, reflux Pulmonary function tests Central or peripheral nervous system depression of chest wall function, respiratory system disease Electromyography Central respiratory drive depressed, neuromuscular disease Chest angiography Vascular anomaly, PE Also therapeutic Consider US guidance Measures lung volume, flow, compliance Measures muscle activity generated by neural outflow from respiratory centers If concern PE, consider extremity US to evaluate for DVT