System/physiology	Example	History	Physical examination	Diagnostic studies
Pulmonary
Alveolar	Chronic pneumonia	Fever, productive cough, shortness of breath	Fever, crackles, increased fremitus, bronchophony	Chest radiography, chest CT, bronchoscopy/bronchoalveolar lavage, culture or biopsy
Interstitial	Idiopathic fibrosis	Exertional dyspnea, dry cough, malignancy, prescription or illicit drug use, chemical exposures	Hypoxia, clubbing, persistent inspiratory crackles	Chest radiography (fibrosis, interstitial markings), chest CT, bronchoscopy/biopsy
Obstruction of air flow	Chronic obstructive pulmonary disease	Tobacco use, cough, relief with bronchodilator, increased sputum production, hemoptysis and weight loss with malignancy	Wheezing, barrel chest, decreased breath sounds, accessory muscle use, clubbing, paradoxical pulse	Peak flow, spirometry, chest radiography (hyperinflation), PFT
Restrictive	Pleural effusion	Pleuritic chest pain, dyspnea not improved with oxygen	Decreased breath sounds, chest morphology, pleural rub, basal dullness	Chest radiography (effusion, anatomic abnormality), spirometry, PFT
Vascular	Chronic pulmonary emboli	Fatigue, pleuritic chest pain, prior emboli/deep venous thrombosis, syncope	Wheezing, lower extremity swelling, pleural rub, prominent P2, murmur, right ventricular heave, JVD	d-dimer, ventilation/ perfusion scan, CT angiography, echocardiography, right heart catheterization
Cardiac
Arrhythmia	Atrial fibrillation	Palpitations, syncope	Irregular rhythm, pauses	ECG, event recorder, Holter monitor, stress testing
Heart failure	Ischemic cardiomyopathy	Dyspnea on exertion, paroxysmal nocturnal dyspnea, orthopnea, chest pain or tightness, prior coronary artery disease or atrial fibrillation	Edema, JVD, S3, displaced cardiac apical impulse, hepatojugular reflex, murmur, crackles, wheezing, tachycardia, S4	ECG, brain natriuretic peptide, echocardiography, stress testing, coronary angiography
Restrictive or constrictive pericardial disease	Metastatic tumor	Viral infection, malignancy, chest radiation, inflammatory diseases	Decreased heart sounds	Echocardiography
Valvular	Aortic stenosis	Dyspnea on exertion	Murmur, JVD	Echocardiography
Gastrointestinal
Aspiration	Gastroesophageal reflux disease	Postprandial, night cough	Intermittent crackles, wheezes	Chest radiography, esophagography, esophageal pH
Neuromuscular
Respiratory muscle weakness	Phrenic nerve palsy	Known neuromuscular disorders, weakness	Atrophy	Maximal inspiratory and expiratory pressures
Psychological
—	Anxiety	Anxiety, depression, history of trauma or abuse	Sighing	Normal