| Disease process |
| Airway obstruction |
| Airway obstruction by tumor or by lymphadenopathy |
| Bronchoconstriction (COPD, asthma) |
| Retained or excess secretions |
| Vocal cord paralysis |
| Obstructive sleep apnea |
| Pulmonary parenchymal |
| Widespread tumor metastases |
| Pneumonia, aspiration |
| Heart failure |
| Pericardial disease, tamponade |
| Lymphangitic tumor |
| Lung resection (eg, lobectomy, pneumonectomy) |
| Pneumonitis caused by antineoplastic therapy |
| Radiation pneumonitis and fibrosis |
| Interstitial lung disease |
| Pulmonary vascular |
| Venous thromboembolism |
| Sinusoidal obstruction syndrome (veno-occlusive disease) |
| Tumor thromboembolism |
| Pulmonary hypertension |
| Superior vena cava syndrome |
| Pleural |
| Pleural effusion (eg, malignant, drug induced) |
| Pleural tumor |
| Pneumothorax |
| Pleural effusion due to lung entrapment by tumor |
| Inspiratory muscle weakness |
| Cachexia |
| Electrolyte imbalance |
| Neuromuscular disease, including paraneoplastic syndromes |
| Steroid myopathy |
| Diaphragmatic paralysis, phrenic nerve paralysis |
| Decreased chest wall compliance |
| Restriction post thoracotomy |
| Restriction due to advanced chest wall tumor (eg, inflammatory breast cancer) |
| Massive ascites |
| Massive abdominal organomegaly |
| Obesity |
| Systemic |
| Anemia |
| Acidosis |
| Arrhythmias |
| Neuropsychiatric |
| Pain |
| Depression |
| Anxiety, including hyperventilation |
| Respiratory panic |
