| Alveolar filling processes |
| Pneumonitis - infectious, aspiration |
| Noncardiogenic pulmonary edema/ARDS (eg, due to infection, inhalation injury, near drowning, transfusion, contusion, high altitude) |
| Cardiogenic pulmonary edema |
| Pulmonary hemorrhage |
| Tumor (eg, choriocarcinoma) |
| Alveolar proteinosis |
| Intravascular volume overload of any cause |
| Pulmonary vascular disease |
| Pulmonary thromboembolism |
| Amniotic fluid embolism, tumor emboli |
| Diseases causing airways obstruction: central |
| Tumor |
| Laryngeal angioedema |
| Tracheal stenosis |
| Diseases causing airways obstruction: distal |
| Acute exacerbation of chronic obstructive pulmonary disease |
| Acute, severe asthma |
| Hypoventilation: decreased central drive |
| General anesthesia |
| Drug overdose |
| Hypoventilation: peripheral nervous system/respiratory muscle dysfunction |
| Amyotrophic lateral sclerosis |
| Cervical quadriplegia |
| Guillain-Barré syndrome |
| Myasthenia gravis |
| Tetanus, tick bite, ciguatera poisoning |
| Toxins (eg, strychnine) |
| Muscular dystrophy, myotonic dystrophy, myositis |
| Hypoventilation: chest wall and pleural disease |
| Kyphoscoliosis |
| Trauma (eg, flail chest) |
| Massive pleural effusion |
| Pneumothorax |
| Increased ventilatory demand |
| Severe sepsis |
| Septic shock |
| Severe metabolic acidosis |
| Miscellaneous |
| Airway protection |
