Respiratory failure occurs when a patient is unable to either obtain enough oxygen or to exhale enough carbon dioxide, or both. There are a variety of reasons why a patient may experience respiratory failure, including pulmonary edema, pneumonia, or airway obstruction. Other causes of respiratory failure include neuromuscular diseases, chest wall disorders, or intrinsic lung diseases, including asthma or chronic obstructive pulmonary disease (COPD).

Furthermore, in the Neurosurgery Intensive Care Unit, patients may experience respiratory failure simply because they are unable to protect their own airway or because they are not alert/awake enough to breath on their own'their respiratory drive may be altered secondary to brain tumors, intracerebral hemorrhages, or elevated intracranial pressure. Patients in respiratory failure may need to be intubated and connected to a ventilator.