Common causes of respiratory deterioration

Respiratory failure can be described as either type 1 or type 2 respiratory failure. In order to define this, an arterial blood gas (ABG) needs to be taken to assess the oxygen (P02) and carbon dioxide (PC02) levels.

Type 1 respiratory failure (T1RF) = hypoxia: PO2 < 8Kpa

Common causes of T1RF that can cause V/Q mismatch:

  • Inflammation of the tissue in the lung or lungs. It is normally caused by bacteria but can also be caused by viruses or fungus. This can cause purulent material, pus and fluid to build up in the alveolar which can impair gas exchange.

  • A blood clot occluding one of the pulmonary vessels. This can impair gas exchange by impairing blood flow to the alveolar and preventing gas exchange from occurring.

  • An excess accumulation of fluid within the pleural space.

  • A collection of air within the pleural space, between the chest wall and lung.

Type 2 respiratory failure (T2RF) = hypercapnia PC02 > 6Kpa with or without hypoxia

A T2RF indicates there is a problem with ventilation. All of the problems that cause T1RF can develop into a type 2 respiratory failure if the patient begins to tire and their respiratory effort decreases (hypoventilation). Most often though, T2RF is caused by a chronic disease process.  

Common causes of T2RF:

  • A chronic inflammatory lung disease, that causes narrowing of the bronchioles and impairment of airflow.

  • Caused by neuromuscular disorders such as motor neurone disease, Guillain-Barré syndrome, high spinal cord injury.

  • Causes absent or reduced breathing during sleep.

  • Opiate based medications and benzodiazepines are the most common drugs known to cause respiratory depression. Problems may occur due to excessive doses or impaired secretion of the drug (AKI).