Oxygen therapy in respiratory failure

• Type 1 failure - treat with unrestricted oxygen therapy i.e. 35+ %; blood gases should be repeated after 20 mins to ensure correction of PaO2 and absence of a significant rise in PaCO2.
  
  
• Type 2 failure and COAD - give 24% O2. Monitor PaCO2 closely by blood gas measurement; if it rises by more than 1 kPa, consider ventilation.

The concentration of oxygen is important to patients with chronic bronchitis and chronically elevated PaCO2 - as these patients rely on hypoxic drive to maintain respiratory effort, it is dangerous to give supplemental oxygen without careful observation as hypoventilation or apnoea may result. Blood gases must be monitored regularly.

Reference

1. O'Driscoll BR, Howard LS, et al. BTS Guideline for oxygen use in adults in healthcare and emergency settings, Thorax 2017;72(Suppl.1):pi1–i89