Oxygen Therapy

Overview

Management of all patients

• Always give oxygen to an acutely ill hypoxic patient, regardless of if they have COPD or not:
  • Any critically ill patient should initially have oxygen via a reservoir mask at 15L/min
  • Hypoxia is more dangerous than hypercapnic respiratory failure in acute scenarios
• Oxygen saturation targets for acutely ill patients are 94-98%:
  • Oxygen is then adjusted as necessary once they have satisfactory saturations
• For patients at risk of hypercapnia (such as COPD), see below
• If GCS ≤8, intubate – these patients cannot maintain their airways:
  • Perform airway manoeuvres and use airway adjuncts in the meantime

Management in patients with COPD

The British Thoracic Society states:

“Patients with COPD and other risk factors for hypercapnia who develop critical illness should have the same initial target saturations as other critically ill patients pending the results of blood gas results after which these patients may need controlled oxygen therapy with target range 88–92% or supported ventilation if there is severe hypoxaemia and/or hypercapnia with respiratory acidosis.”

As long as patients are not critically ill:

• 1^st-line: prior to blood gas results: 28% Venturi mask at 4 L/min + aim for SpO₂ 88-92%
• Once blood gas results are available:
  • If pH and _PCO₂ are normal on blood gas: aim for 94-98%
  • If pH is normal but pCO₂ and bicarbonate raised: aim for 88-92%
    • This is because if the pCO₂ is raised, and so is the bicarbonate, it is likely that the patient has longstanding hypercapnia
  • If pH is 7.25-7.35 and pCO₂ is raised: use non-invasive ventilation (NIV)