Table 1 Recommendations for emergency oxygen use

1. Critical illness requiring high levels of supplemental oxygen	Give 15 L·min⁻¹ via a reservoir mask and once stable, reduce oxygen to aim for a saturation range of 94–98%. If patient at risk of T2RF, aim for the same initial saturation as all other critically ill groups pending ABG.
2. Serious illness requiring moderate amounts of oxygen if the patient is hypoxic	Initially give 2–6 L·min⁻¹ via nasal cannulae or 5–10 L·min⁻¹ via facemask, aiming for a saturation range of 94–98%. If saturation can’t be maintained or initial saturation is <85%, use a reservoir mask with 10–15 L·min⁻¹. If at risk of T2RF, aim for saturation of 88–92%, adjusting to 94–98% if the ABGs show normal carbon dioxide^#. Repeat ABG after 30–60 min.
3. COPD/other conditions at risk of T2RF requiring low dose/controlled oxygen^¶	Before ABG use a 28% Venturi mask (4 L·min⁻¹), aiming for a saturation range of 88–92%, adjusting to 94–98% if the ABGs show normal carbon dioxide^#. Repeat ABG after 30–60 min. If the patient has an oxygen alert card, aim for the target range specific to him/her. If the patient is hypercapnic and acidotic, despite 30 min of appropriate treatment and oxygenation, consider non-invasive ventilation.
4. Conditions for which the patient should be closely monitored but oxygen is not required unless hypoxic	If hypoxaemia develops, follow recommendations as per serious illness (point 2 above)

^#: Unless there is a history of previous hypercapnic respiratory failure requiring non-invasive or invasive ventilation, in which case the target saturation should remain at 88–92%; ^¶: If no diagnosis is known but the patient is >50 years old and a long-term smoker with chronic dyspnoea, treat as presumed COPD. Adapted from the British Thoracic Society guideline for emergency oxygen use in adult patients (tables 1–4) [5].