|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) .