ABSTRACT
In the scenario opposite, the first arterial blood gas will probably show a low pO2 and a normal or low pCO2. With a COPD patient, unless he or she is very hypoxic, you should commence oxygen therapy at 24 per cent, rechecking the arterial blood gas 30 minutes later. The second arterial blood gas may reveal normal gases, in which case you would state to the examiner that you would like to continue oxygen therapy at 24 per cent. Or it may reveal that the patient remains hypoxic, without significant carbon dioxide retention, in which case you would change the valve and flow rate to deliver 28 per cent, rechecking the arterial blood gas after a further 30 minutes. If your ‘patient’ is retaining carbon dioxide, you should state to the examiner that you would discuss the results with your senior, to consider alternative methods of respiratory support (e.g. non-invasive positive pressure ventilation).
