Acute Caremiddle twist
In late July a 34-year-old man attends with both his housemates. All three have had headache, nausea and poor concentration that build up through each evening and settle while they are at work. Their rented flat is warmed by an unflued gas heater that has never been serviced. He is alert and orientated. Respiratory rate 18, heart rate 96, blood pressure 124/76 mmHg, oxygen saturation 99% on room air. His chest is clear and neurological examination is normal. Which one of the following is the most appropriate way to manage his oxygenation while confirmatory testing is arranged?