Intelligent Oxygen Therapy During Activities of Daily Living

Long-term oxygen therapy (LTOT) is prescribed for patients with stable severe hypoxemic respiratory failure according to specific criteria set out in different guidelines from international respiratory societies. The aim of LTOT is to maintain the resting partial pressure of oxygen (PO2) \>60 mmHg or oxygen saturation (SpO2) \>90%. A number of studies have demonstrated that whilst at home, patients on LTOT experience episodes of intermittent hypoxia (SpO2 \<90%) and spend significant amounts of time with SpO2 \<90%. These episodes of desaturation occur most frequently during activities of daily living and may be harmful as they could lead to pulmonary hypertension, arrhythmias and ischaemic heart disease. Simply increasing the LTOT flow rate by 1 or 2 litres in one option but this exposed the patients to hyperoxaemia and the risk of hypercapnia. An another method optimising LTOT is to utilise an auto-titrating oxygen system. These system allow close control of SpO2 by automatically adjusting the flow of oxygen to match a target SpO2. At the Royal Brompton Hospital and Imperial College London, the investigators have developed our own auto-titrating oxygen system - called intelligent oxygen therapy (iO2t). This system has been tested in patients with chronic obstructive pulmonary disease (COPD) and LTOT during a 6 minute walk test with promising results (ERS 2015). The aim of this study is to investigate whether the intelligent oxygen therapy system can reduce intermittent hypoxia in patients on LTOT during simulated activities of daily living. Patients will be asked to a series of activities of daily living over a period of 1 hour including: washing, dressing, putting away shopping and cleaning. The patients will do these activities twice: once on their usual LTOT and once on the auto-titrating oxygen system in a cross-over design.