The assessment of intelligent oxygen therapy (iO2t) in patients with chronic obstructive pulmonary disease on long term oxygen therapy
The case for change
Many patients with lung diseases develop respiratory failure necessitating long-term oxygen therapy (LTOT). The oxygen flow rate is prescribed at a fixed-flow whilst the patient is at rest with the aim of maintaining oxygen saturations (SpO2) ≥90%. However, a number of studies have revealed that once patients are at home on long-term oxygen therapy, their oxygen saturations are very variable with patients experiencing episode of intermittent hypoxia and spending significant amount of time with oxygen saturations <90%. This is dangerous as it can lead to symptoms, stress on the heart, can worsen underlying cognitive problems and exacerbate co-morbidities. We believe that optimisation of long-term oxygen therapy through the use of our auto-titrating oxygen system can lead to reduced symptoms and better outcomes for many patients on domiciliary oxygen.
An auto-titrating oxygen system (which we have called “Intelligent Oxygen Therapy” – iO2T) is a smartphone based application which automatically adjust the flow rate of oxygen delivery to match a given oxygen saturation target. This will reduce episodes of intermittent hypoxia and the time that patients spend with inappropriately low oxygen saturations.
The clinical study
In order to test the iO2T system we conducted a randomised, double blind cross-over study in which patients with chronic obstructive pulmonary disease (COPD) on LTOT completed three 6 minute walk tests (6MWT); a practice walk followed by walks on the iO2T system (designed to maintain SpO2 at 93%) and their usual fixed flow ambulatory oxygen. The primary end-point was the percentage of time spent with SpO2<90% during the 6MWT.
Twelve patients (mean [±SD] age, 69.6±6.4 years; 9 males) with severe COPD (mean FEV1, 0.88±0.44L) were studied. With iO2T system, the median percentage of time with SpO2<90% during the 6MWT was 62.1% [IQR: 22.6-83.7], compared to usual fixed flow oxygen 84.6% [IQR: 42.3-90.0] (P=0.033). The median SpO2 was higher with iO2T system, 89.5% (IQR: 85.1-90.8) vs. fixed flow oxygen 86.5% (IQR: 84.4-90.5) (p=0.038), as was the trough SpO2, 87.0% [IQR: 82.3 – 88.0] vs. 83.5% [IQR: 79.0 – 87.5] (P=0.009). There was no difference in the total distance walked.
Oxygen delivered via the iO2T system designed to meet a target SpO2, maintained SpO2≥90% during the 6MWT for a greater duration of time than usual fixed flow oxygen. This highly practical, smartphone based system has the potential to reduce episodic hypoxaemia in COPD patients, and further optimise LTOT.