Titrated Ambulatory Oxygen in Fibrotic ILD and COPD With Isolated Exertional Hypoxemia

Interstitial lung diseases (ILD) are a group of diseases that frequently affect the gas-exchange surface of the lungs. Many forms of ILD are fibrotic in which the lung tissue becomes scarred, and patients with fibrotic ILD often have low oxygen levels at rest or with activity. Low oxygen levels are also common in chronic obstructive pulmonary disease (COPD). COPD is most often caused by tobacco use and can lead to damage to lung tissue that also affects how well oxygen can get into the blood. Low blood oxygen levels are associated with shortness of breath and adverse outcomes in fibrotic ILD and COPD including increased mortality and reduced quality-of-life. Long term oxygen therapy (LTOT) used for >15 hours per day is strongly recommended in patients with fibrotic ILD or COPD who have low oxygen level at rest based on studies in COPD which showed that LTOT improved mortality. Up to 50% of patients with fibrotic ILD and 25-50% with COPD only have low oxygen levels with activity, termed isolated exertional hypoxemia. Laboratory- and clinic-based studies on ambulatory oxygen therapy (AOT) given during exercise demonstrated improvement in shortness of breath and exercise ability. However, studies on real-world AOT use have not found a significant or consistent benefit in clinical outcomes, patient activity, symptoms, or quality-of-life. This has led to variable AOT prescribing practices worldwide.

AOT can be delivered via portable oxygen concentrators (POC), compressed gas canisters, or liquid reservoirs. Differences in device size, weight, portability, and continuous vs on-demand oxygen delivery likely impact patient activity. Many patients, especially those with fibrotic ILD, often need ambulatory oxygen at high flow rates which exceeds the ability of commonly used POCs. How much oxygen a patient needs with activity is usually determined through a hallway walk test, however it's not known whether these tests accurately predict a patient's real-world oxygen needs, or if AOT titrated to correct low oxygen levels on these tests also correct low oxygen levels during real-world activities.

This study will test the feasibility of a larger clinical trial examining how AOT delivery, titrated to meet individual participant's ambulatory oxygen needs during a hallway walk test, impacts real-world activity, symptoms, and quality-of-life in people with fibrotic ILD or COPD who only have low oxygen levels with activity. We aim to examine the effects of AOT delivered between oxygen tanks and POCs compared to each other and to no oxygen therapy where participants do normal real-world activities breathing regular air. A total of 12 people with fibrotic ILD and 12 people with COPD (24 people total) who only have low oxygen levels with walking will be invited to participate. This study will be conducted at a single site in the United States. All participants will be assigned to 2-week periods using a POC, oxygen tanks, or no oxygen therapy during their normal real-world activities. POC and oxygen tank delivery will be titrated to correct low oxygen levels on a hallway walk test. Measurements of daily activity and real-world oxygen saturations will be continuously measured for the total 6-week study. Measurements of symptoms and quality-of-life will be obtained at the beginning of the study and every 2-weeks. Information about participants' fibrotic ILD and COPD diagnoses and treatments will be collected.

Inclusion criteria

• Adults >= 18 years old and <= 85 years old with fibrotic ILD or COPD able to provide informed consent
• Fibrotic ILD includes idiopathic pulmonary fibrosis, sarcoidosis, or other ILD with fibrotic changes on lung imaging (reticulations, honeycombing, traction bronchiectasis)
• COPD participants will have fixed airway obstruction on spirometry less than 70%-predicted as per Global Initiative for Obstructive Lung Disease (GOLD) diagnostic criteria
• Participants will self-report as being ambulatory outside of home without use of assistance device such as a cane or walker
• Stable lung disease on stable medical therapy for preceding 3 months
• Isolated exertional hypoxemia (SpO2 less than 89% for >=10 seconds) on a 6MWT conducted while breathing room air
• Able to maintain SpO2 >=89% for the full duration of a 6MWT while using the the POC and portable oxygen D-tank at POC setting of no higher than 6 and D-tank flow rate no higher than 6 liters per minute

Exclusion criteria

• People <18 years old or >85 years old
• Participants with mixed ILD and COPD diagnoses
• Resting hypoxemia less than 89% while breathing room air
• Emergency room visit or hospital admission in 3 months prior to recruitment
• Change in medical therapy in 3 months prior to recruitment
• Need for ambulatory assistive device such as cane or walker
• Pregnant
• Currently smoking or residing with a current smoker
• Currently engaged in a pulmonary rehabilitation program
• Participants without a smartphone compatible with the Oxiwear app (necessary to collect Oxiwear oxygen saturation data) or those with a compatible smartphone but without home wifi or cellular service plan allowing for Oxiwear data uploading