Effect of HIgh-flow Therapy in Long-term Oxygen Therapy

This study is testing whether high-flow oxygen therapy (HFOT) — which delivers warm, humidified oxygen at a higher flow rate than standard oxygen — works better than standard long-term oxygen therapy (LTOT) at home for people with chronic lung diseases (COPD or pulmonary fibrosis/ILD) who already need daily supplemental oxygen. **You may be eligible if...** - You are 40 years or older - You have been prescribed long-term home oxygen therapy for at least 15 hours per day for at least 28 days - Your main underlying condition is COPD or interstitial lung disease (ILD) - You use an oxygen concentrator as your stationary home oxygen source (including at night) - Your BMI is below 35 **You may NOT be eligible if...** - You have previously used or are currently using home high-flow oxygen therapy - You use a home ventilator or CPAP machine - You have been hospitalized in the past 2 weeks - You are a current smoker or have open flames near your oxygen source - Your blood CO2 level is very high, suggesting you are retaining too much carbon dioxide - You have suspected severe sleep apnea or obesity-related breathing problems Talk to your doctor to see if this trial is right for you.