This is a prospective, 6 week cross-over study on the effect of High flow nasal cannula (HFNC) delivered air in patients with interstitial lung disease (ILD), in need of ambulatory oxygen therapy.

Primary outcome:

To investigate intra-personal differences in 6MWT, as well as SO2 and BORG score at the end of the 6MWT, at baseline, at 6 weeks and 12 weeks To investigate intra-personal differences in SGRQ at baseline, at 6 weeks and 12 weeks To investigate intra-personal differences in quality of sleep, using the Richards-Campbell sleep questionnaire (RCSQ) at baseline, at 6 weeks and 12 weeks To investigate intra-personal differences in IC, at baseline, at 6 weeks and 12 weeks

Secondary outcome:

To investigate intra-personal differences in FVC, at baseline, at 6 weeks and 12 weeks To investigate intra-personal differences in DLCO at baseline, at 6 weeks and 12 weeks To investigate intra-personal differences in mMRC-score at baseline, at 6 weeks and 12 weeks

In this pilot study we wish to investigate whether treatment with HFNC, delivered by MyAirvo2 (Fisher&Paykel, Auckland, New Zealand) in patients with interstitial lung disease (ILD) in need of ambulatory oxygen therapy (AOT).

Ten patients will be recruited from the outpatient clinic at Department of Respiratory Diseases, Aalborg University Hospital.

The study is carried out as a cross over study, randomizing 5 patients to intitially 6 weeks' HFNC treatment as add on to the patients' personalized usual care followed by 6 weeks observation on usual care and 5 patients to 6 weeks' observation on the patients' personalized usual care, followed by 6 weeks with HFNC as add on to usual care.

At inclusion patients' background information will be registered and patients will be examined with body plethysmography, registering TLC, FVC, RV and IC, as well as DLCO. Furthermore, a 6MWT will be performed, monitoring peripheral oxygen saturation (SO2)and BORG score at the beginning and the end of the procedure as well as analysis of arterial blood gasses (PaO2, PaCO2) at rest. In addition the modified Medical Research Council (mMRC)- score; the Richards-Campbell Sleep Questionaire (RCSQ) and the St. George Respiratory Questionaire (SGRQ) will be carried out at baseline. Following this, patients will be randomized to either usual care or usual care plus HFNC, recommended flow 30 liters/minute, recommended temperature 37o Celsius, recommended use 8 hours/day, preferably at night. After 6 weeks body plethysmography, 6MWT, mMRC, SGRQ, RCSQ and arterial blood gas analysis will be repeated and following this, treatment will cross over; as such, patients initially in the usual care arm will be treated with HFNC as add on according to the recommendations stated above and the previous HFNC treated group will be referred to usual care for the following 6 weeks. At the end of the study period (t=12 weeks), body plethysmography, 6MWT, mMRC, RCSQ, SGRQ and arterial puncture will be repeated in all patients as well as background information will be revisited to note any changes.

Should the patient reach chronic respiratory failure (saturation at rest < 88%) during the study period, patients will remain in study and the airflow during HFNC be oxygenated with whatever amount of oxygen is required to reach saturation >88% during High Flow treatment.

Equipment:

Heated, humidified, air will be delivered to the patients by MyAirvo 2 (Fisher&Paykel, Auckland, New Zealand). Patients will be treated with an intended flow of 30 L/min, intended use 8 hours per day, preferably nocturnal use. Should patients not tolerate the recommended flow, changes in flow are allowed. The Airvo2 device will be delivered and serviced in the patients' homes by VitalAire. Vitalaire will do readings of actual use on the device. At the end of the study, all patients will be offered continuous treatment with the device if so desired.

Inclusion criteria

• Age > 18 years old
• Patient diagnosed with interstitial lung disease
• Capable of understanding oral and written information and giving informed consent
• Newly diagnosed with need of oxygen during physical activity (SO2 <88%).

Exclusion criteria

• Pneumonia or exacerbation of ILD < 6 weeks prior to inclusion
• Other terminal disease than ILD and life expectancy < 3 months
• Patients not capable of understanding and accepting written or verbal information
• Patients with in need of continuous oxygen treatment at inclusion

There a no IPD sharing plans at present

As blinding of high flow treatment in not possible this is an open label study