Ambulatory oxygen in Fibrotic Lung Diseases

Abstract

Introduction and objectives: The hallmark symptom of fibrotic interstitial lung disease (ILD) is breathlessness, which progressively limits the ability to carry out normal activities, with a devastating impact on Quality of life (QoL). Breathlessness on exertion, formally measured by the 6 minute walk test (6MWT), is usually associated with a fall in oxygen saturation, which can be corrected by using supplemental oxygen. However, there are no prospective studies assessing whether ambulatory oxygen provides benefit to patients with ILD and no specific guidelines regarding its use in this patient group. Objectives and Methods: We are currently conducting a prospective, multi-centre trial (clinicaltrials.gov: NCT02286063), funded by the NIHR, investigating the effects of ambulatory oxygen, in fibrotic ILD patients with normal oxygen saturation at rest (SaO2 ≥94%), whose oxygen saturation on room air drops to ≤88% on a 6MWT. The study protocol consists of a four week randomized, cross-over controlled trial of ambulatory oxygen used during daily activities. The optimal oxygen flow rate is determined by titration at the screening visit. We aim to compare breathlessness, quality of life and mobility during two weeks on ambulatory oxygen compared to no ambulatory oxygen supply for the same period in 80 patients with lung fibrosis. The primary outcome will be health status as assessed by the King's Brief Interstitial Lung Disease Questionnaire (K-BILD; scores ranging from 6.4-82.5; minimally important difference 8 points). Key secondary outcome measures include change in breathlessness and QoL (University of California San Diego Shortness of Breath Questionnaire; St George’s Respiratory Questionnaire; Hospital Anxiety and Depression Scale), activity measurements (Sensewear Armbands), and oxygen saturation. Patient reported oxygen cylinder use will be validated with information on oxygen use provided by the oxygen companies. The baseline characteristics of the 39 patients enrolled so far are described in the attached table. Patients' and carers' experiences of the use of a portable oxygen supply will be explored in qualitative interviews in a subgroup of 20 patients and carers. Conclusions: The results of this study should form an essential precursor to setting out ILD-specific guidelines for the use of ambulatory oxygen.