Exercise response to oxygen supplementation is not associated with survival in hypoxemic patients with obstructive lung disease

Abstract

Ahmed S Sadaka,1,3 Andrew J Montgomery,2 Sahar M Mourad,3 Michael I Polkey,1 Nicholas S Hopkinson1 1NIHR Respiratory Biomedical Research Unit at the Royal Brompton Hospital and Imperial College, Respiratory Medicine, London, UK; 2Royal Brompton and Harefield NHS Foundation Trust, London, UK; 3Alexandria University Faculty of Medicine, Chest Department, Alexandria, Egypt Purpose: Hypoxemia is associated with more severe lung disease and worse outcomes. In some patients with chronic obstructive lung diseases who desaturate on exertion, supplemental oxygen improves exercise capacity. The clinical significance of this exercise response to oxygen supplementation is not known.Patients and methods: We identified chronic obstructive lung disease patients at our center who underwent a 6-minute walking test (6MWT) for ambulatory oxygen assessment and who desaturated breathing air and therefore had an additional walk test on supplemental oxygen, between August 2006 and June 2016. Responders were defined as walking ≥26 m further with oxygen. Survival was determined up to February 1, 2017. We compared survival in oxygen responders and nonresponders in patients with obstructive lung diseases.Results: One hundred and seventy-four patients were included in the study, median age 70 years. Seventy-seven (44.3%) of the patients were oxygen responders. Borg dyspnea score improved by 1.4 (±1.4) units (P<0.0005) on oxygen. Median survival was 66 months with death occurring in 84 (48.2%) patients. Kaplan–Meier analysis revealed no survival difference between both responders and nonresponders (P=0.571). Cox regression analysis showed that more 6MWT desaturation, lower 6-minute walking distance on room air, male gender, lower hemoglobin, and body mass index were associated with higher mortality risk.Conclusion: Acute exercise response to supplemental oxygen is not associated with long-term survival in patients with obstructive lung disease. This supports the use of ambulatory oxygen treatment for symptomatic purposes only. Keywords: 6-minute walking test, exercise, hypoxemia, obstructive lung disease, oxygen

Keywords

• 6-min walk test
• exercise
• hypoxemia
• obstructive lung disease
• oxygen