Lack of inclusion of patients

As protocol NCT04223050. This substudy furthermore investigates the role of oxidative stress in the administration of oxygen in COPD patients.

Studies have shown that oxidative stress plays a critical role in the pathogenesis of COPD and its comorbidities. Oxidative stress refers to a state in which the activity of oxidants (e.g. reactive oxygen species (ROS)) outweighs that of antioxidants. ROS can be introduced exogenously by for example cigarette smoke and atmospheric pollution, but is also produced endogenously as a byproduct of ATP production in mitochondria or from immune cells during oxidative burst. When high fractions of inspired oxygen are administered, excess O2 can lead to formation of additional ROS, which depletes antioxidants and induces an inflammation with leukocyte-derived inflammatory mediators migrating to the site of injury. In turn, this causes cellular hypertrophy, increased surfactant secretion, and cellular influx of monocytes and mast cells. During the final, fibrotic phase of oxygen toxicity, irreversible, persistent destruction of the pulmonary lining have occurred with collagen disposition, thickening of pulmonary interstitial space, and fibrosis.

This substudy therefore aim to investigate the relation between oxygen therapy in COPD patients admitted with acute exacerbation, oxidative stress, and mortality.

Inclusion Criteria:

• age 18 years or older
• ability to give informed consent
• previously diagnosed COPD (either confirmed diagnosis at prior hospital - contact or from their general practitioner or confirmed diagnosis by the treating physician in the emergency department (verified by use of relevant medication))
• admitted with acute exacerbation (acute and worsened shortness of breath) of COPD
• requiring oxygen treatment

Exclusion Criteria:

• Instability at arrival requiring immediate lifesaving treatment, e.g. intubation or non-invasive ventilation, within the first 30 minutes
• Expected total length of stay in hospital < 12 hours
• Planned transfer to another hospital within 12 hours
• Unwilling to have repeated arterial blood gas analyses within the first 12 hours
• Patients judged terminal by treating physician in the emergency department
• Non-residents of the particular country
• Expected impossible follow-up
• Fertile women (<50 years of age) with positive urine human gonadotropin (hCG) or plasma-hCG
• Prior participation in the study