Too much oxygen for too little benefit

Long term oxygen therapy has no benefit in patients with stable COPD and moderate resting hypoxemia or exercise-induced desaturation, according to US research.

Professor Christine McDonald, director of respiratory and sleep medicine at Austin Health, said the findings were largely consistent with TSANZ guidelines and strengthened the evidence regarding supplemental oxygen in patients with an SpO2 range of 89-93%.

“This is a well conducted and adequately powered study which confirms the findings of two smaller studies from the 1990s,” she said.

The randomized but non-placebo controlled study of 738 patients found no benefit from oxygen therapy based on either time to death, time to first hospitalisation or a combination of the two outcomes.

There was also no significant difference in COPD exacerbations, COPD-related hospitalisations or all-cause hospitalisations.

Measures of quality of life, anxiety, depression or functional status were also similar between those who received oxygen therapy and those who didn’t.

Professor McDonald said oxygen remained important for COPD patients with significant hypoxemia as per TSANZ guidelines.

“However there is little evidence to support long term continuous oxygen in other COPD patients, especially given patient voiced concerns about social stigma, lack of experience of symptomatic benefit, inconvenience of use and the potential for adverse effects.”

The study found 51 adverse events and three hospital admissions attributed to oxygen therapy including trips over equipment, fires and burns.

Professor McDonald said oxygen can cause small changes in the ventilatory response in the laboratory setting but the size of the effect was insufficient to be clinically relevant.

An accompanying editorial in the New England Journal of Medicine concurred that long term oxygen therapy should not be routinely prescribed to COPD patients with mild or moderate hypoxemia.

However Professor McDonald said there was frequently some difficulty in the translation of clinical guidelines into practice.

“Some practitioners do not have easy access to the testing required to determine need for and benefit from oxygen therapy and patients can sometimes be prescribed oxygen for not very good reasons. We certainly need more review of patients on oxygen as they typically get left on this therapy regardless of benefit,” she said.


Related stories:

Re-set required on use of oxygen therapy for acute care patients

Swim between the oxygen flags : Guidelines

Oxygen is a drug 

Clinical controversies addressed in oxygen guidelines


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