AKT-2029

You are assessing a patient who has recently been evaluated by the community respiratory team for long term oxygen therapy. She is an elderly patient with chronic obstructive pulmonary disease and a Pa02 of 6.9 kPa in air.

According to the available evidence, what minimum daily duration of oxygen use has been shown to significantly reduce mortality in elderly patients with chronic obstructive pulmonary disease and a Pa02 of 6.9 kPa in air?