Comparing 6-Minute Walk Tests for Ambulatory Oxygen Assessment

Patients with lung disease who report breathlessness on exertion are often referred for a 6MWT. During this test patients are asked to walk up and down a corridor (or other flat area) for six minutes whilst their blood oxygen levels and heart rate are non-invasively measured using a pulse oximeter (finger probe) and the distance walked is measured. In addition, a questionnaire that obtains a Borg Score measures the patients perceived breathlessness and leg muscle fatigue both before and immediately following the test. Due to the nature of the 6MWT (hereon referred to as a Max-6MWT), patients are required to walk as far as they can in 6 minutes. This may lead to an inaccurate assessment of their requirement for ambulatory oxygen as this form of exercise may not correspond to their normal daily activities. It may also not accurately measure the normal changes in oxygen saturation (or desaturation) that occurs in these patients during their normal daily activities (such as walking to the shops, walking up the stairs, gardening). In this study, patients who are routinely referred for a Max-6MWT to investigate possible exercise-induced hypoxaemia will be invited to perform an additional walking test which is performed at their normal walking speed, referred here on in as a Nor\_6MWT. We hypothesise that performing a Nor\_6MWT will provide a more accurate assessment of a patients' oxygen requirement, primarily from their oxygen desaturation during the test.