Comparing 6-Minute Walk Tests for Ambulatory Oxygen Assessment

Comparison of the Standard 6-Minute Maximal Speed Walk Test Against a 6-Minute Normal Speed Walk Test as an Alternative and More Accurate Assessment for Ambulatory Oxygen Requirement.

Patients with lung disease who report breathlessness on exertion are often referred for a 6MWT. 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. 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.

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.

Results from the modified walk test will not be provided to the medical team prescribing ambulatory oxygen assessment.

Instructions given to perform the walk test following the international guidelines using the phrase 'as far as you can'.

Instructions given to perform the walk test following the international guidelines except using the phrase 'at a speed you would normally walk'.

Continuous monitoring of SpO2 will allow for the measurement in the drop from baseline to the lowest point (nadir) during the test. Between the walk tests, the average drop will be calculated and compared.

The time from the start of the test and the lowest (nadir) SpO2 will be recorded and compared between the walk tests.

Measurement of the time taken to reach nadir in SpO2 will be recorded to help justify the length of the walk test

Inclusion Criteria: Referred for a standard 6-minute walk test Has the capacity to give informed consent Is aged between 18 and 90 Exclusion Criteria: Lack of capacity to provide informed consent Poor peripheral perfusion that prevents an accurate measurement of SpO2 Contraindicated to perform a Max_6MWT as indicated in the standard HHFT 6MWT SO