The Role of Ambulatory Oxygen in Improving the Effectiveness of Pulmonary Rehabilitation for COPD Patients

Pulmonary rehabilitation (PR) is an exercise program tailored for patients with chronic lung disease that is a core part of the management of patients with Chronic Obstructive Pulmonary Disease (COPD). Many COPD patients develop low oxygen levels (desaturation) during exercise and this is often discovered when they are being evaluated for PR. Current practice is to administer oxygen to COPD patients with exercise-induced desaturation, but this is based on very limited evidence. This limited evidence relates to a short-term increase in exercise capacity and it is not known if this translates into longer term increases in activity or whether providing these patients with oxygen improves outcomes after PR.

In addition it is not known if patients given ambulatory oxygen continue to use it after completing PR. Evidence for a beneficial effect of oxygen would provide a more solid evidence base for its use. Conversely demonstration of no effect would allow reassessment of the use of oxygen and whether the costs are justified. Therefore the aims of this study are to assess the effects of oxygen on outcomes from PR and assess the usage of ambulatory oxygen following completion of PR.

The study will be a randomised, single-blinded study comparing oxygen with air in Chronic Obstructive Pulmonary Disease (COPD) patients undergoing Pulmonary Rehabilitation (PR).

The study subjects will be patients with a confirmed diagnosis of COPD who have been accepted for PR and who are not hypoxemic at rest, but have exercise-induced desaturation (defined as a fall in oxygen saturations (SaO2) ≥4% to at least \<90%, or any fall to a SaO2 \<90%) and demonstrate positive improvement with use of ambulatory oxygen as per the British Thoracic Society 2015 Oxygen guidelines. It is standard practice for patients to have this assessment prior to commencing PR and as part of the assessment the flow rate required to increase the SaO2 to ≥90% during exercise will be determined. Patients will be recruited from PR programs at imperial college health care trust hospitals.

The subjects will be randomised to receive either oxygen at the flow rate determined at the initial assessment to a maximum flow rate of 6 litres per minute, or room air. The subjects will then undergo a standard program of PR over 6 - 8 weeks and then undergo reassessment. 20 patients are required in each group to detect a 30% effect size on the 6 minute walk test (6MWT) with 80% power at the 5% significance level and 29 patients in each group to detect a 25% effect with 80% power. Therefore a minimum of 20 patients per group will be included.

Baseline assessments prior to commencing PR will include symptom and quality of life assessments including Borg scale for assessment of breathlessness, Chronic Respiratory Questionnaire (CRQ), COPD Assessment Tool (CAT) and the Hospital Anxiety and Depression score (HAD). A 6 minute walk test (6MWT) will be carried out as this is a widely used and well validated tool to measure exercise capacity. A handheld dynamometer will be used to obtain more detailed measures of quadriceps muscle strength. In addition we will measure activity at home during and after PR using pedometers as this has never been investigated previously.These are simple devices that can be attached to patients and count the numbers of steps during a day and therefore provide an estimate of activity in the home environment. A yamax Digi-walker SW-200 pedometer will be used to count the number of steps taken per day. Patients will be instructed to wear the device on left side of the body all the time, except when sleeping or showering. Pedometer placement was standardised by placing it on the belt or waistband, in the midline of the thigh, consistent with the manufacturers recommendation and with other studies conducted previously. Patients will be record daily step counts on daily diary cards until their final follow up.

The measures of exercise capacity at the follow up assessment will be carried out off oxygen and will be carried out by an observer blinded as to whether they received oxygen or not during PR. All patients will be provided with ambulatory oxygen for domiciliary use after completing PR.

The hypothesis is that use of oxygen in selected patients improves exercise capacity during PR. The measurable aims will be exercise capacity and on-going usage of oxygen in this patient group.

Primary Objective

Assess the effects of ambulatory oxygen on outcomes from Pulmonary Rehabilitation

Secondary Objectives

1. Assess the proportion of patients that wish to continue to use ambulatory oxygen.
2. Assess the usage of ambulatory oxygen following completion of Pulmonary Rehabilitation
3. Assess whether initiation of ambulatory oxygen before or after PR has any influence on adherence to usage at 8 and 12 weeks.

Eligibility Criteria:
Inclusion Criteria:

1. A confirmed diagnosis of Chronic Obstructive Pulmonary Disease (COPD)
2. Fulfil the clinical criteria for Pulmonary Rehabilitation (PR)
3. Demonstrate exercise-induced desaturation (defined as a fall in SaO2 ≥4% to at least \<90%, or any fall to a SaO2 \<90%) and demonstrate positive improvement with use of ambulatory oxygen as per the British Thoracic Society 2015 Oxygen Guidelines

Exclusion Criteria:

1. Use of long term oxygen therapy
2. Unable to provide informed consent
3. Significant respiratory disease other than COPD
4. Any patient needing more than 6 litres per minute oxygen to correct desaturation
5. Severe desaturation: SaO2 \< 80% during 6 Minute Walk Test
6. Any absolute contraindication to Pulmonary Rehabilitation