COPD is a condition associated with progressive loss of lung function, accompanied by marked disability, especially in those patients with more severe COPD.
A number of pharmacological interventions have been shown to improve quality of life in COPD patients but the most significant changes in health status can be seen after pulmonary rehabilitation. Long-term oxygen therapy is one of the few interventions that can reduce mortality.
The new home oxygen service in England and Wales has enabled the prescription of three main modalities of home oxygen therapy.
Long-term oxygen therapy
Long-term oxygen therapy is prescribed to patients for continuous use at home through an oxygen concentrator for usually 15 hours per day including night time.
In addition to reducing mortality, long-term oxygen therapy improves quality of life, sleep quality and neuropsychological function.
COPD patients suitable for long-term oxygen therapy are those with chronic hypox-aemia, defined as a partial pressure of oxygen in arterial blood (PaO2) at or below 7.3kPa (55mmHg).
In COPD, long-term oxygen therapy is normally given life-long in order to keep PaO2 levels above 8kPa (60mmHg). A low flow rate, usually of two litres per minute, is used though this may be altered depending on the degree of hypoxaemia and hypercapnia.
Long-term oxygen therapy can also be prescribed in chronic hypoxaemia patients with a clinically stable PaO2 of between 7.3kPa and 8kPa, together with secondary polycythaemia, nocturnal hypoxaemia defined as oxygen saturation of arterial blood (SaO2) less than 90 per cent for more than 30 per cent of the time, peripheral oedema or pulmonary hypertension.
COPD patients who require long-term oxygen therapy need to be identified in primary care. They usually have an FEV1 below 40 per cent predicted and may show evidence of peripheral oedema. Such patients should have oximetry performed in primary care and if their SaO2 is at or below 92 per cent predicted, then these patients require referral to a specialist assessment centre for measurement of arterial blood gases and oxygen prescription.
Ambulatory oxygen therapy
Ambulatory oxygen therapy is indicated when COPD patients develop hypoxaemia during exercise and while performing their daily activities.
Most patients requiring ambulatory oxygen therapy will already be on long-term oxygen therapy and have chronic hypoxaemia. The type and amount of ambulatory oxygen required will depend on the patient's mobility and need to leave the home.
Full specialist assessment is required for any patient who is a candidate for ambulatory oxygen therapy.
Some patients may have a PaO2 above 8kPa at rest, but show evidence of arterial oxygen desaturation in oximetry during exercise. In this situation the need for ambulatory oxygen needs to be carefully assessed.
Short-burst oxygen therapy
Short-burst oxygen therapy refers to the intermittent use of supplemental oxygen at home for the relief of breathlessness in patients who are not hypoxaemic. It is usually provided by static cylinders for periods of 10-20 minutes.
There is little evidence available for benefit in COPD patients and this form of therapy should be used only when other established COPD therapies for breathlessness have been tried.
Pulmonary rehabilitation plays a key role in the management of COPD patients, improving exercise capacity, health-related quality of life and breathlessness, and reducing length of hospital stay and number of hospitalisations.
Although evidence suggests that no change in FEV1 occurs as a result of pulmonary rehabilitation, important changes in self-efficacy (for example in functional capacity and confidence in coping with the disease) have been demonstrated.
Both NICE guidance and a Cochrane review strongly support the use of pulmonary rehabilitation in patients with COPD.
Recent evidence suggests that early rehabilitation following an exacerbation of COPD has clinical benefits. Here the challenge is provision of effective early rehabilitation programmes.
Pulmonary rehabilitation is a multidisciplinary programme that aims to optimise COPD patients' functional capacity and empower management and coping strategies.
Guidelines for pulmonary rehabilitation suggest an optimal programme length of six to eight weeks, consisting of graded exercises, disease education, psychological and social intervention.
Clear aims should be discussed with the patient prior to pulmonary rehabilitation and appropriate goals agreed.
Exercise programmes usually include a variety of upper and lower limb exercises, often performed on an interval basis, with training intensity set at 60-70 per cent of maximal oxygen uptake.
During exercise, patients are encouraged to monitor their levels of performance and breathlessness.
Patients are also encouraged to perform exercises once they get home so programmes should include functional exercises that can be easily reproduced in the home setting.
Patients referred to pulmonary rehabilitation must be in a stable state of their disease, have had their medical therapy optimised, be capable of participating in a group class and be motivated to attend.
Units offering pulmonary rehabilitation will have identified criteria for acceptance, which may include ability to attend for the period of the programme.
Patients requiring oxygen therapy during exercise should not be excluded from programmes and assessment for ambulatory oxygen can be performed as part of attendance at pulmonary rehabilitation.
Exclusion criteria should be considered and co-morbidities, such as unstable angina or recent MI, taken into account.
Pulmonary rehabilitation is effective in both primary and secondary care. Basic protocols should be in place that outline procedures for the care and safety of patients.
More severe patients who require oxygen therapy to exercise may be suited to an acute setting, but the benefits of pulmonary rehabilitation in the community is that patients may be seen closer to home.
In some areas local classes are provided in non-clinical settings, such as gyms, supervised by trainers taught to manage patients with breathlessness.
Ms Mikelsons is a consultant cardiorespiratory physiotherapist and Professor Wedzicha is professor of respiratory medicine at Royal Free Hospital, London
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