REVIEW ARTICLE

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THE ROLE OF GENERAL PRACTITIONERS IN HOME OXYGEN THERAPY

Evidence of benefits
Review of existing literature by the Association of Palliative Medicine Scientific Committee (APMSC)¹⁰ reveals that:

1. The British Thoracic Society (BTS) guidelines recommend the use of long-term oxygen therapy (LTOT) in specific patients with COPD to improve survival rather than palliation of breathlessness. Trials tend to use quality and quantity of life measures rather than breathlessness per se as the desired outcome.
2. Short bursts and ambulatory oxygen are widely prescribed to relieve breathlessness of COPD but there are no data to support or refute this practice.
3. In patients with advanced cancer, oxygen is commonly used in the palliation of breathlessness without clear evidence of its efficacy.
4. There is insufficient evidence for use of oxygen for breathlessness in patients with chronic heart failure.

SUPPORTIVE ROLE OF GENERAL PRACTITIONERS

General practitioners (GPs) play an important role in providing patient education and support for patients and family members. Information on how to purchase oxygen sources, its various modes of delivery, and advice on precautions to be taken while keeping oxygen at home are helpful to them. There are many modalities that are useful for treatment of breathlessness. Efforts to minimize anxiety can provide comfort. Bright, airy, spacious room and open windows help to decrease a sense of breathlessness. Recumbent position on a declining chair, relaxation technique, distraction therapy, hypnosis, massage, aromatherapy and acupuncture may make the patient feel better.

Some authors proposed that the reductions in breathlessness could be due to cool air that is directed against the cheeks to stimulate the 2nd and 3rd branch of the trigeminal nerve that in turn will have an inhibitory effect on the cerebral cortex.¹¹ Movement of gases (either air or oxygen) across nasal receptors may also have the same effect.¹² A simple fan blowing cool air on the face is more effective for relief of breathlessness than a 100% non-rebreather mask11 Patient’s report of breathlessness offers opportunity to explore fears related to the illness or other aspects of patient’s life.¹

Therapeutic management of underlying causes should be given priority. Dexamethasone and radiotherapy are useful for shrinking the tumor mass that is obstructing the airway and for relieving superior vena obstruction and lymphangitis carcinomatosis. Antibiotics are used to treat lung infections; bronchodilator and steroid inhalation are indicated for obstructive airways disease; diuretics with or without angiotensin converting enzyme inhibitors are useful for congestive cardiac failure. Blood transfusion can provide transient relief of breathlessness due to anaemia; benzodiazepines may reduce panic attacks that invariably accompany the patient’s fear of being choked to death. Pleural and peritoneal tapping can be performed for massive pleural effusion and ascites that are compressing on the diaphragm and lung parenchyma. For symptomatic relief of breathlessness itself, opioids are indicated as first line treatment not only for those with terminal cancer but also of other causes. Anxiolytics and neuroleptics can also be useful.¹

Supervisory role in LTOT and ambulatory oxygen therapy in chronic hypoxaemia
Patients with COPD, interstitial lung disease, bronchiectasis, and severe asthma have slow descent into breathlessness, are older by the time they have severe disease. Over the years they become familiar with doctors, nurses, hospitals and oxygen equipment; hence it may not be too difficult for them to cope with the complex task of delivery of LTOT.⁹

Long-term oxygen therapy is the only intervention known to increase life expectancy in patients with COPD.¹³ When used in conjunction with pulmonary rehabilitation, it also improves quality of life. Specific benefits include amelioration of cor pulmonale, polycythaemia and pulmonary hypertension, improved neuropsychiatric function, exercise performance and skeletal-muscle metabolism, enhanced cardiac function, increased body weight, and reduced need for hospitalization and possible reversal of sexual impotence.¹⁴

GPs are required to refer patients to a respiratory physician for LTOT and ambulatory oxygen prescription. Appropriate assessment for LTOT requires consideration of 3 factors5:

1. Clinical diagnosis of the disorder associated with chronic hypoxaemia
2. Optimum medical management of the particular condition and clinical stability for at least 5 weeks prior to assessment
3. Arterial blood gas tensions must be measured

For ambulatory oxygen therapy, assessments are performed after pulmonary rehabilitation and are currently designed around the short-term response to supplemental oxygen therapy, when the patient is performing an exercise test such as a 6-minute walking test or a shuttle test. 5 Oximeters are used to record SaO2 during exercise. Supplemental oxygen flow rate that is required to maintain the SaO2 above 90% is noted. Walking distance and measurement of resting / end exercise breathlessness are made using Borg score or Visual Analogue Score.