Chronic obstructive pulmonary disease (COPD) is an umbrella term for a group of respiratory tract diseases that are characterised by airflow obstruction or limitation. It is usually caused by smoking.

Conditions included in this umbrella term are:

• chronic bronchitis
• emphysema
• bronchiectasis

Other names

COPD is also known as CORD, COAD, COLD, and many other acronyms, these three are short for chronic obstructive respiratory, airways, or lung disease. CAL refers to the same disease, and stands for chronic airway limitation.

Working definition

COPD is a chronic, slowly progressive disorder characterised by airways obstruction (FEV1 <80% predicted and FEV1 / VC ratio <70%) which does not change markedly over several months.

Causes

The main risk factor in making a diagnosis of COPD is smoking, which causes chronic inflammation of the main bronchi, thereby leading to airway obstruction. Other etiologies inculde alpha 1_antitrypsin deficiency and idiopathic disease.

Progression

COPD has 3 phases, mild, moderate and severe. The mild form has few signs or symptoms, although there may be occasional shortness of breath on exertion, recurrent respiratory infections and/or a morning cough. The moderate form still has few clinical signs but there are a few more acute symptoms, ranging from a productive cough, shortness of breath on moderate exertion and the acute worsening of of symptoms associated with respiratory infections. In the severe form, the patient may experience severe shortness of breath on minimal exertion (even at rest), is progressively disabling and there may be a constant cough and associate wheeze.

Diagnosis

The diagnosis of COPD is usually suggested by symptoms, that is, it is a clinical diagnosis and no one test is definitive. A comprehensive history from the patient, physical examination and the confirmation of airflow obstruction using spirometry is far more important than a chest X-ray.

The condition is characterised by an increased residual volume (the amount of air left in the lungs after a full breath out), but other lung volumes are usually decreased. The FEV₁/FVC ratio is decreased with COPD, meaning a person can't force out much air from their lungs in one second. (Normally someone can expire about 80% of their vital capacity in one second, this is reduced in COPD).

Management

"Management" is the preferred term used to describe the approach to COPD, rather than "treatment", as it is caused by a variety of separate conditions, the symptoms of which are managed to give the patient the greatest level of comfort. COPD itself is not treated, nor is it curable. However, emphysema is a potentially reversible aspect of COPD, while chronic bronchitis will get progressively worse over time.

By far the most common cause of COPD is tobacco smoking and approximately 15% of all chronic smokers will develop the disease. Thus, smoking cessation is one of the most important factors in slowing down the progression of COPD.

The use of bronchodilators, nebulisers and corticosteroids has been shown to be effective. Patients with chronic disease and significant lung function impairment (FEV1 < 50%) may also benefit from the regular use of inhaled steroids. Oxygen therapy, or non-invasive ventilation (NIV), has also been shown to be effective in the long-term management of severe COPD with low SaO2 (Oxygen saturation in arterial blood, shown as a percentage - normal is 96-98% - using a pulse oximeter).

Surgical management includes single lung transplant in a limited number of cases, which is becoming increasingly easier to perform, and lung volume reduction surgery (LVRS), which is currently being evaluated in a large, national trial in the UK.