Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality, morbidity and disability around the world. It is rapidly becoming the fourth biggest cause of death after cardiovascular diseases and cancer. The disease, commonly known as
chronic bronchitis, emphysema or chronic asthmatic bronchitis, is characterised by a poorly reversible, progressive reduction of ventilatory capacity, due to airflow limitation.
The most diffuse cause of COPD is smoking, although environmental, occupational and indoor pollution also play a role in its aetiology. The symptoms of the disease are a chronic cough, phlegm and exercise dyspnea.
Stopping smoking is the most successful way of slowing down the disease’s progression. But advanced-stage, long-term oxygen therapy (LTOT) increases survival rates for patients with severe chronic hypoxemia (PaO2 ≤55mmHg), provided that
oxygen is delivered for >15 hours a day and that SaO2 remains constantly at >90%.
However, prescription of LTOT has been extended, without supporting evidence, to COPD patients with moderate to mild hypoxemia (PaO2 >55 mmHg and <64mmHg), when associated with some clinical and laboratory signs, and to patients with decreased
oxygen saturation (SO2 <90%) during exercise or sleep (relative indications).
Whether the administration of oxygen in patients with relative indications increases survival or improves quality of life is an unresolved question. Pharmacotherapy with long-acting bronchodilators and, in some selected patients, inhaled
corticosteroids is effective in controlling symptoms and in reducing the frequency and severity of exacerbations, at any stage. In fact, the progression of COPD is accelerated by acute events, signalled by the worsening of symptoms and occasional fever.
This is an exacerbation of COPD.
Mild exacerbations can be treated at home, whereas the severe ones require hospital admission. In patients with severe COPD (a FEV1 <50% of the predicted value), the exacerbation may be associated with respiratory failure (PaO2/FiO2 <300mmHg)
without or with respiratory acidosis (PaCO2 >45mmHg and pH <7.36). Pharmacological therapy for an exacerbation of COPD is based on:
- Frequent inhalation (either by aerosol or MDI) of fast/short-acting bronchodilators, such as salbutamol and ipratropium
- The administration of wide-spectrum antibiotics for a few days
- Systemic use of (oral) corticosteroids
- The administration of oxygenenriched air if hypoxemia is present, to keep SaO2 at >90%
- The use of non-invasive positive pressure ventilation (NPPV) if PaCO2 >45mmHg and pH <7.36
If NPPV fails to improve respiratory acidosis within 2–4 hours, admission to an intensive care unit (ICU) and endotracheal intubation for conventional mechanical ventilation should be considered.
Several randomised controlled trials and high-level meta-analysis have shown that the early use of NPPV in COPD patients with respiratory failure, due to exacerbation, reduces in-hospital mortality significantly, as well as one-year mortality after
the exacerbation. The remarkable advances in our knowledge of the pathophysiology of respiratory failure in COPD, as well as improvements in the technology of the mechanical ventilators used for NPPV, have made the implementation of NPPV available
outside ICUs. Factors affecting the success of NPPV include the severity of the condition, the training and skill of the care teams and the pathophysiological knowledge of the physicians.
LTOT is the most effective treatment for chronic hypoxiemic respiratory failure. NPPV is an effective treatment for acute hypercapnic respiratory failure, provided that the hospital team is adequately trained on both the theoretical background and the
DIAGNOSIS AND PREVENTION
The treatment of an exacerbation of COPD is well established for the vast majority of patients, and follows widely accepted international guidelines. However, often an exacerbation of COPD goes undiagnosed and is not adequately treated because COPD
has not previously been diagnosed.
In fact, COPD is severely under-recognised, under-diagnosed and, consequently, under-treated – an effective smoking cessation programme is not offered to a patient, regular therapy is not prescribed. An exacerbation is often not immediately
recognised, and in the absence of adequate treatment, the severity of the exacerbation increases until hospital or even ICU admission is required.
In-hospital mortality for a severe exacerbation of COPD ranges from 8–15%, while the one-year mortality after hospital discharge can be as high as 40%. The best treatment for an exacerbation of COPD is prevention.
Smokers over 45 years old should undergo spirometry to assess whether a ratio of FEV.1/FVC <0.7 after inhaled bronchodilator suggests COPD. If FEV.1/FVC <0.7 and FEV.1 <80% of predicted value after inhaled bronchodilator, regular therapy with
long-acting bronchodilators can be used to reduce the frequency and severity of exacerbations. If FEV.1 <50%, inhaled corticosteroid should be added to long-acting bronchodilators to further reduce the frequency and severity of exacerbations.
Basic research on the pathobiological mechanisms underlying COPD should be encouraged in order to find better treatments for the disease. In the meantime, smoking cessation programmes and available pharmachotherapy should be offered to patients with
COPD. However, these interventions, which have been proved to be effective, require COPD to be recognised and diagnosed. Without diagnosis, COPD cannot be treated, exacerbation cannot be prevented, and the high mortality rate due to severe exacerbation
cannot be reduced.
The exacerbation of COPD is not only an unpleasant and dangerous event in a patients’ life. It also carries a major socioeconomic burden. Hospital admissions due to exacerbations of COPD account for more than 50% of the direct cost of the disease, which amounts to several millions (even billions) of dollars and euros. Early diagnosis, adequate treatment, and the effective prevention of COPD and exacerbations of COPD are a good deal for the patient and for the societies and economies of
which they are part.