Chronic obstructive pulmonary disease
Exacerbations

An acute exacerbation is a sudden worsening of signs and symptoms that lasts for several days. The key symptom is increased breathlessness, other more pronounced symptoms are of excessive mucus, increased cough and wheeze. A commonly found sign is air trapping giving a difficulty in complete exhalation. The usual cause of an exacerbation is a viral infection, most often the common cold. The common cold is usually associated with the winter months but can occur at any time. Other respiratory infections may be bacterial or in combination sometimes secondary to a viral infection. The most common bacterial infection is caused by Haemophilus influenzae. Other risks include exposure to tobacco smoke (active and passive) and environmental pollutants – both indoor and outdoor. During the COVID-19 pandemic, hospital admissions for COPD exacerbations sharply decreased which may be attributable to reduction of emissions and cleaner air. There has also been a marked decrease in the number of cold and flu infections during this time.

Smoke from wildfires is proving an increasing risk in many parts of the world and government agencies have published protective advice on their websites. In the US the EPA advises that the use of dust masks do not give protection from the fine particles in wildfires and instead advise the use of well-fitting particulate masks. This same advice is offered in Canada and Australia to the effects of their forest fires.

The number of exacerbations is not seen to relate to any stage of the disease; those with two or more a year are classed as frequent exacerbators and these lead to a worsening in the disease progression. Frailty in ageing increases exacerbations and hospitalization.

Acute exacerbations in COPD are often unexplained and thought to have many causes other than infections. A study has emphasized the possibility of a pulmonary embolism as sometimes being responsible in these cases. Signs can include pleuritic chest pain and heart failure without signs of infection. Such emboli could respond to anticoagulants.
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