Acute exacerbation of chronic obstructive pulmonary disease

An acute exacerbation of chronic obstructive pulmonary disease, or acute exacerbations of chronic bronchitis (AECB), is a sudden worsening of

It may be triggered by an infection with bacteria or viruses or by environmental pollutants. Typically, infections cause 75% or more of the exacerbations; bacteria can roughly be found in 25% of cases, viruses in another 25%, and both viruses and bacteria in another 25%. Airway inflammation is increased during the exacerbation resulting in increased hyperinflation, reduced expiratory air flow and decreased gas exchange.[1]^[2]

Exacerbations can be classified as mild, moderate, and severe.^[3] As COPD progresses, exacerbations tend to become more frequent, the average being about three episodes per year.^[4]

Signs and symptoms

An acute exacerbation of COPD is associated with increased frequency and severity of coughing.

In infection, there is often weakness, fever and chills. If due to a bacterial infection, the sputum may be slightly streaked with blood and coloured yellow or green.[5]

Causes

As the lungs tend to be vulnerable organs due to their exposure to harmful particles in the air, several things can cause an acute exacerbation of COPD:

• opportunistic pathogens like Pseudomonas aeruginosa and Klebsiella pneumoniae.^[7]
• Allergens, e.g., pollens, wood or cigarette smoke, pollution^[5]
• Toxins, including a variety of different chemicals[5]
• Air pollution ^{[citation needed]}
• Failing to follow a
  drug therapy program, e.g. improper use of an inhaler ^{[citation needed}
  ]

In one-third of all COPD exacerbation cases, the cause cannot be identified. ^[citation needed]

Diagnosis

The diagnostic criteria for acute exacerbation of COPD generally include a production of sputum that is

A history of exposure to potential causes and evaluation of symptoms may help in revealing the cause the exacerbation, which helps in choosing the best treatment. A sputum culture can specify which strain is causing a bacterial AECB.^[5] An early morning sample is preferred.^[7]

E-nose showed the ability to smell the cause of the exacerbation.^[8]

The definition of a COPD exacerbation is commonly described as "lost in translation",^[9] meaning that there is no universally accepted standard with regard to defining an acute exacerbation of COPD. Many organizations consider it a priority to create such a standard, as it would be a major step forward in the diagnosis and quality of treatment of COPD.^{[citation needed]}

Prevention

Acute exacerbations can be partially prevented. Some infections can be prevented by vaccination against pathogens such as influenza and Streptococcus pneumoniae. Regular medication use can prevent some COPD exacerbations;

• Smoking cessation and avoiding dust, passive smoking, and other inhaled irritants^[5]
• Yearly influenza and 5-year pneumococcal vaccinations^[5]
• Regular exercise, appropriate rest, and healthy nutrition^[5]
• Avoiding people currently infected with e.g. cold and influenza^[5]
• Maintaining good fluid intake and humidifying the home, in order to help reduce the formation of thick sputum and chest congestion.^[5]

Treatment

Based on the severity different treatments may be used.^[3] Mild exacerbations are treated with short acting bronchodilators (SABDs). Moderate exacerbations are treated with SABDs together with antibiotics or oral corticosteroids, or both. Severe exacerbations need hospital treatment, and the prognosis is poor.^[3]

Oxygen

• Inhaled bronchodilators open up the airways in the lungs.^[17] These include salbutamol and terbutaline (both β₂-adrenergic agonists), and ipratropium (an anticholinergic).^[5] Medication can be administered via inhaler or nebuliser. There is no evidence to prefer a nebuliser over an inhaler.^[18]
• Antibiotics are used if a bacterial infection is the suspected cause.^[5] However, antibiotics will not treat exacerbations caused by viruses. Viral infections will usually be cured with time with the aid of proper rest and care. Still, other medications may be needed to control symptoms.^[5] Lipid-soluble antibiotics such as macrolides, tetracyclines, and fluoroquinolones penetrate the lung tissue well.^[7] Macrolides are more active against Streptococcus pneumoniae than the tetracyclines and the older fluoroquinolones.^[7] Within the macrolides, newer ones are more active against Haemophilus influenzae than the older erythromycin. Regimens should generally be given for five days.^[7]
  Choice of antibiotics is also dependent on the severity of the symptoms:
  • "Simple" COPD is generally where a person 65 years or less, has fewer than four exacerbations per year, has minimal or moderate impairment in respiratory function and no
    penicillin allergy, doxycycline or trimethoprim are preferred.^[7]
  • More complicated bronchitis may be when the patient is more than 65 years old, has four or more exacerbations per year, has an
    co-amoxiclav.^[7] Third-line treatment, as well as treatment in penicillin-allergic patients, is a fluoroquinolone such as ciprofloxacin.^[7] An agent active against Streptococcus pneumoniae may have to be added.^[7]
• Corticosteroids such as prednisolone reduce inflammation in the airways.^[17] According to a 2018 systematic review, a shorter, five-day course of systemic corticosteroids is likely comparable to longer (10–14 day) therapy for treatment of COPD exacerbation (Odds ratio (OR) 0.72, 95% confidence interval (CI) 0.36 to 1.46).^[19]
• Theophylline is generally not recommended.

There should also be a "care plan" in case of future exacerbations. Patients may watch for symptoms, such as shortness of breath, change in character or amount of mucus, and start self-treatment as discussed with a health care provider. This allows for treatment right away until a doctor can be seen.^[5]

The symptoms of acute exacerbations are treated using short-acting bronchodilators. A course of corticosteroids, usually in tablet or intravenous rather than inhaled form, can speed up recovery.

The incidence varies depending on which definition is used, but definitions by Anthonisen et al.[23] the typical COPD patient averages two to three AECB episodes per year.^[24] With a COPD prevalence of more than 12 million (possibly 24 million including undiagnosed ones) in the United States,^[25] there are at least 30 million incidences of AECB annually in the US.

References