chronic bronchitis

introduction

normally, about 500mL of sputum is produced each day, and it is usually not noticed. Smokers with chronic bronchitis produce larger amounts of sputum each day, as much as 100 mL/d more than normal.
chronic bronchitis is defined clinically as cough with sputum expectoration for at least 3 months a year during a period of 2 consecutive years not due to another defined cause (eg. tuberculosis (TB))
more common in those over 50 years of age
chronic bronchitis is associated with hypertrophy of the mucus-producing glands found in the mucosa of large cartilaginous airways. As the disease advances, progressive airflow limitation occurs, usually in association with pathologic changes of emphysema resulting in chronic obstructive pulmonary disease (COPD) and cor pulmonale.
Patients with chronic bronchitis have a greater frequency of acute respiratory infections than those without bronchitis, and with symptoms of an acute upper respiratory infection they are more likely to have signs of infection in the lower airways than are healthy control subjects.

generally caused by a combination of:
- chronic inhaled irritants
- genetic factors
- other host factors such as respiratory infections
cigarette smoking accounts for 85-90% of chronic bronchitis and chronic obstructive pulmonary disease
repeated episodes of acute bronchitis
inhalational occupational exposures may also be a cause:
- coal
- manufactured vitreous fibers
- oil mist
- cement
- silica
- silicates
- osmium
- vanadium
- welding fumes
- organic dusts - cotton (byssinosis), jute, hemp, flax, sisal, wood, and various grains.
- engine exhausts
- fire smoke
- fumes of cooking fuels in enclosed spaces
- secondhand cigarette smoke (passive smoking)

avoidance of inhaled irritants, especially cigarette smoke
- 90% of patients smoking-induced chronic cough will have resolution of their cough after smoking cessation.
prophylactic vaccinations for influenza, pneumococcal pneumonia

therapy with short-acting beta 2 adrenergic agonists should be used to control bronchospasm and relieve dyspnea; in some patients, it may also reduce chronic cough.
therapy with ipratropium bromide should be offered to improve cough.
treatment with theophylline should be considered to control chronic cough, careful monitoring for complications is necessary.
treatment with a long-acting beta 2 adrenergic agonists when coupled with an inhaled corticosteroid should be offered to control chronic cough.
if FEV1 of < 50% predicted or for those patients with frequent exacerbations of chronic bronchitis, inhaled corticosteroid therapy should be offered.
central cough suppressants such as codeine and dextromethorphan are recommended for short-term symptomatic relief of coughing.
long-term maintenance therapy with oral corticosteroids such as prednisone should not be used; there is no evidence that it improves cough and sputum production, and the risks of serious side effects are high.
there is no role for long-term prophylactic therapy with antibiotics
the clinical benefits of postural drainage and chest percussion have not been proven, and they are not recommended.
there is no evidence that the currently available expectorants are effective and therefore they should not be used.

early Rx of acute infective exacerbations with antibiotics
therapy with short-acting beta 2 adrenergic agonists or anticholinergic bronchodilators should be administered during the acute exacerbation. If the patient does not show a prompt response, the other agent should be added after the first is administered at the maximal dose.
a short course (10 to 15 days) of systemic corticosteroid therapy should be given; IV therapy in hospitalized patients and oral therapy for ambulatory patients have both proven to be effective.
there is no evidence that the currently available expectorants are effective, and therefore they should not be used.
theophylline should not be used for treatment.
the clinical benefits of postural drainage and chest percussion have not been proven, and they are not recommended.