SPECIAL SELECTED TOPICS- RESPIRATORY SYSTEM DISORDERS-SSTRSDO-QAA 008
1. Define
the types of chronic bronchitis.
Chronic bronchitis is defined as a productive cough lasting
for at least three months in each of two consecutive years after excluding
other causes. Simple chronic bronchitis is characterized by chronic sputum
production without significant airflow obstruction.
Chronic obstructive bronchitis is associated with persistent
airflow limitation and forms part of COPD. Chronic asthmatic bronchitis
combines chronic bronchitis with bronchial hyperresponsiveness. Smokers
commonly develop chronic obstructive bronchitis.
Mucus gland enlargement and goblet cell hyperplasia are
characteristic pathological features. Recurrent respiratory infections worsen
airway inflammation.
Progressive airflow
limitation eventually develops in many patients. Chronic bronchitis remains a
major preventable respiratory disease associated with tobacco smoking.
2. List
the factors important for the pathogenesis of chronic bronchitis.
Chronic bronchitis develops mainly due to prolonged
irritation of the bronchial mucosa by cigarette smoking, which is the most
important risk factor. Air pollution, biomass fuel smoke, occupational dust,
and chemical fumes also contribute. Recurrent respiratory infections aggravate
airway inflammation but are usually secondary factors.
Chronic irritation causes hypertrophy of mucus glands and
hyperplasia of goblet cells, resulting in excessive mucus secretion. Impaired
ciliary function reduces mucociliary clearance and promotes mucus retention.
Persistent inflammation leads to edema, fibrosis, and
narrowing of small airways. Airflow obstruction gradually develops and becomes
irreversible. Repeated infections accelerate disease progression.
These changes ultimately produce chronic productive cough and
progressive respiratory disability.
3.
Discuss the pathologic characteristics of chronic bronchitis.
The bronchi are hyperemic, swollen, and filled with thick
mucus. The bronchial mucosa shows chronic inflammation with infiltration by
lymphocytes, macrophages, and plasma cells.
Hypertrophy of submucosal mucus glands is a characteristic
feature. Goblet cell hyperplasia extends into the small bronchi and
bronchioles. Excess mucus forms plugs that obstruct the airway lumen.
Chronic inflammation leads to fibrosis and thickening of the
bronchial wall. Smooth muscle hypertrophy may also develop. The Reid index is
increased above 0.5 because of enlarged mucus glands. Secondary bacterial
infection is common.
These pathological changes result in persistent airflow
obstruction and impaired ventilation.
4. What
are the clinical consequences of chronic bronchitis?
The hallmark symptom is a chronic productive cough with
excessive sputum production. Patients experience progressive dyspnea as airflow
obstruction worsens. Wheezing and prolonged expiration are common findings.
Recurrent respiratory tract infections occur because of
impaired mucus clearance. Persistent hypoxemia leads to cyanosis and reduced
exercise tolerance. Pulmonary hypertension develops due to chronic hypoxic
vasoconstriction. Right ventricular hypertrophy and cor pulmonale may occur in
advanced disease. Acute exacerbations often require hospitalization.
Respiratory failure may develop during severe exacerbations.
Overall quality of life gradually declines without appropriate treatment.
PROFESSOR OF MEDICINE
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