Bronchitis

Kenan Haver, MD, FAAP

Introduction/Etiology/Epidemiology

•Bronchitis is defined as inflammation of the bronchus or bronchi, triggered by infection or irritation from noxious stimuli (eg, cigarette smoke, pollution).

•It is a common feature of many acute and chronic pulmonary diseases.

•It overlaps with many common disorders (eg, asthma, allergies with postnasal drip, gastroesophageal reflux).

•Treatment without identifying the underlying cause is rarely effective.

•There are 4 types of bronchitis: acute, chronic, protracted bacterial, and (rarely) plastic bronchitis.

Acute Bronchitis

•Acute bronchitis is usually caused by a respiratory infection that manifests with cough, with or without phlegm production that lasts for ≤3 weeks.

•Initially, the cough is dry but can become productive; dyspnea may be present.

•Acute bronchitis is usually accompanied by a nasal discharge that

is watery at first; then, after several days, it may become thicker and colored or opaque. Change in consistency and/or color, by itself, does not indicate bacterial infection.

Chronic Bronchitis

•Bronchitis is considered chronic when it lasts for more than 3 or 4 weeks.

•Chronic bronchitis is often associated with underlying disease (eg, cystic fibrosis, primary ciliary dyskinesia, chronic aspiration).

Protracted Bacterial Bronchitis

•Protracted bacterial bronchitis (PBB) consists of cough associated with high colony counts of potentially pathogenic bacteria and neutrophils in the airway.

•It is seen more commonly in children with airway malacia; this is thought to be due to dynamic collapse that results in retention of bacteria and associated inflammation.

•Children with PBB may be at risk for chronic airway damage, including bronchiectasis.

•Plastic bronchitis is a rare condition seen most often in patients with congenital heart disease who have undergone a Fontan procedure, but it has been reported in children with asthma and sickle cell disease.

•Arborizing, thick, tenacious casts of the tracheobronchial tree produce airway obstruction that may be expectorated or require retrieval with bronchoscopy.

•Selective lymphatic duct embolization has been effective in selected cases of recurrent plastic bronchitis associated with heart disease.

Pathophysiology

•Cough is a normal response to irritation (eg, mechanical, chemical, or inflammatory) of the tracheobronchial tree, mediated by neural reflexes from the brainstem. Cough receptors are in the nose, sinuses, larynx, pharynx, trachea, large airways, ear canals, pleura, pericardium, and diaphragm.

•Resulting inflammation leads to edema and mucus production.

•Resolution typically occurs in 2 weeks.

•Acute bronchitis is most commonly associated with viral respiratory infections.

—Respiratory syncytial virus

—Adenovirus

—Influenza viruses

—Parainfluenza

•Bacterial infections and other pathogens are much less common, including

—Bordetella pertussis

—Mycoplasma pneumoniae

—Chlamydophila pneumoniae

Clinical Features