Chronic Bronchitis

Chronic bronchitis is defined as a cough that occurs every day with sputum production that lasts for at least 3 months, 2 years in a row.

Bronchitis is a term that describes inflammation of the bronchial tubes (bronchi and the smaller branches termed bronchioles) that results in excessive secretions of mucus into the tubes, leading to tissue swelling that can narrow or close off bronchial tubes. Bronchial tubes extend from the trachea and terminate at the alveoli in the lungs. The bronchial system resembles an inverted tree and is sometimes termed the "bronchial tree." A few authors include the trachea and upper airway in the definition of bronchitis.

There are two major types of bronchitis:

• Acute bronchitis
• Chronic bronchitis

Chronic bronchitis differs from acute bronchitis in several ways, for example, pathology, progression of disease, major causes, treatments, and prognosis. Recurrent incidences of acute bronchitis are the first steps that can lead to developing chronic bronchitis, according to some doctors and researchers.

Picture of the structures of the lungs

Chronic bronchitis is defined as a cough that occurs every day with sputum production that lasts for at least 3 months, two years in a row. This definition was developed to help select uniform patient populations for research purposes, for example, to study medication therapies for the treatment of chronic bronchitis.

Many of the bronchi develop chronic inflammation with swelling and excess mucus production. The inflammation causes a change in the lining cells of the airways to varying degrees. Many cells that line the airway lose the function of their cilia (hair-like appendages that are capable of beating rapidly), and eventually, the ciliated cells are lost. Cilia perform the function of moving particles and fluid (usually mucus) over the lining surface in such structures as the trachea, bronchial tubes, and nasal cavities to keep these hollow structures clear of particles and fluids. These ciliated cells that help in the clearance of secretions are often replaced by so-called goblet cells. This group of cells secretes mucus into the airway. The warm moist environment of the airway along with the nutrients in the mucus is an excellent medium for growing bacteria. The mucus often becomes infected and discolored from the bacterial overgrowth and the body's inflammatory response to it. The inflammation, swelling, and mucus frequently and significantly inhibit the airflow to and from the lung alveoli by narrowing and partially obstructing the bronchi and bronchioles.

The muscles that surround some of the airways can be stimulated by this airway irritation. This muscular spasm also known as bronchospasm can result in further airway narrowing. With long-standing inflammation, as can be seen in chronic bronchitis, this muscular spasm and inflammation result in a fixed, nonreversible narrowing of the airway, and the condition is termed chronic obstructive pulmonary disease (COPD). Chronic coughing develops as the body attempts to open and clear the bronchial airways of particles and mucus or as an overreaction to ongoing inflammation. Chronic bronchitis can be a progressive disease; symptoms (listed below) increase over time. Some NIH investigators consider chronic bronchitis a type of COPD.

COPD also includes the entities of emphysema and chronic asthma in addition to chronic bronchitis. These conditions are not always separable and patients often have components of each. In the case of chronic bronchitis, fixed airway obstruction, airway inflammation, and retained secretions can result in a mismatch of blood flow and airflow in the lungs. This can impair the oxygenation of the blood as well as the removal of the waste product, carbon dioxide.

Although people of any age can develop chronic bronchitis, the majority of people diagnosed with the disease are 45 years of age or older.

There are many causes of chronic bronchitis, but the main cause is cigarette smoke. Statistics from the US Centers for Disease Control and Prevention (CDC) suggest that about 49% of smokers develop chronic bronchitis and 24% develop emphysema/COPD.

• Many other inhaled irritants (for example, smog, industrial pollutants, and solvents) can also result in chronic bronchitis.
• Viral and bacterial infections that result in acute bronchitis may lead to chronic bronchitis if people have repeated bouts with infectious agents.
• Also, underlying disease processes (for example, asthma, cystic fibrosis, immunodeficiency, congestive heart failure, familial genetic predisposition to bronchitis, and congenital or acquired dilation of the bronchioles, known as bronchiectasis) may cause chronic bronchitis to develop, but these are infrequent causes compared to cigarette smoking.

The major risk factor for individuals to develop chronic bronchitis is tobacco smoking and second-hand tobacco smoke exposure. However, there are others, such as:

• Repeated exposure to pollutants (especially airborne materials such as ammonia, sulfur dioxide, chlorine, bromine, and hydrogen sulfide)
• Dust
• Repeated bouts of acute bronchitis or pneumonia
• Gastric reflux (by inhalation of gastric contents)

The major signs and symptoms of chronic bronchitis include:

• Cough and sputum production are the most common symptoms. They usually last for at least 3 months and occur daily. The intensity of coughing and the amount and frequency of sputum production vary from patient to patient. Sputum may be clear, yellowish, greenish, or occasionally, blood-tinged. Since cigarette smoke is the most common cause of chronic bronchitis, it should not be surprising that the most common presentation is the so-called smoker's cough. This is characterized by a cough that tends to be worse upon arising and is often productive of discolored mucus in the early part of the day. As the day progresses, less mucus is produced.
• Shortness of breath (dyspnea) gradually increases with the severity of the disease. Usually, people with chronic bronchitis get short of breath with activity and begin coughing; dyspnea at rest usually signals that COPD or emphysema has developed.
• Wheezing (a coarse whistling sound produced when airways are partially obstructed) often occurs.

Other signs and symptoms that may accompany chronic bronchitis include:

• Fatigue
• Sore throat
• Muscle aches
• Nasal congestion
• Headaches

Exacerbation of chronic bronchitis occurs when symptoms worsen or become more frequent. These exacerbations often require antibiotics and may need steroid medication and an increase in respiratory inhaled medications.

Signs and symptoms of exacerbation of chronic bronchitis include:

• Severe coughing that causes chest discomfort or chest pain.
• Cyanosis (bluish/grayish skin coloration) may develop in people with advanced COPD.
• Fever may indicate a secondary viral or bacterial lung infection.

Ideally, a person should seek medical care before chronic bronchitis develops. It is reasonable for people to seek care for tobacco addiction and the occasional chronic cough (occurring less than daily for 3 months) and to get medical help to potentially avoid developing chronic bronchitis. However, any daily cough that lasts for at least 3 months in a person should be investigated by a physician.

If a person develops a chronic cough (3 months or longer), difficulty breathing, sputum production, and other symptoms, it may represent the first bout of chronic bronchitis. Thus, seeking medical care may help slow or prevent the usual progression of the disease.

If a person with diagnosed chronic bronchitis (or COPD or emphysema) develops severe problems with breathing, cyanosis, or fever, they should seek emergency medical care immediately.

Healthcare professionals diagnose chronic bronchitis based on a person's medical history, physical exam, and diagnostic tests. A history of a daily productive (sputum production) cough that lasts at least 3 months, especially if has occurred two years in a row, fits the criteria for a clinical diagnosis of chronic bronchitis. The physical examination often allows healthcare professionals to hear wheezes and a prolongation of the exhalation of breathing, which are signs of airflow obstruction.

A chest X-ray is often performed to help rule out other lung problems (for example, pneumonia and bronchial obstructions). Additional tests such as a complete blood count (CBC), arterial blood gas measurements, CT scan of the chest, and pulmonary function tests are often done to characterize the structure and function of the lungs and to help exclude other conditions (for example, lung cancer, tuberculosis, other lung infections). Often a pulmonologist (a physician with specialized training in the management of lung diseases) can help diagnose and treat chronic bronchitis.

For the majority of cases, the initial treatment is simple to prescribe but frequently ignored or rejected by the patient – stop smoking cigarettes and avoid second-hand tobacco smoke. People should be encouraged in every way to cease smoking, as continuation will only cause further lung damage. Similarly, blocking or removing other underlying causes of repeated bronchial irritation (for example, exposure to chemical fumes) is a treatment goal. Half of the patients with chronic bronchitis who smoke will no longer cough after 1 month of smoking cessation.

Two major classes of medications are used to treat chronic bronchitis: bronchodilators and steroids.

1. Bronchodilators (for example, albuterol [Vent Olin, Proventil, AccuNeb, Vospire, ProAir], metaproterenol [Alupent], formoterol [Foradil], salmeterol [Serevent]) work by relaxing the smooth muscles that encircle the bronchi, which allows the inner airways to expand. Anticholinergic drugs also can act as bronchodilators, including tiotropium (Spiriva) and ipratropium (Atrovent).
2. Steroids (for example, prednisone, and methylprednisolone [Medrol, Depo-Medrol]) reduce the inflammatory reaction and thus decrease the bronchial swelling and secretions that in turn allow better airflow because of reduced airway obstruction. Often inhaled steroids are administered since they have fewer side effects than systemic (oral) steroids. Examples include budesonide (Pulmicort), fluticasone (Flovent), beclomethasone (Qvar), and mometasone (Asmanex). Combination therapy with both steroids and bronchodilators is often utilized. These include fluticasone/salmeterol (Advair), budesonide/formoterol (Symbicort), and mometasone/formoterol (Dulera).

PDE4 Inhibitors

Phosphodiesterase 4 (PDE4) inhibitors are a class of anti-inflammatory agents for certain exacerbations of COPD. They are primarily for exacerbations that involve excessive bronchitis and mucus production. Examples include roflumilast and cilomilast.

Antibiotics

Occasionally, antibiotics are used to treat chronic bronchitis exacerbations caused by bacterial infections. Broad-spectrum antibiotics are often the choice. Examples include:

• Fluoroquinolones (levofloxacin [Levaquin])
• Macrolides (clarithromycin [Biaxin], azithromycin [Zithromax, Zmax])
• Sulfonamides (sulfamethoxazole and trimethoprim [Bactrim])
• Tetracyclines (doxycycline [Vibramycin])

Of course, if a culture is obtained, directed therapy at the specific offending organism is always best.

Over-the-counter (OTC) cough suppressants

Over-the-counter (OTC) cough suppressants such as dextromethorphan (for example, Pertussin, Vicks 44, or Benylin) may help reduce cough symptoms. OTC preparations with guaifenesin (for example, Robitussin or Mucinex) may make patients feel more comfortable but there is no scientific evidence that it helps mucus to become less viscous.

What are other treatments for chronic bronchitis?

• Pulmonary rehabilitation is another treatment method that combines education and graded physical exercise. The education portion often includes smoking cessation techniques and the relationship of tobacco use to symptoms. Breathing techniques can be very helpful in overcoming the anxiety and discomfort of exacerbations. When chronic bronchitis is severe, airflow and blood flow may not move appropriately through the lungs. It is crucial for lung function that airflow and blood flow to the lung are precisely matched. When they are not, drops in oxygen and increases in carbon dioxide can result in profound negative consequences.
• Supplemental oxygen therapy may be an integral part of treatment. Often it is required with activity and sleep. Patients with severe disease may benefit from purchasing a small finger oximeter for monitoring blood oxygen levels at rest and with activity.

Certain "home remedies" may ease the symptoms of chronic bronchitis, such as:

• One of the lessons of pulmonary rehabilitation is to instruct patients on the proper path for air to follow. This involves breathing in through the nose so that the air is moistened, cleansed, and warmed by the function of the upper airways (sinuses). Air is then expelled through the mouth and in some cases with pursed lips to help optimize the lung's function.
• Cold air often aggravates coughing and difficulty breathing, so avoiding cold air or wearing a cold-air mask (such as a ski mask or face scarf) may help when in cold environments.
• Dry air also aggravates coughing so warm, humidified air may help by reducing coughing and also may allow mucus to flow more freely, which may result in better clearing of the bronchial airways and less blockage by viscous mucus.
• Alternative treatments have been suggested by some researchers with little or no evidence of any benefit, and some may even be harmful (for example, herbal teas, high doses of vitamin C, South African geranium herb, eucalyptus oil inhalation therapy, and many others). Check with your doctor or other healthcare professional before using any of these remedies or products.

Although the disease is chronic and progressive, affected individuals who are diagnosed early before much bronchial damage occurs stop smoking (or avoid airborne dust, chemicals, or other situations that lead to bronchial irritation), they often have a good prognosis for many years.

Approximately half of smokers with chronic bronchitis will stop coughing after 1 month of smoking cessation. Most patients will no longer cough with continued abstinence from smoking. If airflow obstruction has occurred, this can improve but the improvement level depends on the duration of injury and the compliance with therapy. The more impaired patients will have a lesser recovery of lung function.

Conversely, those individuals that have continued bronchial irritation have only a fair to poor prognosis, since repeated bouts with the disease usually get worse, with affected individuals having more frequent incidents of coughing and dyspnea over time and further progression of lung function abnormalities.

The major complications of chronic bronchitis include:

• Difficulty breathing, sometimes severe
• Respiratory failure
• Pneumonia
• Enlargement and weakness of the right heart ventricle of the heart caused by lung disease
• Pneumothorax (collection of air or gas in the lung causing lung collapse)
• Polycythemia (abnormally high concentration of red blood cells needed to carry oxygen)
• Chronic obstructive pulmonary disease (some NIH researchers consider chronic bronchitis a type of COPD)
• Emphysema
• Chronic advancement of the disease
• High mortality (death) rate (COPD is the fourth leading cause of death in the United States)

The majority of instances of chronic bronchitis can be prevented by not smoking and avoiding second-hand smoke. Flu and pneumococcal vaccines can help prevent repeated infections that may lead to the disease.

Certain industries (for example, chemical, textile, and farm workers) are often associated with air-borne chemicals and dust; avoiding air-borne chemicals and dust with appropriate masks may prevent or reduce the individual's chance of developing chronic bronchitis.

Good control of asthma may prevent chronic bronchitis from developing. The genetic predisposition to chronic bronchitis is not currently preventable.