Signs & Symptoms and Causes of Chronic bronchitis

Definition- Bronchitis

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. There are two major types of bronchitis, acute and chronic.

Definition-chronic bronchitis

Chronic bronchitis is defined as a cough that occurs every day with sputum production that lasts for at least three months, two years in a row. This definition was developed to help select uniform patients for research purposes i.e. to study medication therapies for treatment of chronic bronchitis. Many of the bronchi develop chronic inflammation with swelling and excess mucus production in chronic bronchitis; 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. 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 epithelial surface in such structures as the trachea, bronchial tubes, and nasal cavities to keep these hollow structures clear of particles and fluids. Mucus-producing cells increase due to irritation. These cells produce a viscous fluid that facilitates cleansing of the airway. If the mucus becomes thick (less fluid or viscous, it may contribute to airway blockage.
With long standing inflammation, as can be seen in chronic bronchitis, scarring inside the bronchial tree may develop. These scarred areas do not clear particles and secretions very well, and can result in a fixed, non reversible narrowing of the airway and the condition, 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.
COPD also includes the entities of emphysema, chronic bronchitis, and chronic asthma. These conditions are not always separable and patients often have components of each. In the case of chronic bronchitis, the fixed airway obstruction, airway inflammation and retained secretions can result in a mismatch of blood flow and airflow in the lungs. This can impair oxygenation of the blood as well as 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.

Causes

There can be 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. Some researchers suggest that about 90% of cases of chronic bronchitis are directly or indirectly caused by exposure to tobacco smoke.

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 as compared to cigarette smoking.


Signs & Symptoms

Cough and sputum production are the most common symptoms; they usually last for at least three 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 for chronic bronchitis, it should not be surprising that the most common presentation is 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.

Dyspnea (shortness of breath) gradually increases with the severity of the disease. Mucus plugs up and makes it hard for them to bresthe. 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.

In addition, symptoms of fatigue, sore throat, muscle aches, nasal congestion, and headaches can accompany the major symptoms. Severe coughing may cause chest pain; cyanosis (bluish/grayish skin coloration) may develop in people with advanced COPD. Fever may indicate a secondary viral or bacterial lung infection. When symptoms worsen or become more frequent, this is often referred to as an exacerbation of chronic bronchitis. These exacerbations often require antibiotics, and may need steroid medication and an increase in respiratory inhaled medications.

Diagnosis

Using a combination of a person's medical history, physical exam, and diagnostic tests. A history of a daily productive (sputum production) cough that lasts at least three 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 caregivers to hear wheezes, a sign of airflow obstruction.

A chest X-ray is often performed to help rule out other lung problems (for example, pneumonia, 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 exclude other conditions.

Reference:
http://www.medicinenet.com/chronic_bronchitis/article.htm#what
http://familydoctor.org/online/famdocen/home/articles/280.printerview.html
http://www.nlm.nih.gov/medlineplus/bronchitis.html