Chronic bronchitis is characterized by over-secretion of mucus, changes in the structure of the bronchi, including inflammation, changes in the tissues of the epithelium, and enlargement of the mucous glands that cause a chronic productive cough for at least three months over two successive years.

Chronic bronchitis follows extended exposure of the tracheobronchial tree to irritants, e.g., dust, cigarette smoke, viral or bacterial infections, or chemical irritants like ammonia.

Increased cough, sputum with pus, wheezing, dyspnea, and occasionally fever may occur from time to time. With progression of the disease, the time between recurrence of symptoms tends to become shorter. Late in the disease, a worsening of symptoms may cause severe hypoxemia with cyanosis, which is accentuated if erythrocytosis is present. Morning headache may indicate hypercapnia. The end-stage of the disease is indicated when hypercapnia, with severe hypoxemia, develops with erythrocytosis. In addition, weight loss occurs in some patients. Hemoptysis may occur. It is usually due to tissue erosion.

Chest x-rays are done to exclude other diseases, e.g., lung cancer. Spirometry is used to measure the obstructive component of the disease. Pulmonary function tests show the distinctive pattern of volume-dependent airway obstruction. Obstruction is usually considered present when the forced expiratory volume in one second (FEV-1) is less than 80% of the forced vital capacity (FVC). Arterial blood gas (ABG) levels are typically abnormal in moderate and severe chronic obstructive pulmonary disease (COPD) due to chronic bronchitis or other obstructive diseases. Basically, ABGs are done to detect hypoxemia and hypercapnia.

Underlying causes are targeted in treatment, and treatment depends on severity of the condition. Environmental irritants are avoided. The primary goal of drug therapy is to reduce dyspnea. Other treatment goals aim to control cough and sputum production. Preventive measures are instituted to prevent influenza and bacterial infections, e.g., receiving annual influenza vaccinations, and a pneumococcal vaccination every 5-10 years. In addition, patients are placed on antibiotics at the first sign of purulent sputum. Moreover, increased use of bronchodilators and oral corticosteroids may also be necessary if a patient is experiencing an acute infection. Generally, patients should receive long-term home oxygen supplementation if the PaO2 is 55 mm Hg or less, or if the PaO2 is 56-59 mm Hg accompanied by symptoms that suggest cardiac involvement, e.g., peripheral edema or elevated blood count. In addition, for cases of right-sided heart failure or biventricular heart failure, treatment includes giving diuretics with caution, and correcting electrolyte imbalances, e.g., hypokalemia. Finally, ventilatory support may be indicated, if hypercapnia accompanied by rapidly rising levels of pCO2 and low levels of pH are revealed via ABGs, since this represents tired respiratory muscles.

Reoccurrence of bronchitis in patients with COPD usually results from viruses, Hemophilus influenzae, and Streptococcus pneumoniae. Acute hypoxemia that may occur with a respiratory infection may lead to confusion and restlessness. Uncorrected hypoxemia leads to pulmonary hypertension, cor pulmonale, reduced free water clearance in the kidney, arrhythmias, polycythemia, and altered mental status. Some patients with severe COPD survive up to 15 years after a diagnosis is made. Death is generally caused by medical complications, e.g., acute respiratory failure, severe pneumonia, pneumothorax, cardiac arrhythmia, or pulmonary embolism.

• May be entitled to special monthly compensation where the Veteran has a single service-connected disability rated as 100% with additional service-connected disability or disabilities independently ratable at 60% or more, which are separate and distinct from the 100% service-connected disability and involves different anatomical segments or bodily systems. See  38 CFR 3.350(i)(1) – Special Monthly Compensation (SMC).

• Consider entitlement to service connection based on chronic effects of exposure to mustard gas and Lewisite under 38 CFR 3.316(a)(2)

• Review special provisions regarding the evaluation of specific respiratory conditions under 38 CFR 4.96(a) - Rating co-existing respiratory conditions and 38 CFR 4.96(d) - Special provisions for the application of evaluation criteria for diagnostic codes 6600, 6603, 6604, 6825–6833, and 6840–6845.