Bronchial asthma, is a disease caused by increased responsiveness of the tracheobronchial tree (passageway for air within the lungs) to assorted stimuli resulting in spasm or constriction or swelling or both of the bronchial tubes.

The condition may be caused by allergens inhaled from the air or respiratory infections or both that subsequently result in spasm of the airway smooth muscle, swelling of the mucosa, and constriction of the bronchi.

The occurrence and severity of symptoms vary from patient to patient, and from incident to incident. Some patients may have episodes that are mild and brief, while others have episodes of coughing and wheezing much of the time. Generally, an attack is characterized by acute episodes of wheezing, coughing, and shortness of breath, or it may occur gradually with increasing respiratory distress. Severe episodes may result in cyanosis and progressive respiratory failure.

Physical examinations are usually normal between attacks. During an attack, auscultation of the lungs reveals wheezing throughout the lung fields on expiration and, at times, on inspiration, and absent or diminished breath sounds during severe obstruction. Loud bilateral wheezes may be grossly audible, and the chest is hyperinflated (containing excess air). The following tests are included:

• Chest x-ray reveals hyperinflated lungs with air-trapping during an attack, and normal findings during remission.

• Sputum analyses demonstrate presence of Curschmann's spirals (coiled spirals of mucus), Charcot-Leyden crystals (colorless, hexagonal, double-pointed and often needle-like crystals), and eosinophils (cell or cellular structure that stains readily with the acid stain eosin).

• Pulmonary function tests (PFT) reveal that during attacks, there is decreased forced expiratory volume (FEV-1), which improves significantly after a bronchodilator is inhaled; increased residual volume (air remaining in lungs after maximum exhalation); and, occasionally, the total lung capacity may be normal between attacks.

• Arterial blood gas (ABG) studies reveal decreased oxygen levels; decreased, normal, or increased carbon dioxide levels (in severe attacks).

• Electrocardiogram (EKG) demonstrates sinus tachycardia during an attack. A severe attack may produce signs of cor pulmonale which resolve after the attack.

• Allergen identification involves skin tests, history of allergic reactions, inhalation methods, etc.

Treatment is designed to prevent the development of chronic symptoms, to maintain pulmonary function as near to normal as possible, to maintain normal activity, and to prevent exacerbations. In addition, the medications used are bronchodilators or other drugs in combination such as adrenergic agents, corticosteroids, or anticholinergics. Furthermore, persistent asthma (status asthmaticus) may require adrenocortical hormone treatment, which, with prolonged use, will lead to the development of serious side effects. Moreover, medications known as leukotriene modifiers work by blocking substances called leukotrienes that are powerful constrictors of the bronchi. Finally, avoidance of excessive exertion, cold air, or allergic agents (e.g., dust, molds, pollen, and animal dander), and identification and elimination of causative factors also constitute treatment strategies.

Patients may have mild, moderate, or severe exacerbations. Some patients with sporadic episodes may have life-threatening occurrences separated by extended periods of no symptoms, or mild symptoms, and normal pulmonary function. Depending on the severity of the condition, long-term therapy varies. Some patients require no daily treatment. Others may require several medications at relatively high doses for extended periods of time.

• 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).

• Diseases of allergic etiology, including bronchial asthma and urticaria, may not be disposed of routinely for compensation purposes as constitutional or developmental abnormalities. Service connection must be determined on the evidence as to existence prior to enlistment and, if so existent, a comparative study must be made of its severity at enlistment and subsequently. Increase in the degree of disability during service may not be disposed of routinely as natural progress nor as due to the inherent nature of the disease. Seasonal and other acute allergic manifestations subsiding on the absence of, or removal of the allergen are generally to be regarded as acute diseases, healing without residuals. The determination as to service incurrence or aggravation must be on the whole evidentiary showing – 38 CFR 3.380.

• Review 38 CFR 3.809a for eligibility for entitlement to Special Home Adaptation grants under 38 U.S.C. 2101(b)

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

• Consider entitlement to service connection based on presumed exposure to fine particulate matter under 38 CFR 3.320

• In the absence of clinical findings of asthma at time of examination, a verified history of asthmatic attacks must be of record.

• Review special provisions regarding the evaluation of specific respiratory conditions under 38 CFR 4.96(a)- Rating co-existing respiratory conditions