-IBIS-1.5.0-
tx
respiratory system
asthma
diagnoses

definition and etiology

definition:
A hypersensitivity reaction causing brochospasm, mucosal edema and increased bronchial mucous secretion leading to respiratory distress.

etiology:
Asthma is most common in children under 10 years old, and is twice as common in males. It affects about 3% of the general population. Factors involved with asthmatic reactions include a variety of stimuli: URI; exercise; emotional upset; food sensitivities; inhalation of cold air or irritating substances (smoke, gas fumes, paint fumes); suppression of previously more minor diseases such as eczema or otitis media with drug therapy; and reactions to specific allergens, such as pollens.

There are two types of asthma:
extrinsic asthma: Also called atopic asthma, this is considered to be IgE-mediated. Attacks are mostly initiated by exposure to allergens: dust, molds, pollens, animal dander, and foods.

intrinsic asthma: This type does not seem related to an antigen-antibody complex. Rather, the bronchial reaction is due to other factors as mentioned above: cold air, exercise, infection, emotional upset and irritating inhalants.

Most patients seem to have a mixture of the two types, although it is thought that the allergic type is the more common asthma in infants and children.

signs and symptoms

signs and symptoms:
The symptoms and their degree of expression tend to vary greatly from individual to individual.

stereotypical attack:
• May begin acutely or gradually.
• Wheezing: High-pitched, through expiration and inspiration. NOTE: hearing no wheezes may indicate severe disease with marked mucous plugging and the beginning of respiratory failure.
• Coughing: Generally non-productive.
• Shortness of breath.
• Use of accessory muscles to breathe.
• Tachypnea.
• Anxiety.
• Increase systolic BP.
• Patient better sitting up or leaning slightly forward.
• Dehydration.
• Lengthened expiratory phase.

lab findings:
• Eosinophilia.
• Sputum: tenacious, rubbery, whitish.
• Chest x-rays may reveal hyperinflation or atelectasis (especially in young children).
• Pulmonary function tests (+) for asthma: decreased FEV1 and FVC (decreases are related to severity of attack)
• Decreased arterial PO2 and increased PCO2 (indicates possibly grave situation)
• (+) allergy testing.

course and prognosis

The course is usually chronic if the stimulating factors are not discovered and avoided, or the genetically weak lungs not strengthened. Some children with asthma outgrow it as they age. Complications include pneumothorax; mediastinal and subcutaneous emphysema; atelectasis; acute cor pulmonale; and status asthmaticus, a medical emergency. Conventional treatment consists of drug therapy for the acute attacks, prophylactic drugs to prevent attacks, and allergy shots once they have uncovered initiating antigens.

differential diagnosis

• Bronchitis.
• Pneumonia.
• Pleurisy.
• Emphysema.
• Foreign body aspiration or embolism.
• Cardiac asthma.
• Pneumothorax.


footnotes