Montgomery County Fire & Rescue Asthma Info

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What is Asthma?

ANATOMY

Air enters the respiratory system through the nose (nasopharynx) and mouth (oropharynx) and passes through the larynx (voice box) into the trachea. At the carina, the trachea branches into the left and right main stem bronchus. The bronchioles branch off of the bronchi and terminate in a cluster of tiny air sacs called the alveoli. The alveoli are covered with capillaries which receive the oxygen from the air in the alveoli and diffuse the carbondioxide into the alveoli to be exhaled.

NORMAL

What is asthma?

ASTHMATIC

Asthma is reactive airway disease, a disease in which the smaller airways react in response to a trigger such as an allergen or an irritant. It is airway hypersensitivity with recerrent, reversible airway inflammation, broncho-constriction (bronchospasm), and mucus gland secretion and hypertrophy (enlargement) of the bronchial muscle. Asthma is a chronic-episodic order: The underlying predisposition to asthma may be chronic, but attacks occur episodically in response to some type of trigger.

Compare the normal bronchus on the left with the asthmatic bronchus on the right.

Bronchospasm is usually characterized by wheezes and prolonged expiration. The normal respiratory cycle is about 1/3 inspiration and 2/3 expiration, or an inspiration/expiration ratio of 1:2. In the asthmatic experiencing bronchospasm, the inspiration/expiration increases to, for example, 1:4 due to the prolonged expiratory phase.

Cardiac Asthma is a term sometimes used to describe congestive heart failure (CHF). While CHF patients usually have a chief complaint of difficulty breathing and have copious amounts of fluid in the lungs, they do not have the bronchospasm associated with respiratory asthma. A key difference in the presentation of CHF is that most patients maintain an inspiration/expiration ratio of 1:1 or 1:2 rather than experience the prolonged expiration phase of bronchospasm.

Click here to listen to lung sounds, including wheezes

Common Asthma Triggers

Allergens: Cats/cat hair - Dogs/dog hair - feathers - foods - grass - hay - house dust (mites) - medications - molds - pollen - roaches - trees - weeds

Chemicals: Colognes/perfumes - cosmetics/hair sprays/lotions - detergents/soaps - vehicle exhaust fumes - household & industrial cleaners - outside dust - paint products/strippers/thinners

Weather: Cold weather - rapid temperature changes - in and out of buildings temperature changes

Emotional Stress

Infections, especially respiratory infections

Ingestants: alcohol - spicy foods

Irritants: Tobacco smoke - smoke from burning - harsh chemicals

Physical Exercise (exercise induced asthma)

Asthma Statistics

Centers for Disease Control & Prevention reports that asthma:
affects 4.8 million children under 18 years old

accounts for 1 in 6 pediatric Emergency Department visits

is the #1 cause of hospitilization in children under 15 years old (200,000/year)

death rate rose 78% in patients under 19 years old between 1980 & 1993

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death rate per 100,000 aged 5-34 years has nearly tripled since 1979