PATHO CH. 22 – Obstructive Pulmonary Disorders

Part 1: Asthma

obstructive lung diseases are manifested by

increased resistance to airflow

classifications of obstructive lung diseases

• obstruction from conditions inside the wall of lumen

• obstruction from increasing pressure around the outside of the airway lumen

• obstruction of airway lumen

examples of obstruction insides wall of lumen

• asthma

• acute bronchitis

• chronic bronchitis

examples of obstruction related to increased pressure outside of the airway lumen 

• loss of lung tissue & elasticity

• enlarged lymph node

• tumor

• emphysema

examples of obstruction of the airway lumen

• presence of foreign body

• excessive secretions

• aspiration of fluids

• bronchiectasis

• bronchioilitis

• cystic fibrosis

• acute tracheobronchial obstruction

• epidlottitis

• croup syndrome

asthma 

lung disease characterized by

• airway obstruction that is reversible

• airway inflammation

• & increased airway reactivity to a variety of stimuli

most common chronic disease in children

asthma

high risk populations for asthma

• african americas

• inner city residents

• premature/low birth weight children

genetic predisposing factors for asthma

• atopy (chromosomes 5, 11, 14)

• structural (smaller airways)

non genetic predisposing factors for asthma

• history of hay fever, eczema

• family history of asthma

• positive skin test reactions to allergens 

types of asthma

• intrinsic

• extrinsic

intrinsic asthma

• adult onset

• non-allergic

• least common type

• no history of allergies

• related to respiratory infections or psychological factors

extrinsic onset

• pediatric onset

• allergic

• 1/3 to 1/2  asthma cases (more common type)

• IgE mediated response is common

exercise induced asthma

• common in both children & adults

• bronchospasm (bronchi narrow) occurs w/in 3 mins after exercise ends & resolved in 60 mins

[exercise induced asthma] heat loss, water loss, & increased osmolarity of the lower respiratory mucosa stimulate

mediator release from basophils & tissue mast cells = smooth muscle contraction

most common stimulators of exercise induced asthma

• running

• jogging

• tennis

IgE mediated allergic reactions

anaphylactic

allergic reactions that are not IgE mediated

anaphylactoid

occupational asthma

• positive skin reactions to protein allergens in the work environment 

• more severe attacks w/ subsequent exposure

• symptoms may clear outside of work and recur upon return

drug induced asthma

• can produce symptoms from mild rhinorrhea (runny nose) to respiratory arrest (breathing stops) requiring mechanical ventilation

• ingestion of aspirin for patients w/ nasal polyps, sinusitis, & asthma

• not immunologically mediated, so skin testing is not useful

food additives that can induce asthma

• tartrazine (yellow dye no.5)

• monosodium glutamate (MSG)

• sodium or potassium

• hops in beer

natural MSG in

• tomatoes

• grapes

• mushroom

which disease can trigger an asthma attack

gastroesophageal reflux disease (GERD)

• gastric acid reflux in esophagus aspirates into lungs & results in bronchoconstriction

immunohistopathologic features of asthma

• denudation (loss of outside layer) of airway epithelium

• collagen deposition beneath basement membrane

• edema (swelling from accumulation of fluid)

• mast cell activation

• inflammatory cell infiltration by neutrophils, eosinophils, & lymphocytes

the most important inflammatory mediator

cytokines

[asthma] chemical mediators that are released upon mast cell activation

• histamine

• leukotrienes (slow reacting substances of anaphylaxis)

• prostaglandins

• bradykinins

• serotonin

• eosinophilic chemotactic factor

[asthma] inflammation of the airway contributes to

• acute bronchospasm (bronchoconstriction)

• mucosal edema

• mucous plug formation

• airway wall remodeling (thickening of basement membrane)

clinical manifestations of asthma

• wheezing

• feeling of tightness in chest

• dyspnea (shortness of breath)

• cough

• increased sputum (saliva & mucus) production

• hyperinflated chest

• decreased breath sounds

• tachycardia

[asthma] a cough is the earliest sign of

exacerbation of asthma

[asthma] tachycardia an early sign of

hypoxemia

clinical manifestations of a severe asthma attack

• use of accessory muscles of respiration

• intercostal retractions

• distant breath sounds w/ inspiratory wheezing

• orthopnea (shortness of breath while lying down)

• agitation

• tachypnea (rapid breathing): >30 breaths/min

• tachycardia: >120 beats/min

• PEFR less than 80 L/min

peak expiratory flow rate (PEFR)

measures how fast person can exhale

PEFRs are affected by

• weight

• height

• age

• gender

• ethnicity

• posture

• effort

• smoking

• circadian rhythm

diagnosis of asthma is based on

• history

• physical findings

• sputum examination

• pulmonary function tests

• blood gas analysis

• chest radiography

radiographic findings for asthma

evidence of hyperinflation w/ flattening of the diaphragm

physical findings for asthma

• cough

• wheezing

• hyperinflated chest

• decreased breath sounds

sputum examination findings for asthma

• charcot-leyden crystals (hexagonal pyramid)

• eosinophils

• curschamnn spirals (mucus casts of bronchioles)

pulmonary function test (spirometry) findings for asthma

• forced expiratory volumes decrease

• PEFR less than 80%

  • FEV1/FVC ratio < 8-%

arterial blood gas (ABG) findings for asthma

• may be normal during mild attack

• respiratory alkalosis & hypoxemia w/ increase in bronchospasm intensity

• PaCO2 elevation

cell blood count (CBC) findings for asthma

• increase in WBCs

• increase in eosinophils

treatment for asthma

• avoid triggers

• environmental control

• preventive therapy

• desensitization (allergen specific immunotherapy)

• medications

medications for asthma help

decrease inflammation and bronshoconstriction

medications to treat asthma

• O2 therapy

• B2 agonists (albuterol)

• parasympathetic antagonist (ipratropium)

• corticosteroids

• leukotriene modifiers

• mast cell inhibitors (cromolyn sodium)

status asthmaticus 

severe asthma attack unresponsive to routine therapy

treatment for status asthmaticus

• epinephrine

• subcutaneous terbutaline (fast acting bronchodilator)

• aminophylline

• intravenous corticosteroids (mainstay of therapy)

• oxygen therapy