Respiratory Disorders:

Question 1

Epidemiology of Asthma:

Answer 1

About 23 million people (7 million children)
Leading chronic disease for children
Asthma is expected to grow
Third ranking cause of hospitalization among children under 15
High economic cost

Question 2

Type I hypersensitivity-Asthma

Answer 2

Triggered by innocouous foreign substance (dust, pollen, dander)

Antigens simultaneously bind more than one membrane bound to IgE on a mast cell
(cross-linking process triggers the release of mast cell granules full of histamine )

Question 3

What are the effects of histamine?

Answer 3

Stimulate bronchoconstriction

Vasodilation and increased capillary permeability causes edema that accum. in the tunica submucosa of the bronchi

Irritation and inflammatory response stimulate the secretion of mucus

Question 4

What does airway obstruction cause?

Answer 4

Decreased expiratory flow rates
Air trapping

Question 5

What are some asthma triggers?

Answer 5

Environmental allergens
Air pollutants
Cigarette smoke
Exercise/cold air
Upper airway infection
Genetic predisposition

Question 6

Clinical Manifestation of asthma:

Answer 6

Cough:
-Hyper-acute= cough non-productive
-Slow-onset/chronic asthma= sufficient mucus to cause productive cough
Wheezing:
-Happens when air is being forced out through constricted bronchi and bronchioles
Insp./Exp. wheezing may be heard at in the last stages of an attack
Tachypnea and dyspnea- use of accessory breathing muscles
Chest tightness and discomfort: inflamm. response induce pain

Question 7

COPD definition:

Answer 7

Abnormal lung function tests that do not improve over a period of several months

Key is reduced expiratory outflow manifested by prolonged forced expiratory volume in one second

Smoking responsible for 90% of cases

Question 8

Classification of COPD:

Answer 8

Umbrella term that includes:
-chronic bronchitis
-emphysema
-refractory asthma (irreversible)
-severe bronchiectasis

Question 9

COPD:Chronic Bronchitis:

Answer 9

Disease caused by chronic inflammation of the bronchi which leads to airways obstruction from hyper-secretion of mucus

Must have cough for at least 3 months out of a year or two consecutive years

Question 10

Causes of Chronic Bronchitis:

Answer 10

Chronic exposure to irritants- cigarette smoke, (most common cause) coal, mineral dust, etc.

Question 11

Pathopyshsiology of Chronic Bronchitis:

Answer 11

Recurrent irritation leads to chronic inflammation
Inflammation leads to release of histamines from mast cells as well as leukotrienes and platelet activating factor
Leading to mucus

Bronchial edema: Caused by increased capillary permeability in the tunica submucosa of the bronchi. Narrowed airway lumen and airway obstruction.

Question 12

Clinical consequences of chronic bronchitis:

Answer 12

Airway Obstruction: edema in bronchial, bronchoconstriction, mucus secretion

Impaired ciliary function: chronic exposure to irritants destroy cilia- mucus secretion also impairs function

Increased risk of resp. infection: chronic mucus production provides warm, wet environment for bacterial colonization (chronic bronchitis easily susceptible to pneumonia due to bacterial infections in bronchi/alveoli)

Question 13

Clinical Manifestation of Chronic Bronchitis:

Answer 13

Tachypnea, dyspnea (may be at rest) due to decreased ventilation and hypoxemia (low O2)

Hypoxemia manifested by SaO2 (oxygen saturation of hemoglobin) and PaO2 (partial pressure of oxygen in body) caused by airway obstruction and air trapping

Hypercapnia and resp. acidosis manifested by high PaCO2 caused by obstruction to expiratory air flow
Clubbing of fingernails occurs in response to chronic hypoxemia

Polycythemia is when hypoxemia causes the release of erythropoietin. This stimulates proliferation and release of red blood cells from bone marrow.
Increased hematocrit (polycythemia) is an attempt by bone marrow to increase oxygen delivery to tissues

Question 14

COPD Emphysema:

Answer 14

Disease characterized by loss of alveolar recoil and destruction of septa between adjacent alveoli- leading to decreased alveolar surface area impairing gas exchange

Question 15

Etiology of Emphysema:

Answer 15

Alpha 1 antitrypsin deficiency -Small percentage are caused by this a genetic lack of enzyme so it’s called Primary Emphysema

Alpha 1 antitrypsin problems are also root of acquired emphysema

Question 16

Pathophysiology of Emphysema:

Answer 16

Alpha 1 antitrypsin deficiency is when its not active in the lung tissue
If alpha 1 antitrypsin in not active in the lungs, elastases produced by alveolar macrophage will dominate leading the enzymatic digestion of elastin and other proteins
Normally elastin fibers on the outside of the alveoli help expel air during exhalation
Breakdown of this elastin reduces expiratory air flow and increased residual volumes

Question 17

Etiology of Emphysema:

Answer 17

-Inhibition of Alpha 1 antitrypsin

-Majority of cases caused by acquired inhibition of alpha 1 (causes same effect as deficiency)

-Secondary emphysema caused by smoking cigarettes
(smokers have 20% chance of developing emphysema)

Question 18

Pathophysiology of Emphysema:

Answer 18

Septal destruction- septa between individual alveoli are destroyed from the protease leading to permanent enlargement of alveoli
Capillaries that lie between the alveolar septa also get destroyed as the alveolar wall disappear

Question 19

Clinical consequences of emphysema:

Answer 19

Loss of elastin causes the alveoli to over-inflate during inhalation
Loss of elastin also reduces alveolar recoil resulting in air trapping
Air trapping causes functional obstruction to airflow in the lungs
Reduced surface area for gas exchange (V-Q mismatching and hypoxemia result)
Hypoxemia and hypercapnia- air trapping leads to decreased in inspired O2. Loss of elastin make it difficult to expel CO2 from alveoli
Loss of alveoli and pulmonary capillaries decrease the available surface area for gas exchange

Question 20

Hypercapnia:

Answer 20

Increased CO2 in arterial blood caused by hypoventilation of the alveoli
Often overlooked

Question 21

Clinical Manifestations Emphysema:

Answer 21

Dypsnea on exertion which progresses to dyspnea at rest (due to decreased ventilation/resulting hypoxemia)

Tachypnea and use of accessory muscles

Prolonged expiration manifested by decreased forced expiratory volume in one second

Increased A-P diameter of chest (barrel chest) due t increased RV from air trapping

Question 22

Complications of COPD:

Answer 22

-Frequent lung infections
-Increased risk of osteoporosis due to oral corticosteroids
-Problems with weight
-emphysema may need to gain weight
-chronic bronchitis may need to lose weight
-pneumothorax (damage lung structures and allow air to leak into chest cavity)
-sleep problems

Question 23

Respiratory Infection: Pneumonia

Answer 23

Infection of lung parenchyma

Question 24

Bacteria causes of pneumonia:

Answer 24

Gram Positive: strep and staph
Gram negative: klebsiella, E coli, enterobacter, etc.

Question 25

Viral causes of pneumonia:

Answer 25

Influenza virus, RSV, parainfluenza, adenovirus, SARS

Causes 2-35% in adults (more in children)

Higher hospital rates from viral PNA. in persons >60 yo

COPD and asthma frequently complicated by resp. viral infections

Immunocompromised increased risk

Question 26

Viral Causes of Pneumonia-Influenza

Answer 26

Annual winter epidemics 6-8x weeks
Transmitted by small particles aerosols
2-3 incubation period
5-7 days max virus shedding

Question 27

Viral Causes of Pneumonia-RSV

Answer 27

2nd most common cause of viral PNA in older adults
Major cause of serious lower resp tract infections in young children
Important pathogen for adults, esp elderly and chronic lung disease pt’s or immunocomp.

Question 28

Classifications of Pneumonias:

Answer 28

Community acquired-
-mortality rate much lower in patient’s not admitted to ICU (nearly 40%)

Nursing home acquired

Nosocomial/Hospital acquired-
- > 48 hrs post discharge Incidence much higher with mechanical ventilation (mortality near 70% in patients with HAP)
-Increases length of stay by 7-9 days
-failure of therapy/pathogen resist./host factors/antibiotic resistance

Ventilator-associated

Question 29

Pathophysiology of pneumonia:

Answer 29

Inflammatory response to pathogen:
-increased capillary perm. allows fluid into interstitial tissue/alveoli

Decreased function area of gas exchange leads to hypoxemia and hypercapnia:
-resp. rate and depth of respirations increase

Mucous production increases:
-helps decrease gas exchange

Question 30

Clinical Manifestations of Pneumonia:

Answer 30

Consolidation: