QUESTIONS

1. What are the five causes of hypoxemia?
    
2. What is a MALT & what is a BALT?
    
3. There are 3 types of normal lung sounds. Describe them.  What? OK. Hint: their names are: bronchial sounds, vesicular sounds & bronchovesicular sounds.
    
4. What is the difference between a type I & a type II pneumocyte?
    
5. Is pneumonia a restrictive or an obstructive disease?
    
6. If you want to nebulize a patient w/pneumonia, do you have to use an expensive nebulizer or can you just use a vaporizer from Sears?
    
7. Exactly what are you hearing when you hear "crackles" & are they usually inspiratory or expiratory?
    
8. Lactoferrin & lysozyme are present in respiratory secretions.  How do these substances inhibit bacterial growth?
    
9. The bronchiole-alveolar junction is especially at risk for infection. Why is this?
    
10. We all know it is a bad idea to aspirate vomit.  Aside from the particulate nature of gastric contents, why is it especially bad to inhale vomit?
    
    
    
    
     

ANSWERS

1. The five causes of hypoxemia are:
   
   a)  reduced oxygen inspiration (generally either caused by high altitude or by an anesthetic gas deliver problem)
   
   b) hypoventilation - hypercapnia is the hallmark, usually an obstruction is involved
   
   c) V/Q mismatch - this is the most common cause of hypoxemia
   
   d) shunt - a V/Q mismatch where V=0
   
   e) diffusion impairment - rare
   
   
   
   
    
2. MALT stands for mucosa associated lymphoid tissue.BALT is a kind of MALT.  BALT stands for bronchus associated lymphoid tissue.
   
   Dogs & cats do not have any BALT :(
   
   
   
   
    
3. Bronchial sounds= the sound of air travelling in an airwayVesicular sounds= the sound of air travelling in an airway as heard through parenchyma (on the lung periphery). Note that air in alveoli travels by laminar flow & thus makes no sound.
   
   
   
   
    
4. Both are alveolar cells. Type I pneumocytes participate in gas exchange.  Type II pnemocytes produce surfactant & have some capacity to re-differentiate into type I cells, tumors, or to undergo squamous metaplasia.
   
   
   
   
    
5. Pneumonia is a restrictive disease.
   
   
   
   
    
6. Bummer but you have to get the expensive nebulizer.  In order to bypass the upper airways & actually get liquid droplets down low into where the secretions are, you need to generate a teeny tiny water droplet.  Nebulizers make 1/2-4 micron size droplets. Vaporizer droplets just smash against the upper airway walls.Be sure to put saline & not water in your nebulizer. Water will prevent drying but you actually want to liquify secretions.
   
   
   
   
    
7. Crackles are the sounds of small airways snapping open.  Usually crackles occur in expiration as that is when higher pressures inside the airways are generated.  At a critical opening pressure, the airway snaps open.  You will hear the same sequence of crackles with every breath.
   
   
   
   
    
8. Lactoferrin sequesters iron so that it cannot be used by bacteria (I think).  Lysozyme is able to cleave the cell walls of certain bacteria.
   
   
   
   
    
9. For one reason it is narrow & thus easy for infected particles to lodge.  Also, it represents a transitional area where the mucociliary escalator stops & the alveolar macrophage system starts.
   
   
   
   
    
10. It is never a good idea to inhale something w/a pH of <2.5.  The acid denatures & dilutes the surfactant which leads to alveolar collapse.  Epithelial necrosis results along w/pulmonary edema, systemic hypotension, bronchoconstriction, & increased capillary permeability.