Step I respiratory physiology

Started by njshibby
Get help with your application

Use all the free resources available to you from SDN: articles, guides, expert advising, forums discussions, and school research.

Browse articles Compare schools My application plan Read Interview Feedback
Practice for interviews Ask an Advisor
N

njshibby

Member
15+ Year Member
Random q's that have been bothering me... When a patient hyperventilates there will be just a minor change HCO3 correct? compensation only happens when pco2 elevated over a day or so.
when a patient hyperventilates how high can PaO2 rise?
Does the A-a gradient change in a cafe coronary?
 
Last edited:
Sort by date Sort by votes
njshibby said:
When a patient hyperventilates there will be just a minor change HCO3 correct? compensation only happens when pco2 elevated over a day or so.
Click to expand...

HYPERventilation will cause a respiratory ALKALOSIS. You'll blow off a ton of CO2, dropping pCO2, and pH will rise. HCO3 doesn't fall (significantly) until renal compensation kicks it, which you are correct - can take a day or so. That is the difference between an "acute" and "chronic" respiratory acid/base disturbance. Acute implies before renal compensation, chronic implies with.
 
Upvote 0 Downvote
A-a gradient remains normal in a "cafe coronary." The patient is not able to get air into his alveoli to undergo gas exchange with the alveolar capillaries. The gradient between the alveolar and arterial gas only increases in situations where there's a problem with optimally getting air that's already in the alveoli to undergo exchange with alveolar capillaries (such as in a shunt situation, diffusion issues, and V/Q mismatches.) In the cafe coronary situation, if air was able to make its way into the alveoli, it'd undergo optimal exchange with the alveolar capillaries-however, there's a chunk of filet mignon in the way.
 
Upvote 0 Downvote
Mortal_Lessons said:
A-a gradient remains normal in a "cafe coronary." The patient is not able to get air into his alveoli to undergo gas exchange with the alveolar capillaries. The gradient between the alveolar and arterial gas only increases in situations where there's a problem with optimally getting air that's already in the alveoli to undergo exchange with alveolar capillaries (such as in a shunt situation, diffusion issues, and V/Q mismatches.) In the cafe coronary situation, if air was able to make its way into the alveoli, it'd undergo optimal exchange with the alveolar capillaries-however, there's a chunk of filet mignon in the way.
Click to expand...

Ok so depends on where it is in the airway...if it's further down maybe in a bronchus then the rest of the lung perfused then the A-a would change im guessing. BRS phys and goljan differed on this.
 
Upvote 0 Downvote
njshibby said:
Ok so depends on where it is in the airway...if it's further down maybe in a bronchus then the rest of the lung perfused then the A-a would change im guessing. BRS phys and goljan differed on this.
Click to expand...

Oh, good point. I guess if there's some food in the distal airways, then you'd have perfusion without ventilation (i.e. a shunt) and there'd be an increase in the A-a gradient.
 
Upvote 0 Downvote
You must log in or register to reply here.