Airway closure Flashcards
What is the physiological basis of airway closure?
Pressure drops as fluid flows through a tube
P1 > P2
AKA- As gas flows through a tube, pressure falls. In the airway, pressure decreases as gas flows along the bronchioles.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/194/703/602/a_image_thumb.png?1470538552)
Forces keeping airway open during inspiration and forces causing closure during forced expiration:
During forced expiration intrapleural pressure becomes what?
Positive
30 cm H20 in picture
![](https://s3.amazonaws.com/brainscape-prod/system/cm/194/703/603/a_image_thumb.png?1470538553)
Forces keeping airway open during inspiration and forces causing closure during forced expiration:
the high intrapleural pressure (30 cm H2O) is transmitted to the what?
Alveoli
38 cm H2O in this picture
![](https://s3.amazonaws.com/brainscape-prod/system/cm/194/703/604/a_image_thumb.png?1470538553)
Forces keeping airway open during inspiration and forces causing closure during forced expiration:
As the air flows along the airway, the pressure in the airway begins to what?
fall
(remamber as fluid or gas flows through a tube, pressure falls)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/194/703/605/a_image_thumb.png?1470538554)
Forces keeping airway open during inspiration and forces causing closure during forced expiration:
At some point in the airway the intrapleural pressure sufficiently exceeds airway pressure, and the airway does what?
closes
![](https://s3.amazonaws.com/brainscape-prod/system/cm/194/703/606/a_image_thumb.png?1470538555)
Forces keeping airway open during inspiration and forces causing closure during forced expiration:
in the diagram the airway closes when the pressure falls to 19cmH2O
![](https://s3.amazonaws.com/brainscape-prod/system/cm/194/703/607/a_image_thumb.png?1470538556)
why does the trachea not close then?
b/c it has rings
what part of the airway is suceptable ro collapsing
bronchioles to alveoli
why do the mainstems not collapse?
b/c they have rings also
Closing volume (CV) and Closing Capacity (CC):
at some point during forced expiration, airways begin to close. The volume that can subsequently be exhaled is called the
closing volume
Closing volume (CV) and Closing Capacity (CC):
What makes up the closing capacity
the closing capacity is the closing volume plus the residual volume
CC = CV + RV
![](https://s3.amazonaws.com/brainscape-prod/system/cm/194/703/612/a_image_thumb.png?1470538557)
Closing volume (CV) and Closing Capacity (CC):
the CV and CC are measures how?
nitrogen washout test
and
helium dilution method
Closing volume (CV) and Closing Capacity (CC):
what happens if your CC is higher than your FRC?
you have no reserve (no FRC)
Closing volume (CV) and Closing Capacity (CC):
what typw of pt may have a CC higher than FRC
Elderly
Closing volume (CV) and Closing Capacity (CC):
since older peoples CC exceeds their FRC what does this mean in relation to thir airway closure?
they close without forced expiration