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If the intrapleural pressure at the end of inspiration is 210 cmH2O
and the intrapleural pressure during expiration is 30 cmH2O, the equal
pressure point will be closest to point?
options include,A,B,C,D,E points placed inbetween from alveoli to mouth(assuming single alveoli drawn )after few distances each.
can anyone answer if understood well.?
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near oropharanx?
just a guess
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ans : point B
dont know if this concept impt for exam purpose or nt but finally got what does it mean,as i found interesting so sharing.
Equal pressure point (EPP) is the point where Intrapleural pressure and Alveolar pressure are equal. This is similar to the Starling resistor concept in the lung. Instead of flow being determined by the difference between alveolar and mouth pressure- flow is determined by the difference between alveolar and Intrapleural pressure difference.
In forced expiration, both intrapleural pressure and alveolar pressure will increase. However alveolar pressure will decrease along the length of the airway until a pressure of zero at the mouth, whereas intrapleural pressure will remain the same. Therefore there will be a point where intrapleural pressure will be equal and subsequently greater than alveolar pressure.
If the EPP occurs in the larger cartilaginous airways, the airway remains open. However, if the EPP is in the smaller airways, it will collapse.
Increasing the force of expiration does not overcome EPP since it will increase both alveolar and intrapleural pressure.
Another interesting concept is that EPP moves distally as expiration progresses because as air leaves the alveolar unit, the pressure in the alveolar decreases hence the pressure in the airway decreases as well.
EPP is the cause of dynamic airway compression.
hope it helps.
