Why expiration is more difficult than inspiration in emphysema?
due to decreased dynamic compliance
In emphysema there is widespread destruction of the airways; causing dynamic obstruction of airways.
That’s why it is difficult to exhale air.
Inspiration is actually easy as the compliance is increased due to loss of elastic forces.
In emphysema the dynamic complains decreases resulting in dynamic obstruction. Also, loss of elasticity results in reduced recoil, making it harder to push air out in the expiratory phase.
That’s why type 2 respiratory failure more common
I’m somehow confused with this explanation…if closing tendency is greatly increased wont it be easier to expire. Also how can it collapse when it has lost elasticity?
closing tendenancy of AIRWAY leading to alveoli is increased ( due to los of elastin fibers which help in keeping airway open during expiration)
NOT the Alveoli itself.
Therefore, air entering alveoli during inspiration is trapped inside alveoli leading to overdistended alveoli.
closing tendency increase means airways trying to remain closed…making it difficult to push air out…
elastic nature make them remain open…otherwise they get collapsed…
so loss of elasticity increase closing tendency…
Elasticity is lost of airways, during inspiration the lungs are expanding due to out pulling by negative pressure, that’s why the lumen of small airways also get pulled outside and lumen become wider during inspiration…but in expiration all positive pressure from outside compressing the lungs ,thus shrinking the lungs and so also the airways…as these are non-compliant the airway lumens get collapsed thus trapping the air in alveoli