VQ mismatch Flashcards
What is the benefit of upright sitting on VQ match?
Gravity increases intrapleural pressure - so alveoli at the bases are slightly compressed - meaning they have a large potential for ventilation
ONLY EFFECTIVE IF COMBINED WITH DEEP BREATHING EXERCISES
Why are deep breathing exercises important in upright sitting?
Because additional inspiratory effort is required to ventilate the basal alveoli - since they will be more compressed and inital force to overcome the compression is high
What is the effect of side lying on VQ match?
Lower lung (unaffected) has a lower residual volume due to abdominal contents compressing it under gravity - BUT it has the greatest potential for ventilation
There is an increased perfusion to the lower lung due to the effects of gravity on the hydrostatic pressure of the vessels.
When is upright postitioning more appropriate than side lying?
in patients with bilateral pathology
What is a VQ match?
when the alveolar ventilation and the capillary perfusion are both effective - meaning gas exchange is effective
what is a shunt?
VQ mis-match where there is a lack of alveolar ventilaton (e.g. due to mucus plug), but perfusion is effective - means that blood enters the left side of the heart deoxygenated
What is VQ mismatch due to physiological dead spacE?
When there is alveolar ventilation without capillary purfusion (e.g. due to pulmonary emobolus)
what is VQ mismatch due to anatomical dead space?
Where there is ventilation without perfusion in the non-gas exchange surfaces of the respiratory tract
Where is potential for ventilation the greatest?
in the bases of the lungs due to increased alveolar density
