When VA/Q is infinity, it means
-Ventilation / perfusion ratio - normal = 4l/min/5l/min=0.8 - AV/Q= INFINITY - Means Perfusion (Q) to lungs is zero that is blood supply to that area is hindered making it awasted ventilationin those alveoli. - This may be due to pulmonary embolism causing |ed Physiological DEAD space . DEAD SPACE- Some of the air a person breathes never reaches the gas exchange areas but simply fills respiratory passages where gas exchange does not occur, - called so as its not useful for gas exchange. Physiologial / total dead space = anatomical dead space +alveolar dead space (non perfused/ non functioning Alveoli) In Atelectasisventilation: perfusion ratio (VA/Q) iszero. it is is the most common cause of a physiologic shunt.
Dead space
The PO2 of alveolar air is 159 mmHg and PCO2 is 40 mmHg
Paial pressure of O2 and CO are equal
Atelectasis
NEET Jan 2020