Question

What does the phrase "ventilation-perfusion inhomogeneity" mean?

Answer 1

Ventilation means the breathing in of air into the alveoli. V stands for ventilation.

Perfusion is the blood passing through the pulmonory capillaries around the alveoli. It is represented by Q.

The oxygen from the air in the alveoli is taken into the capillaries and the CO2 from the heart in the capillaries are taken inside the alveoli.

Ventilation perfusion ratio is the ratio between ventilation and perfusion. V/Q

Normally , into the respiratory tract 4 litres of blood pass through every minute and 5 litres of blood pass through the alveolar capillaries per minute.

So the V/Q ratio is 4/5 that is 0.8 .

The value of V/Q can be less than or more than 0.8. This higher or lower V/Q ratio is called ventilation perfusion inhomogenity. It occurs mainly because of any part of lungs do not receive oxygen but there is blood flow ,or if in any part of lulungs there is blood flow but no oxygen. This occurs due to any kind of diseases of the respiratory tract like Asthma, pneumonia, chronic obstructive pulmonary disease, chronic bronchitis etc .