Question

1.what effect would an increase in interstitial fluid have on the rate of gas exchange in the respiratory membrane would it slow the rate down or speed it up? what would you do for diffusion distance?

2. what effect would an increase in the interstitial fluid have on the size of the neighboring alveoli? would increase their size or decrease the size and what effect would this have on gas exchange?

Answer 1

Answer 1:

Presence of interstitial edema will slow the diffusion process

Explanation.

• The diffusion of gas across the alveolar membrane into the blood vessel is a passive process.
• It is assess by the Fick's equation.
• As per the equation, the diffusion across the respiratory membrane is inversely proportional to the membrane thickness. (Alveolar)
• In the presence of interstitial edema, increase the alveolar membrane thickness.
• This increases the diffusion distance.
• In other words, the distance the gas molecule has to travel to reach the alveoli increases.
• Therefore, in the edematous alveoli, the gas diffusion decreases.

In order to improve gas diffusion, I would need to reduce the diffusion distance. This can be achieved by two ways

1. Providing positive pressure ventilation
   1. Positive pressure will thin out the fluid in the alveoli.
   2. This will reduce the alveolar membrane thickness.
   3. Hence, it will reduce the diffusion distance.
   4. This will improve diffusion as diffuse is inversely related to membrane thickened
2. RReduce the edema fluid with the help of diuretics. This will work only if the cause of edema is transudative (example cardiac failure) But if the edema is due to inflammation diuretics have no role

Answer 2

The Air fluid ( non - edematous) alveoli adjacent to the edematous alveoli will enlarge inside.

Explanation

• The edematous alveoli will have a tendency to collapse.
• This will exert a tethering effect on the adjacent air-filled alveoli.
• This exposes the air-filled alveoli to distending forces.
• So the air-filled alveoli will increase in size.

Assuming that the alveoli is a sphere, and increase in the radias of the alveoli will increase the surface area of the alveoli.

As a result, more surface area will be available for gas exchange.

So this will improve the gas exchange.

However, the alveoli has it physiological limits, overdistenstion can lead to voltrauma.

As a result, the respiratory membrane will be damaged and hence gas exchange will get hampered.