Study group discussion: Transpulmonary pressure

What is transpulmonary pressure and its significance?

I remember it's something like... General lung pressure without alveolar pressure. I don't know.

It's the difference between the intrapleural pressure and the alveolar pressure. The athmosphere pressure is constant, but air still needs to flow in and out of our lungs, so we adjust the pressure inside our body.

The basic principle is that air flows from higher pressures to lower, so we constantly change the pressure in our lungs to higher or lower than the atmosphere.

Transpulmonary pressure (when everything is fine) is always positive.

I'm getting what he is saying, go on!

Transpulmonary pressure is always positive, intrapleural is always negative and alveolar fluctuates.

That's how I remember from my physiology classes, anyway.

Yeah, alveolar fluctuates so that air can flow in and out easily.

Transpulmonary pressure is basically the elasticity of the lungs. The recoil.

Since atmospheric pressure is relatively constant, pressure in the lungs must be higher or lower than atmospheric pressure for air to flow between the atmosphere and the alveoli. It is nothing but the elastic recoiling of the lungs. If 'transpulmonary pressure' = 0 (alveolar pressure = intrapleural pressure), such as when the lungs are removed from the chest cavity or air enters the intrapleural space (a pneumothorax), the lungs collapse as a result of their inherent elastic recoil. Under physiological conditions the transpulmonary pressure is always positive; intrapleural pressure is always negative and relatively large, while alveolar pressure moves from slightly positive to slightly negative as a person breathes. For a given lung volume the transpulmonary pressure is equal and opposite to the elastic recoil pressure of the lung.