Is it possible to feel lung overexpansion prior to injury?

[JanK]

We've all learnt that one of the golden rules for diving is never to hold breath, since you risk lung damage on ascent.

What I'm wondering about is: wouldn't you notice that the lungs are expanding and wouldn't the excess pressure in the throat or mouth (depending on where exactly you close your airway) give you some sort of indication that you need to exhale? And wouldn't the chest also expand as much as when you take your deepest breath and provide you with some indication? Or does the lung overexpansion injury actually happen before the maximum expansion?

 

[DocVikingo]

Hi JanK,

It takes a surprisingly small pressure differential to cause a lung expansion injury. A diver well might not be aware of this differential or have any other physical indication until the lung tear has already occured.

Regards,

DocVikingo

 

[cutlass]

Hi JanK,

It takes a surprisingly small pressure differential to cause a lung expansion injury. A diver well might not be aware of this differential or have any other physical indication until the lung tear has already occured.

Regards,

DocVikingo

Indeed. Dancing furiously around the technical minutiae of ventilator therapy, it can generally be said that we aim to keep pressures (relative to ambient) below 30-35 cm/H2O (about 0.4-0.5 psi) to avoid alveolar/small airway damage (volutrauma). The threshold for major airways (barotrauma) is about 45-50 cm/H2O (about 0.6-0.7 psi).