I have asthma. It’s allergy induced and I generally only have trouble with it for approx 2 weeks a year (when the seasons change and my allergies act up). Even when I do have trouble with it, the worst that happens is that I have a little difficulty breathing which goes away once I use my inhaler. If I don’t have my inhaler handy however, I’m fine and just slightly uncomfortable. I would never dive if I have had an attack within the past 4-6 weeks, but even if I had an attack underwater, I don’t think it would effect me breathing from my regulator. What I’m concerned about is that since during an attack it becomes harder to breathe in, it also becomes harder to breathe out, and if I were to have an asthma attack while ascending, I may not be able to exhale at the same or faster rate that the gas is expanding in my lungs. My question is, if this were to happen, would I feel pain/pressure in my chest/lungs before a lung over-expansion injury occurred that would cause me to slow my accent or would I end up ascending to the surface feeling fine only to be in serious condition a few moments later?”
It takes a surprisingly small pressure differential between the inside and the outside of the lung to cause an overexpansion injury. The tissue surrounding alveoli can rupture with only a 1.5 pounds per square inch (psi) rise in internal pressure (typical pressure in a car tire is around 30 psi).
While the affected diver may feel like s/he has been struck in the chest area, most often s/he will not be aware of this differential or have any other physical indication of the lung tearing until it has already occurred and air has leaked into the extrapleural space or an arterial gas embolism has been precipitated.
Your situation reportedly involves asthma and requires special consideration. You should find the following informative –> Can I dive with asthma?
Many of those with asthma can be controlled with long-acting bronchodilators and inhaled corticosteroids. Divers who do not respond adequately to these and must regularly rely on fast-acting rescue meds shouldn’t be engaging in SCUBA.
Your pulmonologist is in the best position to make the decision on the advisability of diving.
This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual, and should not be construed as such.”