Can you feel a lung over-expansion injury happening?

[rickthompson]

First of let me tell you that 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?

Again, I've spoken to my doctor about diving with asthma and since I only have allergy induced asthma and only experience attacks rarely (and at predictable times), he has cleared me to dive. I'm just curious whether or not you would actually feel the onset of a lung over expansion injury.

[Jax]

These folks on this forum are pretty good, so you came to the right place.

However, have you contacted DAN? DAN | Mission

Nonemergency medical questions
1-800-446-2671 or +1-919-684-2948, Mon.-Fri., 8:30 a.m.-5 p.m. (ET)

All other inquiries
1-800-446-2671 or +1-919-684-2948

You don't have to be a member to call them, but if you are diving and are not DAN insured, shame on you!

[Blue Sparkle]

if you are diving and are not DAN insured, shame on you!

First of all, OP, interesting question - about whether you can feel a lung overexpansion injury (I don't know.)

Second of all (and sorry as it is a bit of a tangent, but at least I didn't start it ), why shame on the OP if not DAN insured? I've just been insurance shopping and I was thinking of going with Dive Assure, because of the primary/secondary insurance difference. From my understanding the DAN organization and DAN insurance are separate, and the insurance is (more or less) just an insurance plan written by an underwriter. Not to say it's not good, but just that it's not the same thing as the DAN research/resource arm, which you can call with questions (and also join?)

OTOH, I may be misunderstanding, in which case I'd like to know more, since I'm insurance shopping. From your response it sounds like there is something more worthy about the DAN insurance specifically.

Blue Sparkle

[Cave Diver]

I'm just curious whether or not you would actually feel the onset of a lung over expansion injury.

To the best of my knowledge, as I'm not a doctor, you won't feel the onset. You may feel some discomfort once the injury has occurred depending on the extent of it. This includes difficulty breathing from blood flooding the lungs, or a shortness of breath and weakness from poor circulation/gas exchange.

As long as you are able to maintain an open airway, exhale and manage your ascent rate, I don't think an over expansion injury would be a major concern. If you feel that you may have a tendency to bolt for the surface and your airway may be restricted, that could certainly be an issue.

[Duke Dive Medicine]

Rick,

In my experience, most of the time the aftermath of the pulmonary overinflation pretty much overrides any memory a diver might have of "feeling" it happening. The U.S. Navy Diving Manual says that the diver may feel a sensation similar to a blow to the chest. If you were moving slowly and ascending with trapped air, you may feel the lung expanding, depending on how much air is trapped.

An asthma attack under water is a bit more complicated than simple air trapping. Constricted airways considerably increase the work of breathing, as you've experienced. It's difficult enough on the surface, but under water, gas density becomes a factor. For example, at 66 FSW (3 atmospheres absolute), air is three times as dense as it is on the surface. In the event of an asthma attack, it would be considerably more difficult to breathe at depth. This can lead to hypercapnia, panic, and rapid ascent. The bottom line is that you can't predict the severity of an attack at depth just by looking at what your episodes feel like on the surface.

Clearance to dive for asthmatics is controversial. Some physicians just say "no". Others, like yours, are more liberal. Our criteria are that the diver must not be dependent on medication (including inhalers) to control the asthma, and must have normal PFT values both resting and during exercise.

Best regards,
DDM

[TSandM]

You are quite right to be worried about exhalation, because that's the problem with asthma to begin with, even on the surface. It will be worse at depth.

The scariest part of lung-overexpansion injury is that it is rarely manifest as something simple like a pneumothorax . . . it tends to present as gas embolism, and those are really bad news, and frightening often fatal.

If I were you, with your history, I'd get some pulmonary function testing done -- and I certainly would never, ever dive with any symptoms. (BTW, I have mild asthma, only symptomatic after viral infections, and I don't dive if I don't think my breathing is 100% normal.)

[sheeper]

I also have asthma (very well controlled). And I cannot stress enough that you need to be evaluated/cleared by a doc who understands diving and asthma related dive medicine.

[scubaholt]

Rick I can only speak from my experience. No. My doc explained that there is not of nerves where my injury was. Didnt feel a thing until symptoms started showing up.

[DocVikingo]

Hi Rick,

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 (http://www.thefreedictionary.com/alveolus) can rupture with only a 1.5 pounds per square inch (psi) rise in internal pressure.

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 (AGE; Air Embolism (Arterial Gas Embolism)) has been precipitated.

Your situation reportedly involves asthma and requires special consideration. You should find the following informative --> See post #6 in the following thread Can my friend go SCUBA diving if she has asthma?.

Regards,

DocVikingo

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.

[Duke Dive Medicine]

Clarification for my previous post since my edit button is gone: we will clear certain asthmatics to dive provided they're stable and well-controlled on their medication regimen. Medication use is not an automatic contraindication.