Asthma Question

[TONY CHANEY]

There is a common misconception about the lungs, lung capacity, and breathing. People think breathing is about getting O2 in. Well, of course, but it is mostly about getting CO2 out. For that you need to easily push the air in and out through the 'pipes' (trachea > bronchus > respiratory bronchioles > alveolus. The process of moving air (breathing) has not a whole lot to do with lung volume, which is primarily determined by gender, size, age, and genetics.

Not predetermined by size and genetics! It is based on gender coupled with ideal body weight. The lungs do not grow past adulthood with size and to my current study there is no way to measure how genetics come into play. Please enlighten me. So if a patient is 500 lbs and you ask me to put them on a tidal volume of 1000 ml, then I will hand you a chest tray for a pneumothorax.

 

[fmerkel]

You are correct about [ideal body weight]. I was too simplistic in using the term 'size', by which I meant how tall you were.
The important point was that you really cannot change lung volume in any meaningful way. Some wind instrument players putting years of work into in can get some incremental changes, but most of the meaningful use is not volume so much as muscular improvement and control.

There are some small variations based on race that are taken into account when doing spirometry. Women tend to have smaller lungs than men for equivalent size, and we all lose lung volume as we age. There is a genetic component but it's not something you can use on a statistical basis. One of the women in my profession at the hospital had lung volume that was much above what she should have had, which is a trait that ran in her family. My wife has smaller lung volume than her size would indicate, which kind of annoys her but doesn't seem to have any impact on her diving ability.

Lung volumes are not directly tied with aerobic performance and I doubt it would help much in scuba to have a big set of lungs, though it probably wouldn't hurt you either.

FWIW, I have what I call 'cough variant' asthma. When I get 'some' colds (not all), I get a nasty persistent cough.
My lung volumes and flow characteristics do not change, meaning no bronchospasm. I am not improved by bronchodilators (Albuterol), but I generally respond very well to inhaled steroids. Once I'm completely over the insult I don't need medication anymore. But I do not dive during this period.

 

[Pedro Burrito]

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A ScubaBoard Staff Message...

Moved from Divers with Disabilities to Diving Medicine

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[DocVikingo]

Yep, his concern (and now mine to a lesser extent) is the trapping of air in the alvioli and its expansion as you ascend. Not life threatening if it occurs in one Lund, but terminal if it happens in both.

Hi MJs1946,

This is not correct.

The bronchospasm & mucous plugging that can occur with asthma increase the risk for developing alveolar rupture and the formation of arterial gas embolism (AGE). AGE can occur with the involvement of only a single lung. This is quite a serious situation, and, if the scenario occurs in both lungs it's likely to be more serious, but is not necessarily "terminal."

As fmerkel has indicated above, spirometry does nothing the detect lung scarring--it simply measures lung function. X-rays can provide some information on this by showing shadows possibly suggestive of pulmonary scar tissue, but clearly high-resolution computed tomography (HRCT) is the gold standard for imaging lung scarring.

Regards,

DocVikingo

 

[MJS1946]

So, am I to assume that I need to find a lung specialist who is also a "diving Doctor"? I have gone back on the Dulera with the hope that it will help improve lung function. Is DAN the source to find the doc I need?

 

[fmerkel]

DAN is one option.
PM sent.