Asthma and diving equipment

[Genesis]

(and I ain't a MD so its a guess!) is that the number of molecules of air inspired and expired at 100' is more than the number at 50'.

That is, you're moving more mass of air (even though the volume is the same) through your lungs, and it may be the mass flow that is stripping off the moisture.

I find that I get far worse "cottonmouth" at 100' than at 50', but that as long as I keep aware of it and trigger salivation, or pop a Tic-Tac before going in the water, its managable. If I forget, then it gets rather bad....

 

[DivingDoc]

tampascott once bubbled...
It's too bad this thread didn't go further. I'd like to here more on this, and think the original question was excellent.

I am not an asthmatic, per se, however, I have a real problem with dry air. I live in Florida, on the Gulfcoast, so dry air is not a problem for me. However, when I go out to the Rockies to sky, WHAM, bronchitis.

Same with diving lately. If I do six dives over a couple of days, I get bronchitis. My problem is clearly the dryness of the air.

A lot of my diving is 80 - 100 ft. If I exert myself, which I do a lot, it gets real bad.

Anything new on this, or any updated information on that bio-filter thing?

As an MD who specializes in treating asthma, I highly suspect that you are having exercise, cold, and dry-air induced asthma -- not bronchitis. I think you should see an allergist or a pulmonologist and have an evaluation and some pulmonary function testing.

 

[DivingDoc]

Genesis once bubbled...
(and I ain't a MD so its a guess!) is that the number of molecules of air inspired and expired at 100' is more than the number at 50'.

That is, you're moving more mass of air (even though the volume is the same) through your lungs, and it may be the mass flow that is stripping off the moisture.
....

I think you are probably correct. The air at 100' is more compressed than at 50' -- 4 times the density of air at the surface (roughly 4 atmospheres at 99'). That means that resistance to airflow is greater -- that is, it takes more effort to move the greater density of air.

It's possible also that as you said, the greater total amount of air being exchanged can pull more moisture out of the airways.

Good hydration is the key to minimising dry mouth.

 

[SM Diver]

DivingDoc once bubbled...


As an MD who specializes in treating asthma, I highly suspect that you are having exercise, cold, and dry-air induced asthma -- not bronchitis. I think you should see an allergist or a pulmonologist and have an evaluation and some pulmonary function testing.

Thanks. I had an episode a couple of weeks ago that alarmed me enough that I will take your advise. We're normally real good about dropping the jug right on the ledge, but missed it. I was on my last tank of the day, got down to 90ft, and was swimming all out to find the ledge, and went in the wrong direction. Within 5 minutes I had bronchospasms and could not breath well. It was not a fun ascent, although I was pleased that I was able to maintain control in spite of the feeling that I couldn't get air. Nonetheless, it's not a situation I want to be in again.

By the way, I can excercise all I want without asthma. Jog 15 miles a week, no problem. It's the dry air combined with excercise that gets me.

 

[DivingDoc]

tampascott once bubbled...


Thanks. I had an episode a couple of weeks ago that alarmed me enough that I will take your advise. We're normally real good about dropping the jug right on the ledge, but missed it. I was on my last tank of the day, got down to 90ft, and was swimming all out to find the ledge, and went in the wrong direction. Within 5 minutes I had bronchospasms and could not breath well. It was not a fun ascent, although I was pleased that I was able to maintain control in spite of the feeling that I couldn't get air. Nonetheless, it's not a situation I want to be in again.

Under these circumstances, you would have a great risk of barotrauma during the ascent. What sorts of problems did you notice? If I were you, I wouldn't dive until you had a thorough evaluation for this problem. Would suggest Dr. Lackey in Tampa if you are near there. I hope you are not a smoker.

 

[SM Diver]

Thanks. PM to follow.

 

[The Iceni]

tampascott once bubbled...
. . , got down to 90ft, and was swimming all out to find the ledge, . . I had bronchospasms and could not breath well. It was not a fun ascent, although I was pleased that I was able to maintain control in spite of the feeling that I couldn't get air. .

Tampascott,

I just read your posts and have to say I am quite concerned.

For goodness sake take Divingdoc's advise and get checked out. You appear to be quite oblivious to the danger you face if you suffer any bronchospasm at depth, if that is indeed what it was.

Sadly, during an attack you are not in control of anything:-

Bronchospasm is a reversible form of obstructive airways disease with features of breathlessness and wheeze during an attack but it is obstruction during expiration not inspiration, so the positive pressure effects of high performance regulators, such as the Apeks ATX100, will not really help during bronchospasm.

At all other times the lungs are perfectly normal as is exercise tolerance. During an attack the obstruction is at the level of the small airways, trapping small pockets of air in the alveoli and small airways in the affected parts of the lung alone.

The localised obstruction has exactly the same consequences as holding your breath during an ascent. The trapped air has nowhere to go and so expands as the ambient pressure reduces on ascent. The inevitable consequence is "the bubble bursts" allowing air into the pleural cavity > pulmonary barotrauma > tension pneumothorax > arterial gas embolism > curtains?

Bronchospasm at depth must be avoided at all costs.

Inhaled steroids are brilliant in this respect, far better at raising the threshold for the triggering of an attack than i suspect any manipulation of equipment, although the warm, moist air with a rebreather must help if cold dry air is the trigger.

Tampascott, it sounds like you may be in the cohort of apparently mild asthmatics who falsly believe they are not at risk, and not even asthmatic. The vast majority of deaths from asthma are in such patients (usually otherwise fit young men) who have very mild symptoms, that is until they suffer a catastrophic attack far from medical help and/or seek help too late.

Please be sensible and don't become a statistic. :doctor:

 

[The Iceni]

Hi Divingdoc,

I trust you gave tampascott similar advice. Mine may have been a bit OTT.

Asthma is a disease affecting expiration, not inspiration.

Among other things you asked

The moisture issue: . . . . I asked DAN about this and they responded that the increase in air moisture would probably not be significant as the humidity level would drop considerably when the temperature of the air rises as it goes from the secondary to the lungs (which are at body temperature).

Well, when we breath air at any temperature it is warmed by the airways so its humidity is always reduced when it reaches the lungs. I am not sure that DAN are right as it is all relative.

One thing has occurred to me though. Nasal breathing will help to humidify and warm the inhaled air (from the turbinates) more than the traditional mouth-breathing regulator. So nasal breathing via a full face mask might help certain asthmatics who do not want to go the rebreather route.

The easy breathing issue: I should think that easy breathing would be inherently important for an asthmatic. In particular, if the asthmatic diver has to "suck hard" to extract air from his/her tank, this would help to close small bronchi and bronchioles by lowering their interior pressure.

Quite the opposite as I am sure you must know. Inhalation is caused by the production of a relative vaccuum in the pleural cavity outside the lungs, not in the airways. The lungs passively expand against this due to the pressure supplied by the regulator at the oropharynx. This is why, as you know, in an asthma attack it is the pressure outside the airways that causes them to collapse during forced expiration.

A reg that is associated with as low a work of breathing as possible would therefore be desireable.

Apart from the resistance of the exhaust flap valves, regulator design does not affect the work of exhalation in any way.

If it has any effects, positive pressure (venturi) inhalation will simply cause more air trapping during bronchospasm, surely? In any case the trials of IPPV you quoted demonstrated no benefit.

Food for thought. :doctor:

 

[SM Diver]

Thank you for the concern.

Please be assured that I am fully aware of the dangers associated with asthma and diving, and that I have an extensive medical background including having worked as a professional paramedic-firefighter for 8 years.

Last week I received a full evaluation from an asthma specialist who is also an avid diver. Peak flow and pulmonay functions test were not only normal, but well above normal. One more test will be done next week, but it does not appear that I have asthma.

So, what happened to me at 90', and why did I feel the sudden feeling of "impending doom" and acute shortness of breath. I have come to realize that it had nothing to do with bronchospasm, but I will be happy to share the experience here publicly because a) people know that I dive deep, and I don't want them thinking I am a suicidal idiot, and b) maybe my experience will help someone.

A quick recap on the event:

The dive plan was to jug a ledge in 90', go down, hunt the ledge, come up. I got down, and the ledge had not been properly jugged. Vis was not great, I was not on the ledge, and I was swimming fast in order to find it, but could not get myself oriented to it. After about six minutes of hard swimming, my heart started pounding, I felt I was having trouble breathing, and the feeling of impending doom occurred.

Now, I might as well get this part out of the way. Spearfishermen, at least in the Gulf, largely solo dive. I was down by myself, as I am 90% of the time. It's a personal choice, and I don't expect you guys to agree, and I don't recommend it. Riding motorcycles is a personal choice, too, but we don't chide every biker for placing his life in danger. However, I do point out that aspect of what happened because maybe it played a roll.

In short, a couple of things happened here. First, I probably had a build up of C02 at depth, which can cause panic symptoms and a sudden onset of shortness of breath. Secondly, within a two hour time frame before my dive, I saw a high pressure hose break, and two o-rings fail. That was getting inside my head pretty good, and that is where the solo issue may have come in to play this dive, especially since I had no redundant air (now, that is stupid, I admit. If you're going to dive solo, for God's sake have the sense to have redundant air).

If you've never experienced anxiety at depth, it's not pleasant, especially when you're out of range to CESA. You're "flight" instinct takes over, and your only thought is, I need to get to the surface, NOW. To be totally honest, I remember telling myself, "I have to rely totally on myself to overcome this. And I can do this." As stated, the trouble breathing wasn't bronchiospasms, it was the "my throat is closing" feeling you might get when extremely anxious. I was able to overcome the anxiety and make a slow, controlled ascent to 30 feet, at which times my symptoms had abated (more evidence it was not asthma), and I hung for about 5 minutes. I knew I was within easy CESA range, and the feeling of comfort was regained.

In an abundance of caution, I took the full physical, but by the time I got to the doctor's office I already knew what had happened. Personally, I felt the best thing for me was to get back in the water and dive, and make some modifications to the way I dive.

The main change I have made is to quit running a marathon down at 100.' I was free shafting large, powerful fish and running after them, and stringing them up. It is extremely exerting. My approach to spearing has totally changed. I get to depth, get comfortable, and move around SLOWLY, not overdoing it. When I shoot a fish, I used to "spring" into action. Now, I just lazily swim over to him and string him up.

I am laying off the bigger fish for a while, and taking fish that are easier to string. This last trip, I set a goal of knocking about 20% off my SAC, which I did. I don't do dives without a good feeling of comfort. This last trip, I laid off some of the deeper dives past 110'.

The second thing I am going to do is get fully redundant. I have never dived with a pony. I am going to start diving doubles (a steel hp100, and hp65).

I have dived several times since this episode, and have been completely without symptoms having implemented these changes. I have confidence in myself that if something happened at depth, I can overcome anxiety and think in a cool, rational manner, and, frankly, I think the experience has made me a smarter and better diver.

 

[The Iceni]

tampascott once bubbled...
. . . I have come to realize that it had nothing to do with bronchospasm, but I will be happy to share the experience here publicly because a) people know that I dive deep, and I don't want them thinking I am a suicidal idiot, and b) maybe my experience will help someone.

A quick recap on the event:

. . .Vis was not great,

. . . After about six minutes of hard swimming, my heart started pounding, I felt I was having trouble breathing, and the feeling of impending doom occurred.

. . . I probably had a build up of C02 at depth, which can cause panic symptoms

. . . two hour time frame before my dive, I saw a high pressure hose break, and two o-rings fail. That was getting inside my head pretty good, . . . anxiety at depth, it's not pleasant, especially when you're out of range to CESA.

. . . Your "flight" instinct takes over, and your only thought is, I need to get to the surface, . . .the trouble breathing wasn't bronchiospasms, it was the "my throat is closing" feeling you might get when extremely anxious.
The main change I have made is to quit running a marathon down at 100.' . . It is extremely exerting. My approach to spearing has totally changed. I get to depth, get comfortable, and move around SLOWLY, not overdoing it.

Hi again tampascott,

I seem to remember from reading your earlier posts about your style of diving and didn't think you could have suffered bronchospasm at depth. (In addition you did not suffer pulmonary barotrauma which I suspect would have been almost inevitable).

This is a thread on asthma and I completely agree with your assessment so will not labour the point but as you say, "maybe my experience will help someone." an attitude which is to be applauded.

Sounds to me like dark narcosis. - a combination of background nitrogen narcosis worsened by the synergistic effects of

1. dark (poor Vis).
2. carbon dioxide build-up
3. subliminal anxiety (memories of the earlier failures being solo and no redundancy)
4. stress and acute anxiety, with adrenaline release
5. cold?
6. high oxygen partial pressures?
   [/list=1]Beware the incidence pit!
   
   I have suffered an identical experience in similar circumstances and intend to train up to use Trimix for next season.
   
   Glad to hear you now believe in redundancy.
   
   Safe diving!
   
   (What do you do will all those fish?)