Asthma and diving equipment

[DivingDoc]

As many of you know, recommendations have recently been relaxed regarding SCUBA diving and asthma. See:

http://www.ymcascuba.org/ymcascub/asthmatc.html
http://thoracic.org/chapters/state/california/adobe/asthma.pdf
http://www.mtsinai.org/pulmonary/books/scuba/asthma.htm

So my question is: if an asthmatic dives, are there certain aspects of their equipment that would improve the saftely of diving with asthma?

Considerations I can think of include: moisture of air that one breathes; a regulator that's very easy breathing; and whether an overbalanced reg that "pushes" air into you at deeper depths.

The moisture issue: Mares Abyss and the Sherwood Oasis use metal foils which cause moisture from one's exhaled air to condense and therefore adds to the moisture in the air coming from the tank. Exercise induced bronchospasm is less likely to occur in warm moist air than in cold dry air. 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 bocy temperature).

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

The overbalanced issue: This, I am not sure of. Yes, if bronchi wer having a tendency to close during a dive, pushing air in at increased pressure might have a tendency to open those bronchi, though I am not sure about this. Back in the '70's we used to treat people with status asthmaticus who were hospitalized with IPPB (intermittent positive pressure breathing). That is, when they breathed in on the nebulizer, there would be a "push" under increaed pressure into the patients mouth/lungs. This practice was discontinued, however, when studies showed that the patients given IPPB did not get better any faster than those who didn't. Also, if the regs in question pushed air in at a lower relative pressure at shalower depths, the alveolar clusters that got extra air pushed into them by virtue of the increased air pressure at depth, might have more of a tendency to close once the extra pressure was lessened at shallower depths, which could lead to barotrauma or air embolism.

I'd like to know what the docs on this forum think, or if there are any other aspects of diving equipment that might be helpful for asthmatic divers, please bring that up also.

 

[Drew Sailbum]

I'm certainly no doctor but if humidity really does help, then the Apollo Bio-filter might be an item of interest. It is a small wick that you soak with distilled water before each dive. It mounts in a small housing between the first stage regulator and the air supply hose. It claims to add 30-70% humidity to the air. MSRP is $195.

A cheaper item which may help hydration is the SCUDA an underwater drinking system. I don't know how much it would affect the breathing air, if at all.

As far as positive pressure breathing goes, I think the engineers might have to have a little input. With modern scuba regulator design, I think it is either on-demand or fully free-flowing. I would think that regulator re-design would be necessary to provide positive pressure breathing.

 

[DivingDoc]

The Apollo Biofilter was one of the items I was looking at, but DAN raised the objection that although the humidity of the inspired air is 70%, the air in the airways would be much lower since the temperature of the air increases as it goes from second stage to the diver's airways. Also, in the biofilter, there is the chance of bacterial contamination. But I'm still intrigued with the idea.

What I was saying regarding the pressure is that the owner of one of the LDS's told me that the Apeks was mostly a tech reg and that it was overbalanced such that at greater depths the pressure at the end of the second stage becomes a bit higher and there is a sort of extra "push" into your mouth.

So it's not a matter of inventing a reg that does that -- it's already been here for years.:viking:

 

[rcohn]

If I were so close to an asthma attack that a small change in humidity or air pressure would have an effect, I wouldn't be diving. No change in gear should be needed.

If someone really requires warm moist air, a rebreather might be a good option.

Ralph

 

[DivingDoc]

Originally posted by rcohn
If I were so close to an asthma attack that a small change in humidity or air pressure would have an effect, I wouldn't be diving. No change in gear should be needed.

If someone really requires warm moist air, a rebreather might be a good option.

Ralph

Yes -- rebreathers might be good -- tell me more about them.

I'm not talking about someone being close to an asthma attack -- just talking about adding an extra margin of safety. Exercise induced bronchospasm occurs in response to cooling and drying of the airways. That is why doctors find that swimming (where the air just above the surface is warmer and moister) is an easier exercise for asthmatics to do than, say cross-country skiing.

 

[rcohn]

Well, (not speaking for anyone else) I don't need a margin of safety, when I'm using Flovent or a similar steriod inhaler attacks just don't occur. This has included such activities as speedskating in very cold dry air at maximal exertion levels, far beyond anything I've ever encountered while diving. If I felt the moisture level in the air might make a difference I wouldn't be diving.

As I understand the YMCA protocols, the asthmatic diver should be well enough controlled that an extra margin of safety is not required.

Ralph

 

[DivingDoc]

Originally posted by rcohn
Well, (not speaking for anyone else) I don't need a margin of safety, when I'm using Flovent or a similar steriod inhaler attacks just don't occur.

As I understand the YMCA protocols, the asthmatic diver should be well enough controlled that an extra margin of safety is not required.

Ralph

It's great that your doctor is managing your asthma in accordance with NHLBI guidelines.

And I have read theYMCA SCUBA ASTHMATIC DIVER PROTOCOL
and think it is well designed. Dr. Duke Scott, Medical Adviser to the program, has told me by e-mail that they have had over 300 divers with asthma complete the program and so far have had no problems.

However, a margin of safety or a measure of redundancy is not related to whether you expect to need it. Why do you think that jumbo jets or the space shuttle have backup computers for their backup computers and all sorts of redundant safety features. Is it because they expect to have problems? No. It's because when it comes to life support equipment (such as space shuttles and passenger airlines), it's just good planning. With life support equipment, it's always best to optimize everything you can.

Now, can we get back to my original question? I'd like to hear from the MD's on this forum. :doctor:

 

[rcohn]

DivingDoc,

Gee, sorry I gave my opinion and apparently frightened the MDs away. I'll be sure to keep very quiet in the future so our timid MDs will feel safe enough to venture onto the board and give your oh so important questions the definitive answers they deserve.

Oops I lied, here comes another opinion. Sorry again, I guess the MDs will never answer you now.

The subtle effects you are so concerned about all come at a price. Rebreathers provide warm moist air but bring a wide range of risks, costs, and complications. Moisturizers in the low-pressure hose require maintenance to prevent microorganism growth and maintain water supply. Placing the filter in the LP hose can't be improving regulator performance. Few divers will like having an overtuned positive pressure regulator ramming air into their lungs and freeflowing violently, and I believe positive pressure breathing violates European CE standards.

To add these various risks and complications there needs to be a clearly defined benefit. For example, a rebreather will provide moist air, but you now have a range of new problems that might kill you. Does that increase the diver's safety? For an asthmatic diver that satisfies the YMCA protocols I don't believe the minimal (or nonexistent) benefits justify the hassles and risks.

For asthmatics who can't satisfy the YMCA protocols but choose to dive anyway that is obviously a different story, the risk/benefit analysis shifts. If I could no longer satisfy the YMCA protocols, I'd give up scuba and stick to freediving. Divers who choose to continue are largely on their own, they will need to evaluate their individual condition and select the equipment that suits there needs. For example, a rebreather may be the only viable option for a diver whose attacks are triggered by cold dry air.

 

[SM Diver]

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?

 

[SM Diver]

Also, I can't remember the physiology of why exerting yourself at 100 fsw tires you out more quickly than, say 50 fsw.