DivingDoc
Contributor
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.
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.
system. I don't know how much it would affect the breathing air, if at all.
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.
