Pulmonary Oedema incident

[InTheDrink]

Thanks Dr Smith,

A lot of what you say seems to make sense (although like you say, the whole area is somewhat opaque given the infrequency of the issue).

My tips to avoid IPE?
When diving I think avoiding stress and over exertion are probably my main take-aways. If diving CCR then I'd double the non-exertion bit and also maintain *adequate* loop volume.

On land keeping fit, BP down and avoiding non-essential meds.

Oh, and did I mention Don't Over Exert!!!

John

 

[bowlofpetunias]

Great info thanks everyone esp Dr Smith .....

 

[TSandM]

Lovely post, Dr. Smith! I suspect some and maybe all of the factors you have listed may play a role, as well as the intrinsic reactivity of an individual's pulmonary vasculature. I am aware that there are folks at Duke studying this entity, doing tests like Swanning patients and having them exercise, and perhaps those studies will shed a little light on the etiologic factors.

 

[peterbj7]

If diving CCR then I'd ... maintain *adequate* loop volume

Can you expand on this?

 

[InTheDrink]

Can you expand on this?

Yes, of course. With the disclaimer that I was a novice CCR diver with ~25 hrs on CCR so no really qualified to make any statements of serious worth on this set up.

Minimum loop volume is what is usually desirable. So one breath and no more on the loop.

But less than one breathe on the loop is a BAD THING. IMO at least. That's what I mean by adequate. How you keep it adequate may be up to you or your unit, but adequate it should be.

I believe, although who knows for sure, that sucking against empty counter lungs whilst descending and not manually adding gas was a factor in my episode. Am I right? **** knows. It's just a word of warning.

 

[peterbj7]

During the initial descent my counter lungs are usually completely empty so breathing in is an impossibility and I don't try. It's usually the only way I can descend. Then after my descent is established, at maybe 10-15 ft I can start adding diluent and breathing. That first breath is wonderful! Throughout the dive I maintain minimum loop volume, so that after breathing in normally the counter lungs are empty. During an ascent that's quite hard to maintain. Tho' I have rather more CCR hours than you, and reached instructor level around 8 years ago (though I didn't complete that rating for unrelated reasons).

 

[Duke Dive Medicine]

Dr. Smith, excellent post, and a very eloquent explanation as to why we shouldn't rush to label every incident of pulmonary edema in a diver as immersion pulmonary edema. In our experience so far, the 'purest' IPE, so to speak, happens in triathletes and military combat divers who are in excellent physical condition and have few (if any) comorbidities.

 

[InTheDrink]

During the initial descent my counter lungs are usually completely empty so breathing in is an impossibility and I don't try. It's usually the only way I can descend. Then after my descent is established, at maybe 10-15 ft I can start adding diluent and breathing. That first breath is wonderful! Throughout the dive I maintain minimum loop volume, so that after breathing in normally the counter lungs are empty. During an ascent that's quite hard to maintain. Tho' I have rather more CCR hours than you, and reached instructor level around 8 years ago (though I didn't complete that rating for unrelated reasons).

Of course, on initial descent you have that initial empty CL. I was thinking more about later in the dive and on aggressive descent.

I could probably have described it better by saying you want to ensure min loop vols at all times during descent. Else you're relying on ADV and I don't think that's a great idea. It is somewhat unit and unit version dependent. Evolution generous, rEvo less so altho latest version apparently more so.

To be even more explicit: if it feels like you're sucking concrete through a straw you're probably doing something wrong . Among other things this was a mistake I made.

 

[retendokid]

Dr. Smith, excellent post, and a very eloquent explanation as to why we shouldn't rush to label every incident of pulmonary edema in a diver as immersion pulmonary edema. In our experience so far, the 'purest' IPE, so to speak, happens in triathletes and military combat divers who are in excellent physical condition and have few (if any) comorbidities.

Given how little is known, and the relative rarity of diving-related pulmonary edema, I wonder if there is any utility in using a resource like Scubaboard, which links divers from around the world and harnesses the power of the world wide web, of creating a Pulmonary Edema Reports Page (or whatever you want to call it) where cases and accounts can be reported by divers. Collating cases into a single repository concentrates the events and allows common features and risk factors to become recognized. This kind of thing is done routinely for rare diseases and conditions. As it is, these accounts get scattered on various threads and forums....

I think the limitation of an organization like DAN, which may well collect diver reports of these events, is that accounts are not made public so people with knowledge or experience may never have opportunities to comment or observe patterns, and collectively we may fail to recognize that these events are occuring with greater frequency than suspected.

 

[Duke Dive Medicine]

Given how little is known, and the relative rarity of diving-related pulmonary edema, I wonder if there is any utility in using a resource like Scubaboard, which links divers from around the world and harnesses the power of the world wide web, of creating a Pulmonary Edema Reports Page (or whatever you want to call it) where cases and accounts can be reported by divers. Collating cases into a single repository concentrates the events and allows common features and risk factors to become recognized. This kind of thing is done routinely for rare diseases and conditions. As it is, these accounts get scattered on various threads and forums....

I think the limitation of an organization like DAN, which may well collect diver reports of these events, is that accounts are not made public so people with knowledge or experience may never have opportunities to comment or observe patterns, and collectively we may fail to recognize that these events are occuring with greater frequency than suspected.

We're starting to do that here at Duke. IPE is getting a lot more online visibility in the triathlete community, and through threads like this one, the diving community. Pete and Howard do a fantastic job of search engine optimization so that often when a diving-related topic is searched, Scubaboard threads are at or near the top of the list. When a diver comes here with questions about pulmonary edema, someone typically refers him/her to us if we don't pick it up right away. Dr. Moon's research assistant has recently established a Scubaboard user name, DukeIPE, and has an alert set up for new internet postings on immersion pulmonary edema.

Dr. Moon and his team have already published several papers on the subject: Risk factors for immersion pulmonary edema: h... [J Appl Physiol. 2011] - PubMed - NCBI, Effects of hyperoxia on ventilation and pulmo... [J Appl Physiol. 2010] - PubMed - NCBI, Effects of head and body cooling on hemodynam... [J Appl Physiol. 2009] - PubMed - NCBI. They continue to actively research IPE and are transitioning to a couple of new studies: one that looks at overhydration as a risk factor, and another that is looking at mitral valve regurgitation.