Water entry with regulator in mouth can cause embolism?

[Thalassamania]

Thal, it would seem that the cause of the embolism is NOT having the reg in your mouth BUT violating "the rule" of "Never Hold Your Breath" while underwater. Or am I missing something here?

I'm not really sure. There was much discussion at the time. Was the problem actually a breath hold? Was the breath hold associated with an instinctive valsava due to the drop and contract with the water surface, or cold? Was there a free flow problem? Was there an actual overpressurization due to depression of the purge? I doubt the last, we ran some informal tests that suggested that it was not likely to create enough pressure differential that way unless the exhaust valve was stuck shut.

 

[ScubaSarus]

Well Pete any air you breathe without the reg above the water will just return to its original volume on the divers rise. But if a diver is nervous and hyperventalating thru the reg while jumping in may get a significant gulp of air on the way down. And this air will increase in volume on the way up; if his air ways closes, and embolism can occur.

This is a rare event (anomalie) but rare events occur when divers do rare unusual things.

 

[rstofer]

Then too, the ascent rate of a full wing is probably going to exceed any rational value.

I would think that a diver doing a proper boat entry where they intended to resurface wouldn't even get their head wet. Then again, what do I know about doubles?

I would be more concerned about entering through an overhead surf. Here the diver has little or no control over the change in ambient pressure.

Richard

 

[Pearldiver07]

I thought about this, and I would think you'd need some very particular circumstances.

About the Gulf-Diving boats you make a significant drop when you stride in (4-6 feet, depending on how you judge the wave/roll?). Given that, if you hit the water slightly face down, descended a few feet due to an under-inflated BCD, and the impact with the water caused a purge, didn't allow excess air to escape, then I SUPPOSE that it might be POSSIBLE.

Of course, this is all assuming a healthy individual.

But this is a very small potential that I don't think that Vegas bookies would even hazard a guess on.

I wouldn't worry about this - there's lots more to sweat right now - it's tax season!!!

 

[Mr Carcharodon]

Back in one of my classes we were cautioned not to do shore entries with a regulator due to the potential of lung over expansion injury. The rational was that a breath taken at the bottom of a 4 foot or higher wave would provide enough pressure gradient to cause injury at the other side of the wave. The recommendation was based on an embolism that did occur in the surf zone. But there have been at least two cases of drownings in Southern California that have occurred in the surf zone in recent years. In those cases the victims might well have survived had they keep their regulators in their mouths. As usual there is a need to balance relative risk. Using a regulator but exhaling when depth is decreasing significantly seems like a reasonable middle ground.

 

[Thalassamania]

... In those cases the victims might well have survived had they keep their regulators in their mouths. As usual there is a need to balance relative risk. Using a regulator but exhaling when depth is decreasing significantly seems like a reasonable middle ground.

Sounds to me like classic equipment based solutions to problems that are really skill deficiencies. If the surf is too big for a diver's skill level I recommend going to a more protected entry/exit or staying on the shore.

 

[ScubaSarus]

"The rational was that a breath taken at the bottom of a 4 foot or higher wave would provide enough pressure gradient to cause injury at the other side of the wave."

Ive yet to understand why people do shore diving in swells as such. The vis has to be awful.

 

[Thalassamania]

"The rational was that a breath taken at the bottom of a 4 foot or higher wave would provide enough pressure gradient to cause injury at the other side of the wave."

I've yet to understand why people do shore diving in swells as such. The vis has to be awful.

The vis, while it sucks in the surf line, is often great 100 yards off the beach.

 

[LeadTurn_SD]

Intersting topic, and not something I've ever given too much thought to I guess. Thanks for bringing it up.

It would seem that the danger of embolizing following a typical giant stride entry is really quite minimal, but I guess still a remote possibility. I'm typically more concerned with surge when shore diving, and think that a strong surge while fairly shallow with a near empty tank would be more of a worry.

Note: Training for me in the 70's for giant stride was with snorkel in mouth (like Thal describes), but then we also practiced with reg in mouth. I think our instructor wanted us to be comfortable either way.... These days I still use a snorkel on most entries, both boat or shore.

 

[Lucy's Diver]

For my next hard hat dive I will be certain to bring my tender in with me so he can hat me in the water.