Water entry with regulator in mouth can cause embolism?

[RubberDucky]

Hi All,

Browsing these forums last night I came across a comment from someone that appears to be a highly experienced diver, stating that entering the water with a regulator in your mouth has caused embolisms in some cases[1]. This was in response to a video someone had posted about divemaster skills[2].

This person's statement has me very confused for a few reasons:

1. I am PADI OW certified, and of the 3 boat dives I've done so far, I've put my regulator in my mouth before jumping off the boat (with the palm of my right hand holding the regulator firmly in place, and my fingers of the same hand holding my mask firmly in place), as instructed.

2. In the "OPEN WATER DIVER Manual" from PADI (ISBN 978-1-878663-16-0), on page 113, the book states the following (emphasis mine):

When you must enter the water from a raised platform such as a boat, wall or pier, you may use a giant stride entry. To do this, secure your equipment, check that your BCD is about half-inflated, place your regulator in your mouth and hold your mask tightly in place. When your buddy's ready, check the area below, then simply step out with one foot.

I've searched the forums, googled, and consulted the handful of diving books I have, and can't find anything about getting an embolism by entering the water with a regulator in your mouth.

My questions, for anyone kind enough to provide some insight, are as follows: what is the risk of getting an embolism by entering the water with a regulator in your mouth? Even if it's .01%, that's a risk I'd rather not take. If something has changed since I was trained (Jan 2008), where can I find information on the new procedures?

Thanks for your time!

[1] scubaboard.com/forums/3964826-post42.html
[2] youtube.com/watch?v=qmAmkx1TeXM#t=8m37s

 

[lmorin]

I wouldn't worry about it. Even if it is true (strange things do happen and I'd really need to see the cause-effect relationship established to believe that boat entry with reg in mouth yields PAE, even rarely), the incidence has to be mind bogglingly low. Everyone is taught to enter with reg in mouth; essentially everyone does. You do the calculations from there. The chance of a PAE from a boat entry with reg in mouth has to be less than the likelihood of dying while typing a ScubaBoard post.

 

[knotical]

Sounds rather like an urban legend. I've been around diving for just shy of 50 years, and I never heard this one until now. I too would be curious to know if this happens, and if so what is the mechanism. It would be great to get some authoritative documented evidence.

 

[don Francisco]

You'd have to go out of your way to get an embolism fron entering with a reg in your mouth.

Before entering you're breathing air at surface pressure, so even if you dropped a few feet down and came back up there's no risk of embolism or expansion injury. To create problems, you'd have to drop a few feet down into the water on entry, inhale a good breath at that depth, then hold it as you came back to the surface. Can this happen? Of course but it's not exactly a likely sequence of events.

Stick to the way you were trained. If this were a meaningful risk, the training protocol would have addressed it.

BTW- Please don't screw up the statistics. After entering and dropping a few feet down, don't inhale and then hold your breath as you resurface. (I think this falls under the never hold your breath rule)

 

[Digger54]

Hmmmmm...... Sounds odd to me too, though I admit my limited experience and I'm certainly not a pro. I thought maybe looking at the post in its context would give a clue. It's in Basic Scuba Discussions/ Going pro.

Somebody's going to have to explain the logic of not having the reg in mouth on entry under normal circumstances.

Until then mine will be in my mouth on entry and in my mouth on exiting the water until I am securely back on the boat/shore.

If I am waiting on the surface for my buddy or group to all get in the water I may remove the reg after entering to conserve air if there's not a lot of choppy water.

The only thing that I can fathom (pun intended) that could cause problems might be from the purge valve being pressed on entry and causing a lung overexpansion injury by a clumsy, overanxious or inexperienced diver???? An injury similar to that which could occur from a diver sealing his mouth over a free-flowing regulator?

Since I started typing my post, don Francisco added his. I can see how an individual that is over weighted or had very little air in his BC could plunge down a few feet on entry and if they inhaled at a few feet of depth and did a breath hold could get in trouble. I was always taught to enter rather positively buoyant. Gosh, I don't think I have ever gone deeper than two or three feet doing a back roll from several feet above the water from a boat.

I naturally before entry take a breath and hold it during entry to help guarantee positive buoyancy, so no harm done there.

 

[Garrobo]

I don't know where else you would put the reg except in your mouth to do any good.

 

[Melicertes]

I cannot see how having your reg in your mouth when entering the water can lead one to embolize, at least not from anything related to breathing off your regulator at the time of entry into the water. But then I'm no medical or decompression expert so I might learn something from some of the gurus on here to the contrary in this thread.

The way I understand it is that for typical diving gas mixes the inert gasses in the mix do not get used by the body during metabolism although they do dissolve into the body's various tissues at various rates, depending on the various tissue types, under hyperbaric conditions. I see no embolism risk during the part of the dive that the diver is gas loading, provided he or she is not doing a sawtooth profile, an emergency ascent or something similar. Any gas bubbles would dissolve into the tissues as the ambient pressure increases. The problem comes when you're reducing the ambient pressure and the dissolved gasses that the body did not or could not use come out of solution.

As I understand we always have microbubbles forming during decompression whether we surface ever so slowly or not so slowly, the problem is that with faster ascent rates the bubbles come out of solution quicker and tend to form larger bubbles than with slower ascent rates, hence the idea of ascending slowly and perhaps even using deep stops. When these microbubbles encounter nuclei, or particles (which could even be other microbubbles) around which they can collect to form larger bubbles the risk for DCS and embolism increases as the ambient pressure continues to decrease; again this is the reason for ascending slowly and in a controlled fashion.

Since you're entering the water and have not yet had the opportunity to on-gass any inert gasses from your breathing mix under pressure, I see no reason why one would expect there to be a risk of embolism with or without the regulator in your mouth. So unless I am missing something entirely my current view on the matter is that it is probably a myth with no foundation. If someone has some research that suggests this is real, I'd like to see it.

 

[RubberDucky]

Thanks a bunch for all of your replies. If I ever come across any actual supporting information on the subject I'll post it here, although it sounds very unlikely at this point, thankfully so!

 

[diver 85]

No wonder @ times I've felt dead over the last 20+ years....

 

[Straegen]

I fail to understand how it is possible an embolism would be created from a reg in your mouth and stepping into the water. Something has to be in the bloodstream and then it has to travel and cause a blockage. None of these things seem related to a regulator in your mouth. I think this is some pretty stupid cautionary practice. I would guess not having it in your mouth and causing this scenario more likely: jump in, the reg bouncing up hitting your nose, causing a massive nose bleed that causes a rare human blood shark feeding frenzy to spontaneously erupt killing the participant.

I am not a doctor so maybe there is something to this, but I REALLY (and I mean REALLY) doubt it.