Lung overexpansion, please help

[Louwhale]

Still looking for a specific depth, maybe a call to PADI tomorrow...

---------- Post added August 20th, 2013 at 12:25 AM ----------

If you are so unsure about the most basic concepts of physics associated with diving, you probably shouldn't be teaching 8 yr old kids to dive..

my kid was diving to 60 feet when he was 9 (with me), but I knew what the hell I was doing..

Dear Dumpster I'm simply trying to nail down a SPECIFIC DEPTH...I've heard different numbers so far from various professionals, anywhere from 3 to 6 feet. Again, if PADI courses operate in "less than 6 feet", wouldn't that indicate that 5 feet is OK, and 4 feet even better. I'm a Rescue diver, very familiar with the concepts of physics associated with diving and will obviously tell them not to hold their breath...
On a different note, I am also familiar with the certification levels, including kids. Here's a quote from the PADI website you may find interesting:
"Junior Open Water Divers ages 10-11 years old must dive with a PADI Professional or certified parent/guardian. Dives must not exceed 12 metres /40 feet."
So Dumpster, when you dove with your kid at 60 feet when he was nine, would ignoring both the 40 feet max depth rule and not waiting til he was 10 make you ignorant? You be the judge,
Cheers.

 

[Storker]

I'm simply trying to nail down a SPECIFIC DEPTH...I've heard different numbers so far from various professionals, anywhere from 3 to 6 feet.

You can't.

As with almost everything else physiology- and medicine-related, there is no hard line in the sand. You've already been given a single number, 4 feet. That number's like the diving tables. Some can experience a lung barotruma from less than 4 feet, some can be lucky and not experience a lung barotrauma from 6 feet or even more. Some can be lucky and not get bent even when exceeding the NDLs, some are unlucky and end up bent even well within the NDLs.

That there is no hard line in medicine is why I'm a firm believer in ample safety margins when it comes to potentially deadly pastimes.

 

[DevonDiver]

I read a medical report stating the SHALLOWEST recorded lung over-expansion injury (life threatening pulmonary barotrauma - arterial gas embolism) was from 30cm in a swimming pool.

 

[Subcooled]

At 30cm or 1ft the pressure is 1.03 bar ie. there is a 3% increase in pressure. It is a bit difficult to believe that this small pressure change could cause a pulmonary barotrauma. Please provide some hard evidence. I've heard that 5 metres or 16ft could be a problem. Don't blame me for any deaths, though. I know nothing. I am no doctor. You should consult a professional and not ask this question on some internet forum.

 

[DougK]

Would not a simple test be to fill a balloon up at 4 feet and let it go to the surface to see it it pops? But I do agree medically the younger a person is the less developed parts of the body can be. A child could be more susceptible than an adult at the same depth.

With all that said, I just watched a news segment on the record depth holding free diver and that blew my mind, what these people were doing. So maybe we are over thinking things. (I know they are breathing air a surface pressure, I just mean these people are taking a huge chance and living.)

 

[Max Speed]

Still looking for a specific depth, maybe a call to PADI tomorrow...

Cheers.[/FONT]

121.92cm

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[MXGratefulDiver]

As with most things scuba-related, there are no "specific" answers. How much expansion is "safe" will depend a great deal on how much air is in their lungs when they close their throat. The most dangerous place for expansion injuries is near the surface, because as you approach the surface the percentage of expansion per foot increases. From four feet to the surface is roughly a 12% expansion. How "safe" that is will depend on how full their lungs were when they closed off the system.

The balloon analogy doesn't accomplish much ... lung alveoli aren't rubber, they're only a few cells thick, and by design they're permeable. Balloons are useful for showing how gases behave under pressure, but they are not useful for measuring how much expansion is safe for human lung tissue.

How deep is safe is impossible to put a specific number on ... my answer would be if you have any doubts about their ability to comprehend the concept of "don't hold your breath" you should not take them below the surface on any compressed gas. This holds true whether they're children or adults. A better use of their time would be to get them comfortable in the water on snorkeling equipment, where expansion injuries won't be a concern. That time will be well-spent when they're old enough to grasp the concepts and risks of diving on scuba gear.

... Bob (Grateful Diver)

 

[Skittl1321]

Again, if PADI courses operate in "less than 6 feet", wouldn't that indicate that 5 feet is OK, and 4 feet even better.

PADI runs what they feel is a safe course for children (and adults...). That doesn't make it risk free. There is no depth that is completely risk free.

 

[Crowley]

So - we're in Basic Scuba Discussions and somebody is asking a reasonable question and then there are accusations of ingorance tending towards an implication of "basic stupidity and a failure to understand the basic laws of physics". Why not try some objective and reasonable answers which might include helpful advice?

Pulmonary barotrauma is entirely possible in 6 feet/2 metres(ish) of water. As one poster previously mentioned, this does assume that a "full" - ie maximum lung capacity breath is being held. It is also true to say that kids tend to be rather fearless and listen to advice - strange as that may sound, in my experience, it is actually true. When it comes to covering bases, to a certain extent, they are already covered, because the risk and liability involved in teaching kids to dive safely is rather vast, but it's also quite easy to do so, with some very basic safety guidelines, just like teaching kids to look both ways before they cross the road, because there's always some idiot adult driving a car who isn't looking at anything outside their smartphone.

There is a risk - there is always a risk with scuba diving (or crossing the road, or eating food, or even going to the lavatory) - but these risks can be minimised by some simple, basic instruction and careful observation. The risks in 6 feet/ 2 metres(ish) of water are minimal, but the risk of serious injury is dependent on several very deleterious factors, and if a child - or adult - is confident enough to descend to that depth in the first place, then the chances are that everything will be okay.

It's wise to be sensible to the risks of breathing compressed air underwater, even in shallow water, but a little bit of common sense, a good briefing, and some simple observation helps to minimise those risks to the point where they are almost (but not fully) removed.

Safe diving,

Crowley

 

[Jim-SAR]

PADI has a "Discover Scuba" course where the kids are supervised by instructors and dive masters. Why not just let those that are qualified do it.

I'm a PADI Master Scuba Diver and a Divemaster candidate, but I don't want the liability of endangering kids in a swimming pool. Yes, everything "might" go well, but there's also the possibility that it won't.


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