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Deep Dives On Air - Inherent Problems S&L Term

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Deep Dives On Air - Inherent Problems S&L Term

Post Number:#1  Postby John F SeaDemon » Fri Feb 09, 2007 7:51 pm

There has been a lot said about diving deep within recreational limits, and also of recreational divers going past the 40-meter limit (130fsw) doing "touch-and-go" etc...even down to 50 meters. First let me just run this by and present my understanding of deep diving physiology, obtained not fully from or during my DM and or Decompression Procedures courses, but through my readings. This topic has also been touched in the BASIC SCUBA DISCUSSIONS topic of this forum.

As we know, open water divers are given a limit of 18 meters to dive, advanced open water divers to 40 meters after having doen their deep dive specialty.

First and foremost, with diving and breathing compressed air, comes Nitrogen narcosis (N2 Narc). For those recreational divers who love going deeper than 40 meters doing their "touch-and-go", let it be known that the depth 40 meters is the limit set by the US Navy as the deepest depth divers on air can do useful and meaningful work. In some divers, N2 Narc onset is between 24m to 30m, although that figure will vary from day to day for respective divers.  The deeper they go, the more narced they'll get. And at 66 meters (if we employ a PPO2 of 1.6) it borders on O2 toxicity.

The higher mental functions such as ability to reason - to make potential life-saving judgments, to remember recent events, to learn new tasks and to focus concentration on a specific task are first affected.  (One reason for commercial hard wire communications is in Commercial Diving so that surface personnel can monitor a diver's ability to function and remind the diver what is to be done).

In warm waters like ours, especially if the viz is good as Sipadan, dives will feel euphoric and over-confident..so you get lots of people who do touch and go to depths beyond recreational limits because they feel immortalised. Then when the water turns cold, or neither the surface nor the bottom can be seen, or viz turns bad due to thermocline, the diver will get a sense of impending doom, and often go into panic. They do stupid things like removing their regulator, or the BCD harness completely. Which is why fatalities occur at these depths when narced. Simply limiting dives to shallower than 30 meters is usually the answer to N2 Narc.

Other long term effects of deep air diving is osteonecrosis (did I spell that right?) and loss of hearing (ring ring inside my head now ;D), and this affects all kinds of diving...commercial, military, technical and recreational alike. Others include liver changes, decreased pulmonary functions.

[highlight]My questions to the respected docs are: [/highlight]

1) is my understanding here correct?
2) why are open water divers limited to 18 meters (60 feet) before they can go deeper after doing their deep dive adventure specialty?
3) what are the other implications of deep air diving and diving beyond your trained limit?
4) what are the other implications that I and other forum members need to know?

Thank you.
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#2  Postby divedoc » Fri Feb 09, 2007 9:08 pm

Wow SD, sometimes ur Q's are soo technical sangat lerr...Nanti kalau i bagi a technical answer, i takut everyone in MUW will be scared stiff to dive anymore!!

I couldn't agree more with ur understanding. With deeper dives, comes greater complications. N2 narcosis starts at about 30-40m, and when that comes into effect, certain higher mental functons such as motor functions and decision making abilities becomes affected. Imagine being at that depth and at total lost of control of urself. This is no joke!! I've heard stories of divers trying to buddy-breath with fishes at 30m!!

As for the limitation, i couldn't comment much as this is the prerequisite of any dive agencies, PADI, NAUI...The max is 18m probably to make the newbie diver get accustomed to a shallow-not-so-shallow depth. Diving requires confidence, and if one isn't confident, imagine what will happen if one get panicky at depth >18m and shoots straight to the surface?? Probably Caduceus could answer this Q.

As for implications of deep air diving, u are right, it's dysbaric osteonecrosis, by the way. Other adverse effects include hearing loss and permanent neurological deficits, most commonly as a result of a decompression accident. However, studies have shown that prolonged hyperbaric exposure without any decompression accident have also caused these adverse effects. That's why for the Navy, we routinely have a baseline Long-bone X-ray screening before they go to depths greater than 50m. Although we have yet to encounter any cases of dysbaric osteonecrosis, a diver may not present with any bony pains until after about 20-40 years after he retires from diving.  

I'll be sure to update u on ur Q's as this is a REALLY GOOD TOPIC for our forum!
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#3  Postby John F SeaDemon » Fri Feb 09, 2007 9:33 pm

Hahaha..don't get too technical la...I thought my questions aren't that technical. Maybe the medical terminologies are. I'm just trying to get forum members to think more about how they dive when they dive..and that includes me. I think we take it for granted because it's water and think scuba diving has less inherent dangers than skydiving (Caduceus and I share that). But I've been thinking, even aluminium bodied aircraft suffer from metal fatigue due to decompressions and recompressions, what more our own body and bones.

I certainly do hope that, other than the normal topics where we have fun, forum members would participate in discussions such as this. Ask away, even if it seems stupid. We will never learn if we don't ask.
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#4  Postby Jim » Fri Feb 09, 2007 10:37 pm

...tumpang lalu skit.... Max depth for aow is 30m. The max absalute depth for recreational divers is 40m

Agreed that some terms do sound technical. But if can elaborate it in layman's term would be very benificials. Am for one would like to know more of this kind of topic. Keep it coming doc.....
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#5  Postby John F SeaDemon » Fri Feb 09, 2007 10:54 pm

Hahahaha..that's why you're the Instructor and I'm not. I'd do deep dive adventure specialty for AOW at 40m and see how they remain neutrally buoyant before doing some calculus or Algebra.

The only term you may not understand is osteonecrosis...my malay friends say "Tulang mati"
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#6  Postby Jim » Sat Feb 10, 2007 10:12 pm

Hehehe..... The term i like is MC. Then can go see movies.....

IMHO i feel that awareness amongst divers regarding deep diving is still lacking. Many people still bragging how deep they went last dive. This is like taking unnesessary risk on to yrself.  
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#7  Postby John F SeaDemon » Sun Feb 11, 2007 2:28 am

Hehehe..... The term i like is MC. Then can go see movies.....

IMHO i feel that awareness amongst divers regarding deep diving is still lacking. Many people still bragging how deep they went last dive. This is like taking unnesessary risk on to yrself.  


That is so true.
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#8  Postby John F SeaDemon » Sun Feb 11, 2007 7:15 am

Divedoc,going bak to what you said about the mental (and possibly motor) impairment at depths exceeding 30 meters, I believe there is a reason for recreational training agencies limit recreational divers to only that depth, and use that depth even as a maximum for deep diving and some form of narcosis management to take place as that would be the borderline if the instructor needs to yank the diver to a safer depth (as N2 Narc is easily diminished by going to depths lesser than 30m).

I understand also that as depth increases, the chances of getting DCS increases, hence the saying if you don't want to get DCS, don't dive at all, and that severe recreational diving DCS often involve the spinal cord. The worst part is most recreational divers who do deep dives untrained do not understand the severe implications such as having to use a walking stick or wheelchair to walk or to go to the toilet, cannot control the flow of urine or the BIG ONE, and the [highlight]loss of the ability to have sex[/highlight] (I purposely highlight this because other symptoms may not be important enough for majority of the divers in here). DAN puts the number of those still having physical impairment after 3 months post-treatment at 13%.  In the US, 60% of recreational divers do not recognise the symptoms of DCS, and over 50% do not know how to plan dives using the RDP and/or deco tables.  Yet, we find recreational divers who go deep simply for kicks and/or to be able to brag at how deep they can go, as mentioned by Jim up there.  And these divers do not understand that DCS either kills or maims, and is also a progressive disease..and as such may get worse until treated. Last year there was a case of a local dive instructor who had DCS but was left untreated (he went to a local hospital and the doctors there did not recognise the symptoms), went back diving after being discharged and died!

In actual fact, more than 70% of DAN treatments involve depths greater than 24 meters (80 fsw). I hope divers trained to do recreational dives read this and take note.

I hope the docs here can shed more light on the dangers of untrained deep diving. My knowledge is limited.
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#9  Postby John F SeaDemon » Mon Feb 19, 2007 1:30 am

One more thing..aren't young children more susceptible to dysbaric osteonecrosis?
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#10  Postby Snafu » Mon Feb 19, 2007 1:47 am

Dysbaric Osteonecrosis .. was told that this does happen, especially to commercial divers that do deep AIR dives due to Nitrogen.... is hard to prove it, after all it happen after so many years of diving & no proper research being done to it.

Doc .. would you be interested to do more research on it?

Every year doing Long bone X-ray is not good also ... exposures to radiations

;D
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#11  Postby divedoc » Mon Feb 19, 2007 2:23 am

[color=#cc0000] ...Doc .. would you be interested to do more research on it?

Every year doing Long bone X-ray is not good also ... exposures to radiations

;D



Snafu my friend,

Mana ada aku buat long bone survey every year?? I'd do it only once before they commence deep diving and 4 yearly thereafter. Itupun u tau le the navy ni, bukan ramai yg buat deep dives, kalau ada pun lepas 4-8 yrs dah berhenti from service. The problem with doing a research on Dysbaric osteonecrosis is that investigators tend to lose study subjects due to compliance...u pun tau lah, brape ramai of u all yg nak jumpa Dr lepas berhenti kerja?? Disebabkan takut nak tau yg diri sendiri ada masalah kesihatan, langsung taknak jumpa Dr...And for this particular disorder, one has to follow-up the study subjects for a loooooong period of time to see the results (if there is any!!!). But anyway, that's a good suggestion which i might consider. Thanx Bro!
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#12  Postby John F SeaDemon » Mon Feb 19, 2007 2:44 am

Hahaha..typical "what I don't know won't kill me" attitude. I'd rather I know what I'm up against so I know what strength I need to fight it.  So I do complete check up even for HIV, VDRL etc. My younger brother's a chain smoker..and although he regularly works out (more than I do), the last check-up we did together saw him having hypercholesterolemia...far higher than mine, and he was asked to stop running on the treadmill after 8 minutes because doctor was not happy with what showed up on the graph.

I'd rather know how much longer can I live, so I can divide my time into how many sex sessions I can have before my body quits. ;D
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#13  Postby divedoc » Mon Feb 19, 2007 3:24 am

Hahaha..typical "what I don't know won't kill me" attitude. I'd rather I know what I'm up against so I know what strength I need to fight it...  


Biasa lah SD, Malaysians will alwiz be Malaysians. I'm glad you're some of the concerned few who does not take for granted about their health in general...
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#14  Postby John F SeaDemon » Thu Mar 08, 2007 11:14 am

Doc, what are the other long term effects of deep diving, especially without the proper knowledge to do so safely?
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#15  Postby Snafu » Thu Mar 08, 2007 12:21 pm

[highlight]My questions to the respected docs are: [/highlight]

1) is my understanding here correct?
2) why are open water divers limited to 18 meters (60 feet) before they can go deeper after doing their deep dive adventure specialty?
3) what are the other implications of deep air diving and diving beyond your trained limit?
4) what are the other implications that I and other forum members need to know?

Thank you.


Hmmmmm.... Only My Opinion

1. Yes & N2 is the main cause of DCS & Narcosis
- If we dive within the NDL .... DCS risk is less but still exists.
- Deeper we go the more Air we breath, as 79% is N2...we breath more of it at depth...higher risk

2. 18m max is for them to build up their diving confident & experience, new divers tend to get funny feelings as they hit the 18m & below. Is easier for buddy to assist at shallower depth.

3. DAD implications ... Narcosis hit on the mental state of alertness will lead to accident which will effect the diver & others on the trip.
- The skill that diver learn during open water are not enough to get diver out of trouble at depth.
- Lack of DAD understanding will lead to DCS
- DAD with extra task loading then normal can & will bring the panic button level lower then normal
- N2 might give long effect damage with brains & bones ... Studies Needed in This AREA as the rest above are proven
- STML (Short Term Memory Loss) ... Memory laps ... Slow thinking on surface

4. Implications as above ... Dive within your limits & build your dive slowly
- Dive like you want to dive forever & be conservative
- Diving is a sport, is SAFE just like any other sport ... infact is safer then BOWLING as long as the diver understand the theory behind it & not against it.

DAD- Deep Air Diving

Continue AOW diving education ONLY when we understand better about the basic of SCUBA & able to do the skills by instinct as it will safe life & make us a better diver.

Just my Personal Opinion.

;D
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#16  Postby dp » Thu Mar 08, 2007 4:14 pm

The worst part is most recreational divers who do deep dives untrained do not understand the severe implications such as....the [highlight]loss of the ability to have sex[/highlight].



aisey... now have to change my nick from deepblu to shallowblu....



but interesting topic, nonetheless.  :)
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#17  Postby SeaDemon » Thu Mar 08, 2007 11:31 pm

Good summary by Snafu
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#18  Postby mnim821 » Fri Mar 09, 2007 12:00 am

Thanks SeaDemon for bringing up this topic. I reckon its imperative for everyone to adhere to dive limits as obviously no one would like to get into any accident. Also, IMHO we need to respect the environment which is not ours to live in and ego definitely doesnt have a place underwater. I don see the point why divers race with each other to see who has dived deeper, unless you're doing it competitively. What's important is we dive safely so that we could go back to our families accident free. Nonetheless, if it happens, it's God's willing.  
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#19  Postby SeaDemon » Fri Mar 09, 2007 12:23 am

If they want to race just to brag for show-and-tell, then they should race to reach the surface first.
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Re: Deep Dives On Air - Inherent Problems S&L Term

Post Number:#20  Postby Jim » Fri Mar 09, 2007 8:45 am

Thanks SeaDemon for bringing up this topic. I reckon its imperative for everyone to adhere to dive limits as obviously no one would like to get into any accident. Also, IMHO we need to respect the environment which is not ours to live in and ego definitely doesnt have a place underwater. I don see the point why divers race with each other to see who has dived deeper, unless you're doing it competitively. What's important is we dive safely so that we could go back to our families accident free. Nonetheless, if it happens, it's God's willing.  


i 2nd that..... To me dive deep with a valid purpose & objective is ok. But to do deep for the sake of it is no, no.... Stay shallow. Less risk & can enjoy more bottom time.
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