Divers thoughts on the Thai caves!?

[robhwa]

As a long-term diver, vertical caver of many years, but with only a little cave diving experience in Florida, this whole thing is fascinating to me. This is "Floyd Collins" all over but with a better ending. O2 could serve two purposes, replenishing in the cave's or enriching the breathing air, though I am leaning toward the later. Adding additional O2 to the air divers are breathing has a long history. Breathing O2 enriched air makes one more alert and less subject to fatigue, and also reduces the partial pressure of N2 in the air. N2 causes N narcosis and the "bends" when it dissolves in blood and other body liquids under pressure (i.e. pressure of water while diving) and then comes back out of blood as bubbles when surfacing. N narcosis is kind of fun, but they don't want it in the diving operation for sure. They don't want the boys "drunk" with N narcosis or they may not pay attention. They also don't want them to have the bends, which is not fun in any way. Additional O2 in the breathing air can help. In the cave air the main problem isn't likely O2 depletion, but CO2 toxicity, which would kill long before O2 was depleted. I'm not sure of the effect of a lot of water in the cave, as CO2 might dissolve in it and keep the level low. In subs, they use CO2 "scrubbers", also similar to what the guy used in the "Martian". Probably the risk of embolism or DVT is at a minimum with these kids...they are young, unlikely to be overweight, they are soccer players, which means they probably are in fairly good shape and likely healthy overall. All are negative risk factors for PE and DVT.

[spuncopper]

I am not sure the O2 was for divers, but yes one atmosphere of O2 can kill you. I thought the Oxygen was for replenishing levels in the cave, not for divers. At one point O2 was down to 15% where the team was. Normal air is 20% O2 and 80% Nitrogen. It could also have been used when the kids were walking with heads out of the water.

Hey Wandering Sage Brush,

I'm very familar with O2 in diving, I'm a retired US Navy First Class Diver (NEC 5342) HeO2 type. I've split and mixed and humped many an O2, He and HeO2 bottle aka tanks(I'm talking the large industrial size tanks used in the gas racks) over the years.

If you watched Bill Neely's report this morning he didn't say a word about oxygen. I e-mailed the network concerning his erroneous and over dramatized report. He spoke only of tanks of air as all the other reporters had been doing all along.

Actually air isn't quite 80% nitrogen and 20% O2, it's closer to 78 nitrogen, and 19% O2 with difference made of other inert gasses, but, that's just splitting hairs.

Take care and be safe.
Spuncopper

[spuncopper]

I am not sure the O2 was for divers, but yes one atmosphere of O2 can kill you. I thought the Oxygen was for replenishing levels in the cave, not for divers. At one point O2 was down to 15% where the team was. Normal air is 20% O2 and 80% Nitrogen. It could also have been used when the kids were walking with heads out of the water.

Hey Wandering Sage Brush,

I'm very familar with O2 in diving, I'm a retired US Navy First Class Diver (NEC 5342) HeO2 type. I've split and mixed and humped many an O2, He and HeO2 bottle aka tanks(I'm talking the large industrial size tanks used in the gas racks) over the years.

If you watched Bill Neely's report this morning he didn't say a word about oxygen. I e-mailed the network concerning his erroneous and over dramatized report. He spoke only of tanks of air as all the other reporters had been doing all along.

Actually air isn't quite 80% nitrogen and 20% O2, it's closer to 78 nitrogen, and 19% O2 with difference made of other inert gasses, but, that's just splitting hairs.

Take care and be safe.
Spuncopper

[robhwa]

As a physical chemist, I was struggling with understanding how an atmosphere that is normally 21% O2 and only 400 or so PPM CO2 could go to 15% O2 without producing enough CO2 to kill everyone. It couldn't without a sink for the CO2 that didn't produce O2 or a sink for the O2 that didn't produce CO2.

I tried reading more about this, and found some information from the problems they had with Biosphere and Biosphere II in Arizona (https://en.wikipedia.org/wiki/Biosphere_2), which was supposed to be sealed of matter (including gasses) and only exchange energy with the outside. They found that the CaCO3 in the concrete absorbed CO2 so that emitted CO2 from respiration couldn't be turned back into C and O2, and O2 dropped through that normal respiration. They had to open up and let the O2 replenish by exchange with outside air.

Most caves are Karst (limestone or CaCO3), so there may be a source of adsorbing CO2 there, and CO2 readily dissolves in water, so that may be a sink that would allow O2 to drop. If anyone sees anything written about this, please let me know. In these cases, the O2 brought in could have been to replenish cave air. Sorry if this doesn't have much to do with C-Dorys, but I assume C-Dory people are interested in this rescue, which was utterly fantastic. My only experience in "rescue" in caving was body recovery, and I have been thinking about those boys in that cave from the first time I heard of it.

[localboy]

My wife tells me a Thai rescuer died. A retired Sgt Major and Thai special forces member. Anyone? First I heard this.

[spuncopper]

Oops my bad. Air is 78% N2, 21% O2, 1% misc. gases. Must be getting old.

My beef was with poor reporting. The said reporter continually referred to oxygen tanks being carried in which enfered they were diving 100% O2. Other reporters referred to them as air tanks or SCUBA tanks with air.

The rescue, THAT was amazing.


take care and be safe.
Spuncopper

[spuncopper]

Oops my bad. Air is 78% N2, 21% O2, 1% misc. gases. Must be getting old.

My beef was with poor reporting. The said reporter continually referred to oxygen tanks being carried in which he implied they were diving 100% O2. Other reporters referred to them as air tanks or SCUBA tanks with air.

The rescue, THAT was amazing.

take care and be safe.
Spuncopper

Now how did my last post, post twice?? Getting OLD! or just heavy fingers.

[thataway]

Yes, an ex Thai seal, joined the rescue team. He ran out of air (what ever gas mixture, which I assume was normal compressed air as in normal scuba tanks-some special forces use an enriched oxygen mixture--perhaps our Navy divers can address that. Usually 32% oxygen, and clearly labeled. ). The Thai ex special forces guy was extremely fit, cyclist marathon runner. It seems like at times it is the luck of the draw--or he pressed too close to the margin. In any case a real tragedy.

I too have been following this rescue--it is a major technical rescue. Fortunately all of the boys and the coach are out safely. Hopefully there will be no more loss of life in the technicians and divers as they remove the rest of the rescue team. I had read that both low O2 and elevated levels of CO2 were issues in the "room" where the boys and coach were trapped.

I don't think there was much risk of the "bends" or nitrogen narcosis since this involves a certain depth and atmospheric pressures in excess of one atmosphere. However these is a confirmed case of the "bends" from a dive depth of 10 feet--time and number of repudiative dives are not documented.

I have been a free diver since 1946, and when I was scuba certified in the 1960's it was a revolution to me. I could sit on the bottom and move slowly for a long time using the scuba tanks. I also was involved in the safety regulations which took affect in S. Calif for recreational dive boats. Unfortunately I had to pronounce several poorly trained divers dead at Catalina. Some programs were shut down, and increased safety for the "cattle boats" was effected. I was amazed that Florida did not have similar regulations: Underwater recall, a skiff or inflatable to pickup down current fatigued divers. Strict protocols for rescue and taking the victim to a recompression center etc. I have never done mixed gas, and the deepest depth I have been to is in the 130 foot range (to stop two divers who had nitrogen narcosis, and were going deeper.) 120 feet is the usually accepted depth for atmospheric compressed air. Diving is serious business, even in shallow water. i am amazed at these rescue teams and the discipline of the soccer players! Well done rescue!

[Robert H. Wilkinson]

[Foggy]

Safe cave diving requires considerable advanced training beyond basic
SCUBA certification. Even then it is considered dangerous by many in
the know who never describe it as being safe. Historically, there are many
documented horrific accounts of fatalities SCUBA diving in caves.

Why an adult would intentionally lead a group of boys into an extensive under
ground cave/tunnel in the rainy season is beyond me. Fortunately, for those
involved, and their families, the outcome has surpassed the odds.

Aye.
Grandpa used to say, "Been down lately?"

Foggy
PADI Basic SCUBA Diver
#81364490 07/19/1981
PADI Advanced Open Water Diver
#9903446363 03/16/1999

[robhwa]

Bob; Increased O2 vs N2, (Nitrox) is pretty mainstream in recreational diving for many years now, not just used by special forces. It is generally sold as a means to reduce N2 absorption into the blood by reducing N2 partial pressure, thus increasing bottom dive time compared to ambient (78% N2, 21% O2). Most dive computers can be programmed for O2 up to 50% and they immediately increase your dive times since you will clearly absorb less N2 with less partial pressure of N2.

Many people claim enhanced feelings of strength and endurance from the additional O2, but that is not generally what Nitrox diving is advertised for. Usually the O2 used is 32%, or 50% higher than ambient 21%. There seem to be few problems with any O2 toxicity with such a modest increase in O2.

The main problem with higher O2 in external systems is more intense fire. Things that aren't flammable may become so with higher O2, as with the Apollo 1 fire.

Higher O2 would provide clear advantages in this rescue, particularly if you are moving tanks miles through caves. Higher O2 can be more efficient, like was done there. Probably more important is that moving slowly underwater, even relatively shallow depths give time for N2 to be absorbed into the blood. Higher O2 helps reduce this.

[Pacificcoast101]

[Foggy]

About nitrogen in the blood under pressure (one atm pressure for every 33' of
water depth), some years back I was on a live aboard dive trip in the Bahamas.
Two, three, maybe four non-decompression dives per day was not unusual.
Then maybe even a shallow night dive. The dive master kept a close eye on
everyone's dive computers and logs to help keep people out of trouble.

Three young yahoo maverick divers refused to show the dive master their dive log.
Turns out they were intentionally going 'deep' with compressed air for the 'high'.
Early nitrogen narcosis (aka "rapture of the deep" "Martini's Law") causes a
euphoric effect similar to a little too much alcohol - every 50' of depth being equal
to consuming one martini. Too deep and you lose orientation, get confused, do
stupid things and risk not resurfacing. Rumor aboard was they were going about
250' for a very short time and the 'high'. The math speaks.

Aye.
Grandpa used to say, "You can play with fire, even under water."

[Foggy]

About 'extra oxygen', I know of several aging individuals who possess what I
call an 'anti-death wish' and therefore subject themselves to a pricey series of
hyperbaric oxygen treatments to delay the inevitable. Don't know any science
to support this but, as they say, "You can't take it with you".

Otherwise, there are proven medical uses for hyperbaric oxygen (HBOT) that
include treating decompression illness (the bends), gas embolism, gas gangrene
and carbon monoxide poisoning. And, yes you guessed it, gangrene and CO
poisoning are not direct consequences of SCUBA.

Aye.

[Pacificcoast101]

http://www.alertdiver.com/?articleNo=1836