Decompression needed for Chilean miners...?

[Dr Deco]

Hello Readers:

DCS in Mines

As most surmised, you cannot get DCS from a mine of this type. Reading the remarks on the CNN website, most also agreed that DCS was not possible. I was pleasantly surprised at the number of those responders who knew what caisson disease was.

There are some mines where compressed air is employed to prevent the inward seepage of water through the walls and into the works. This was actually the original use and observation of the French physicians who correctly observed that the problem only arose upon exiting the works. They coined the phrase “You only pay when leaving.” It was found that draft animals that stayed below for weeks that they could not exit the mines alive. They were not aware that this was a saturation decompression situation and the ascent of four feet per hour was as fast as the mule could “lock out.”

Physician’s Response

It is incorrect to surmise that DCS would occur in this case. It is a possibility that he was somewhat misquoted. I have given many interviews and always asked for a “read back” before publication. This avoided many problems for me and embarrassments for the author when later called in by the editor.

We all wish the miners the best of success in the coming days.

Dr Deco :doctor:

 

[KY_BOB]

I had been wondering this myself but never ask.

Weren't first documented first of the "bends" from men digging a tunnel in New York? Were they considerably deeper? I know this isn't diving related, I'm just asking out of curiosity.

 

[tridacna]

I had been wondering this myself but never ask.

Weren't first documented first of the "bends" from men digging a tunnel in New York? Were they considerably deeper? I know this isn't diving related, I'm just asking out of curiosity.

The digging areas were pressurized to keep water out. The depth was inconsequential. The bends were caused by rapid ascent to the surface from "depth". But it was the pressure of the AIR pumped down there that caused the problems. And yes, they were digging the caissons for the foundations of the Brooklyn Bridge.

 

[KY_BOB]

The digging areas were pressurized to keep water out. The depth was inconsequential. The bends were caused by rapid ascent to the surface from "depth". But it was the pressure of the AIR pumped down there that caused the problems. And yes, they were digging the caissons for the foundations of the Brooklyn Bridge.

Makes since, thank you.

 

[Dr Deco]

Hello KY BOB:

The first observation of DCS was in mine work performed by a French engineer named Triger. He sunk a metal caisson in 1839 to restrain water during operations through quicksand. During the construction of a tunnel beneath the Loire River, he employed the technique, building a bulkhead at the tunnel entrance, and filled the interior with compressed air.

This method was successful in retarding the water and keeping the interior dry, but it resulted in painful joint symptoms in the workers shortly after exit from the works, “maladie du caisson.” It was the prevailing opinion that the major cause was either the damp, cold working conditions or the squeezing of the blood from the extremities into the trunk of the body by the increased pressure. However, if these were explanations possessed any truth, how then could the problem only arise when you left the conditions of the mine?

The site physicians Pol and Watelle noted,

“I should say here that two workmen, after passing seven consecutive hours in the compressed air, experienced rather keen pains in the articulations, half an hour after leaving the shaft. The first complained of a very shap pain in his left arm, and the secon experienced a similar pain in his knees and left shoulder; rubbing with spirits of wine soon relieved this pain in both men; they kept on working the following days.”​

Reference

Pol B and Watelle TJJ. Memoire sur les effets de la compression de l’air appliquee au creusement des puits a houille. Ann. D’Hygiene Publique et de Medecine Legale. 1854


Dr Deco :doctor:

 

[TimKy]

"....rubbing with spirits of wine soon relieved this pain in both men; they kept on working the following days.”
Dr Deco :doctor:

So, it wouldn't be totally unfounded if I thought I felt some pain after a dive and asked a cute female divemaster for an emergency rubdown with some wine? Just making sure that I have some sound medical evidence on my side!

 

[knowone]

Where's the mine?
It's a deep underground vessel in Chile with a couple of pipes poking out of it.

 

[DandyDon]

I failed to consider that Dr.Walker might have been misquoted. It's been a lonnng time since I was interviewed for stories, but now I remember the problem. Some editors like to change words around too, sometimes changing meanings entirely.

Thanks Dr.D - glad you could stop by and confirm our consensus.

 

[KY_BOB]

Hello KY BOB:

The first observation of DCS was in mine work performed by a French engineer named Triger. He sunk a metal caisson in 1839 to restrain water during operations through quicksand. During the construction of a tunnel beneath the Loire River, he employed the technique, building a bulkhead at the tunnel entrance, and filled the interior with compressed air.

:doctor:

Thanks Doc, it makes perfect since. They were breathing compressed gas, just as we do when we dive.

The ambient pressure of the miners is a very slight increase compared to even a shallow dive. In effect, the workers during the bridge construction were basically the same pressure that we would experience diving to that depth in order to keep the water out and they were there working for hours on end. No wonder they experienced DCS or, as it was know at the time, "the bends".

 

[Crush]

DandyDon,

The actual calculation can be carried out, but here is why I think that the bends is not a likely outcome without doing the math:

1. Elevation dive tables are available in 2000 foot increments. If you are within 1000 feet of sea level, you assume sea level pressure. The miners are less than 2000 feet below the surface, are they not? I dive 4000 feet regularly. This is analogous to treating a 90 ft dive as 110 ft wrt DCS. Not a huge hit;

2. The air in the mine is very hot (28 C or thereabout?) Hot air is less dense than cold air. The air cools up the shaft as you rise, but the net effect of the decreased air density in the mine makes the pressure at the bottom of the shaft less than it would be if the air column had the same uniform surface temperature. For example, air at 30C (mine bottom) is about 5% less dense than air at 15C (a surface estimate). Again, not a huge difference, but it is a plus for the miners.

Have you seen the (small) size of that cage??? I dive in LOTS of thermal protection, but THAT would press the limits of my self-control.