ever heard of: deep water scuba blackout, blank open eyed stare, breathes tank empty?

[scubafanatic]

...the other day I read a brief mention of 'deep water scuba blackout'....whereby a diver suddenly slips into an unaware state, the eyes remain wide open, the body relaxes, and the diver calmly keeps breathing their tank until empty.....there is no sign of any panic or struggle, the reg remains in their mouth, and they've sucked the tank dry....anyone know what would cause this ?

 

[nereas]

Thats not deep water blackout. That is instead simply extreme narcosis. You can get this anywhere between 150 fsw and 185 fsw.

Deep water blackout normally results from a surge in CO2 loading in the blood while under high pressure at deep depths breathing a helium mix. Deep water blackout is fairly sudden unconsciousness, whether or not preceded by extreme tunnel vision. It normally is not an issue shallower than 250 fsw.

 

[Hank49]

...the other day I read a brief mention of 'deep water scuba blackout'....whereby a diver suddenly slips into an unaware state, the eyes remain wide open, the body relaxes, and the diver calmly keeps breathing their tank until empty.....there is no sign of any panic or struggle, the reg remains in their mouth, and they've sucked the tank dry....anyone know what would cause this ?

Was there any mention of a high partial pressure of oxygen (> 1.6) associated with this syndrome?

 

[nereas]

Was there any mention of a high partial pressure of oxygen (> 1.6) associated with this syndrome?

High ppO2 levels are associated with convulsion and blackout. That is different from what is commonly termed deep water blackout.

 

[ianr33]

Thats not deep water blackout. That is instead simply extreme narcosis. You can get this anywhere between 150 fsw and 185 fsw.

Deep water blackout normally results from a surge in CO2 loading in the blood while under high pressure at deep depths breathing a helium mix. Deep water blackout is fairly sudden unconsciousness, whether or not preceded by extreme tunnel vision. It normally is not an issue shallower than 250 fsw.

I am going to disagree with much of that!

Cause of deep water blackout is CO2 buildup. it is MUCH LESS likely when breathing a helium mix as the density of the gas is less,allowing better flow and thus better CO2 exchange.

It certainly CAN be an issue on air at less than 250 feet when working hard.
http://www.scuba-doc.com/faqphys.html#Deep Water (3rd from bottom)

 

[nereas]

I am going to disagree with much of that!

Cause of deep water blackout is CO2 buildup. it is MUCH LESS likely when breathing a helium mix as the density of the gas is less,allowing better flow and thus better CO2 exchange.

It certainly CAN be an issue on air at less than 250 feet when working hard.
http://www.scuba-doc.com/faqphys.html#Deep%20Water (3rd from bottom)

My entire point was that it is likely triggered by CO2 build up in the blood.

Therefore you cannot disagree with very much of that, since we agree at least on the fundamentals of it.

 

[TSandM]

I think you were reading the same book I just finished, about the Andrea Doria deaths.

CO2 retention was implicated in that case, I believe, because the diver was known to skip breathe. CO2 is very narcotic. I believe that diver was on mix, so nitrogen narcosis shouldn't have been the cause, although nitrogen can do it, too -- There is a graphic description of that in Sheck Exley's Caverns Measureless to Man, where a diver went unresponsive at around 450 feet, presumably secondary to narcosis. A combination of the two, I think, was believed to be the cause of death of the diver who died at 1000 feet in the cave in South Africa.

 

[wedivebc]

Therefore you cannot disagree with very much of that, since we agree at least on the fundamentals of it.

Well let's see, you made 3 points, 2 of which were completely wrong I am with ian on this.

 

[Gene_Hobbs]

Here is the UHMS workshop on the topic that may serve as a good starting point for your search:

Lanphier EH (ed). Unconscious Diver: Respiratory Control and Other Contributing Factors. 25th Undersea and Hyperbaric Medical Society Workshop. UHMS Publication Number 52WS(RC)1-25-82.Bethesda: Undersea and Hyperbaric Medical Society; 1982; 160 pages. RRR ID: 4278