Depth Blackout?

[Nomad-Diver]

Reading Sheck Exley's "Blueprint for Survival" Blueprint for Survival - NSS CDS on page 13 it mentions "Depth Blackout".

From 150 ft and deeper, "A victim of depth blackout appears to be asleep with their eyes open and does not move other than continuing to breathe. It is not known why the victim retains their mouthpiece, but it's a fact that victims of depth blackout will go on breathing, lying inert on the bottom, until they run out of air"

I've never heard of this condition before, in a SCUBA context. I can understand Oxygen Toxicity, but that would have convulsions and no guarantee of a reg staying in place.

Is it known by another name these days? Was it found to be a non-diving related underlying medical condition instead, perhaps ?

 

[northernone]

I'll be interested in the responses!

My friend has a dive buddy who goes unresponsive at depth. Motionless and calm breathing but doesn't "come to" until lead shallower. It was unofficially put down to narcosis and he stays shallow mostly to not annoy his buddies.

-Edit- Here's the account: "Yes. Depth was approx 110 at 2000ft altitude. Water temp 45F or so. Blacked out, unresponsive, didn't recall anything from the dive. Came to around 60ft. Nope. Felt fine on the surface. No known health issues" -edit-

Haven't heard of it elsewhere... Other than the "blueprint for survival." Or the legendary "rapture of the deep" stories.

Cameron

 

[Jack Hammer]

I believe what he was referring to was one of the side effects of diving deep air. Its one of many reasons diving deep on air is frowned upon and considered a generally bad idea these days.

 

[Duke Dive Medicine]

Mr. Exley summarized it on page 14; the phenomenon is most likely related to profound nitrogen narcosis, probably with a CO2 toxicity component in some cases as well.

Best regards,
DDM

 

[Kevrumbo]

There's the infamous Andrea Doria wreck fatality (July 1998) of a tech diver who was known to have "skip-breathed" a lot to conserve Air:

"Richard Roost, a forty-six-year-old scuba instructor from Ann Arbor, Michigan, one of the five Doria fatalities of the last two seasons, was highly skilled and physically fit. His body was recovered from the Doria's first-class lounge, a large room full of shattered furniture deep in the wreck. It's a scary place, by all accounts, but Roost seemed to be floating in a state of perfect repose. Though he had sucked all the gas from his tanks, there was no sign that he had panicked. Crowell suspects that he simply "took a nap," a likely victim of hypercapnia. . ."

Everest at the Bottom of the Sea

Deep Descent

 

[The Chairman]

I saw it happen pretty shallow: about 140fsw on a wreck off of Miami. The man claimed he hadn't had a problem until he looked at his PDC.

 

[Nomad-Diver]

Thank you all for the feedback. Live and learn...

 

[boulderjohn]

I was told by someone who did deep air dives with Exley that he was explaining this phenomenon from first hand experience. He apparently suffered that situation on more than one occasion, woke up, and continued the dive. This person believes that that is why he was tied off on his fatal dive. This person believes he realized a blackout was coming and tied himself off so that he could continue the dive when he woke up.