Depth Blackout

[boulderjohn]

Might want to talk to Boulderjohn about it:

http://www.scubaboard.com/forums/basic-scuba-discussions/300536-i-narcd.html

Um--not sure I see the point in the reference.

 

[Lenaxia]

One of the problems with CO2 intoxication is that, if it gets severe enough, it causes respiratory depression, so the patient no longer attempts to correct the elevated CO2.

I may be wrong on this, but I believe that high CO2 doesn't cause respiratory depression so much that is just causes things to shut down and die.

CO2 is primarily transported via dissolved gas in the blood, which means at depth, CO2 can be dissolved to a significantly higher level than it can be at the surface (very little CO2 is actually transported on red blood cells). In extreme scenarios, this would cause blood pH to drop drastically and I would imagine denature virtually every protein in your blood.

Ugh, just imagining asphyxiation via denatured blood sends chills up my spine....

Just to sate my own personal curiosity, it seems hemoglobin denatures around 2.0-3.2 pH.
ScienceDirect - Biophysical Chemistry : Circular dichroism kinetics of acid denaturation of hemoglobin and of its β-subunits

 

[dumpsterDiver]

Some people i dive with had a similar incident. An air dive to 180 ft. The victim was a 50-yr old male smoker, appeared to be in poor shape and had a very bad hacking cough before the dive. Diver descended solo and some time afterward, another diver noticed him in a total stupor, standing on the bottom, breathing and not moving.

Diver signaled and got no response. Victim was physically drug up to anchor line and swam up. At a shallower depth (maybe 100) diver regained motor control and seemed fully alert and functional.

Rescue diver brought him to 20 ft and put him on 100% oxygen on tethered deco bottle. A few minutes later the diver went into convulsions. Victim was brought to surface, left with the people on the surface so that deco could be completed by other diver. Diver told the surface people only that he had deco to do and "do not give him oxygen". before descending.

Diver was cut from harness, lifted into boat and checked for vital signs. No vital signs were detected, even after repeated checking over a few minutes. Boat crew figured the guy was just "dead" since they interpreted "give him no oxygen" as meaning he was beyond resuscitation and must have been found dead at 190 feet. No CPR or rescue breaths were delivered, nor any first aid (my buddies )

Body was laid out on deck, while crew considered placing body in cooler. After several minutes the diver began to cough and awoke with a terrible headache and exhibited no long term symptoms.

This does not sound like passive panic to me at all.

 

[lamont]

passive panic seems more like an active-spin lock or livelock to me, while depth blackout seems more like a deadlock.

 

[Graeme Tolton]

Some people i dive with had a similar incident. An air dive to 180 ft. The victim was a 50-yr old male smoker, appeared to be in poor shape and had a very bad hacking cough before the dive. Diver descended solo and some time afterward, another diver noticed him in a total stupor, standing on the bottom, breathing and not moving.

Diver signaled and got no response. Victim was physically drug up to anchor line and swam up. At a shallower depth (maybe 100) diver regained motor control and seemed fully alert and functional.

Rescue diver brought him to 20 ft and put him on 100% oxygen on tethered deco bottle. A few minutes later the diver went into convulsions. Victim was brought to surface, left with the people on the surface so that deco could be completed by other diver. Diver told the surface people only that he had deco to do and "do not give him oxygen". before descending.

Diver was cut from harness, lifted into boat and checked for vital signs. No vital signs were detected, even after repeated checking over a few minutes. Boat crew figured the guy was just "dead" since they interpreted "give him no oxygen" as meaning he was beyond resuscitation and must have been found dead at 190 feet. No CPR or rescue breaths were delivered, nor any first aid (my buddies )

Body was laid out on deck, while crew considered placing body in cooler. After several minutes the diver began to cough and awoke with a terrible headache and exhibited no long term symptoms.

This does not sound like passive panic to me at all.

Something just doesn't sound right here... wouldn't you check for a pulse before you put someone in cold storage? I would certainly hope so... If not, i would certainly re-evaluate who I am diving with!

 

[Kevrumbo]

One of the problems with CO2 intoxication is that, if it gets severe enough, it causes respiratory depression, so the patient no longer attempts to correct the elevated CO2.

I may be wrong on this, but I believe that high CO2 doesn't cause respiratory depression so much that is just causes things to shut down and die.

CO2 is primarily transported via dissolved gas in the blood, which means at depth, CO2 can be dissolved to a significantly higher level than it can be at the surface (very little CO2 is actually transported on red blood cells). In extreme scenarios, this would cause blood pH to drop drastically and I would imagine denature virtually every protein in your blood.

Ugh, just imagining asphyxiation via denatured blood sends chills up my spine....

Just to sate my own personal curiosity, it seems hemoglobin denatures around 2.0-3.2 pH.
ScienceDirect - Biophysical Chemistry : Circular dichroism kinetics of acid denaturation of hemoglobin and of its β-subunits

_________

In medicine, hypoventilation (also known as "respiratory depression") occurs when ventilation is inadequate (hypo means "below") to perform needed gas exchange. It generally causes an increased concentration of carbon dioxide (hypercapnia) and respiratory acidosis. As the hypoventilation progresses, the PaCO2 increases; anxiety may progress to delirium; and patients become progressively more confused, somnolent, and obtunded. This condition occasionally is referred to as carbon dioxide narcosis.
What are the symptoms of respiratory depression?

Taken from Undersea Biomedical Research, Vol 5, No. 4 December 1978 Hesser, Fagraeus, and Adolfson:

"Studies on the narcotic action of various gases have shown that the ratio of narcotic or anesthetic potency of CO2 and N20 approximates 4:1, and that of N2O and N2 30:1. From these figures it can be calculated that CO2 has at least 120 times the narcotic potency of nitrogen. Our data would suggest that the narcotic potency of CO2 is even greater, i.e., several hundred times as great as that of nitrogen.".

Skip-breathing (as in Richard Roost's case on the Andrea Doria), or heavy exertion & work-of-breathing at extreme depth (such as befell David Shaw in Bushman's Hole) are two infamous fatal examples of the vicious pathophysiological cycle described above.

 

[OneRestlessNative]

Diver was cut from harness, lifted into boat and checked for vital signs. No vital signs were detected, even after repeated checking over a few minutes. Boat crew figured the guy was just "dead" since they interpreted "give him no oxygen" as meaning he was beyond resuscitation and must have been found dead at 190 feet. No CPR or rescue breaths were delivered, nor any first aid (my buddies )

Something just doesn't sound right here... wouldn't you check for a pulse before you put someone in cold storage? I would certainly hope so... If not, i would certainly re-evaluate who I am diving with!

Do people even read before commenting? I'd seriously be concerned on the lack of effort at a revival attempt though.

 

[Lenaxia]

_________




Skip-breathing (as in Richard Roost's case on the Andrea Doria), or heavy exertion & work-of-breathing at extreme depth (such as befell David Shaw in Bushman's Hole) are two infamous fatal examples of the vicious pathophysiological cycle described above.

Thanks for the source Kev! Looks like we were talking about pretty much the same thing, except I skipped the whole narc part and straight to the dead part.

CO2 narcosis... very interesting.

 

[LiteHedded]

Something just doesn't sound right here... wouldn't you check for a pulse before you put someone in cold storage? I would certainly hope so... If not, i would certainly re-evaluate who I am diving with!

Do people even read before commenting? I'd seriously be concerned on the lack of effort at a revival attempt though.

among other things

 

[SNorman]

Did I really just read this?

"These 4,294,967,295 members have said "Thank you." to TSandM for this useful post: "

The maximum value of a 32 bit unsigned integer is 4,294,967,296... Do a bit of bad math and subtract below zero using an unsigned int and it'll wrap around to a huge number, among other code errors.