Panic and the Hypercapnic Alarm Response

[Kevrumbo]

Scary stress reaction in an experienced cave diver and Scuba instructor, after a wing inflator detachment malfunction and an active physical exertion kicking ascent to surface with double sidemount cylinders, further compounded by surfacing in a potentially low oxygen/high inert gas asphyxiant ambient environment.

Note the classic symptoms of hyperventilation, work-of-breathing, and finally panicked rejection of a working and functional 2nd stage regulator by the victim ("Can't get enough air out of it. . .!"), which is one of the major irrational cognitive signs of a distressed diver in Hypercapnic Alarm Response:


The "air hunger" or "air starvation" instinct is a powerful driver, and a scary enough motivator that can potentially make you do irrational things like reject a regulator, or hold your breath on a panicked ascent to the "easier breathing" air of the surface:

The most common physiological response and potential malady of all divers resulting from heavy physical exertion at depth is metabolic Carbon Dioxide retention and poisoning; Of the PADI mantra, the first two maxims are the most important in getting out of a vicious cycle of metabolic CO2 poisoning that is quickly spiraling into acute Hypercapnia:

STOP. BREATHE. (THINK. ACT.). . .

"In terms of treating hypercapnia, the time-honored “PADI advice” for an out-of-breath diver to “stop, breathe deeply, and rest” remains valid, but should be appended with “... as soon as you feel symptoms of hypercapnia” because it is often not followed until it is too late by highly motivated technical divers. The period of rest should be used to review options to favorably modify the situation. A quick review of the breathing equipment may be rewarding. For example, hypercapnia may be caused by the added breathing resistance of partially closed cylinder or rebreather mouthpiece shutoff valves. . ."
https://www.diversalertnetwork.org/files/Tech_Proceedings_Feb2010.pdf , p.33

 

[Dan]

Scary.

Thanks for posting it.

I jumped into rough sea without power inflator connected to the air hose once. Instead of trying to reconnect the air hose in the water, I swam hard back to the boat for help, I just don’t think straight when I panic. A good lesson to learn when facing a problem, don’t panic!

At the time my right hand was holding a camera. Reconnecting the air hose back to the power inflator required both hands to press the quick connector together against 150 psig pressure. I could have calmly latched the camera caribiner onto a D-ring to free my right hand.

 

[TONY CHANEY]

Thanks for posting. Seldom does this stuff ever get caught on video outside a controlled study. She clearly was on the cusp of total respiratory failure. Thank God she had good team mates.

OBTW, it's a respiratory situation...not metabolic.

 

[Kevrumbo]

Thanks for posting. Seldom does this stuff ever get caught on video outside a controlled study. She clearly was on the cusp of total respiratory failure. Thank God she had good team mates.

OBTW, it's a respiratory situation...not metabolic.

No. It's precipitated by an exertion metabolic CO2 build-up, the normal urge to breath and the tachypneic response to physical exercise in order to expel the excess CO2; but further exacerbated by surfacing in the ambient low Oxygen and inert gas asphyxiant of the dome room environment. It then degenerates into panic and respiratory distress as she refuses the regulator because of its work-of-breathing -again she says, "Can't get enough air!" -as she rejects the reg (the inadvertent purge valve press by her aiding teammate at that instant didn't help)- and literally suffocates herself trying irrationally to breath the dome room's hypoxic "bad air" and attempting to d'off her gear as well.

This diver is lucky she had teammates who quickly and calmly recognized the situation (note the teammate who commanded, "NO! STOP! Stop. . . Stop", as she struggled to get out of her gear), and insisted that she breathe the regulator and "good" breathing gas source despite its high WOB, holding it in place for her as she regained normal respiration physiology and clear headed cognition.

(I would like to also know their account of how difficult it was for the egress, with her flooded wing and using her drysuit as back-up buoyancy)

 

[Schwob]

@Kevrumbo (and the divers in the video): Thanks for posting!

 

[mmadiver]

Hats off to the teammates for taking calm assertive action

 

[TONY CHANEY]

Kevrombo. You have gone into the void of a vast amount of divers that have discovered a few new terms like CO2 retainer (with no clinical Dx), Metabolic CO2 retention (which you should really research and find out that it does not happen in an acute situation). I have tried to assist you and I feel that you are very smart but you really cannot continue to post information that is clearly false. So I just warn others to not listen to you and I hope that you and the divers you dive with do not follow your misinformed teachings.

 

[Kevrumbo]

Kevrombo. You have gone into the void of a vast amount of divers that have discovered a few new terms like CO2 retainer (with no clinical Dx), Metabolic CO2 retention (which you should really research and find out that it does not happen in an acute situation). I have tried to assist you and I feel that you are very smart but you really cannot continue to post information that is clearly false. So I just warn others to not listen to you and I hope that you and the divers you dive with do not follow your misinformed teachings.

There's no "misinfomed teachings" in the simple common sense advice of ceasing physical exercise, and then breathing from a known good air source like a scuba regulator to regain normal resting respiration physiology and a nominal breathing rate.

You're a Respiratory Therapist @TONY CHANEY , what doesn't make sense to you? You may have issue with etiology, but the remedy is the same and clearly NOT false!

Metabolic CO2 retention (which you should really research and find out that it does not happen in an acute situation).

The research of Carbon Dioxide retention in Scuba Diving:

• https://www.diversalertnetwork.org/files/Tech_Proceedings_Feb2010.pdf , see page 12, "Respiratory Issues in Technical Diving".

• ". . .Under normobaric and hyperbaric conditions, the single factor that limits the ability to increase ventilation is the rate at which gas can be exhaled from the lungs. The ability to exhale gas is reduced during hyperbaric and diving conditions. As gas density increases, increased effort is required to exhale gas (i.e.,it takes more work to move a heavier gas). . ." Carbon Dioxide, Narcosis, and Diving | Global Underwater Explorers

• ". . .To give you some sense of the small changes in arterial blood levels required for these phenomena, PCO2 around 5kPa is the average normal level, 6.2kPa is the upper limit of the normal range, and over 8.5kPa sudden incapacitation is likely. Experiments show that levels between 6.5 and 7.5 are not uncommon in divers working underwater. The point is that small changes in PCO2 of 1kPa or less can have very important implications for the safety of the diver. . ." Advanced Knowledge Series: Basic Carbon Dioxide Physiology

• "Normal respiration in divers results in alveolar hypoventilation resulting in inadequate CO2 elimination or hypercapnia. Lanphier's work at the US Navy Experimental Diving Unit answered the question, "Why don't divers breathe enough?" -->http://archive.rubicon-foundation.o...le/123456789/3327/NEDU_1956_02.pdf?sequence=1 -->http://archive.rubicon-foundation.o...le/123456789/3362/NEDU_1958_07.pdf?sequence=1 -->http://archive.rubicon-foundation.o...ndle/123456789/3809/NEDU_56_05.pdf?sequence=1

you really cannot continue to post information that is clearly false

This is the point in illustration that I'm making:

Look at this simple graphic demonstration of the dynamics of immersion work-of-breathing, exertion physical exercise, and ambient pressure differential, just by trying to talk and tread water at the surface at the same time:
Now what if @Dr Simon Mitchell in the video was at depth in heavy physical exercise and further handicapped by the increased breathing gas density and regulator WOB of air? -->An increased spike of metabolic CO2 that he may not be able efficiently expel fast enough through regulator ventilation resulting in CO2 retention, worst case deteriorating into frank Hypercapnia. What if he were to also exacerbate the situation by surfacing into a cave dome room's deficient oxygen environment and attempt to breathe the ambient "bad air"? -->Further acute respiratory distress going into essential hypoxia by inert or noxious gas asphyxiation.

The solution in both instances is to get back on and stay on the known good source of breathing gas -your regulator- regain a resting nominal homeostatic ventilation & respiration rate, and cease & desist all physical activity contributing to the metabolic CO2 spike.

 

[Fibonacci]

Yes lucky some cool heads helped her through... but what was the specific equipment failure?
BC inflator hose detached or the whole hose came off the flange and then the wing filled with water?

 

[Kevrumbo]

Yes lucky some cool heads helped her through... but what was the specific equipment failure?
BC inflator hose detached or the whole hose came off the flange and then the wing filled with water?

She says in the video that it came off in her hand -it sounds like she pulled off the inflator/deflator valve from the hose.