Almost unconscious during Dive

[DON-PNW]

Hello, Looking for any insight or advice although I feel that this will not be easy to determine what the cause was but here we go...

Last month during my decent as I passed approx 60' fsw I became nauseous, skin and head tingling sensation, and hard to concentrate. At 70 few I stopped my decent and realized that I was not doing well and felt that I could "pass out". I then notified my dive buddy that I wasn't doing well and started a slow controlled accent to the surface. The feeling I was having continued all the way to the surface but did diminish. I went on 100% oxygen at the surface for 40 minutes. After being on the surface for ~ 5 minutes all symptoms went away. Here is some dive details that may or may not be useful. Thanks in advance.

* This has never happened before or since.
* The dive location is one that I have 80 dives logged so far.
* I have 410 logged dives, I dive 6 times a month as a paid Divemaster.
* 49 Years old in good shape, non drinker.
* The onset of symptoms happened ~ 8 minutes into the first dive of the day
* Gas = Air
* Max depth on dive 72 fsw
* Fresh water dive, water temp 49 F, neoprene drysuit with undergarments
* Last time I dove was 6 days prior to incident, empty stomach ( I did not have anything to eat prior to dive accept for 4 big cups of coffee)
* Dive buddy was breathing same air as I (i.e. we filled our tanks same time at the same dive shop)
* I have never experienced Narcosis before, I regularly dive this spot that has a max depth of 110 fsw.

Thanks again!

 

[2airishuman]

Neck seal too tight.

Pure uninformed speculation on my part, but I somehow doubt if it was a medical problem specific to diving.

 

[thirdparty]

I would look into the neck seal too. This is no joke, I've seen a short video about a dive accident where a public safety diver trainee fainted and died due to neck seal constriction.

 

[boulderjohn]

It could be a number of things.

Your description is almost exactly what happened to a diver I was with last year, with the exception that after showing your symptoms, he also got pretty bad vertigo. He turned the dive at 150 feet (we were going to 280), and he was in bad shape when we reached the surface. He started feeling better almost immediately, though, and he was fine after some time on oxygen.

He had a suspicion that turned out to be true. On a dive trip a few weeks before, he had had a very hard time clearing his ears. On this dive, clearing had been very easy--too easy. An ENT confirmed that he had a pinhole opening in his eardrum. His problems were caused by water entering the ear, and the symptoms were relieved simply by getting out of the water.

 

[Duke Dive Medicine]

Hello DON-PNW,

A few thoughts:
Reading your description, middle ear barotrauma or water intrusion wasn't the first thing that popped to my mind, but I think it's a possibility. Other posters mentioned a tight neck seal; I think that's a reasonable possibility as well.

I don't think that bad gas can be ruled out entirely, though gas toxicity symptoms don't typically resolve that quickly. There is a phenomenon where the oil in a compressor transiently overheats and produces toxic gases; one tank could be bad and the next one perfectly fine. Did you have your gas analyzed?

Given that you said you had four cups of coffee on an empty stomach, it's possible you were hypertensive, especially if you were descending in a head-down attitude. Extreme hypertension could produce symptoms like that, and if you reversed your body position on ascent this could have resolved it.

This is a bit more unlikely, but I would also wonder about some sort of sinus squeeze. If you have a bony dehiscence in one of your sinuses (i.e. part of the bone is absent and there's nothing but soft tissue between the brain and sinus), it's possible that the sinus was compressed to the point where it affected your brain. This would also explain the symptom resolution on ascent. That's admittedly a bit of a reach but not unheard of.

Hope this helps.

Best regards,
DDM

 

[MaxBottomtime]

The part I didn't understand is the paid Divemaster. I've never heard of such smoke and mirrors, especially in the PNW.

 

[mi000ke]

This is a long shot but I experienced something similar when diving off a boat that kept the engine running (will not go with that op again). While at the surface before descending, one of our buddies needed to get back into the boat having forgot something or other, and I decided to get out and adjust something (can't recall what it was), but while he kept his reg in his mouth while ascending the boat ladder, i had mine out and took a few good wifs of engine exhaust. I started my descent and then had to call the dive. Symptoms cleared after breathing air (not pure oxygen) for about 15 min.

 

[luscioman]

Do you take any type of medications?

 

[Kevrumbo]

Hello, Looking for any insight or advice although I feel that this will not be easy to determine what the cause was but here we go...

Last month during my decent as I passed approx 60' fsw I became nauseous, skin and head tingling sensation, and hard to concentrate. At 70 few I stopped my decent and realized that I was not doing well and felt that I could "pass out". I then notified my dive buddy that I wasn't doing well and started a slow controlled accent to the surface. The feeling I was having continued all the way to the surface but did diminish. I went on 100% oxygen at the surface for 40 minutes. After being on the surface for ~ 5 minutes all symptoms went away. Here is some dive details that may or may not be useful. Thanks in advance.

* This has never happened before or since.
* The dive location is one that I have 80 dives logged so far.
* I have 410 logged dives, I dive 6 times a month as a paid Divemaster.
* 49 Years old in good shape, non drinker.
* The onset of symptoms happened ~ 8 minutes into the first dive of the day
* Gas = Air
* Max depth on dive 72 fsw
* Fresh water dive, water temp 49 F, neoprene drysuit with undergarments
* Last time I dove was 6 days prior to incident, empty stomach ( I did not have anything to eat prior to dive accept for 4 big cups of coffee)
* Dive buddy was breathing same air as I (i.e. we filled our tanks same time at the same dive shop)
* I have never experienced Narcosis before, I regularly dive this spot that has a max depth of 110 fsw.

Thanks again!

Rule Out CO2 Toxicity Symptoms in Scuba Diving, due to momentary physical exertion with inefficient ventilatory cycle to expel excess metabolic Carbon Dioxide build-up.

Continuing and a vicious spiraling work-of-breathing cycle into frank Hypercapnia upon further descent to deeper depths (60 to 70 fsw) with resultant increasing gas density of Air and narcosis (both N2 and CO2).

Rising blood CO2 (‘hypercapnia’) is a problem in diving for several reasons. First it can cause unpleasant symptoms such as headache, anxiety and shortness of breath. These can precipitate panic. If the levels get high enough CO2 can cause incapacitation and unconsciousness. Collectively, these manifestations are often referred to as ‘CO2 toxicity’. Interestingly, those who tend to retain CO2 generally suffer fewer early unpleasant symptoms, and indeed, may not develop symptoms until they are close to the second tier of problems (incapacitation and unconsciousness). . .

. . .if the work involved in breathing increases unnaturally (which occurs in diving for a variety of reasons) the breathing controller in the brain appears predisposed to allowing the blood CO2 to rise rather than drive the extra work required to move sufficient gas in and out of the lungs to keep CO2 at normal levels. When this happens with CO2 we refer to it as ‘CO2 retention’; a situation in which we are not breathing enough to eliminate the CO2 we are producing. The more the work of breathing increases (eg. because we are deeper breathing a denser gas, or because our regulator is performing poorly), and the more CO2 that is being produced (eg. because of exercise) then the more likely CO2 retention is to occur. . .

. . .Interestingly, there is also significant variability between individuals in respect of their tendency to retain CO2. Some peoples’ respiratory controller will adjust breathing to maintain their normal level of CO2 irrespective of how much the work of breathing increases, whilst others are very vulnerable to CO2 retention when an increase in work of breathing blunts the sensitivity of normal control. The latter group are often referred to as ‘CO2 retainers’. It is simply a failure to breathe sufficiently to eliminate all the CO2 that is being produced in the body. This can occur any time the work of breathing increases, and in diving this applies to normal open circuit scuba diving. . .

The second reason high levels of CO2 are a problem in diving is that CO2 can precipitate other diving related problems. In particular, CO2 is a narcotic gas and high CO2 levels will substantially worsen nitrogen narcosis. . .

Advanced Knowledge Series: Basic Carbon Dioxide Physiology

To break this CO2 build-up cycle, stop your descent and hold at shallow depth, relax & try to regain with a few minutes of full slow controlled inspiratory/expiratory breathing to eliminate the excess CO2, and cease & desist all physical exertion/exercise that's stimulating production of metabolic CO2. Abort the dive as necessary if symptoms continue or worsen.

 

[DON-PNW]

Thank you everyone for your comments. I did check my air in the tank and it came back just fine. I did end up going in for a consult (this happened again a couple days after this event) with a specialist and after going through it in detail and answering the doctor's questions he is confident that the problem I was experiencing is what is called Alternobaric Vertigo. This is just a good reminder that diving while congested can lead to problems especially if you are not patient (as in my case) with properly clearing upon decent.