My first ever oh sh*t moment. (CO2 hit?)

[L13]

The lesson seems clear. When conditions are less than optimal, back off on the risk factors whether it's depth, time, workload, ppO2, ???

Needs repeating.

 

[steinbil]

get a rubber freedive belt. they are nice and stretchy and you can wear it low on the hips where there is no potential for restriction in breathing.

I myself would be very surprised if I ever felt buzzed at just 100 feet, but I am affected (more often than I like) with a reverse squeeze. I can descend very rapidly, but sometimes if I want to come up just 10 feet off the bottom, I can get really dizzy. It would be super scary if It had not happened 100 times before and I didn't know what it was. Perhaps your recollection is fuzzy and you ascended a little and THEN got dizzy?

And I think the Co2 theory is probably viable as well, plus you could easily have had all three, narcosis, co2 and reverse squeeze a little?

Interesting! I had not considered that. My recollection is definitely a little fuzzy, and I do remember signalling to ascend to a shallower depth before this happened, so it is quite likely that we had already starting ascending a little, or maybe even stabilized at a new depth. Looking at the profile from my computer it might have happened around the 22 minute mark at a depth of 25m (82ft).

Wouldn't a reverse squeeze be accompanied by a noticeable discomfort in the ears, though? My ears usually equalize on their own without any effort (sometimes I wiggle my jaw a little). I don't remember my ears bothering me at any point of the dive.

 

[steinbil]

The symptoms do sound like excess CO2.

I don't know if this will help you, but I always concentrate on longish, full exhales whenever things are getting a little iffy. This clears CO2 efficiently and keeps hyperventilation at bay.

You don't need to breathe fast to get enough O2 at depth because the number of O2 molecules you get per breath (i.e., pp02) is so high.

This is exactly what I did, and it seemed to work to calm down my breathing, so I would say this is very good advice.

 

[steinbil]

I had a very similar experience on Nitrox32 swimming into a strong current at 112 feet. But when I told a DAN physician (a cave diving friend) about it, I described the vision as looking like poorly edited VHS tape where the two divers I was with appeared to jump as if frames were missing. He immediately thought that might be micro seizures in the cerebral cortex and that I was close to a seizure due to CNS tox. Other symptoms included hearing a freight train in my head, and there were others I no longer recall.

I tried stopping and resting and signaling my buddies but when they didn't notice, I felt l needed to ascend without delay. Three bull sharks circled like vultures expecting dinner on my way up. The shallower I got the better I felt. I thought it was CO2 myself. My friend the doc leaned more toward oxtox. Either way, you feel like you are going to die down there.

Welcome back.

I did not experience any aural or other symptoms other than the visual/disorienting and anxiety. Otherwise the description sounds similar - only difference I would point out is that to me it seemed like my head was moving but my vision was lagging - as if focusing took longer and I only recall the clear images and not the blur in between, or as if blinking very slowly which I guess is also a possibility - as opposed to feeling like my surroundings moved, but I guess that could just be a minor difference in how the same symptom is perceived. Maybe the slow-motion sluggish feeling of narcosis combined with blinking with my eyes to clear my head was what I was actually experiencing...

I also did not consider oxtox - that's very scary to think about. My "EAN32" was slightly rich at 33.2%, so at 100ft that would be around 1.33PO2. Still doesn't sound scaringly high considering the recommended limit at 1.3 for the working part of the dive and I did not feel like I was exerting myself at the onset of the symptoms. But I guess it is right on the limit, and if there was CO2 retention that could provoke an oxtox incident. I will definitely keep this in mind for the future.

 

[Trace Malinowski]

ppO2 of 1.41

When I took my Nitrox course 1.4 was the max for planning with short excursions allowed to 1.6. I was just checking to see if the recommendations have changed and found this on the DAN site, "Divers who tend to retain carbon dioxide during exercise may be at increased risk [for toxing]."

So it may well be a combination with increased CO2 for whatever reason leading to incipient O2 toxicity.

The lesson seems clear. When conditions are less than optimal, back off on the risk factors whether it's depth, time, workload, ppO2, ???

There was a cave fatality where a woman was on a ppO2 of 1.4 using Triox.

 

[Beau Holden]

but I am affected (more often than I like) with a reverse squeeze. I can descend very rapidly, but sometimes if I want to come up just 10 feet off the bottom, I can get really dizzy. It would be super scary if It had not happened 100 times before and I didn't know what it was.

The first time this happened to me, it was after a 130+ dive in a quarry and were ascending in open water on a line. It hit me around the 30 foot mark and I literately thought I was going to pass out. I was the last one in a team of three or four (I don't remember) ascending and they had swam off looking for paddle fish. I swapped over to me necklace and pulled it tight and pushed through it. Now I know when its coming on and just drop down a little bit and it will start to pass. Matter of fact, it is part of the pre-dive briefing now that I discuss with any new buddy.

I'll agree, this sounds more like what the OP experienced. On OC at 100-ft on 32% it would seem like you would have to be working really hard to take an CO2 hit.

 

[Beau Holden]

Interesting! I had not considered that. My recollection is definitely a little fuzzy, and I do remember signalling to ascend to a shallower depth before this happened, so it is quite likely that we had already starting ascending a little, or maybe even stabilized at a new depth. Looking at the profile from my computer it might have happened around the 22 minute mark at a depth of 25m (82ft).

Wouldn't a reverse squeeze be accompanied by a noticeable discomfort in the ears, though? My ears usually equalize on their own without any effort (sometimes I wiggle my jaw a little). I don't remember my ears bothering me at any point of the dive.

I have no pain it my ears. It is just a rapid on set of sever to light vertigo symptoms. just drop down until it clears and start back up.

 

[steinbil]

Wow, this is giving me something to think about. It is a little disconcerting that the way to deal with it is the opposite of what you would normally do (ascend). But I guess if you are aware of it any time you are ascending, it should be possible to connect the dots and just descend back a little, especially since other symptoms usually get better while ascending. Still scary to think about descending while feeling like that when I'm still pretty deep at 82ft, so I would have to be pretty sure of the cause to be confident doing that. I do, however, see that because I normally don't have to equalize at all, I'm less aware of this problem.

Question:
Would the symptoms of a reverse squeeze dissipate if I was able to "reverse-equalize"? I can control the muscles to open my eustachian tubes without creating any air pressure, so I might be able to fix a reverse squeeze by simply activating these muscles. If I could recognize the problem, that is.

 

[steinbil]

Middle-Ear Barotrauma or Reverse Squeeze​

What It Is: It is the most common ear injury. Pressure must be released from your middle ear as you ascend, or the expanding air will bulge and possibly break your eardrums.
What You Feel: Pressure, then pain, which can be intense.
What to Do: Stop your ascent. Try the equalizing techniques you use when you descend. Ascend slowly; the last 30 feet can be the most difficult and painful.

Inner-Ear Barotrauma​

What It Is: When you fail to equalize your middle ears, you can injure delicate inner-ear structures like the cochlea and the vestibular canals — and the damage can be permanent.
What You Feel: Deafness, tinnitus (a ringing or hissing in your ears) and possible vertigo, accompanied by nausea.
What to Do: Abort the dive and see an ear, nose and throat specialist as soon as possible.

Outer-Ear Barotrauma​

What It Is: If your ear canal is blocked by a tight hood, a glob of wax or a nonvented earplug, it becomes another dead-air space that you can’t equalize when you descend. Your eardrum bulges outward, and increasing pressure in the surrounding tissues fills the canal with blood and fluid.
What You Feel: Similar to middle-ear barotrauma, including pain.
What to Do: Keep your outer ear clear.

From sportdiver.com

This is similar to what I have read when taking my OW and what I have based my understanding on. Because I didn't experience any pressure or pain in the ears, I really didn't consider a reverse-squeeze. Also since I've never had trouble equalising, I thought it wouldn't happen to me. This could of course also make me complacent about it...

 

[Beau Holden]

Question:
Would the symptoms of a reverse squeeze dissipate if I was able to "reverse-equalize"? I can control the muscles to open my eustachian tubes without creating any air pressure, so I might be able to fix a reverse squeeze by simply activating these muscles. If I could recognize the problem, that is.

Here is a link that dicusses the problem. How to Deal with Other Ear Problems