My lesson learned...

[solodiver71]

I wanted to share a incident that occurred with me when I was a new diver (19 yo certified OW Diver for almost a year with about 10-15 dives).


Back in the early 90's I was diving in a lake in Missouri on a sunny spring day. I had a couple of buddies with me and decided to make our first dive a deep one near the dam on a site I had never visited. One of my buddies was from the area and had made many dives there so he was going to lead our expedition. We decided our plan was to go down to about 100ft to a marker that was placed near a large bolder near the dam and then slowly make our ascent back up making our safety stops and then float on the surface for a little while.


We descended down to the boulder just fine.. No one had any issues with clearing and we began to just hangout for a couple of minutes looking around. Nothing much to see except the boulder and a line that was tied to it that kept going deeper. We then started our slow ascent up per the plan and was exploring while we were following the lead diver. At this point things began to change which started a chain of events that I will always remember for the rest of my life.


A few minutes after leaving the boulder, a very loud sound started to roar through the water from all directions.. It sounded like some type of engine that started and I realized that it must be the Dam's turbines. At that time I had no idea how close we were or not to those turbines and I started to panic which made me swim a lot quicker than normal. By this time I started to feel like I wasn’t getting enough air for some reason. I looked at my spg and I was fine on air for the dive but there was something wrong. I was getting air out of my regulator just fine as well as switching over to my octo. I was at total loss on what the issue was and began to really panic.


By this time, I was next to the lead diver who could see I was having issues. I gave him the "out of air" signal and so he passed his primary to me and grabbed his Octo for his use. While I was breathing on his reg he grabbed my pressure gauge and gave me a very puzzled look and started to try communicate with me with hand signals. At this point, his primary wasn’t working for me as well and could only think I was having a medical issue. All this happened in a matter of about 10-15 seconds. I decided that I had no other choice but to bolt to the surface to get some air. I began finning with my buddy holding on to me as I was fighting to reach the surface. Fortunately for him he was experienced enough to let me go so he could make his safety stop. What felt like forever, I finally made it to the surface took a huge breath and started to calm down. At this point I felt like I was now able to breath. My buddies made it to the surface eventually and we started a very slow trek back to the shoreline.


We made it to the shore and I was already feeling much better and was just really freaked out by what occurred. As a precaution I went to the emergency room to get checked out and they found nothing wrong with me except being a little dehydrated. The ER Doctor who treated me was a former dive instructor and I explained what occurred. I learned that because of my panic and task loading I was was over breathing my regulator and breathing back the CO2 I was exhaling which was displacing oxygen. This gave me the sensation of “not having air”. After getting released, I left the ER and called it a day. I was so disappointed with myself I really thought I was going to walk away from diving for good.


In hindsight, there was so many errors with this dive starting from poor planning and lack of discussion about the dive site to lack of enough training on handling issues. I was very fortunate that I didn’t end up getting bent or worse drowning due to errors that were made. Its true what they say about “What doesn’t kill you… “ I did gain much insight from the experience but definitely would have rather read this on Scubaboard.com if it had existed back then.. ha!..


Thanks for reading.

 

[Kevrumbo]

Thanks for relating what is probably one of the scariest first & most common physiological problems we all faced as novice divers:

A more dangerous narcosis condition is when you start to physically exert & breathe harder at deep depths (for example, kicking hard into an opposing current at 30m); this sets off the spiraling & vicious cycle of CO2 Retention/Hypercapnia/Hyperventilation, and a form of Narcosis due to CO2 which is much more acute than that caused by Nitrogen alone.

Exertion CO2 narcosis can come on either insidiously or suddenly, and is described as the panicky feeling "Dark Narc", as opposed to the euphoric experience of Nitrogen narcosis. Can result in severe cognitive impairment at depth or worst case stupor and ultimately unconsciousness. . . In order to break this CO2 build-up cycle, you have to relax with a few minutes of full slow controlled inspiration-expiration breathing: --cease & desist all physical exertion that stimulates hyperventilation and abort the dive if necessary..

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.

"

Originally Posted by TSandM Overbreathing the regulator MEANS a CO2 hit . . . It means the increased work of breathing of using a regulator is enough, at the current demand, to prevent you from exhausting all your CO2. All regulators can deliver more gas, faster than you can use up oxygen, but the small increase in resistance involved in trigger the inlet valve and opening the exhaust valve can make the difference between being able to keep your CO2 normal under heavy work loads, and not being able to keep up. Panic in the experienced diver?

Originally Posted by TSandM CO2 in the bloodstream is completely determined by minute ventilation, assuming the gas you are breathing does not contain additional CO2. Bailing to open circuit definitely makes it POSSIBLE to reduce the blood CO2 level, assuming you can achieve a higher minute ventilation than what's required to keep the CO2 where it is (which is in part related to level of exertion). It may not, however, be possible to reduce CO2 fast enough to clear your head and get rid of the panicky feeling, in part because the natural tendency when panicky is to breathe as fast as possible. On scuba, this means reducing the efficiency of the ventilation, because too much of it is just going to exchange gas in the trachea and large bronchi, which don't exchange gas. That's why we are taught in OW that, if we begin to "overbreathe our regulator" (meaning the diver feels short of breath despite breathing as much as he can), we are to STOP, hang onto something (reduce exertion) and breathe SLOWLY and DEEPLY. It is then possible to reduce CO2. What may not be possible is to stay rational long enough to do it. Panic in the experienced diver?

https://en.m.wikipedia.org/wiki/Hypercapnia