Nitrogen Narcosis - Deep air dives

[Landlocked123]

I have been on about 20 dives past 100 on air. Deepest was 143. I felt no symptoms. We performed some short tasks at depth that involved securing a shotline weight at the bottom the existing support/weight. We spent 1.5 minutes at depth. By our assessments we were not impaired in any way. We performed the tasks; tying a prussik loop and strobe to the shot line etc. Is there any study that has empirical data showing how much time and uptake causes symptoms ? I have been unable to find specific scientific data anywhere. I know it apparently varies from person to person but I would have expected to feel very noticeable symptoms. Also looking to hear from others who have experienced Narcosis. How severe were the symptoms? What depth and bottom time ?

 

[northernone]

I have been on about 20 dives past 100 on air. Deepest was 143. I felt no symptoms. We performed some short tasks at depth that involved securing a shotline weight at the bottom the existing support/weight. We spent 1.5 minutes at depth. By our assessments we were not impaired in any way. We performed the tasks; tying a prussik loop and strobe to the shot line etc. Is there any study that has empirical data showing how much time and uptake causes symptoms ? I have been unable to find specific scientific data anywhere. I know it apparently varies from person to person but I would have expected to feel very noticeable symptoms. Also looking to hear from others who have experienced Narcosis. How severe were the symptoms? What depth and bottom time ?

Here's a place to start:
Diving, Nitrogen Narcosis - StatPearls - NCBI Bookshelf

Ever asked a drunk how drunk they are?

Cameron

 

[RyanT]

Highly variable. I've been at 175' on air in warm, clear water with only a very mild buzz and I've been narced hard at 100'. If I experience: pre-dive stress (e.g. overheated, seasickness on the boat), swim hard, experience low viz, or get cold, my symptoms get noticeably worse and appear at shallower depths. When I have been noticeably narced, the symptoms usually appear quickly upon arriving at the bottom, or even during the descent. I've recently been paying attention to "subtle" symptoms, such as, how "thick" does my gas feel. I notice that when I slow down and "look" for the subtle symptoms, they are often there, shallower than I think they should be. If I pay attention, it's not unusual for me to notice the subtle effects at around 115-120'.

 

[Bob DBF]

If everything goes well, you never notice you are narked. The issue is that when things go wrong you then find you are impared, which will be quite a surprise.



Bob

 

[Stoo]

Up in Tobermory, we have chamber which takes divers on "educational" dives. Year ago, I volunteered there and participated in a number of those dives.

The dives typically included repeating little puzzles and the like at 100' or 150' for more advanced (i.e. AOW) divers. Generally, people made a mess of simple written chores (Like signing their names...). Almost universally, the "students" said that they weren't narc'd... until they had a look at what they'd written.

Having said all that, I do "deep" air dives every weekend. I did 155' solo in 42° water just yesterday in fact. I didn't feel the least bit narc'd I'm sure partly because I dive like that every week. On the other hand, on some occasions, I might dive a titch deeper, say, 170' and I look at the back of my camera and just think, "So many buttons...". And ya, if the excrement hit the oscillator, I'm pretty sure my response might not be textbook. I take steps to make sure I really minimize the chances for that excrement to hit.

Yes, I could add a little helium, but the reality is that I'm doing these dives dozens of times a year. Often, the decision to make these dives is last minute and determined by wind and weather. And frankly, diving helium all the time would be both inconvenient and expensive. The LDS doesn't blend. So now I need to get my own helium, a Haskel, a compressor and a few cascade bottles... and build a shed to keep it all in.

So ya, deep air it is for me, unless it's a special occasion.

 

[ajduplessis]

Bob hit the nail on the head! Please understand that once you descent your ppn2 will increase and have an impact on your ability to quickly and correctly perform tasks when stressed.

Self assessment is not a great strategy and will give you a false sense of security. I am one of those divers that did not think narcosis impacted me until I had to deal with unexpected problems at depth. Fortunately I had someone to help me.

Do not under estimate the effect of narcosis even if you believe you are fine.

 

[Dark Wolf]

Also, keep in mind that it changes from person to person.

A friend of mine used to refuse to dive with us much deeper that 100' on air. This was an experienced, and good diver. He finally told us one weekend that much past 100, and he was geeked out of his gourd.

It affects us all differently. From diver to diver, and dive to dive.

Lobo

 

[Compressor]

It would be educational for folks to be videotaped at depth then correlate it with what divers thought about their level of narcosis.

I think the results will be variable. The variability will even be present when the same divers make the same dives on different days.

Narcosis is a physiologic phenomena and predicting it is not straightforward.

 

[Caveeagle]

Effect of nitrogen may be different, but ones perception of the effect are also different and prone to your own self awareness. Ego and peer pressure, task loading, muscle memory of basic tasks are also all very relevant.

The other “elephant” in the room is co2 buildup, which is highly narcotic.

If you have never breathed helium in the 100-125’ range, i think you would be surprised.

 

[Landlocked123]

So I totally get the concept of not being able to fully self diagnose oneself but same as a drunk person or person with a buzz you know when you either one of the two. At least I did before I stopped drinking 4 years ago. As i mentioned we performed the tasks we had set out to achieve and we are intentionally breaking up tasks over multiple dives so as to not task overload. I think had we been experiencing moderate to high level symptoms we would have not been able to perform the tasks. I am going to read up on as many studies I can find. Certainly the risk if real as we were exposed to a PN4.2. Sunday we are executing another dive to 145 this time to attach a lift bag to the weight holding the shotline in pace as we need to move it to a shallower depth. Bottom time is going to be 2 mins max. Definitely also concerned about C02 and another reason we are limiting each dive to 1-2 tasks at a time. Very little to no exertion associated with the tasks..