Tech class and narcosis?

[Germie]

IANTD has the advanced recreational trimix course. That is a limited decocourse using trimix. You can dive to 51m/167 feeth with a maximum of 15 minutes deco.But it allows you to dive trimix.

Narcoses is caused by nitrogen, but by CO2 too. And the heavier the gas, the more dense the gas, the more chance you produce more CO2.
Inert gasnarcoses has everybody, but some are less sensitive than others and sometimes you are more sensitive that day then another day.

 

[stuartv]

See if any of the diving clubs/groups in your area offer a chamber dive. That way you have the opportunity to experience getting narced in a controlled environment. I'll be doing a chamber dive in the near future. The chamber operator will take us down to 130ft/40m. You can even count it as a logged dive - take your computer with you, put it in a bucket of water (which activates it), and it will register the depth changes, etc.

Onset of narcosis is influenced by more than just depth. E.g. cold, and dark. If you actually feel narced in a chamber ride to 130', then I suppose that would be a good indication that you REALLY don't want to be diving to 130' without Helium, but beyond that I am skeptical that such a chamber ride would have any value whatsoever in really having an appreciation for being really narced during a dive.

And the idea of logging a dive because you brought your dive computer along in a chamber ride is, well, I reckon that's up to you. I don't even count hour long dives in the pool as dives in my log. Counting it as a dive when you didn't even get in the water at all.... *sigh* Don't get me wrong. My pool dives are in my Subsurface log, so I can keep any notes about them that I may want, and just to be able to recall when I was in the pool and why. But, they are all numbered 0 and don't count in my "# of dives logged."

If you are attempting to qualify for something that has a minimum # of dives, do you really think a chamber ride should count? If someone does 25 dives in actual water and 25 chamber rides, can they get their Master Scuba Diver card?

 

[Kevrumbo]

Onset of narcosis is influenced by more than just depth. E.g. cold, and dark. If you actually feel narced in a chamber ride to 130', then I suppose that would be a good indication that you REALLY don't want to be diving to 130' without Helium, but beyond that I am skeptical that such a chamber ride would have any value whatsoever in really having an appreciation for being really narced during a dive.

And the idea of logging a dive because you brought your dive computer along in a chamber ride is, well, I reckon that's up to you. I don't even count hour long dives in the pool as dives in my log. Counting it as a dive when you didn't even get in the water at all.... *sigh* Don't get me wrong. My pool dives are in my Subsurface log, so I can keep any notes about them that I may want, and just to be able to recall when I was in the pool and why. But, they are all numbered 0 and don't count in my "# of dives logged."

If you are attempting to qualify for something that has a minimum # of dives, do you really think a chamber ride should count? If someone does 25 dives in actual water and 25 chamber rides, can they get their Master Scuba Diver card?

As part of a HBOT Recompression Crew, multiplace/multi-lock chamber rides are further classified and logged as "dry dives" since they're tracking their inert nitrogen uptake along with undergoing any decompression O2 profiles during training runs, and during real medical hyperbaric treatments with a dive casualty. Obviously, medical treatment or training dry dives are not wet water recreational dives and shouldn't be considered as such "logged dive prerequisites" for further recreational certification.

The Los Angeles County/USC Catalina Hyperbaric Chamber has an attending physician's policy which takes into account the potential effects of narcosis during a patient's Recompression Therapy. The examining Doctor inside the chamber cannot prescribe or perform any ancillary treatment (i.e. injection of a medication like a pain killer for example), while under hyperbaric pressure because of the real effects of nitrogen narcosis (along with the potential medical-legal malpractice implications). In other words, the physician has to return to ambient sea level pressure via an auxiliary chamber lock, and then make a conscious decision to prescribe treatment as necessary (i.g. draw the correct dosage of medication into a hypodermic needle, pass it through a small auxiliary chamber lock to be pressurized, and have one of the Paramedics inside administer the injection to the Patient).

So @stuartv , you shouldn't be "skeptical that such a chamber ride would have any value whatsoever in really having an appreciation for being really narced during a dive" ,especially if making some very time critical decisions. Making a snap decision at 165fsw on how much pain medication to inject a patient in a Recompression Chamber can be just as bad a relative outcome as in making an ad hoc decision to go inside a Cave at 165fsw breathing Air on single tank. . .

 

[stuartv]

So @stuartv , you shouldn't be "skeptical that such a chamber ride would have any value whatsoever in really having an appreciation for being really narced during a dive"

So, the narcosis in a chamber ride is JUST like being narced at the same depth on a real dive?

 

[Kevrumbo]

So, the narcosis in a chamber ride is JUST like being narced at the same depth on a real dive?

What do you think @stuartv ?

Every year the Fire Suppression system of the USC Catalina Hyperbaric Chamber is tested under pressure. Anything that we do not want to get wet is either removed or sealed in plastic. The Chamber Crew, wearing wetsuits enter and the Chamber is compressed to 165 fsw (6 ATA, 50 msw). At depth the deluge system and the fire hoses are tested. When the ascent from 165 fsw to the first decompression stop at 30 fsw begins the fog starts to roll in as the moisture condenses out of the air. The Total Decompression Time following the dive to 165 fsw for a 12 minute Bottom Time (time from start of descent to beginning of ascent) is about 33 minutes

 

[stuartv]

I don't know. I haven't done a chamber ride and I haven't seen anyone in that video do a real dive to the depth.

I gather you've done both. And I was asking you. Do you think the experience of being narced in a chamber is just like being narced on an actual dive to the same depth?

 

[Kevrumbo]

I don't know. I haven't done a chamber ride and I haven't seen anyone in that video do a real dive to the depth.

I gather you've done both. And I was asking you. Do you think the experience of being narced in a chamber is just like being narced on an actual dive to the same depth?

Yes. It's a reasonable and safe simulation in the Catalina video above to a experience a dive to 50msw/165fsw.

If you want a more definitive experience, then you would have to use the NEDU Ocean Simulation Facility in Panama City FL, a submerged test subject "wet pot" hyperbaric chamber, with supplied air, exercise bikes and water temperature control to simulate your exact physiologic and environmental parameters that you desire @stuartv . . .

 

[stuartv]

Yes. It's a reasonable and safe simulation in the Catalina video above to a experience a dive to 50msw/165fsw.

If you want a more definitive experience, then you would have to use the NEDU Ocean Simulation Facility in Panama City FL, a submerged test subject "wet pot" hyperbaric chamber, with supplied air, exercise bikes and water temperature control to simulate your exact physiologic and environmental parameters that you desire @stuartv . . .

I don't need a simulation. Thanks, though.

 

[boulderjohn]

So, the narcosis in a chamber ride is JUST like being narced at the same depth on a real dive?

Nothing is the same as the way you were narced at a specific depth on a real dive, even if you do the same dive to the same depth on the next day.

 

[Tassi Devil Diver]

I did an SSI DP course over 10 years ago where the maximum depth was 55m (180ft) on air. Skills like removing mask swimming whilst reeling a line and back in were done at 40 and 45m I had to do mine at 50m because we ran out of bottom time on the 45m dive for the three of us all on the course to do the skill, I was shitting myself because of the narcosis, I got through it just!! Then the final dive was to 55m a hot drop on to sand about 4nm off shore, do our 15min bottom time and then ascend. Vis was poor there was a moderate current and rather dark on the bottom, as the end of 15 minute bottom was coming to an end I started to feel rather anxious, my breathing started to build along with an uneasy feeling, we began our assent, and there is a period of the assent I can't remember, I just remember struggling to ascend, I was breathing like freight train my vision was narrow I had no idea what was going on around me, at one point I remember my instructor looking me in the face asking if I was ok and I gave him the not sure signal. Anyway arrived at 30m and things cleared up and really had no idea what just happened. We swapped to our first deco gas and got a shock when I looked at the content gauge of my back gas and was around 40 bar (should have been at 100 plus bar). Then had to deploy an SMB and went to remove it from its location at the base of my wing and was not there. By this stage my instructor was arriving at our level and he had my DSMB. What happened was my DSMB had unrolled itself and become wrapped around my legs inhibiting my ability ascend (all oblivious to me at the time). The instructor handed me my DSMB and I deployed and completed the deco and dive. All through the 30 or so minutes of deco I was wondering what just happened as had very little recollection of the assent from the bottom to around 30m, and thought I had flunked the course, a horrible feeling hanging there in mid water.

Back on shore and going through a debrief afterwards we discussed the troubles I had pointing to narcosis and discovered a few other things going on around me that I was not aware of like the dive master on the course having to help me assessed as I was apparently sinking at one stage, no idea this was happening at the time. I thought for shore I had failed. My instructor spoke to us individually and acknowledged the issues I had with narcosis and explained I had passed the course as was pleased with the way I had regained my composure. In the end I was just happy to get through it and vowed never to do a dive like that again. The course pushed me to my limits.

I have since gone on to do numerous deep air deco dives some to 55m, but always made sure we used a shot line or was adjacent to a wall/ steep reef and only when conditions were good. I had a number of horrible narcosis moments feelings of impending doom etc, but was always close to the shot or near the wall so would start to ascend and would soon clear. I went on to do OC trimix and eventually a rebreather and MOD2 trimix which has been a real godsend no more narcosis and horrible feelings of impending doom.

Thankfully now days it seems those deep air extended range type courses now have the option of using helitrox which I would have made use of if it was an option when I did my course all those years ago now.