Nitrogen Narcosis

[oren413]

at 30msw/100fsw the partial pressure of the nitrogen we breathe is 3.2.. assuming breathing 20/80 air... other than that its physiological differences in people that effects when exactly it happens

 

[wedivebc]

I should know this question by now but are post dive headaches & slight nausea indicative of nitrogen narcosis or CO2build-up or possiably both?

Classic CO2 symptoms. But CO2 is believed to intensify narcosis symptoms.

 

[DCBC]

I should know this question by now but are post dive headaches & slight nausea indicative of nitrogen narcosis or CO2build-up or possiably both?

Post-dive headaches and nausea are not factors of nitrogen narcosis, as once the increased PN2 is reduced, all narcosis symptoms disappear before the diver reaches the surface. As has been mentioned, this sounds like an increase in CO2, resulting most likely from poor ventilation.

Carbon Dioxide levels can increase the severity of narcosis at depth in a similar way as cold water temperature, anxiety (largely due to cold water and poor visibility), rapid descent (which causes a momentary CO2 build-up), and fatigue.

 

[OneBoatNut]

No the discussion was started as a fellow diver asked me what would be the issue with a bounce dive to 220?
I have had many deep dives and he was asking the possible dangers, I wanted to advise him that it isn’t the Partial Pressure that is the danger (at least not at 1.6) it is the narcosis and to attempt anything you are not trained for is risky at best.
I said along with training you must be in good shape as physiology is a great factor in many things on a dive.
Also adipose cells can harbor more micro-bubbles and being overweight doesn’t help.
Not that overweight divers shouldn’t dive so don’t get offensive if you are over weight, it is a fact cardio is a major factor in any activity.
Also the more efficient the cardio vascular system the more efficient off gassing.

Anyways my thoughts were on narcosis and getting in shape will increase your capabilities should the need arise.

 

[DCBC]

...my thoughts were on narcosis and getting in shape will increase your capabilities should the need arise.

I agree that divers should keep in-shape. Fitness reduces a diver's chance/severity of DCS and provides him/her with enhanced physical ability in the event of an emergency.

I don't believe that the weight of an individual is a reliable indicator of cardiovascular fitness. It's true that these often go together, but people can have one without the other.

Unless you're referring to a working diver, excellent cardiovascular fitness offers no protection against narcosis.

 

[DiveNav]

.....Unless you're referring to a working diver, excellent cardiovascular fitness offers no protection against narcosis....

To reverse this .... does diver fitness level affects - or not - Nitrogen Narcosis ?

AM (aka eDiver)

 

[DCBC]

To reverse this .... does diver fitness level affects - or not - Nitrogen Narcosis ?

As I understand it, the mechanics behind nitrogen narcosis is largely unknown and there are many theories that have manifested themselves over the years. One theory is that when the PPN2 increases, the nerve transmissions are altered in various areas of the brain which result in the presence of gas molecules that have been dissolved in the nerve cell's fatty membranes causing narcosis.

If a diver works hard, it is believed that increased gas is manifested in the nerve cell's fatty membranes causing nitrogen narcosis symptoms to intensify. A working diver's fitness is felt to be a mitigating factor. It's worthy of mention that light work has not intensified the narcotic affect. At least this has not been the case from my personal experience.

As an aside, it has long been accepted that hard work at depth results in gas pockets being formed (believed to be the result of a vacuum effect caused by tendon use) which has contributed to decompression sickness. The commercial diving and military sectors factor this into the appropriate decompression profile. Fitness is a mitigating factor and high fitness is expected when using U.S. Navy and DCIEM military tables. If your not a Navy SEAL, give yourself lots of leeway.