Nitrox Certification?

[DiveGolfSki]

Hey String,

I'm still waiting for you to send me a link to that DAN article about Nitrox not providing an additional layer of safety when used on standard tables.

By the way, I did check IANTD's website, they too list SAFETY/DCS as a reason for using Nitrox. IANTD FAQ

Whoa!!! IANTD's website states that:

EANx diving has many advantages over air diving.
Some of the benefits are:
1. EANx, when used with standard dive tables or computers, provides a tremendous safety factor.
In fact, when utilized in this fashion, the actual nitrogen accumulation is that for a 10 to 20 feet (3 to 6 meter) shallower dive.
This application of EANx is ideal for divers who simply wish to be more conservative individuals who are not "as young as they once were" or those who may not be in the peak of physical fitness.
2. A significant increase in bottom time no-decompression limits.
3. A reduction of the possibility of decompression sickness.
4. A slight reduction in nitrogen narcosis.
5. A reduction of decompression time if the no-decompression limits are exceeded.
6. Reduced fatigue after the dive (declared by many EANx divers).

String, wassup with #4? I thought that wasn't a benefit? Are those reasons ranked in order? Should #2 be number #1.

Totally confused....

 

[String]

This would obviously only hold true for the gas that has not been metabolized. The last time I checked humans metabolize oxygen.

A very tiny amount. In the region of 4%.


It would appear IANTD contradict themselves from the FAQ and the other link to their web site i provided. The PADI enriched air book im looking at though does mention oxygen is to be considered as narcotic.

The DAN link i'll chase up tomorrow as its already midnight and i need to drag it out via divernet website where it was reported (im not a member of dan). The conclusions were statistically insignificant increase in safety for air vs nitrox as air tables. Im not going to dig it out tonight as just back from pool training, have gear to wash and sleep to get.

 

[lamont]

honestly, i'm not going to bother with arguments on this topic on the internet or from certifying agencies.

i've never experienced anything underwater to suggest anything other than nitrox being as narcotic as air, and helium being the only thing in the mix which reduces narcosis. you'll have to take me on a dive and show me how i'm wrong before i'll listen to any argument.

 

[DiveGolfSki]

A very tiny amount. In the region of 4%.


It would appear IANTD contradict themselves from the FAQ and the other link to their web site i provided. The PADI enriched air book im looking at though does mention oxygen is to be considered as narcotic.

The DAN link i'll chase up tomorrow as its already midnight and i need to drag it out via divernet website where it was reported (im not a member of dan). The conclusions were statistically insignificant increase in safety for air vs nitrox as air tables. Im not going to dig it out tonight as just back from pool training, have gear to wash and sleep to get.

Could you please provide evidence of the 4%. Also, case studies that a mix PPO2 of 1.4 has caused narcosis.

Just in case you've got NAUI's Nitrox book, it states "There is no certain evidence that breathing oxygen enriched air reduces the risk of narcosis." but it also goes on to state "Theoretically it might, BUT clinical studies have produced mixed results, perhaps because the individual differences among human subjects outweigh the physics."

Obviously, you do have concrete evidence to contrary. Care to share it?

 

[Santa]

Amen.... or a garden hose.

You guys must have the most amazing lung capacity ;0)

 

[jakubson]

Currently that claim isnt a sensible one to make. Even though common sense would dictate less nitrogen is good, latest research (including DAN) showed the % margin was so small as to be statistically insignificant.

There are various reasons for this including the fact standard tables for recreational diving are very safe but there was no measurable improved safety margin when people investigated it despite this going against what would seem logical - the effect is tiny.

Add that to the fact nitrox costs 3-4x that of an air fill here there are quite a few reasons why its not used exclusively.

From the link you provided in post #60
http://www.divefortyoung.com/whatisnitrox.html

Let's take a look at the diving accident statistics! DAN (Divers Alert Network) has statistics of DCS cases in the USA, which is based on DEMA/NUADC and PADI New Diver Benchmark reports. According to them, the probability to get DCS by air diving is about 0.004% (1 to 25000). Based on this number, and on the PADI Undersea Journal 3/97 magazine, the probability to get DCS by air diving even once during 500 dives is 1.98% (1 to 50). The risk is 1.49% in nitrox diving in same amount of dives. So... so far the difference is marginal, even though nitrox seems to be a bit safer.

One way to view this is "statistically insignificant." Another way to view this is a reduction from 1.98% to 1.49% is a 25% reduction, which could be statistically significant. It all depends on sample size, ...

Beauty is in the eyes of the beholder. No, Nitrox is not magic. But for some applications, particularly multiday, multidive trips that have not had extensive reserach done (although some has been done), it probably has benefits against diving the SAME profile on air (assuming MODs, CN clocks are respected).

Just my $.02

 

[pants!]

Another way to view those numbers is to say that those diving Nitrox are more likely to have a greater level of training than those diving air, and that accounts for the difference... not the gas itself.

 

[mstudley]

Could you please provide evidence of the 4%.

Well.... that's why stuff like rescue breathing/CPR work. Ambient air has roughly 21%O2, we metabolize about 4%O2 and breath out roughly 16%O2. This is pretty common knowledge for anyone who has ever taken basic CPR or high school human physiology....

-- Matt

 

[cummings66]

What CPR courses have that in it? I used to teach it and do not recall that in the ARC courses, nor even why they would include it. It's not like the guy walking down the street needs to know a figure like that. The who essense of the course is that it's better to try it and possibly succeed than not and certainly have the guy expire.

Same with the skills, it's best to try it even if you don't quite remember the exact number of compressions because anything you do is better than nothing.

It has been a few years since I instructed though.

 

[lamont]

What CPR courses have that in it? I used to teach it and do not recall that in the ARC courses, nor even why they would include it. It's not like the guy walking down the street needs to know a figure like that. The who essense of the course is that it's better to try it and possibly succeed than not and certainly have the guy expire.

You don't need to know that to do CPR, obviously. But it is why rescue breathing works, because you've got 16% O2 or so in your exhaled breath. It was covered in my course.