Fatigue and nitrox

[ianr33]

But if you are still pushing your no dec limits, how would nitrox benefit you? You are still getting the same nitrogen loading. You just get it faster using air.

You would be offgassing faster in the shallow/safety stop part of the dive so for the same length of safety stop will exit the water with less nitrogen loading.

Now, the difference in the amount of N2 eliminated between breathing air or 32% during a 3 minute safety stop is probably trivial, but you did ask!

 

[Bubbletrubble]

@DocVikingo:

1. Could you please share what the blinding protocol was for the Lafere et al. study? (I don't have access to the full paper.)
2. I'd also like to know whether CFFF is a useful measure of cognitive/mental fatigue. Is it possible that some EEG- or ERP-based protocols might provide more useful measures?

 

[Charlie99]

When I started diving back in 1998 I found that long multilevel dives that pushed NDL limits left me fatigued. It was a different feeling than dives that weren't pushing NDL limits.

Nitrox solved that problem.

Then I discovered deep stops and started adding them to my ascent profile.

Then I found that I didn't have the fatigue problem on either air or nitrox.

One diver's observations .... take if for what it's worth, but it appears that I was feeling the early effects of decompresson sickness. In other words, sub-clinical DCS.

Adding more margin, either through better ascents or through the use of nitrox decreased the feeling of fatigue.

Designing a test to validate this scientifically would require taking divers right up to the edge of DCS, or more accurately, a little ways into the fuzzy zone of sub-clinical DCS.

 

[DocVikingo]

@DocVikingo:

1. Could you please share what the blinding protocol was for the Lafere et al. study? (I don't have access to the full paper.)
2. I'd also like to know whether CFFF is a useful measure of cognitive/mental fatigue. Is it possible that some EEG- or ERP-based protocols might provide more useful measures?

Hey Bubbletrubble,

Good questions.

1. The full text article is silent on any explicit blinding protocol for either experimenters or subjects.

However, it is obvious that EAN subjects were aware of their gas status as all divers dove their own personal computers and the nitroxers were directed to set them to EANx32.

Not a very good methodology I must say, especially since the research easily could have been double-blind.

2. I believe that recognized, objective and intuitive behavioral measures of vigilance, reaction time, attention/concentration and kindred would be superior to either CFFF or EEG/ERP-based protocols, but of course some of these tools are not in their present incarnations suited to the u/w environment. Additionally, EEG/ERP-based devices, even if they could be modified for u/w application, would be far more expensive, cumbersome and time-consuming than the CFFF gizmo used in this study.

As with so much of diving physiology and medicine research, I guess we'll just have to muddle along as best we can with what we get.

Regards,

Doc

 

[Bubbletrubble]

@DocVikingo: Thanks for the reply. It's strange that the group didn't incorporate blinding into the experimental protocol. Not very rigorous and, as you pointed out, no good excuse for this. *sigh* Makes me wonder about the training of the senior researchers who were overseeing this study and whether the article was peer-reviewed. Not good. Not good at all.

My guess is that the group had access to the CFFF gizmo. That's why they used it. It was probably gathering dust in the corner of the lab. During a beer hour, one of the scientists probably started a discussion about how the instrument could be used in a future study.

As with so much of diving physiology and medicine research, I guess we'll just have to muddle along as best we can with what we get.

Well said.

 

[DocVikingo]

@DocVikingo:My guess is that the group had access to the CFFF gizmo. That's why they used it. It was probably gathering dust in the corner of the lab. During a beer hour, one of the scientists probably started a discussion about how the instrument could be used in a future study.

Hey Bubbletrubble,

Believe it or not, they actually had it designed and built specifically for this study by a recognized instrument manufacturer.

Regards,

DocVikingo

 

[Bubbletrubble]

Believe it or not, they actually had it designed and built specifically for this study by a recognized instrument manufacturer.

One would hope that the group has plans to use the CFFF gizmo in some other (more useful) way. But then again, maybe not.