Diving "Conservative" vs Nitrox

[boulderjohn]

Thanks for the add John. Not much additional to contribute; Neal Pollock and Richard Harris sum it up pretty well in the DAN article. I'm not aware of any peer-reviewed literature that compares increasing computer conservatism with breathing EAN for the same dive profile. Changing gradient factors adds another dimension to this question and makes it even harder to study. Some studies that have been done since the 2014 DAN article, for what they're worth:

A 2020 study that used 40% nitrox, possibly one of the ones that @boulderjohn mentioned with a relatively small n (13):

Does oxygen-enriched air better than normal air improve sympathovagal balance in recreational divers?An open-water study - PubMed

Effects of the hyperbaric environment on the autonomic nervous system (ANS) in recreational divers are not firmly settled. Aim of this exploratory study was to (1) assess ANS changes during scuba diving via recordings of electrocardiograms (ECG) and to (2) study whether nitrox40 better improves...

pubmed.ncbi.nlm.nih.gov

A 2016 study on divers who bubble a lot, which should be interpreted in the context of the study on the high degree of variability in venous gas emboli cited by Dr. Mitchell in another recent thread:

Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial - PubMed

ISRCTN 31681480.

pubmed.ncbi.nlm.nih.gov

Best regards,
DDM

Thanks for this, but you may have missed the reason you were summoned. Starting t post #54 and continuing here and there is a discussion about both blood oxygen levels and hyperbaric oxygen treatment.

 

[Duke Dive Medicine]

Thanks for this, but you may have missed the reason you were summoned. Starting t post #54 and continuing here and there is a discussion about both blood oxygen levels and hyperbaric oxygen treatment.

Thanks John. I'm not 100% sure of the question but FWIW, dissolved oxygen does play a significant role in hyperbaric oxygen therapy. This was discussed in this thread. Increasing the inspired partial pressure of O2 will dissolve more O2 into the bloodstream. Breathing nitrox does just that as compared to compressed air, but it's not the same as breathing 100% O2 at hyperbaric treatment pressures.

Best regards,
DDM

 

[Blackcrusader]

When I go diving I am usually doing 3 day dives and a night dive. On a two week vacation of 12 diving days I do around 40 plus dives. SO that's 12 days straight diving. I am not pushing NDL's all the time but I do when I want to get video or photo's and pigmy seahorses often around 30m plus so Nitrox is better for extended NDL.

Depending where I am diving I am often doing 75 - 90 minute dives. If I do a trip on air I feel no different to doing the dives on nitrox.
Also on my dives I like to come up shallow and spend 15 mins around 8m or less dawdling around reefs. When I dive like this my mind is blank and I really slow down my breathing as I am so relaxed.

Last trip in Bali all dives on Nitrox and only a few dives to around 30m. I know that often my guide is on a Suunto and one thing is by the third dive I may stay around 25m for most of the dive. The guide can't stay with me as I am using 45/95GF on my Perdix. So I get some quiet time to go really slow to the point of just stopping sometimes at one place for several minutes.
In my 60's and find younger people are tired trying to match my dive schedule. But then they want to party late at night and get on the booze. I am back in my hotel room by 9pm and might do some checking of the days video and photo's for an hour. Up at 7am for breakfast and I eat well. I get a good nights sleep from diving.

Air or nitrox.. always feels the same to me.