Aging, DCS, and Deeper Diving

[diverdoug1]

It doesn't. You simply dive reading the computer which assumes nitrogen loading of air, not the reduced nitrogen in nitrox. IOW, you will run out of bottom time sooner than if you had dialed in the nitrox mix.

End result is you finish your dive with reduced tissue saturation. That is the goal, not more bottom time.

One drawback to doing this, is that (computer dependent) you will not have a visual warning when approaching your PPO limited max depth. Have to watch that closely.

In addition to not having an alarm for maximum ppO2, you also will not be monitoring OTUs.

 

[pickens_46929]

These are very helpful replies ... I have not paid enough attention to hydration. I thought the boat crews were passing out water because it was hot . I can fix that: hydration is high on the priority list.

Just as a recent reminder here about hydration and the profiles you were posting, would refer you to:

http://www.scubaboard.com/forums/ask-dr-decompression/300225-hydration-hydration-hydration-bent-coz.html

 

[Dr Deco]

Hello jcr:

You have received several worthwhile postings concerning age and DCS. If age is a deleterious characteristic, I suspect it is more associated with physical fitness than anything else is.

Some data collected on older individuals at NASA did show increased bubble formation in the forty and older set but this was with protocols that were severe enough to generate large number of Doppler detectable gas bubbles. Such severity is not encountered by recreational divers. Older subjects were nit tested since the population is selected to reflect the current age range of EVA astronauts.

Older divers need to surrender to the "physiology of age." They need to limit dissolved nitrogen loads, reduce strain and activity levels, and be mindful that adipose tissue [fat] dissolves considerable nitrogen. This can be released into the venous system as bubbles that in turn can lead to arterialization.



Dr Deco :doctor:

 

[Mr Carcharodon]

It is interesting to note that you asked about reducing the risks of DCS with aging but came up with a list of actions that appears to be unrelated to age. But it still seems like a pretty reasonable list. I would add spending more time at your safety stops which your computer is already telling you is helpful. It is worth remembering that you can reduce your risk either by taking on less nitrogen (shorter dives, shallower dives or lower partial pressure of nitrogen), or by spending more time letting the nitrogen in your system offgas (slower ascents and longer safety stops).

Did you have symptoms of DCS that you are trying to address or is the concern rooted in the computer going into the “yellow”? It is probably worth paying attention to what you body is telling you. Fatigue is considered a symptom but when you are doing many hours of diving per day sorting out DCS related fatigue from the fatigue from the physical effort of the dive may not be possible. A lot of the computers are pretty dumb. Their inputs are worth paying attention to. But listening to your body may be equally important.

 

[JCR]

If age is a deleterious characteristic, I suspect it is more associated with physical fitness than anything else is.[/COLOR]

I can affect my physical conditioning so that is good news. While I cannot affect my aging, knowing any other age-related physiological factors that need to be considered is in part what prompted by question. Thanks for your reply it is helpful!

Did you have symptoms of DCS that you are trying to address or is the concern rooted in the computer going into the “yellow”? It is probably worth paying attention to what you body is telling you. Fatigue is considered a symptom but when you are doing many hours of diving per day sorting out DCS related fatigue from the fatigue from the physical effort of the dive may not be possible[/COLOR].

Fortunately no DCS symptoms ... I was not particularly tired, but on the safety stop when the computer was in the yellow zone I thought about if there are any considerations related to age and DCS and diving in general that I should have thought about before doing those deeper dives after the previous fourteen dives.

The information in response to this post helps to place age, DCS, and diving in better perspective. Thanks again for your comments.
JR

 

[Lopaka]

In addition to not having an alarm for maximum ppO2, you also will not be monitoring OTUs.

Of course, but we know that is not much of a concern to the majority of enhance air divers even with nitrox dialed in.

 

[LeadTurn_SD]

Interesting topic, and great responses. I have nothing to add, just want to give this thread a gentle "bump" so more will see it

Best wishes.

 

[Kern]

The other thing (and possibly the most important) to do to decrease your risk of DCS is to remember that EVERY dive is a decompression dive. Slowing your ascent profile can greatly decrease microbubble formation. On most of my dives, my ascent rate is between 1FSW / 6 seconds, and 1FSW / 10 seconds. Make sure that you don't blow to the surface after your safety stop. Always do a safety stop. When I do a liveaboard and get the opportunity to watch other divers frequently, I am usually cringing as I watch divers rush up to the hang bar to then dutifully do a 3 min. stop, and go on to POP to the surface. I am sure if I put a pre-cordial ultrasound on them, it would sound like a bowl of rice crispys.

I'd consider these ascent rates to be far too slow for any part of the ascent below 6mts.
Ascent rates are a trade off. Going too slow will have some tissues on gassing. Tables are designed with a given ascent rate in mind to maximise off gassing without passing critical supper saturation. Going slow is OK, going too slow defeats the purpose.

 

[diverdoug1]

I'd consider these ascent rates to be far too slow for any part of the ascent below 6mts.
Ascent rates are a trade off. Going too slow will have some tissues on gassing. Tables are designed with a given ascent rate in mind to maximise off gassing without passing critical supper saturation. Going slow is OK, going too slow defeats the purpose.

Our research shows these ascent rates are resulting in lower microbubble formation. Our sample size is not large enough at this time to prove a chi square greater than .05, with respect to specific rates, but within the test divers we have measured in our study, all have shown a statisticallly significant decreases in precordial doppler signatures / minute, using these ascent rates in non-deco dives with maximum depth less than 100 FSW. Perhaps I should not suggest these ascent rates until we have published and have peer review (but the results thusfar have certainly caused me to modify my personal dive profiles). Would be happy to listen to any suggestions KERN has for my study.

 

[Amazz]

I think it's extremely important to set your computer accurately to nitrox, then dive air TABLES if that's the plan. If there is a DCS incident or dive accident, the computer tells the story. I'll be returning to diving soon and will need to minimize bubbles. I'll be diving the max nitrox mix allowed on extremely conservative air tables. O2 saturation will be a concern for me. That's what the computer is for. Tick tock tick tock.