Aging, DCS, and Deeper Diving

[JCR]

I just returned from a Cozumel trip –16 dives in 6 days, the most four in one day. The last two dives of the trip raised some questions about aging, diving, and the risk of DCS. As background, I am 64 plus and in reasonable physical condition (on my last stress test I reached level 5 on the Bruce protocol with 15+METS). From what I understand there is no conclusive finding about aging and DCS as long as the aging diver is in good physical condition. Maybe I am wrong about that.

After the last two dives some questions came to mind about putting myself into a position of increased risk for DCS. The first dive of the last day had a max depth of 109 feet with a gradual ascent to a five-minute safety stop with bottom time of 115 minutes (using steel 120 tank). After a surface interval of 150 minutes, the second dive had a max depth of 74 feet for 115 minutes with the same general profile as the first dive (gradual ascent from the max depth). At one point in the second dive my computer (Oceanic Datamax Pro) was in the yellow (Caution Zone), but it gradually receded into the Green Zone during the safety stop. As I watched that happen, I had a conversation with myself about three things I know to change on the next dive trip.

1) Don’t dive that deep – the DM explained the dive profile and I should have stayed higher than the rest of the group. It would have been easy to do and it would not have adversely affected the experience of either dive.
2) Get certified for Nitrox and use it as if I were diving on air.
3) Devote more effort to physical conditioning.

Anything else I can do to address any potential relationship between DCS and aging?

Thanks
JR

 

[DocVikingo]

Sure are, JR:

1. Perform deep stops when appropriate (e.g., "Rules for the NAUI Recreational RGBM Tables (Air, EANx32, and EANx36); 1. make a 1-minute safety stop at half the depth between bottom and surface for depths in excess of 40 fsw (12 meters); 2. make a 2-minute safety stop in the 15 fsw (5 meter) zone after the deeper safety stop; 3. make a 3-minute safety stop in the 15 fsw (5 meter) zone
for all bottom depths shallower than 40 fsw (12 meters)").

2. Avoid activities that may generate seed bubbles/micronuclei (e.g., vigorous exercise during the dive, climbing boat ladders with gear on after a dive, lifting heavy gear immediately after a dive).

3. Maintain good general physical conditioning, and in particular cardiovascular and circulatory fitness, and avoid excess fatty weight.

4. Stay extremely well hydrated.

5. Once EAN cert, use the highest 02 mix allowed by your training and dive plan, of course diving it to air tables.

No doubt others will contribute more suggestions.

Regards,

DocVikingo

 

[dkktsunami]

109' for 115 minutes? Unless these were essentially bounce dives to depth with most of the dive done under 35' you might be pushing the odds a little bit.

 

[JCR]

109' for 115 minutes? Unless these were essentially bounce dives to depth with most of the dive done under 35' you might be pushing the odds a little bit.

Initial descent was to about 70-80 feet then a gradual decent to the max depth then a gradual ascent up with periods of time in the 70--50- 40 etc... depth. I think this was a fairly typical Cozumel dive profile -- we did not stay at 109' for much time -- it was an easy ascent from there. However, afterward, I wondered if physical conditioning alone mitigates any aging issues that might be associated with higher risk of DCS when doing deeper longer dives.

THANKS!
JR

 

[TSandM]

I believe, although I would have to go look again because I haven't in a while, that although age is mentioned in OW classes as a risk, there are no real data to show that older divers are more susceptible to DCS. Poorly conditioned divers, however, are, as level of exertion is correlated with increased nitrogen absorption.

Maintaining ideal body weight, staying active and fit, being hydrated and rested, not pushing deco limits, diving the right mix, and applying appropriate ascent strategies are good ideas for ALL divers.

Lynne

 

[blue steal]

I am trying to understand something here. (Newbie perspective only not being Nitrox certified)
If one dives using Nitrox but leaves the computer set to air instead of Nitrox mode how does that change anything BT wise? It seems it just gives you a more conservative "buffer" of time before you reach deco.
Thanks DocVikingo for your previous articles, they have been quite helpful.

 

[Lopaka]

If one dives using Nitrox but leaves the computer set to air instead of Nitrox mode how does that change anything BT wise?

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.

 

[drbill]

I'm an older diver (62) and have done my deepest diving in my senior years (to depths of 200 ft on air). When I was in my 20s I probably only rarely went below 60 ft, and only undertook the deep diving out of scientific curiosity (about the physiological effects and the marine life down there).

I did not undertake these dives until I had spent at least 2-3 months gradually increasing my maximum depth and assessing the effects of the dives on me re: narcosis, etc.

When doing such potentially risky dive profiles, I always over did the safety side once I'd started the ascent back. Multiple deep stops followed by long periods in the shallows (< 30 ft) which is easy to do here on Catalina given our very steep offshore slopes. If I incurred any deco obligations (as I often did), I tried to double or even triple the required deco assuming my gas permitted it (it usually did). I also exercised caution about strenuous activity during and after the dives, and avoided hot showers after diving (I needed cold ones anyway after seeing some of the beauties on board the dive boat!).

I also maintained a high level of hydration by drinking plenty of water the night before and on surface intervals between my dives. In addition I avoided alcohol.

Doc Vikingo offers good advice from a medical perspective (as usual!). Although a "doctor" of the non-medical variety, I only wish I played one on TV (for the paycheck).

 

[JCR]

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. Similarly, the issue about physical exertion at the level of climbing up the ladder after a dive with tanks on is news to me. I regularly climbed up the ladder with tanks on, probably mostly to prove I could do it since it would have been much easier to doff the rig and hand it to the boat crew. So, I know to be more attentive to exertion immediately after a dive.

I have not searched the literature much beyond a simple Google query about aging as a risk factor, but based on what I did find and your responses, seems that good physical conditioning (cardiovascular and circulatory) and attention to body fat and other risk factors are more of a concern that just "aging."

Dr. Bill, I think I understand your point about progressing to deeper dives over a period of time and ensuring hydration AND "avoiding alcohol." I assume you mean that in a period of intense deeper diving, you do not consume. As a recreational diver, my understanding is that a glass or two of wine after diving is not a concern?
- Alcohol and DCI

Thanks again, this is very helpful.
JR

Additional Information about aging:
A little more digging found work sponsored by DAN that offers some encouraging information about aging and diving. The 2003 DAN Research Newsletter summarized findings from a study -- http://jap.physiology.org/cgi/reprint/94/2/507 -- about aging and CO2 with the following comment:
One of the key questions was whether older divers retain carbon dioxide at
high levels while diving,&#8221;said lead author Heather Frederick, M.D. &#8220;We
found that even at a depth of 60 feet with moderate exercise, healthy older people experience increased levels of retained carbon dioxide that was statistically significant at the surface, but clinically insignificant
compared to younger subjects. http://74.125.95.132/search?q=cache...ted+dives+at+2.8+ATA&cd=9&hl=en&ct=clnk&gl=us

 

[diverdoug1]

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.