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Yeah I was thinking somewhat along those lines. You can also dive to 70' on Air and end the dive at 35 minutes or even 30 and have that same conservative advantage.
Nitrox for older divers
- Thread starter 2Bobbyo
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While it could be a true statement, It is not the point. There have been independent risk factors identified with each one increasing the risk of DCS independent of each other. While obese 40 year old who has been imbibing and dehydrated who is in poor physical health and over-exerted himself during the dive and ignored a safety stop is in higher need of NitrOx or help in general, it does not diminish an increased risk associated with age alone. One has to be mindful of that and use either more conservative profile or get some odds ratio decrease by using Nitrox...
People keep saying there are added risk factors for divers as they age but no one has said what they are, if it’s a general health issue then you can’t use age alone to measure the risk because as I’ve said there are plenty 60 year olds healthier the 40 year olds. Also the unhealthy 40 year old doesn’t have to be dehydrated or over-exerted to suffer a bend. I don’t know why you added those conditions.
Hi mac. The reason I added those is because they are all independent risk factors for DCS, just like age. Having said that neither one individually or all of them added together (I added them together to make a point) “guarantee” that you will get DCS. On the other hand, there are “undeserved “ hits even for some who do everything right. It is like a bucket of water and you either add water to it (factors that increase odds ratio) or subtract from it. The factors that I mentioned for a 40 year old all would add risk. Age would add risk (independently of health). NitrOx would subtract it. Conservative profile would subtract it. Having said that, they are all probabilities. I saw a lady the other day who was 98 years old, she smoked since she was 12, and did not develop any cancers or heart disease and obviously outlived most of her peers. Her argument was that tobacco use is not bad. While it is hard to argue with her, everybody understands that she drew out a lucky ticket and it is not the norm for majority of people. So just like with my bucket of water analogy - you don’t know where you are starting on any given day, so if you Already have some factors against you, try to get some to help you to stay out of trouble. There are things we got away with when we were younger, that I wouldn’t try now even if I can still get away with them...
AfterDark
Contributor
Judging by my experience nitrox other than extending NDL wouldn't do anything for you that a longer SS can't do.
I'm 66 nitrox cert. and have used it but since I don't reach NDL at any depth without double tanks I rarely use nitrox.
I'm 66 nitrox cert. and have used it but since I don't reach NDL at any depth without double tanks I rarely use nitrox.
If all these risks that you mentioned can be lessened by diving nitrox using air tables why aren’t all divers been advised to do it. What is the reason the older diver is more at risk between divers in similar health. What I’m asking, is there a specific reason, other than general health that makes an older diver more likely to develop DCS
wstorms
Contributor
If you approach the body as a mechanical device, I can imagine (but have no relevant background) that age on its own is more of an indicator of general wear and tear? Veins, valves, joints, everything has been working longer and might not operate at peak performance anymore (yet still be sufficient to be considered "good health").
Think about a car engine that out of the factory could power the car to 200 mph. Although that is really impressive, in normal life you will never need the 200 mph capacity. As general wear and tear sets in, the engine is no longer able to deliver its peak output, but still delivers plenty for normal everyday use (including the occasional acceleration), so the engine is considered "healthy".
Quite a few aging processes impact each other and (deco)stress susceptibility as a result.
For example, even though somebody might be really fit and strong, if they lift a heavy doubleset this might impact the joints more than it would with a younger diver and therefore increase the chance of a DCS hit.
Since it is unlikely that all individual contributing factors (status veins, status joints, status XYZ) are all measured individually and then combined in some form of objective measure, they are lumped together in the general health term. On average, general health declines with age, so from a risk indicator point of view age might be useful, especially combined with other riskfactors.
Something like
certain age + really fit = risk X
certain age + overweight = risk Y (X < Y)
certain age + really fit + cold dive = risk Y again
certain age + overweight + cold dive = risk Z
Think about a car engine that out of the factory could power the car to 200 mph. Although that is really impressive, in normal life you will never need the 200 mph capacity. As general wear and tear sets in, the engine is no longer able to deliver its peak output, but still delivers plenty for normal everyday use (including the occasional acceleration), so the engine is considered "healthy".
Quite a few aging processes impact each other and (deco)stress susceptibility as a result.
For example, even though somebody might be really fit and strong, if they lift a heavy doubleset this might impact the joints more than it would with a younger diver and therefore increase the chance of a DCS hit.
Since it is unlikely that all individual contributing factors (status veins, status joints, status XYZ) are all measured individually and then combined in some form of objective measure, they are lumped together in the general health term. On average, general health declines with age, so from a risk indicator point of view age might be useful, especially combined with other riskfactors.
Something like
certain age + really fit = risk X
certain age + overweight = risk Y (X < Y)
certain age + really fit + cold dive = risk Y again
certain age + overweight + cold dive = risk Z
Not according to DAN statistics,
The overall per-capita DCS claims rate (DCR) was 20.5 per 10,000 member-years. Based on the age-adjusted DCR, males submitted 28% more claims than females. Male-to-female difference was greatest between 35 and 40 years of age and disappeared by the mid-50s. Highest rates were observed in the 30- to 39-year age category, after which DCR declined with increasing age. Highest yearly DCR was estimated in 2002. Insurance dropout rate was greater among those who had DCS in the first year of their insurance compared to those who did not have DCS in their first year.
According to this the older you are the least chance you are of getting DCS older divers are wiser divers. The 30 to 39 year olds should start using nitrox on air tables
The way I think about it, an older diver has more scar tissue from lumps and bumps along the way. Wholly apart from the risk of silent cardiovascular disease in an otherwise healthy 60+ year old, I think about scar tissue and its poor perfusion compared with other tissues (like muscle) as being more reluctant to give up nitrogen due to its poorer blood supply. That type of tissue is more likely to bubble after acquiring a nitrogen load. And the scarring may not be just in muscle or joints. Think of silent mini strokes or silent heart attacks that you never even knew you had. Those tissues won't easily give up nitrogen either, and they're not in benign places.
That's my rationalization for using nitrox all the time as an older diving physician/former hyperbaric doc.
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