"Riding your Computer Up" vs. "Lite Deco"

[KenGordon]

Interesting. I suspect the correct interrtation of the 0.01 probability is not one in 10,000 dives but perhaps one in 1000 divers is predisposed to DCI and may suffer an injury 1 in 10 dives. I suspect they are medical anomolies rather than representative of the general diving population

So what? This is kind of what DevonDiver is getting at. Having done a good number of dives you may get to be confident that you probably do not fall into a group who are susceptible to DCS. Having said that my mate with the PFO had many hundreds of dives over lots of years before he got an otherwise unexplained bend.

I don't think many people can really be sure they are not in that 1 in 1000 or whatever the rate is. So diving prudently means that if you find you are you may get away with it.

Recall that PFOs are present in something like 25% of the population.

 

[redacted]

So what? This is kind of what DevonDiver is getting at. Having done a good number of dives you may get to be confident that you probably do not fall into a group who are susceptible to DCS. Having said that my mate with the PFO had many hundreds of dives over lots of years before he got an otherwise unexplained bend.

I don't think many people can really be sure they are not in that 1 in 1000 or whatever the rate is. So diving prudently means that if you find you are you may get away with it.

Recall that PFOs are present in something like 25% of the population.

Are you suggestng that all diver should assume they are in the PFO group and, therefore, 5 time as likely to suffer a DCI event than those without a PFO? If so, what should those divers be doing differently, besides playing more golf rather than diving?

 

[boulderjohn]

He went to a recompression facility where a severe DCI was diagnosed. He received three sessions of recompression treatment over a three day period.

Two comments.

1. a severe DCI was diagnosed. Once again: DCI means Decompression Illness, a diagnosis that includes both Decompression Sickness (DCS) and lung overexpansion injury. The symptoms for the two are are similar, but since the treatment is the same, the need to make a true differentiation in the diagnosis is unnecessary. A lung overexpansion injury can happen on any dive, including a shallow end of the pool training session. According to a joint DAN-PADI study, it is the most common accident-related insjury in scuba.

2, As I said in a recent post in one of these maddening threads, a private statement by DAN released in a thread a couple of years ago indicated that a large number of people treated for DCI did not in fact have DCI but were misdiagnosed and treated anyway. Many such ailments misdiagnosed heal with time--the time spent in a recompression chamber would be just about right.

You need more than an anecdote here or an anecdote there to build a case.

 

[dumpsterDiver]

Two comments.

1. a severe DCI was diagnosed. Once again: DCI means Decompression Illness, a diagnosis that includes both Decompression Sickness (DCS) and lung overexpansion injury. The symptoms for the two are are similar, but since the treatment is the same, the need to make a true differentiation in the diagnosis is unnecessary. A lung overexpansion injury can happen on any dive, including a shallow end of the pool training session. According to a joint DAN-PADI study, it is the most common accident-related insjury in scuba.

2, As I said in a recent post in one of these maddening threads, a private statement by DAN released in a thread a couple of years ago indicated that a large number of people treated for DCI did not in fact have DCI but were misdiagnosed and treated anyway. Many such ailments misdiagnosed heal with time--the time spent in a recompression chamber would be just about right.

You need more than an anecdote here or an anecdote there to build a case.

You are saying that lung overexpansion injuries are more common than ear injuries, like torn eardrum. etc. ? I know a lot of people who have been bent, many more who have had barotrauma to the ears and none who have had lung expansion injuries.

 

[KenGordon]

Are you suggestng that all diver should assume they are in the PFO group and, therefore, 5 time as likely to suffer a DCI event than those without a PFO? If so, what should those divers be doing differently, besides playing more golf rather than diving?

I am not a doctor but look at the numbers. Given all these people who have PFOs are diving, but not very many get bent then yes perhaps the risk WITH a PFO is what we should be what we should be guarding against.

 

[boulderjohn]

You are saying that lung overexpansion injuries are more common than ear injuries, like torn eardrum. etc. ? I know a lot of people who have been bent, many more who have had barotrauma to the ears and none who have had lung expansion injuries.

Thank you for correcting my typing error. I meant to say it was the most common accident-related fatality in scuba.

 

[redacted]

I am not a doctor but look at the numbers. Given all these people who have PFOs are diving, but not very many get bent then yes perhaps the risk WITH a PFO is what we should be what we should be guarding against.

Unfortunately, assuming or even knowing you are in a high risk group does not help much unless you know how to compensate for it, unless you are willing to simply quit diving. All you really know is the edge is closer than your tools are telling you.

 

[KenGordon]

You need more than an anecdote here or an anecdote there to build a case.

These are not anecdotes, they are quotes from the BSAC Incident report. Have another one

June 2007 07/131

A pair of divers conducted a 30 min dive to a maximum depth of 20m. Shortly after leaving the water one of the divers complained of a headache and a tingling in her fingers. The Coastguard was alerted and the diver was placed on oxygen. The casualty became more distressed and she was taken by ambulance to hospital. DCI was suspected and a PFO test was planned.

There is a probability distribution. You expect short shallow dives to be less likely to cause DCS and they seem to, most of the cases are more aggressive or faulty ascents, but enough are not to suggest that it does not take banging up against deep NDLs to be hurt.

They categorise the reasons for the incidents, such as missed stops, bad ascents, deep or repeat dives. The one for 'within limits' was 14% that year.

 

[KenGordon]

Unfortunately, assuming or even knowing you are in a high risk group does not help much unless you know how to compensate for it, unless you are willing to simply quit diving. All you really know is the edge is closer than your tools are telling you.

The tables etc were built on the whole population, some of the dives will have been done by people with PFOs and so the tables are valid for people with undiagnosed PFOs. If you do not know whether you do or not then dive normally, otherwise do what a doctor tells you.

I come at this from the idea that you should train and educate divers so the NDL is just a detail of today's dive. If they need to dive past it they can because they know how to do that properly. Being able to do the stops, plan the gas etc means not being afraid of the limit and doing the stops after a reasonable NDL rather than pushing the NDL as doing the stops is not 'allowed'.

Clearly that is a bad business plan for tourist dives so it doesn't generally happen.

 

[lowviz]

...//... I come at this from the idea that you should train and educate divers so the NDL is just a detail of today's dive. If they need to dive past it they can because they know how to do that properly. Being able to do the stops, plan the gas etc means not being afraid of the limit and doing the stops after a reasonable NDL rather than pushing the NDL as doing the stops is not 'allowed'. ...//...

Tourist diver or not, my fundamental objection to the NDL pablum that the OW/AOW agencies proffer is rooted in the obvious dereliction duty to continue seamless dive education. Deco is verboten until the OW/AOW diver chooses to flip his/her own switch and then be welcomed as an incoming tech diver?

Problem with this?

Anybody else see a disconnect? (Solo divers need not reply, we were born that way)