i tried to fly out today and i ended up being bent

[Blastman4444]

A couple of folks have nibbled at the problem, but no one's really honed in on it. The reported dive profile DOES violate the NOAA flying after diving (FAD) table, which calls for at least 24 hours before ascending to 10,000 ft in an unpressurized aircraft for any nitrogen loading above repetitive group "H" on the Navy tables - the mishap diver was certainly beyond that, based on the reported dive profile.
The 12-18 hour guidance is strictly for commercial aircraft, whose cabin altitudes these days run around 4500'. (the guidance assumes less than 8000'). That extra 2000 feet of cabin altitude throws the 18hr guidance out and the diver is now on the NOAA FAD table guidance... which calls for a minimum 24 hour SI, and, as this incident has just proven, is apparently pretty good guidance.

I suspect that too, but the fact that the diver was outside the NOAA FAD table as well sorta points to the efficacy of that table, eh? I should also mention that people have, in fact, gotten bent in unpressurized airplanes without ever having been diving in their lives, so it is possible to get bent in an airplane without being bent first. (That's why we'd pre-oxygenate before flying high altitude test flights)
Rick

I'm not sure I buy the PFO explanation.

Typically, when is venous bubbling in the post-dive period the greatest?
Is it 5 minutes after surfacing, 30 minutes, 1 hour, 3 hours, 12 hours, or 24 hours?
Based on published data, I'd venture a guess that venous emboli peak at some point between 30 minutes and 2 hours post-dive.
Taking this into consideration...and then superimposing the change in ambient pressure from sea level to whatever the cabin pressure was at 10,000 ft....I'm not sure if there would be enough of a bubble burden 20 hours later to elicit spinal cord DCS even in the presence of a PFO.
I'd argue that if the patient had a PFO (and PFO is a true risk factor for DCS), he would have experienced the hit shortly after the conclusion of his last dive...not almost a day later.

After a 20 hr post-dive interval, this asymptomatic individual boarded a commercial flight whereupon he experienced numbness/tingling in all of his extremities once the plane reached an altitude of 10,000 ft. Assuming that cabin pressure was kept within a range equivalent to 2000 - 8000 ft. in altitude and taking his dive profiles and pre-flight interval into consideration, this would place him on the "exceptionally prone" end of the DCS spectrum.

Rather than jump to a DCS diagnosis, I would be very careful in ruling out other causes of the patient's symptoms.
I would ask whether the patient was on any prescription/OTC/homeopathic medications.
I would ask whether the patient had a history of circulation, diabetes, or heart disease issues.
I would ask whether the patient has a history of chronic back pain or acute trauma to the vertebrae.
I would also have to consider anxiety/panic attack in the differential.

If I could rule out all of those other potential causes...and presumptive treatment for DCS (rides in the hyperbaric chamber + breathing O2) resulted in resolution of the patient's symptoms, then I would settle on a diagnosis of DCS and just say that, for whatever reason, the diver was very unfortunate to experience the hit.

The answer is no to all those questions above and shortly after I was dived in the chamber the tingling and numbness started to go away. I'm a lot more concerned about flying now then I ever was before I pushed my flight home out to saturday so I would be 72 hours out from my last treatment as they recommended. I don't want to push my luck again. I still feel a slight tingling in my legs but the doctors think it's just needs time to resolve it as it comes and goes not all the time.

 

[ThomasScherrer]

will your DAN insurance cover all cost, if they can prove you actually violated no fly time
and pressure groups and you did know all this actually before you dove and flew.

 

[GrumpyOldGuy]

will your DAN insurance cover all cost, if they can prove you actually violated no fly time
and pressure groups and you did know all this actually before you dove and flew.

He did not violate DAN's recommendation of 18 hours, so this question is moot. The 24 hours is common on many computers and might be recommended by other agencies, not DAN.

 

[Rick Murchison]

He did not violate DAN's recommendation of 18 hours, so this question is moot. The 24 hours is common on many computers and might be recommended by other agencies, not DAN.

DAN's 18 hour recommendation is irrelevant to this mishap as it is based on a maximum altitude of 8,000'. By going to 10,000', the mishap diver is outside the DAN parameters.
Rick

 

[daniel1948]

We keep hearing that DCS is a statistical event. With statistics there are always outliers. Some individuals on some occasions will go beyond the limits without an event. Others will experience the event in spite of being well within the limits. From reading the above, it sounds as though the OP was within the limits, but just barely. It was a statistically unlikely event, yet one that will happen to a small number of individuals. I think the OP was just unlucky in getting the hit, and very lucky in getting prompt treatment.

I take this as a reminder to always be extremely conservative both in my dive profiles and in my no-fly time, as well as things like staying hydrated and not diving if I don't feel well or I'm uncomfortable with the plan. One thing I like to do is snorkel, rather than dive, on my last day. I've always loved snorkeling.

 

[GrumpyOldGuy]

DAN's 18 hour recommendation is irrelevant to this mishap as it is based on a maximum altitude of 8,000'. By going to 10,000', the mishap diver is outside the DAN parameters.
Rick

Sorry Rick but you are overlooking the fact that virtually all commercial flights in the US are in pressurized cabins that maintain pressure of 8,000 feet or better. So DAN's 18 hour recommendation is relevant.

 

[DandyDon]

He did not violate DAN's recommendation of 18 hours, so this question is moot. The 24 hours is common on many computers and might be recommended by other agencies, not DAN.

I really think that leaving the 24 hour clock from the previous century on dive computers is there to make the lawyers happy. My Oceanic computers also show a more realistic count down clock to clear.

 

[vladimir]

when the aircraft got to about 10 k feet started to feel strange my left hand and arm started to tingle then my right arm and both legs.

By going to 10,000', the mishap diver is outside the DAN parameters.
Rick

Sorry Rick but you are overlooking the fact that virtually all commercial flights in the US are in pressurized cabins that maintain pressure of 8,000 feet or better. So DAN's 18 hour recommendation is relevant.

You can see where Rick got the idea that the OP went to 10,000 feet, but the OP's language leads me to believe that he was not being precise and that he was probably exposed to standard commercial flight pressure.

 

[GrumpyOldGuy]

You can see where Rick got the idea that the OP went to 10,000 feet, but the OP's language leads me to believe that he was not being precise and that he was probably exposed to standard commercial flight pressure.

I do see how it could be confusing. The question though of could/would DAN insurance withhold benefits if you violated DAN recommendations regarding safety standards is interesting. Not being a lawyer so I am not qualified to state an opinion though.

I still hold to the 24 hour clock being a very imprecise rule and will continue to use the NOAA ascent to altitude for guidance. It is not great, but the best I know of and free to use.

 

[ianr33]

I do see how it could be confusing. The question though of could/would DAN insurance withhold benefits if you violated DAN recommendations regarding safety standards is interesting. Not being a lawyer so I am not qualified to state an opinion though.

Far as I am aware DAN makes no mention of this in their policies (Although the Standard plan has a depth limit of 130 feet)

Not a lawyer either but presumably DAN would need to spell out any exclusions which would quickly get very tricky. (Is diving air below 100 feet "safe" ? )