lamont
Contributor
Now, we add to the problem of ascent [depressurization] the complication that some divers may be harboring bubbles in their tissues. One can see how this now is a second problem to simply determining residual tissue nitrogen. When DCS "hits" are found that occur 10 hours after diving, it is clear that this is most likely a residual bubble problem and not one of residual nitrogen.
Last time I looked into this, the kinds of profiles that were resulting in symptoms were something like 60 mins @ 60 feet, with a 60fpm ascent, with a 2h(?) surface interval and another dive just like it -- followed by ascent to 8,000 ft 12 hours later.
I'd argue that "harboring bubbles" was the primary cause there, and that those profiles exceeded all kinds of limits and that the divers in question were most likely subclinically bent before their ascent to altitude.
The justification for those kinds of profiles is that they do happen in the recreational diving community and any kind of unform rules about flying-after-diving needs to take into account the worst cases. Unfortunately, for divers who always do adequate decompression, that can just lead to them ignoring the results of these studies completely (I know of one technical agency with instructors who believe that these rules are 'bull****' and regularly fly after teaching technical courses).
PFO vs. non-PFO is also another factor that is typically ignored in these kinds of studies since they're designed to only address the average diving case.
So, what are the limits of non-PFO divers, who perform adequate decompression and stay within limits? Are there really cases where those divers, after 2 recreational dives and a 6 hour SI, ascend to 8,000 ft and get bent?