Wayan said:
"So as you can see it is not as simple as saying this person has a hit get them back in the water. It is a medical management problem and this needs to be the first consideration....Is it medically viable to IWR this person........"
I totally agree. There are many circumstances where IWR is not wise nor justified, even though the victim badly needs recompression.
However, I have been very surprised in how many cases IWR actually has been effective in and I think that with proper knowledge, training, equipment and further studies - it can be even more useful in the future than it currently is. Point being, it currently is not very useful because of the lack of the foregoing by all parties including in the medical community.
If the medical community can come around to an agreement that IWR is useful and then develop some protocols to use when advising DMs or operators in distress over the phone in appropriate situations, it would enhance diving safety. Just saying not to use it because of the risks will not improve diving safety. We need to find out how to use this tool effectively. I'm sure some cavemen once said fire is too dangerous to use.
To progress, we need to examine and learn. We need more studies done and finally have the medical community come around to this and develop safe, standard treatment protocols to use when the situation arises and when appropriate.
Then again, what do I know? I'm not medically trained and I could be all wrong. And that's why I started this discussion to begin with.
For instance, here's some food for discussion(Ran Arieli, Israel Naval Medical Institute, Haifa, Israel) in 2007:
"It has been shown that the solubility of a gas in water equilibrated with a mixture of gases is not, as postulated by Henry's law, a linear function of the gas pressure (3, 4). This phenomenon was explained by the effect of one dissolved gas on stabilization or destabilization of the water structure, which in turn affects the saturation solubility of another gas (1). The theory suggests that reduced stability will decrease the saturation solubility. Maharajh and Walkley (3) showed that in water equilibrated with a mixture of 50% oxygen and 50% nitrogen, the saturation solubility of oxygen decreased to 73% of the value expected according to Henry's law, whereas that of nitrogen decreased to 84% of the predicted level. When the other gas was helium, the saturation solubility of oxygen declined more, to 66% of the predicted level. On the other hand, when a mixture of H2 and N2 was used at high pressure, there was a mutual increase in solubility (3, 4). The main effect of one gas on the solubility of the other occurs when the concentrations of both gases are equal; the effect is diminished when one gas predominates.
The total amount of dissolved inert gas in mixed-gas diving should, therefore, be less than that expected according to Henry's law, thus lowering the risk of decompression sickness. Air diving decompression tables have been extended to nitrox by calculating the equivalent air depth and to other gas mixtures used in diving by calculating the equivalent mixture depth. However, these new tables are unnecessarily conservative, because there is less dissolved gas in the tissues when breathing gas mixtures in which no one gas predominates, compared with a binary mixture consisting of a low level of oxygen and a high concentration of inert gas. In some hyperbaric oxygen treatments, the oxygen is transported in a dissolved phase, such that in both the arterial and venous blood the hemoglobin is fully saturated with oxygen. Less dissolved oxygen than expected will be transported when a balanced gas mixture (such as 50% He + 50% O2) is breathed. The effect of one gas on the solubility of another appears not to have been taken into account in compression-decompression calculations."
Can IWR treatment benefit by using EAN 50 for this reason? Or Heliox 50/50? Maybe these gas mixtures are superior to pure 02. Maybe not. We just don't know.
