Quote: (Originally Posted by
Brian A)
There also seems to be something else in play in that the 2 examples sited here (mine and LCFs) are also where the diver is doing there deepest dive to date, suggesting that there could also be a bodily reaction to stress or "first nacosis" perhaps?
It would be interesting if there were more examples of this relatively shallow blackout.
There are plenty of examples from the free diving world. Although for different reasons.
I'd be interested in knowing if either of your cases had some hyperventilation or breath holding due to cold or stress. Leading to dramatically elevated CO2 which on the surface would be more self limiting but at even slightly elevated PP lead to loss of conciousness. After loss of conciousness the victim then started normal-ish breathing spontaneously but the sum narcosis had not yet dropped sufficiently to regain conciousness.
After ascending the ppCO2+N2 drops and conciousness returns. It may have returned at depth given some extra time. Or it have retriggered some hyperventilation and cycle would begin again.
Richard