dave4868:
In this case, based on your report, I don't see any evidence of panic or any warning signs of a problem. Just bringing the unconscious diver to the surface could cause lung expansion injury and the some of the signs you report.
girlydiver:
When we questioned the buddy after we asked him if he saw any blood when he was trying to put the regulator back in he said "yes in his eyes". That is why we think he panicked, spit out his reg and shot to the surface before his buddy brought him up. It only takes approximately 4 feet of ascent while holding your breath for you to embolise. When he turned to check on him and noticed the reg out he also noticed his buddy was slightly higher than him. Whatever really happened we will never know!!
Thank you for providing this last, possibly key, information about the buddy seeing blood "in" the victim diver's "eyes" at depth. It's hard to say exactly what this signifies, but is it still reasonable to conclude that barotrauma occurred prior to incapacitation? Are there other possibilities? I don't know, I'm just asking.
We might ask, when the victim was found at depth, was this evidence of blood in his eyes possibly related to choking and drowning at depth and not arterial gas embolism (AGE)? Was the blood that was seen on the victim when brought to the surface related to drowning or to embolism? Or was it related possibly to a separate event of barotrauma that might have occurred when the unconscious victim was brought to the surface?
In this case, we really can't surmise that there was an ascent by the victim prior becoming incapacitated, can we?
Although it's undoubtedly a sensitive issue for those involved in this incident, this last bit of information about the "blood" in the victim's "eyes" at depth begs the question of "how often did the buddies check on each other?" or "what was the window of time between the last 'ok' and the finding of the incapacitated buddy"? That might shed some light on whether the victim had time to ascend far enough from 40' to have barotrauma. You would then be stuck with the question of how he got back down close to the other diver near 40' with a slight current blowing and whether he would have been able to do it on his own power.
I'm
not suggesting that any inquiry or judgment be made about the buddy, as that could add to his trauma. I'm sure this is hard for him to deal with as it is.
Needless to say, how frequently a diver should check on his buddy will, of course, vary with conditions, primarily visibility and current. It will also vary with the abilities and/or needs of the divers.
When I'm actually doing a "buddy dive" (in my local conditions of 10-20' vis and minimal current), I'll look at my buddy about every ten seconds and sometimes more frequently if he's not keeping abreast or if he's approaching the limits of the vis. Of course, I'll slow down or wait or suggest he swim abreast or closer, but unfortunately, some divers tend to follow directly behind the leader making it harder to keep track of them.
My usual buddies are experienced and we generally don't need such close watching, but when I'm with unknown or new divers, I definitely try to avoid buddy separation since that can quickly become a high-risk situation for them.
Regarding barotrauma on ascent, I believe it should be clarified that breath-holding while ascending
4 feet has the
potential to cause barotrauma
if it occurs in very shallow water and
if the lungs were quite full to start with. It's less likely to cause a problem in deeper water holding less than a full breath.
So the assumption is that the diver panicked enough to ascend far enough and fast enough to embolise but then had the good sense to let enough air of of his BC to remain neutral so he could float in the water column? I cannot confirm the 4 foot requirement to embolise, but I would speculate that a truly panicked diver would take more than 4 feet to stop ascending to regain control (and they would have to stop very abruptly so they could still remain neutral per the statement that the diver was found floating mid-water column).
It's still a somewhat confusing account from what we've heard, but it's great to have the details we've been given. You're right, some things are still unclear at this point, such as:
girlydiver:
He got an Ok before they left the line and started drifting. He got a couple more OK's from his buddy and the next time he turned to check him out he was floating without his reg. He swam right over and put the reg back in but there was no fight or struggle and his eyes were unmoving. They were only at 40 feet and they had just barely made it to the bow of the wreck.
From this we might deduce that there was
no ascent, since it sounds like the victim was neutral ("floating"), as you point out.
No doubt, some of the details need clarification.
It would help to know how much time transpired between the last "ok" and finding the victim.
There was a recorded case of AGE for a diver repairing the prop on a sailboat in less than 6 feet of water. I don't think it would take very much expansion at all to force gas bubbles into your bloodstream.
I think I read that a relatively small decrease in ambient pressure can cause barotrauma in an already fully inflated lung while holding one's breath, something like 2 psi, IIRC. Since pressure changes are greater in shallower water, the situation could become traumatic if one is ascending while straining, lifting or holding something underwater. That might lead one to hold a deep breath in during the ascent. The ascent may be unintended or unnoticed, too.
I also doubt he panicked. AGE could have resulted from simple breath holding or even a medical condition like a PFO. He likely would not have had any warning and simply blacked out.
Finally, newer divers often swim negative, especially in current.
If there is a lesson in this, it's a reminder to never hold your breath and that maybe equipment should evolve so that you don't drown if you become unconscious.
The confusing part is that we have some fairly reliable-sounding reports of a bloody discharge. Was it from drowning or barotrauma?
To be caused by "simple breath holding" at a depth of 40' would require substantial ascent and a full breath before it would cause barotrauma, I think.
I hope we can get more information and I appreciate all that girlydiver has provided.
Dave C
