Panic in the experienced diver?

[Jaydubya]

As close as I have ever came to panic...

During an Intro to Cave class I hyperventilated after aspirating water (it was the culmination of a series of problems that day- I should have turned the dive way before- and definitely would today). I was overbreathing my regulator and still could not get enough air. If the surface had been an option I might surely have bolted, but as it was it was I had to either get my breathing under control or die. I had the presence of mind to realize all this. My team mate frantically trying to help me was actually making it worse. I managed to give him a strong hold sign, centered myself and got my breathing under control. In a couple of minutes it was as if nothing had even happened. In the debriefing my instructor busted my chops for not keeping in trim during that episode. He had been playing the role of the lost buddy, watching us from off in the distance, when it happened and had no clue what was going on except that I was knees down near the cave floor and we were taking a long time to come looking for him. After I told him what happened he thanked me for deciding not to die during his class. I politely told him "you're welcome"

[Doppler]

CO2 in the bloodstream is completely determined by minute ventilation, assuming the gas you are breathing does not contain additional CO2. Bailing to open circuit definitely makes it POSSIBLE to reduce the blood CO2 level, assuming you can achieve a higher minute ventilation than what's required to keep the CO2 where it is (which is in part related to level of exertion). It may not, however, be possible to reduce CO2 fast enough to clear your head and get rid of the panicky feeling, in part because the natural tendency when panicky is to breathe as fast as possible. On scuba, this means reducing the efficiency of the ventilation, because too much of it is just going to exchange gas in the trachea and large bronchi, which don't exchange gas. That's why we are taught in OW that, if we begin to "overbreathe our regulator" (meaning the diver feels short of breath despite breathing as much as he can), we are to STOP, hang onto something (reduce exertion) and breathe SLOWLY and DEEPLY. It is then possible to reduce CO2. What may not be possible is to stay rational long enough to do it.

Are you sure you do not dive CCR, Ms?

Your short post very succinctly summarizes one of the most prevalent myths and misunderstood bits of physiology among CCR divers... namely that bailing out will "fix the problem" when there is a scrubber breakthrough or some other issue which compromises the scrubber bed.

The fact is that without some further action (as mentioned) the panicy feeling brought on by elevated levels of CO2 does not go away... certainly not for a good while.

Anyway, when do we get to go diving?

[DA Aquamaster]

Fear in general and panic in particular can be addressed by slowly approaching the triggering event over time - more or less successivley approximating the event until the real deal / full experience is not all that scary any more, or less pleasantly through "flooding" where you experience the event, survive it and in the process conclude it is a) surviveable and b) not as bad as you thought.

In the real world, successive approximation or habituation to the event is probably a much wiser approach and that speaks directly to more experience giving the diver both a wider range of tools to fall back on to provide viable options to resolve the situation (reducing the perception that things are out of control, hopeless, etc), and a greater psychological buffer against panic in that situation in general.

In general, the longer I dive, the greater my ability, confidence and comfort level, but some of it is still environmentally dependent. Pinnacle dives, by their envelope/comfort zone pushing nature are more stressful. Similarly, dives in unfamiliar conditions are more stressful until experience and confidence pushes the comfort zone back out to normal levels. I think that is part of the "cave gets bigger" phenomenon. As a cave diver develops, his skills get better, his SA improves and in general he has more cognitive respources to devote to the dive and prevent potential problems. All of those factors increase the margin separating the diver form an event that could induce panic.

The CO2 issue is also interesting. I suspect more often than not, an OC diver doing a pinnacle type dive, whether it is depth, penetration distance, or just really demanding conditions, starts to think about conserving gas. If that then results in the diver artificially lowering his ventilation rate, then CO2 retention occurs and the anxiety level will start to rise and magnify the impact of anything that does go wrong.

Personally, when I begin to feel my anxiety level increase, I assess why, determine the course of action needed to reduce it, and then act to make that happen. Sometimes that means turning the dive, other times it just means modifying the plan or adding in some other safety precaution or action to eliminate the anxiety inducing factor.

I think the important thing is to accurately self assess and monitor the dive as it progresses to ensure the psychological comfort zone stays large enough to allow you to accomodate potential emergencies without reaching a point where bolting or trying to claw through the ceiling appear to be your most viable options.

[Akimbo]

CO2 in the bloodstream is completely determined by minute ventilation, assuming the gas you are breathing does not contain additional CO2. ….

In addition to your excellent advice to relax and breathe deeply, ensure you are in a horizontal position to put the regulator diaphragm near the same depth as your center lung mass. That also reduces minor drysuit squeeze on the chest and diaphragm. A few inches of water pressure differential can make a difference when you are near the edge.

To expand on your point, contemporary open circuit regulators have significantly lower inhalation and exhalation resistance under maximum flow rates than conventional un-assisted rebreathers. Respiratory workload can have nonlinear effects on lung ventilation efficiency, especially at higher gas densities and physical workloads. There are also dead space issues with higher rebreather mouthpiece volume. That is further compounded when the mouthpiece is added to oral nasal volume in full face masks and hats (as opposed to the hoses connecting directly to the oral nasal).

There have been experiments with powered gas circulation on tethered rebreathers for deep diving operations. They proved unworkable at the time for a variety of somewhat unrelated reasons, but there may come a time when the concept is revisited.

[drbill]

One of the most important things a diver can learn about themselves is how they react to potentially serious situations. Our ability to deal with them undoubtedly improves with experience, but I have seen "experienced" divers panic when faced with a real problem. So far I am fortunate in that over the 50 years I've been diving, I've learned that I retain a fairly clear head when faced with even potentially life threatening problems. Of course I could be living in "da Nile."

[Akimbo]

…. Of course I could be living in "da Nile."

I hear the diving sucks there, on so many levels.

The problem every creature faces in life is it only takes one mistake to end it.

[2LongGone]

Excellent thread! I will have to say that out of the people I've been around who did not panic in a given situation some of them didn't realize they were in a dangerous position to begin with.

KC