29 August, 2008

The Moment I was Hoping Would Never Come....

This post has been kindly contributed by Ken Chan, a veteran diving instructor currently based in Hong Kong and one of the founding members of the Sandy Bottoms Divers Club. If you live in Hong Kong or if you are just passing by and have time for a dive or two you should definitely check them out:
The Moment:
Last Saturday I was out diving, the first time out at sea for my two open water students.
Dive one was on a sandy bottom, max depth 6 mtrs and bottom time was 24 minutes.
The last exercise was a “5-point-ascent”. My students performed it very well, a textbook ascent. Though the fin-kick wasn’t that beautiful, hands were up, air was released from their BCDs as they went up, no faster than 18 mtr/min, all the while turning around and looking up.
Just as we were about to reach the surface something looked wrong. One of my students stopped kicking and started going down again with head slumped down.
I grabbed the BCD, brought the diver up and established positive buoyancy while telling the other student to hold on to the dive marker next to us. I called the student’s name but got no reply, there were no signs of breathing either.
My student had blacked out and stopped breathing less than 30 cm from the surface!

I started Rescue Breaths and called/signaled for help in between. (Wow was I glad there were no other divers on the surface*) Just before help arrived, my student regained consciousness. Very weak and barely breathing, but conscious.
I removed weight-belt and BCD and towed my student to the boat. Another instructor and the boatman took care of the other student and equipment respectively.

My student recovered on the boat while the other divers were returning to the boat. Once back in Sai Kung, it was straight to the hospital.
As the doctor and nurse did their tests, I expressed my thoughts regarding an excessive amount of CO2 as a possible cause. They put her on oxygen to flush-out any possible excess CO2. I then called DAN / DES for some more input. Could it be as simple as hyperventilation leading to hypercapnia? Doesn’t that happen to free-divers only? DAN / DES advised to contact the HK hyperbaric chamber, just in case bubbles were a factor, which I did. Not much help there. Once they heard we were already in a, public, hospital I was told just to wait to see what the doctor would say and do.

Results from the blood-tests showed a high CO2 level, likely b/o hyperventilation and/or shallow breathing.
My student would be fine but was kept overnight for observation none-the-less. The next dive with my student has already been planned.

I now think that maybe one, or more, of the fatal accidents in HK with divers going missing and found drowned at the bottom of shallow water might have had hypercapnia as a cause. Little or no experience (in low viz) lost from your buddy and low light are enough to get one to hyperventilate/breath very fast.
I learnt a number of things, though not exactly the way I had in mind to learn about this. At least all my training paid-off.

What to take from this?
- Our practice, at SBD, of only taking as many students you can see (as you swim behind
them) diving, is spot on.
- Never wave your arms for attention, unless in an emergency. Local divers seem to
habitually surface far away from their boat and then wave for the tender to pick them
up. As I was downwind from the boat I could not be sure that I could be heard correctly
on the boat so “waving” was important to get the message across.* Hence I was glad no
other divers were on the surface.
- Know your rescue skills and practice those skills.
Thank you Ken - - - - The Frog Man

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