Hypoxia/Near Drowning Stoney Cove 3rd March 2007

The Purist

(sorry folks, this goes on a bit!)

A bit of background before we start - I've been diving the KISS since 2001. I've had a fairly well documented manufacturing problem with my KISS which meant that water could enter the stack even after a successful +/- test, so I quickly learned about the fun of CO2. Before finally diagnosing the problem (which Gordon helped me with & then supplied spares FOC) I was getting my buddies to check my pre-dive prep, then still getting flooding so I became suitably paranoid about my rebreather and was always fastidious in prepping it and doing my pre dive checks.

The real time story of what happened

We arrived at Stoney Cove at about 11.30 and were able to park just under the bridge in the upper car park. We hit the on site shop as my buddy wanted a new thermal top then ran through all our pre-dive tests & kitted up for our first dive. Into the water from the bus stop at about 12.15, pootled off to the right along the wall at about 20m, got bored, came up to about 10m, pootled back, my buddy did a couple of drills and we got out. My neckseal had been a bit loose on entry so I'd got some water down my neck & I was a bit chilled, but nothing too bad. I was also keen to get used to my Shearwater HUD on this dive, it was only my 2nd dive using this and I was pretty pleased with its operation.

We had an hour for lunch - I was a bit chilly as the sun decided to hide behind a cloud on an otherwise glorious day, then we kitted up again just after 2.

We were on the quayside part of Stoney so we shifted our kit to the side of the water, then sat down & got into it - I went onto the loop to do a pre-breathe and had the PO2 steady at around 0.3-0.4ish. That's a bit lower than I normally do, but we were only planning another pootle so I wasn't too stressed. I dropped into the water just ahead of my buddy and was disappointed to feel my neck seal leaking again, then we submerged & did our bubble check. My buddy had spotted a small leak from the turret on my dil 1st stage on the 1st dive and confirmed it was still there, I checked his kit (new shiny Inspo stuff with no leaks at all, pah!). I had a quick scan of my displays then we turned to head off on our dive. After a few fin strokes I realised all was not well and signalled to my buddy that we should head back to the exit, he gave me an OK - it then gets a bit hazy - I remember going for my DSV switch and seeing some bubbles coming out of the reg, but I'm not sure why I even went for the switch in the first place.

The next thing I know, I'm feeling warm and fuzzy, everything's dark and all I can feel is my heart beating in my chest. I start to hear voices then faces start to come into view and the voices start making sense. I start telling them I'm OK and they can leave me alone (I got a bit stroppy apparently) then they start trying to dekit me, which is when I got proper stroppy as I could get my arms out OK. I stood up rather shakily (somehow I was at the slipway) and was walked over to the wall and sat back down. One of the group who'd assisted was a trained chamber operator and he gave me a good DCI check - I was mentally coherent by then but physically feeling poorly, but there was no sign of DCI. A paramedic was already on the scene and an ambulance arrived at some point - my assessor then told them that they could stand down the helicopter which was en route as I wasn't showing symptoms.

Stepping back a bit, my buddy's side of the story is that after I signalled to head for the exit I turned, stopped, went for the DSV and then slumped/shook/spasmed in some way - he got to me, realised something was up (eyes open but no response), lifted me to the surface then towed me to the slipway exit, calling for help. On the surface I was apparently blue, not breathing and one chap checked for my pulse, couldn't find it and started giving CPR, another brought an O2 kit down. The Stoney rescue boat arrived with further O2 and it seems that once I was on O2 I started to come round. Several people I've heard from since the incident (including my buddy) said they were convinced I was dead, another has said I was the bluest person they've ever seen.

I was stuck into the ambulance, hooked up to a machine that goes ping and then they said they were going to try to 'canulate' me - ie. stick in a drip (no jokes required). I was too cold and they couldn't find a vein, by this time I was mentally sharp but still felt wiped out and was occasionally nauseous. I was also feeling a chest pain when I inhaled deeply - this was due to the CPR as it now turns out, but I was unaware of that and my thoughts were towards DCI or lung injury so I was careful to explain this to the ambulance crew.

The ambulance took me to Leicester Infirmary where I was hooked up to more machines that go ping, still on O2, and another doc had a go at finding a vein - he eventually got a bit of blood out on the 3rd attempt and took it off for a test. I must have been there for about 45mins to an hour when my buddy arrived, and he was good enough to phone my Mrs to let her know the score and get me some chocolate!

I was in the resuss bit of the A&E ward until about 5.30ish (I think) by now I was changed & sat up in the bed, off O2 and feeling more together. I was transferred down to another ward where we waited for the head doc to come around & discharge me - at about 7pm we got bored and asked to see him, and were out the door about 7.45. At the time we thought that was that, and I'd had a lucky escape - but it's not that simple...

What went wrong?

I've downloaded the profile from my Sensus (attached) & the log from my HS Explorer is:

(time) (depth) (temp)
000015 CC 00 0000.0 18
000030 CC 00 0000.0 18
000045 CC 00 0001.5 18
000060 CC 00 0001.8 17
000075 CC 00 0002.4 17
000090 CC 00 0003.0 17
000105 CC 00 0003.6 16
000120 CC 00 0004.2 16
000135 CC 00 0004.5 16
000150 CC 00 0004.8 16
000165 CC 00 0004.2 15

I was in the water for no more than 2 minutes before blacking out. It's about 70 seconds into the Sensus log when everything goes flat, which I'm guessing is the time when I slumped. The only apparent defect with the KISS is a free flow of the ADV - I'm guessing the (old Mk 1) valve was knocked by some rough handling when I was beached - this was categorically not present in the pre breathe or the 1st dive otherwise the PO2 wouldn't have been stable and the loop pressure would have been noticeable. Crucially, while underwater I didn't notice any constriction of the loop volume as you'd expect from having gas entering the loop, and a KISS diver was part of the resuss team and he also confirmed there were no gas leaks evident. Somehow I must've got dil (10/50) flooding my loop, failed to notice it, made the wrong decision when I did notice it (going for the DSV switch) and then went hypoxic - basically I failed to diagnose and manage an equipment malfunction. I haven't yet stripped the unit down to take a more detailed look at any of the components.

My current theory of what happened does however involve the ADV. I was in the water about 30 seconds before my buddy, and noticed what I thought were bubbles from my neck seal after it leaked on the 1st dive. I now think that my vertical position in the water with the ADV just below/breaking the surface may have caused the ADV to leak gas into the loop, with the bubbling coming from the OPV. Because there was already hydrostatic pressure on the loop from my in-water position I didn't notice the extra WOB, so was probably breathing neat 10/50 at this time and dropping my loop PO2. Once properly submerged the ADV got a more static load on the diaphragm and so behaved itself.

What about the display scan after the bubble check? Well, this would be around 60+ seconds into breathing a hypoxic mix - and crucially I can't remember the readings I saw. It's possible I was already confused and either mis read the displays or, since we were at 2 or 3m at this time I may have mis-read 0.13 as 0.3, or maybe I just looked at them as a reflex action and didn't take in what I saw - similar to those deep air days.

What about the HUD? Well, first off I knew it would be flashing red LEDs at me anyway as I hadn't tried to hit a set point yet, secondly we were in bright, shallow water so it wasn't particularly obvious and finally it was only my third dive with this so it wasn't an intuitive monitoring system. Basically it's so new to me that we can discount it as an effective warning system.

Whatever the cause, the bottom line is that complacency and laziness nearly got me killed. 10/50 is the wrong diluent to use at a site with a 35m max depth - I used it because I've only got 1 dil cylinder and it had 10/50 in it, and I was too lazy/tight to think about ditching that for air. 10/50 is one thing that will have to change if & when I get back to deep diving.

What next?

It took a while for events to really sink in - just how close I'd come to being another statistic or thread in the memorial forum - and now I'm realising just how really deeply it's affected me. Two days after the incident I was feeling tired, had a raging headache and was feeling disconnected from my legs so I did the sensible thing and called the duty diving doc in Portsmouth. We had a long chat where DCI was all but eliminated as a cause, with physical and mental shock were suggested but he did recommend a visit to my GP to get a full check up & eliminate other possible causes such as fits or a "heart attack".

My GP is currently talking to other specialists to see if we can organise tests to eliminate other causes, even though I now think they are tenuous possibilities at best. Mentally I've been totally preoccupied with this, and still have occasional bad moments where things trigger the wrong memories/thoughts. My GP is helping me sort this out too. A few days after the incident I tried to get into a 4m deep pool, just for a swim - I made it but it took 5 minutes of psyching myself up to get in, and I nearly walked away. The thought of being 30 miles offshore and leaping into 70m+ is just a non starter right now.

So why post this?

First off, to highlight how just a few seconds of complacency can kill. My OC breathing rate was around 6 breaths a minute, so we're talking no more than 12-15 breaths between a happy, well person on the surface and total blackout. I know what I should have done now, but hindsight is always 20/20.

Also to highlight that laziness in choosing a diluent, going for the easy 10/50 option, adds risk to any diving in shallow water. I'll have to have a rethink about how to approach dil selection and encourage anyone diving 10/50 to make sure their approach is squeaky clean.

Thirdly, to ask for help. If anyone was at Stoney that day and saw anything of my incident I would really like to hear their story - I'm keen to get as much information as possible about what happened. Also, I know there are other divers who have been through similarly unsettling incidents and have 'got back on the horse'. At the moment I don't even know how to start working out where I go from here, so any feedback from those guys would be really welcome.

And finally...

I obviously owe a massive debt to my buddy, plus the bystanders who brought down O2 and assisted with the rescue and also to the rescue crew from Stoney Cove. A public thank you to them, and thanks also to those who have been in touch so far and filled in their side of my story.

Cheers for now

Keith

Attached Images

Dive log.jpg (76.5 KB, 1222 views)

JOHNU

Glad your ok! Thanks for sharing.

John

dan140465

Hi Keith

Many thanks for sharing the details of your incident, very sobering reading, all the best.
Glad to hear you are gettin back on the horse.

Danny

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Same S**t different Day !

bgpartri

It's great to hear that you survived and thanks for sharing your incident.

When the Shearwater GF was in Beta testing, several users including Lynn complained that there was a bug. At the beginning of some dives they were getting a LOW PPO2 warning. I also assumed it was a bug, since of course they were starting the dive with a high ppo2. It was only after reviewing the logs that we discovered that it is not unusual for the ppo2 to drop quickly at the beginning of a dive on mCCRs.

The explanation we have come up with is this:
1) You start the dive with a .4 or .5 ppo2 and 10/50 in your tanks.
2) You exhale from the counterlungs to decrease your bouyancy and sink.
3) You hit the ADV and it fills your lungs with mostly 10/50.
4) In addition, you may be exerting a bit more then.

It's usually not a problem as long as you quickly get some depth. Once you're at even 3 meters, you've got a breathable ppo2 and the orifice can keep up.

But the GF was clearly reporting a ppo2 of less than .4 for at least 10 seconds.

I'm not trying to say that this is what happened to you, but it is something to be aware of with mCCRs.

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Good judgment comes from experience. Experience comes from bad judgment.

Mdemon

Thank you.

Glad you're still here.

Shaunzxr

I shouted for the Boat when your buddy shouted at me.
There was a lot of training going on at the slip at that time.
Every other person was doing some kind of rescue. The divers were at one minute simulating rescue then doing it for real.
I saw your face when you came up the slip, it wasn't looking good. I looked away then looked back and you were sat up and your face was nice and pink.
Phew!! I thought you were a gonner. Glad your OK
Shaun

Ferg3333

Thanks for taking the time to post your experience. I was there at stoney with my club doing training and saw the incident. I have nothing to add to your post as it is composed and well thought out and I wish you every luck in returning to diving your confidence has been knocked in the unit, but that will heal over time and you will ultimately be more cautious in future. All I can say is well done for confronting what has happened, and starting the slow process of returning to the water.

John Langley

Glad your OK.
I have been diving the KISS for about 2 years, and I nearly always dive with 10/50.
Very scary.

J.L.

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www.aqualanddivers.co.uk

www.oceandiving.co.uk


Thank your mother for the dripping.

PaulTG2

Hello,

Thank you for your posting. Postings like this help me learn and improve. Thank you!

In terms of rebuilding confidence after the event. I had a similar event in flying that caused me to examine if I would ever get in the cockpit again. With quite a bit of self examination and help from friends I not only continued to fly, but ended up with a wide variety of piloting experience.

One of the keys for continuing on for me was to change how I approached flying. I began taking a very serious approach to training -- shooting for proficiency and understand above just completing the testing process. I studied accidents for root causes, learned more of the reasons why behind what I did, and practiced to proficiency on a regular basis. I even questioned they "why" behind what I had been taught.

This, more intensely serious approach, helped me regain proficiency and make me a better pilot. The same approach has carried over into Rebreather diving to make me a safer diver.

It wasn't that I lacked a serious approach before, I just developed a professional and methodical approach after that helped me to feel confident.

Good luck on diving in the future. PM me if you ever need an ear to talk through what you're working on.


--Paul

Dave Crampton

I'm just really glad to hear your still here to tell us of your incident. It was a really enlightening read and has drilled home a fewpoints I need to keep in my mind about Rebreather diving.

Good luck peicing together the full account and I hope your able to move on from this. Good luck what ever you decide to do next.

Dave C