A Nasty incident

[The Iceni]

Fresh water drowning;- all caused by osmosis.

Instead of air, low osmotic pressure fresh water finds its way into the alveoli. Since the osmotic pressure of water is infinitely less than that of the plasma there is a mass transfer of water from the alveoli into the pulmonary vascular bed. This, of course dilutes the arterial blood.

This subsequently results in mass transfer of fluid from the (diluted) plasma into all muscle and connective tissue cells and interstitium, resulting in swelling of these cell types; seen as oedema.

One of the affected cell types is the erythrocytes, which swell and burst due to the stretching of their cell walls to accomodate the greatly increased volume within the cells; haemolysis. This releases haemoglobin molecules into simple solution. Anaemia and asphyxia results . In addition these molecules clog the filter mechanism in the glomerulus of the kidneys; which are no longer able to function.

Waterlogging of the lungs can be relatively easily reversed and the lungs often recover (dry lungs).

Cerebral odoema also occurs with the risk of brain damage and fatal "coning".

Compare this with salt water drowning.

Sea water is about three times the concentration of plasma. Thus the osmotic pressure is the reverse of that seen in fresh water. This has two effects. Fistly if even a small ammount of sea water reaches the alveoli they become filled with a blood-stained foam, from the plasma, which "smothers" gaseous exchange.

Secondly, high osmotic pressure salt water causes the denaturing of surfactant which is required to keep the lungs inflated. The lungs deflate and acute lung injury results (formally known as adult respiratory distress syndrome). The is very difficult to treat and death is due to asphyxia.

Before the dive my renal function was fine, as it is now. I agree that electrolyte disturbance is a feature of chronic renal failure and potassium concentrations, in particular, can be associated with cardiac arrythmias and LOC but not in my case!

I have written this from memory, so it may be incomplete. However, as I understand it the treatment of fresh water near drowning is more successful than salt-water near-drowning.

Regards,

 

[bwerb]

my wife and I both have to slap our foreheads and say "doh!...freshwater, not saltwater." Now it makes sense. We couldn't figure out how the renal necrosis came about as a function of near drowning. Thanks for your insight.

 

[Alban]

Good to see your back Dr T you have been missed


Yours Alban

 

[Peat Bogg]

Dr Paul

I have read about your accident and it is a scary thing to hear about. I am happy you are recovering and regaining your strength.

With lots of respect and I'll pray for your continued recovery.
Also the decision to hang up your fins is the right one. A lot of times we forget about our loved ones we would leave behind if we don't come back from a dive.

Peter T.
:scatter:

 

[bluebanded goby]

Dr. Paul, owing to the fact that I'm not a daily visitor to the board I've only now seen your post about your nasty incident. I'm sure I echo many others when I tell you what a great help your information has always been for me over the past couple of years. We are very fortunate that you made it through the ordeal.

I might mention as someone who swore off scuba for a year and a half following a pair of chamber visits until I got a neuropathy problem sorted out, freediving is a great alternative. Although most freedivers hereabouts are sport spearfishers, I've specialized more in underwater photography and had a lot of fun with it. I tend to stay shallower than about 25 feet and make relatively short dives, and thus medical risks such as shallow water blackout are negligible. I've enjoyed it so much, in fact, that although I'm currently working gradually back into conservative scuba, I expect that the majority of my diving will continue to be breathhold. Just a thought as an alternative to totally abandoning underwater exploration.

The only other possibly helpful thought I might offer is that I've often seen critical events like this in my life and the lives of friends lead to interesting turning-points (as the saying from de Rojas's "La Celestina" goes, "When one door closes, fortune will usually open another"). I certainly hope that wherever this takes you will be rewarding in the end.

 

[The Iceni]

I recently collected my kit from the police.

My 7-litre twinset was empty, but was labelled (by me prior to the dive) as containing 32.6% Nitrox consistent with the blender log and 32% on the dive computer (not the 34 % I latterly believed) and the 7-litre stage cylinder was full. On the main contents gauge was attached a note stating that it was faulty. Indeed it was reading 40 bar although not connected to any cylinder.

The immediate implication was that I had "run out of gas" due to the gauge during the dive. However I do not believe this was the case, even if the gauge was faulty. I will explain why below.* In addition I am certain I would have remembered that!

Of course, one of the first things I did when I got home was to download my dive profiles for that day. These confirmed all that I remembered. The first dive was to a maximum of 22 metres (on the Stanegarth) with the first 14 minutes spent at 6 metres. Towards the end of bottom-time was a blip when I swapped masks and there was a short "stop" seen at 14 metres on the ascent, when I released the SMB followed by a 1 minute safety stop at 6 metres. We surfaced after a total run time of 48 minutes (a no-deco dive for me).

My content's gauge at the end of that dive read 130 bar, which is entirely consistent with my average RMV at about 17 litres per minute. I was a little surprised to seen the water temperature was 12 degrees.

I thought it was much colder.

The plan for the second dive (after 1 hour 55 mins surface interval) was, again, to stay about 20 metres maximum and me to practice CBL on ascent with a buddy who had, in fact, recently completed his diver rescue course.

With 130 bar in a 14 litre twinset I had sufficient gas for an absolute, rock-bottom, total of about 30 minutes at that depth with that RMV. (14 x 130 = 1,820 litres. At 3 bar RMV = 18 x 3 = 54 l/min. 1,820/54 = 33 mins). My relative novice buddy was using a 12 litre 232 bar single of air for the second dive ( ~ 2,784 litres) but his RMV was greater than mine at about 25 l/min. In any case the plan was to ascend well before either of us reached 50 bar and well before my buddy, diving air, had clocked-up any deco obligation. He would have been limited to under 20 or so minutes run time for the second dive so we had planned that.

The profile of the second dive is very interesting. I descended to 22 meters and stayed at approximately that depth for a run time of 17 minutes and then we started the ascent. This appeared to accelerate at 17 M (I suspect this is when we commenced the practice CBL) but at 12 M (18 mins run-time) I am seen simply to drop rapidly back to the bottom at twenty metres (67 feet) and I stayed there until RT 32 minutes. At this point I am seen to make a rapid and apparently buoyant, ascent. Clearly I was on the bottom, unconscious, for 14 whole minutes!!! (No deco obligation, thank goodness!)

My intact survival was a genuine miracle.

*If I had run out of air at that 18-minute point my RMV for the second dive would have been in excess of 35 l/min, well above my average. I do not think I can have run out of gas, however it does, I admit, remain a possibility with an apparently faulty gauge. However, I think it more likely that my regulator free-flowed after I lost consciousness, and this is consistent with the excess bubbles witnessed by those on the surface. As for the faulty contents gauge, several items of my equipment were damaged during the rescue (including my HID lamp) and the gauge most certainly did not register 40 bar when I originally attached the regulator prior to the dive! As I remember starting the CBL I am sure I would have remembered if I had simply run out of gas.

The cause of the accident remains a mystery but I look forward to seeing my buddy, Chris's profile.

(I have now attached a printout of the index dive profile)

 

[Dryglove]

Dr Paul Thomas once bubbled...
I recently collected my kit from the police.

My 7-litre twinset was empty, but was labelled (by me prior to the dive) as containing 32.6% Nitrox consistent with the blender log and 32% on the dive computer (not the 34 % I latterly believed) and the 7-litre stage cylinder was full. On the main contents gauge was attached a note stating that it was faulty. Indeed it was reading 40 bar although not connected to any cylinder.

The immediate implication was that I had "run out of gas" due to the gauge during the dive. However I do not believe this was the case, even if the gauge was faulty. I will explain why below.* In addition I am certain I would have remembered that!

Of course, one of the first things I did when I got home was to download my dive profiles for that day. These confirmed all that I remembered. The first dive was to a maximum of 22 metres (on the Stanegarth) with the first 14 minutes spent at 6 metres. Towards the end of bottom-time was a blip when I swapped masks and there was a short "stop" seen at 14 metres on the ascent, when I released the SMB followed by a 1 minute safety stop at 6 metres. We surfaced after a total run time of 48 minutes (a no-deco dive for me).

My content's gauge at the end of that dive read 130 bar, which is entirely consistent with my average RMV at about 17 litres per minute. I was a little surprised to seen the water temperature was 12 degrees.

I thought it was much colder.

The plan for the second dive (after 1 hour 55 mins surface interval) was, again, to stay about 20 metres maximum and me to practice CBL on ascent with a buddy who had, in fact, recently completed his diver rescue course.

With 130 bar in a 14 litre twinset I had sufficient gas for an absolute, rock-bottom, total of about 30 minutes at that depth with that RMV. (14 x 130 = 1,820 litres. At 3 bar RMV = 18 x 3 = 54 l/min. 1,820/54 = 33 mins). My relative novice buddy was using a 12 litre 232 bar single of air for the second dive ( ~ 2,784 litres) but his RMV was greater than mine at about 25 l/min. In any case the plan was to ascend well before either of us reached 50 bar and well before my buddy, diving air, had clocked-up any deco obligation. He would have been limited to under 20 or so minutes run time for the second dive so we had planned that.

The profile of the second dive is very interesting. I descended to 22 meters and stayed at approximately that depth for a run time of 17 minutes and then we started the ascent. This appeared to accelerate at 17 M (I suspect this is when we commenced the practice CBL) but at 12 M (18 mins run-time) I am seen simply to drop rapidly back to the bottom at twenty metres (67 feet) and I stayed there until RT 32 minutes. At this point I am seen to make a rapid and apparently buoyant, ascent. Clearly I was on the bottom, unconscious, for 14 whole minutes!!! (No deco obligation, thank goodness!)

My intact survival was a genuine miracle.

*If I had run out of air at that 18-minute point my RMV for the second dive would have been in excess of 35 l/min, well above my average. I do not think I can have run out of gas, however it does, I admit, remain a possibility with an apparently faulty gauge. However, I think it more likely that my regulator free-flowed after I lost consciousness, and this is consistent with the excess bubbles witnessed by those on the surface. As for the faulty contents gauge, several items of my equipment were damaged during the rescue (including my HID lamp) and the gauge most certainly did not register 40 bar when I originally attached the regulator prior to the dive! As I remember starting the CBL I am sure I would have remembered if I had simply run out of gas.

The cause of the accident remains a mystery but I look forward to seeing my buddy, Chris's profile.

(I have tried to attach a printout of my profiles but, even zipped, the file is too big. I am trying to rteduce it's size. Ignore the current attachment! If you want to see them PM me with you email address)

Thanks for keeping us up to date on your findings.I find all this very interesting.Once again i am so glad you survived this incident.It gives me the chills reading about it sometimes.

 

[Saturation]

Hello Dr. Thomas:

Thanks for posting and analyzing your gear for us. It reads like for the most part, your gear is unlikely a major contributor to the accident and there was no gas switch between your stage cylinder and your back gas.

If you don't mind, did you have a CT or MRI done?
Are you neurologically without even trace focal lateralizing signs?

Looking at CAGE as a possibility as despite its low probability, oxtox appears even lower.

Best wishes,

Marv

 

[The Iceni]

gozumm once bubbled...
did you have a CT or MRI done?

Yes indeed, on about day six, but sadly I cannot give too much detail publicly for obvious reasons, do feel free to send me a private message.

Larry Stein has suggested carotid sinus compression as a possible cause.

I have to admit I did not get away entirely scot-free but I will be fit to return to work at the end of the month.

 

[Saturation]

Dr Paul Thomas once bubbled...

Yes indeed, on about day six...

Larry Stein has suggested carotid sinus compression as a possible cause....

Thanks for the reply Dr. Thomas, will do so.

I guess Dr. Stein is looking at causes of in-water syncope.

BTW: Does the HSE also analyze the quality of your gas?