Hypoxia

[rbdave]

Has anybody on the list experienced Hypoxia on their units and been able to react in time?

Cheers

Dave

 

[saturated]

I've experienced it in a chamber under controlled conditions. My experience was that I had no physical symptoms prior to black-out. Scary stuff.

 

[jepuskar]

You see, just another reason to justify to use PO2 monitors. I know a couple people on this board alone who will refuse to dive a rebreather without one.......and because of that, they have a good chance of being around for awhile.

I also heard that hypercapnia sneaks up on you too. The lack of CO2 sensors for rebreather divers really aggravates me. I have been in contact with several manufacturers of CO2 sensors, but I think they are just not capable. I dont quite understand this yet, but damn...this can be solved.

 

[rbdave]

I agree with the comments about all units should have ppo2 sensors. I now dive an inspiration which is great.

However before this unit I used to dive a homebuilt which initially did not have ppo2 monitoring. It relied on me counting my breathes. Which brings me to the reason for my post. I experienced the effects of low O2 and it is noticable prior to blackout.

There is a general sense of well being and a mental slowing. I doubt that I would have recognized it but because I was counting my breaths it became apparent. I reacted instantly grabbing my OC but as I did my feild of vision collapsed to tunnel and then nothing. I had spat the loop but not quite got the reg in when this happened. I was on deco at 3 metres at the time and had made 2 quick kicks toward the surface. The last kick I made had no power but it was enough to get me to the surface at which point my vision instantly returned. I had gotten my oc in my mouth but spat this upon reaching the surface. I was diving solo at the time so would certainly have drowned.

I personally find Hypoxia way more scary than hyperoxia but there is a very small window in which to react.

Perhaps this post will help someone to react at that critical time.

I hope that none of you are ever there as I suspect most cases probably end in fatalities.

Cheers

Dave

 

[The Iceni]

rbdave once bubbled...
Has anybody on the list experienced Hypoxia on their units and been able to react in time?

Hi Dave,

It is generally accepted that you will have very little warning of impending hypoxia and simply lose consciousness within milliseconds of vision dimming - if that is experienced. You were VERY lucky. Do you know why you suffered dilution hypoxia? Was it a failure of both injectors?

Ever tried to stop yourself from fainting? It is a similar situation.

I would not recommend this; but when we were children we experimented with hyperventilation followed by breath-holding sitting on the edge of our bed. Unconsciousness resulted every time!

We lost consciousness due to the reduction in oxygen before the carbon dioxide level rose sufficiently to produce the reflex urge to breath. This is because the prior hyperventilation flushed out all the CO2.

Free-divers??????

 

[fins wake]

I also heard that hypercapnia sneaks up on you too. The lack of CO2 sensors for rebreather divers really aggravates me. I have been in contact with several manufacturers of CO2 sensors, but I think they are just not capable. I dont quite understand this yet, but damn...this can be solved.

As several people on this board have indicated, CO2 sensors are being developed by APD for the Inspiration and seem to exist for the elusive Infinito.

But let's not kid ourselves!

Even if functional and reasonably cheap CO2 sensors are developed - and it's a much more difficult issue than first meets the eye - it's just another set of sensors to evaluate carefully under water. Are they working? Are they out of line? etc.

Today's solution is to carefully follow manufacturer guidelines and not exceed them! I strongly suspect that will be standard operating procedure even if CO2 monitoring is successfully implemented.

In fact, I could envisage problems if people run their scrubbers way beyond guidelines and then, in the middle of a deco dive at 50 metres suddenly get a 15 minute breakthrough warning with a 40 minute deco obligation ...

Sorb is cheaper than your life. Just switch it when it should be switched and you'll be fine.

 

[Mverick]

Dr Paul Thomas once bubbled...

I would not recommend this; but when we were children we experimented with hyperventilation followed by breath-holding sitting on the edge of our bed. Unconsciousness resulted every time!

We lost consciousness due to the reduction in oxygen before the carbon dioxide level rose sufficiently to produce the reflex urge to breath. This is because the prior hyperventilation flushed out all the CO2.

We used to do this as kids. In a little different way.

Bend over a little and start taking deep breaths flushing the lungs. Quickly. Hyperventilating.

Take a last deep breath, hold it and stand up.

Have a friend that's behind, wrap his arms around you like a bear hug and lift you off the ground. While you tilt your head back.

Within a short time you'll faint. 20 to 30 seconds if I remember right.

Friend gently sets you onto the ground.

Little different way's of coming back. Some people convulse. Some just wake up.

Feels like you fell asleep. Lots of time you remember a small dream that happened during the time you were out.

Once you start to faint though. You go fast....... I would say you notice the world closing in and wham you're out.

Let's you know how fast it is by trying it.

You'd think as kids we would have something better to do.

That's one thing that kinda freaked me out about free diving. Same ritual at the surface. Difference being nobody lifting you off the ground with pressure to your lungs.

 

[caveseeker7]

... Dave,
solo diving a RB and doing so without pO2 monitoring, that's a double whammy. Your guardian angel must have callusses.

fins wake once bubbled...
Sorb is cheaper than your life.

Wise words.

 

[saturated]

You were extremley lucky,

Everyones physiology is different, when I did the chamber tests some individuals did notice "the tunnel effect". But the majority of us just blacked out with no precursors. The only way to survive hypoxia is to know your ppo2. Flying blind is a good way to become a statistic. The golden rule, Know your po2.

 

[jepuskar]

That is a neat little experiment to try..although im not going to.


Although, I wouldnt mind going for a chamber ride one of these days.

In fact, my local hospital has a chamber..I wonder if I could go for a ride...hmmmmmm

Time to bring the video camera.