Can O2 hits reoccur on a dive

[scuubaadoo]

Got to talking with a diving buddy and this question came up. If you are wearing a FFM , have an O2 hit and it passes, do you have to cut some time off ascent to get to the surface quickly b4 it happens again or now that you've had your hit are you "tolerant" and can take your time coming to the surface. Side question are so "tolerant" because you have already had any hit your going to get, that you can continue to dive.

Thanks

 

[TeddyDiver]

What the **** you have in your tanks? If it's O2, there's no Nitrogen loading so feel free to ascend, and while ascending the PO2 will decrease, and the danger of new O2 hit dissappears. You don't become immune to a new hit bcs there's no excact exposure strength/time/factor to rely on. It just hits more or less randomly.
Ascend during a hit may cause lung overexpansion and serious embolia.
Why would you exceed PO2 limits?

 

[Charlie99]

Yes, a diver may convulse again.

Somewhere I saw a description of an oxtox incident (a student in a GUE Tech 1 class, I believe) where the diver convulsed both at depth on an untested, excessively high FO2 gas; and then convulsed again during the ascent, even after being put on the lower FO2 backgas of the instructor.

Convulsions don't kill you provided you keep breathing gas rather than inhaling water and you aren't ascending while having the airway closed by convulsions.

 

[Charlie99]

Why would you exceed PO2 limits?

Usually through a dumb error: 1. Not properly analyzing gas, or 2. breathing the wrong tank -- i.e. deco bottle at depth.

The GUE incident was caused by not analyzing the backgas. In several other accident reports the conclusion was that oxtox was brought on by inadvertently breathing a rich deco mix while at depth.

 

[pipedope]

An O2 tox is an emergency and the dive is OVER!
Then the question becomes, how long does it take to get to the surface SAFELY?
If there is significant deco obligation then the diver should do the deco that is required.

Someone must supervise the diver continuously on the way up for any other problems.

 

[Thalassamania]

Oh gee ... we can continue the dive as soon as I stop twit, twit, twitch, twitch, twitching ... ah ... that's it, now were was I.

What the F!?

 

[rawls]

Oh gee ... we can continue the dive as soon as I stop twit, twit, twitch, twitch, twitching ... ah ... that's it, now were was I.

What the F!?

 

[scuubaadoo]

To those that just want to unload testosterone, I asked a question to learn. If you don't know what the mechanism is, don't posture. how does O2 hit work, READ the details I specificly said FULL FACE MASK. so drowning is not the question. this is why I don't come here to often anymore. all chest puffing little info

 

[Diving Doc]

To those that just want to unload testosterone, I asked a question to learn. If you don't know what the mechanism is, don't posture. how does O2 hit work, READ the details I specificly said FULL FACE MASK. so drowning is not the question. this is why I don't come here to often anymore. all chest puffing little info

In short scuby, O2 tox is a factor of partial preassure (pp) of oxygen at depth. Depending on which agency you are with, there is a limit to your exposure. With PADI normal recreation al diving is 1.4. that is when you reach 1.2 pp PADI say that you are at an unacceptable risk of o2 tox.

If you have a hit, the fact that you have had a hit does not give you more tolerance, in fact i would say quite the reverse and to continue to dive would be extremely dangerous.

As you ascend, the 02 pp should be decreasing, therefore a normal ascent with the necessary obligations should be carried out if it can be done safely...buddies should be extremely aware of each other in this case.

Am i right in assuming that you have not done a nitrox course? If so, i would strongly recommend that you get onto one asap!

I hope this helps, but if you feel that you need some more info, please feel free to pm/email me. I think the phone bill from over there might be a bit much.

 

[ianr33]

An O2 seizure is the bodys mechanism to stop the input of more damaging oxygen.Stop breathing for a while and you cut off the oxygen supply.
A seizure indicates that the body has reached its limit.When breathing resumes after a few minutes I would imagine that you are still very close to that limit. (Backed off a little but still very close) If the PO2 is not immediately reduced the chance of seizing again will be very high. IMHO