Convulsions...

[rabe]

Working to avoid oxygen toxicity is a much better use of your time then trying to mitigate the consequences of oxygen toxicity.

You’re probably not going to survive if you tox in the water.

absolutely right

 

[Neilwood]

From my history as a first aider (and also having my father with epilepsy), if an Ox Tox convulsion is anything similar, then I seriously doubt if any mechanical device (short of a FFM) would help prevent ingestion of water. Even with another diver holding the mouthpiece in or use of a gag strap I would suspect would be of little use.

As @PfcAJ suggests, better to plan & work to avoid it than mitigate it.