In case of an O2 convulsion, what procedure should be followed first?

In the event of an O2 convulsion, shifting both divers to air is the most appropriate initial action. This is essential because the primary concern during an oxygen convulsion is to break the cycle of hyperoxia, which can exacerbate the convulsions and lead to further complications. By transitioning to air, the partial pressure of oxygen is significantly reduced, which helps to mitigate the risk of additional convulsions and promotes recovery.

Once the divers are on air, other critical measures can then be taken, such as administering proper medical assistance and managing ascent if necessary. It is also vital to ensure that the affected diver is stabilized, but this should not take precedence over the necessity of transitioning them to air to avoid further complications related to oxygen toxicity.