surface, the casualty's life jacket should be inflated, if not already done. When surfaced and buoyant, the casualty's mouthpiece should be removed if still in place, and in the case of a rebreather, the dive/surface valve should be switched to "surface" setting to prevent the loop from flooding and weighing down the casualty. The rescuer should signal for emergency pickup. (Recreational divers may not have this option.) he rescuer should check whether the casualty is breathing, and start rescue ventilation if necessary. If an upward excursion occurred during the actual convulsion, the casualty should be transported to the nearest available chamber and be evaluated by a person competent to recognize and treat diving-related illness. Thalmann further comments that the decision whether to ascend with a diver who is convulsing is tricky, and cites the US Navy Diving Manual again, specifically: If a diver convulses, the breathing apparatus should be immediately flushed with a gas of lower oxygen content, if possible. (This is only appropriate with rebreathers, full-face masks with more than one gas supply connected, or with surface supply.) If depth control is possible, and airway and gas supply is secure (helmet or full face mask), the diver's depth should be kept constant until the convulsion subsides. If an ascent takes place it should be done as slowly as possible. (To some extent this is incompatible with the need to get the victim to a place where treatment is possible.) If a diver surfaces unconscious because of an oxygen convulsion or to avoid drowning, the diver must be treated as if suffering from arterial gas embolism. Thalmann further commented that a full face mask is desirable for use with high oxygen mixes, as it allows the diver to be kept at depth until the convulsion subsides, and that a diver who loses the mouthpiece must be surfaced as they will try to take a breath when the convulsion stops, and on open circuit, that as long as the diver has the mouthpiece in place and is breathing, it should be left until the diver can be removed from the water, but should be removed on the surface if rescue breathing is necessary and possible. Furthermore, the main goal while the diver is in the water is to prevent drowning, and secondarily ensure that the airway is open after the convulsion stops by keeping the neck extended. 2012 UHMS recommendations The