These symptoms may include difficulty breathing, confusion, lowered alertness, a change in the level of consciousness, unclear thinking, visual problems, paralysis, and chest pain.

Keep airway open and check for breathing. If necessary, start and continue rescue breathing and/or CPR.Observe the diver constantly, checking breathing and pulse.If the diver doesn't require CPR or rescue breathing, keep the diver lying level on the left side supporting the head (called the recovery position). Don't let this position interfere with transportation or other aid, and should not be used :CPR is required. If the diver is responsive and more comfortable lying prone, that's fine.

Administer emergency oxygen if possible.
Keep the diver still and maintain a normal body temperature by protecting the diver from heat or cold.Seek emergency medical assistance.If unable to accompany the diver to medical treatment, write down as much background information as possible and attach it to a conspicuous place.