b'Underwater Diving AccidentsChapter(Refer to page 60)Provide as near to 100% oxygen as possible.Entonox (50% nitrous oxide gas in oxygen) must NOT be used in diving emergencies.Note: A flat (horizontal) posture without leg elevation is recommended in injured divers who have impaired consciousness or rapid-onset neurological symptoms or signs, to prevent any gas bubbles in the blood stream (gas emboli) from going to the brain.Administration of 100% oxygen reduces the size and number of gas bubbles in the bloodstream and tissues.252 Underwater Diving Emergencies'