In the UK it is likely that paramedics and the ambulance service will administer Entonox gas as a pain relief.
Entonox - which is also known as 'gas and air' or laughing gas - is a 50:50 mix of Oygen and Nitrous Oxide. It is an anaesthetic gas, used for emergency on-site pain relief. However it should never be administered to a scuba / rebreather diver within 24 hours of surfacing.
Why is the administration of Entonox not advised during this 24 hour window? It is possible that that the use of Entonox gas can bring on Decompression Sickness because it increases the divers inert gas load. It could also cause gas in the body (middle ear, sinuses etc) to expand.
Divers by their very nature travel. It is quite possible to have a car accident on the way home after a dive, or at work, play or any other time within 24 hours of diving. It is also quite possible that the diver may not always be conscious or lucid following the accident. Therefore wearing something to alert paramedics that "NO ENTONOX" should be administered is useful. It helps to eliminate all doubt and helps keep the diver safe.
MV Valhalla - the Scapa Flow based liveboard - has kindly donated 400 of these bracelets to EUROTEK. The first 400 delegates that book a EUROTEK.2016 weekend delegate pass (Saturday 8th and Sunday 9th October 2016) will receive one of these in their Blancpain Fourth Element goodie bag.