Oxygen First Aid

Administering high-concentration oxygen to an injured diver, the standard first response to suspected decompression sickness or gas embolism.

Oxygen first aid is the immediate treatment for a diver with suspected decompression illness: the injured diver breathes the highest possible concentration of oxygen, ideally 100 percent, while emergency help is organized. Breathing pure oxygen at the surface steepens the gradient that drives inert gas out of the tissues and shrinks bubbles by replacing nitrogen with a gas the body consumes, while also improving oxygen delivery to tissues that bubbles have starved of blood flow.

Delivery matters: a demand valve or a non-rebreather mask with an adequate flow rate gives far higher concentrations than a simple mask. Oxygen should be started as early as possible and continued until professionals take over, even if symptoms fade, because improvement on oxygen does not mean the injury is resolved. Alongside oxygen, keep the diver lying down, protect from heat or cold, encourage fluids if fully conscious, and call DAN or local emergency services.

Dedicated courses from DAN and the training agencies teach oxygen provider skills in half a day, and dive boats in most regions are expected to carry an oxygen kit. Knowing where the kit is stowed belongs in every dive briefing. The kit itself needs care: cylinders require periodic testing, and a kit that was never checked has a way of being empty when needed.