1 - Volume - You need enough fluid in a closed system to maintain pressure to push that fluid.

2. Oxygen carrying capacity - Oxygen binds with red blood cells which then deliver it to every cell in your body.

Right now the prehospital setting can more or less manage #1, we have been for a century with Normal Saline.

There is some stuff circulating (pun intended) regarding fluids that can transport oxygen but it will be years before we can use it