Hyperbaric Oxygen Therapy (HBOT) combines increased atmospheric pressure with increased inspired oxygen to drive more oxygen into circulation. Typically oxygen is carried on red blood cells. While in a hyperbaric chamber under increased atmospheric pressure, oxygen is also infused into the blood plasma or liquid of the blood. With more oxygen in circulation, our oxygen-carrying capacity increases dramatically. The benefits of HBOT are due both to this acute infusion of oxygen, the pressure on the body, and the changes in the expression of various genes, at least 8000 of them, during a more extended hyperbaric protocol. The genes modulated by oxygen help decrease inflammation, create more blood vessels, and prevent cells from dying (apoptosis).
Inside a hyperbaric chamber, we simulate the pressure you feel under a certain amount of seawater. It is this pressure that drives supra-physiologic levels of oxygen into circulation due to Henry's Law, a physics law which states that the more pressure put on the gas (in this case, oxygen), the more of that gas that goes from a gaseous form to a liquid form. Typically oxygen is carried on red blood cells but when there is pressure, oxygen can diffuse directly into the plasma of the liquid of our bloodstream in huge amounts, up to 12 times what's possible just on red blood cells. This is the key to HBOT. Without pressure, there would be no oxygen super saturation. This is why a face mask of oxygen is not the same as HBOT.