Hyperbaric chambers are any number of enclosures, which can be pressurized to allow a person inside to experience higher atmospheric pressures than the normal environmental pressures. For example, a treatment at an elevation of 12,000 feet above sea level using a 4 psi (1.27 ATA) can simulate a decent of ~5,843 feet to 6,157 feet above sea level.
At higher elevations, the barometric pressure is lower. This decrease of pressure also decreases the oxygenation of blood, and is known as anoxia—where molecules of oxygen exert less pressure on the walls of the alveoli (Dalton’s Law).
How does hyperbaric therapy work?
Hyperbaria – Increased atmospheric pressure as a means of increasing
oxygen uptake without an enriched oxygen source
Hyperoxia – Increased total oxygen content
Hyperbaria is based on the concept of the relationship of gas pressure and uptake in liquids (blood, plasma and tissues). Henry’s Law states that “a gas is dissolved by a liquid in direct proportion to its partial pressure.” For example, at sea level, atmospheric pressure is 760 mm Hg, the oxygen concentration is 21% and the body’s oxygen content or partial pressure, pO2, in blood and plasma is ~ 40 mm Hg.
Red blood cells have a limitation as to how much oxygen can bind with hemoglobin. The plasma portion of the blood typically has about a 3% oxygen concentration.
By placing someone in a in a 3 psi pressure hyperbaric environment, the increase in atmospheric pressure at sea level goes from 760 mm Hg to 915 mm Hg. This increase in gas pressure, increases the partial pressure of the oxygen gas and thus forces more oxygen to be dissolved in the plasma. This saturation of oxygen in the blood, due to the Hyperbaric Oxygen Treatment or HBOT, allows the extra oxygen to be diffused or transported to the surrounding body tissues. Thus, oxygen transport by plasma is significantly increased under HBOT. At three atmospheres pressure, enough oxygen can be dissolved in the plasma to support the oxygen demands of the body at rest in the absence of hemoglobin!
Source – Oxyhealth.com