Let us first begin by knowing what exactly is hyperbaric oxygen treatment. Hyperbaric oxygen therapy involves inhaling 100% oxygen at greater than one atmosphere absolute (ATA) in a pressurized chamber. The air we breathe at sea level is defined as 1 ATA.
Many of the clinical uses of hyperbaric treatments conducted in fixed or portable hyperbaric chambers have been at pressures above 1.5 ATA. However, recently, some researchers have been using lower pressures of hyperbaric oxygen therapy with good results in some conditions. The abbreviation conventionally used for hyperbaric oxygen therapy is HBOT.
What actually happens in a portable hyperbaric chamber –
HBOT increases the amount of oxygen that is carried in the plasma. Typically, hemoglobin which circulates in the blood stream carries almost all of the oxygen in our body to tissues.
Only 0.3% of oxygen is dissolved in the plasma which is the fluid in our blood vessels not counting the red cells, white cells and platelets. Hemoglobin is normally 97% saturated or full of oxygen.
However, with HBOT, the amount of oxygen that is dissolved into the plasma can increase many fold. In fact, some animal studies have shown that hyperbaric oxygen treatment can keep an animal alive without circulating red blood cells. There is an old paper called “Life without blood” that studied this in a pig. Therefore, in conditions where hypoxia (or decreased amount of oxygen) is present, such as with decreased blood flow, we would expect HBOT to help overcome this problem.
Interestingly, HBOT causes vasoconstriction of blood vessels which actually causes decreased blood flow. However, because it increases the amount of oxygen in plasma so much, the overall result is increased oxygen delivery to tissue. Because it causes decreased blood flow, hyperbaric oxygen treatment decreases swelling, including swelling in the brain, after injury or ischemia.
One of the properties of HBOT that is rarely discussed is the anti-inflammatory effect of HBOT. Several animal studies have revealed that Hyperbaric oxygen therapy has potent anti-inflammatory tissue effects with equivalence to diclofenac 20 mg/kg noted in one study using HBOT at 2.4 ATA and 100% oxygen.
Hyperbaric oxygen treatment usually conducted in a a portable hyperbaric chamber has also been shown to decrease markers of inflammation including IL-1, IL-6 and TNF-á in humans. So we get decreased blood flow, increased oxygenation, decreased swelling and decreased inflammation, all from one treatment.