Introductory Chapter: Hyperbaric Oxygen Treatment: Old Treatment with New Understanding

Hyperbaric oxygen treatment (HBO2) is a widely accepted adjuvant therapy in various health conditions that exhibit impaired tissue blood flow. At high pressures, the delivery of the dissolved oxygen in plasma is enhanced, which contributes to better tissue oxygenation, cellular metabolism and ultimately, healing. However, this is not the only potential mechanism for improved outcome of many diseases treated with HBO2, since oxygen is highly reactive molecule and can induce upregulation of many various enzymatic systems in the cell, at cellular, genetic and molecular level. Particularly, vascular/endothelial function is affected by the HBO2. Our understanding of these mechanisms of the HBO2 effects is still emerging. There have been many controversies related to the HBO2 protocols and indications. It is known that, as well as HBO2 exhibit beneficiary effects on the tissue perfusion, it demonstrates high toxicity at higher pressures, due to increased oxidative stress and barotrauma. On the other hand, there is still a lack of the translation of the knowledge on the mechanisms of action of HBO2 obtained from the experimental research to the clinical practice.