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HBO has a DNA-damaging and possibly mutagenic potential. In vitro studies with mammalian cells suggest that HBO-induced oxidative DNA damage mainly leads to gross genetic alterations and chromosome aberrations. Under therapeutic exposure conditions, DNA damage is detected with the comet assay, but mutations and chromosome aberrations are not observed in peripheral blood cells. A very simple and efficient way to avoid HBO-induced DNA damage is to start with a shortened treatment before the standard protocol is applied the following days. Therefore, the hyperbaric community should think about an adaptation of the commonly used treatment protocols [ABSTRACT FROM AUTHOR]

The value of hyperbaric oxygenation has been well established in the treatment of hypoxic and ischemic wounds in which local oxygen tensions are below optimal for healing. The greatest benefit of hyperbaric oxygen therapy is achieved in situations where the nutritive flow and oxygen supply to the repair tissue are compromised by local injury or infection, but in which the regional vascular network, a prerequisite for oxygen to reach tissues is intact or only partly damaged. On the other hand, hyperbaric oxygen seems to possess significant angiogenic potential in tissues suffering from chronic lack of oxygen due to defective vasculature. During wound healing the presence of oxygen takes on additional importance because of the increased demand of reparative processes like cell proliferation and synthesis of collagen. In addition, superoxide generation by polymorphonuclear leukocytes, which is essential for bacterial killing, is critically dependent on tissue oxygen levels. Ischemic soft tissues also benefit from hyperoxygenation through improved preservation of energy metabolism and reduction of edema. It may be generally stated, that any treatment that augments the oxygen supply or avoids hypoperfusion of the wound tissue tends to increase the rate of healing and decrease the susceptibility to infection [ABSTRACT FROM AUTHOR]

Reperfusion injury is a complex but clinically well-defined entity although its complete mechanism is not entirely elucidated yet. The re-oxygenation phase is characterized by vasoconstriction, platelet and polymorphonuclear leukocytes activation, and release of mediators and the production of free radicals. The goals of the available therapeutic approaches are to oppose directly the consequences of re-oxygenation following the ischemic phase. Clinical and research evidence demonstrated that hyperbaric oxygen could be effective to reduce or stop ischemia-reperfusion related injury. Although many unanswered questions remain and the effects of hyperbaric oxygen seem paradoxical at first glance, the supportive literature is growing [ABSTRACT FROM AUTHOR]

Physiologic effects of hyperbaric oxygen on microorganisms and host defence mechanisms against infection fall into three categories: a direct action on anaerobic bacteriaan indirect action on the microbicidal capability of polymorphonucleocytes and macrophages by raising or restoring normal oxygen pressure within the infected areas.an enhancement of the antimicrobial activity of some antibiotics. These actions have been proven both in vitro and in animal studies and are the basis of the use of HBO in selected infectious processes. [ABSTRACT FROM AUTHOR]

Hyperbaric oxygen (HBO) in the pressure range used for therapeutic purposes induces haemodynamic changes both at the macro- and micro circulatory levels. In normal subjects, systemic haemodynamic changes mainly concern the heart rate (an effect related to both the barometric and the oxygen pressures). Arterial blood pressure tends to increase slightly. Cardiac output is maintained or moderately decreased due to compensating responses which may fail in patients with pre-existing cardiac failure. At the microcirculatory level, HBO causes vasoconstriction with a decrease in microcirculatory blood flow but with no decrease of oxygen pressure in the tissues. This hyperoxic vasoconstriction does not appear in previously hypoxic areas where the microcirculatory blood flow remains unchanged. Consequently, oxygen pressure in the tissues increase to levels close to normal. The reappearance of cyclic vasomotion seems to indicate an improvement in the local metabolic condition. The haemodynamic and microcirculatory effects of HBO appear to be effective in compensating ischemic conditions, particularly in cases of heterogeneous microcirculatory hypoperfusion [ABSTRACT FROM AUTHOR]

The mechanisms of oxygen transport, the relationship between oxygen delivery and consumption and determinants of tissue oxygen tension are considered with a brief introduction to the measurement techniques currently available in the clinical setting. An overview of clinical research from the last decade to the present is given with regard to the various organs. Evaluating the effects of hyperoxia at the tissue and cellular level as well as monitoring and titration of oxygen dose will be a challenging field of research in the future [ABSTRACT FROM AUTHOR]

Increased pressure has no effect on solid parts of the body or fluids, but it does on gas filled cavities. Pressure effects directly on the middle ear and indirectly effects on the inner ear are described, with particular reference to equalizing pressures in the middle ear and the development of alternobaric vertigo. Pressure effects on the sinuses, airways and lungs occur only when ventilation is impaired. To understand pressure effects on ventilation, the influence of gas pressures on gas exchange and the concept of oxygen window are described. Changes in ventilation are shown on the basis of the alveolar gas equation and the breathing responses to decreased and increased oxygen pressure. Reasons for toleration of hypercapnia, changes between laminar and turbulent gas flows at different pressures, and variation of ventilation responses at increased pressure are discussed. In the final section, the toxic effects of nitrogen and other inert gases, together with those of carbon dioxide, are described with reference to air breathing at increased pressure [ABSTRACT FROM AUTHOR]

Oxygen was discovered by Joseph Priestly in 1772. Since then, the chemical characteristics of the molecule have been established, together with its physiological properties relative to the transport and the utilization of oxygen by the cells and tissues. The role of the oxygen free radical, which are toxic reactive species, is important to consider in the practice of hyperbaric oxygen therapy [ABSTRACT FROM AUTHOR]

Within the scope of this book, a review is presented regarding general characteristics of gases: constants, pressure and density, composition of air, and characteristics of oxygen, nitrogen and carbon dioxide as major components of air. Relevant information is given regarding the basic gas laws of Boyle and Amontons, the universal gas equation, the gas laws of Dalton and Henry and the laws of diffusion (Fick). In addition the principle of adiabatic processes (Joule-Thomson effect and adiabatic decompression) is described [ABSTRACT FROM AUTHOR]