The author presents an overview of treatment effects of inhalation of 100 % oxygen in a hyperbaric chamber when treating patients with a chronic, not healing defect. She stresses qualities of 100 % oxygen inhaled under pressure of 2.6 ATA during the treatment of these defects: not only hyperoxygenation (100 % binding on haemoglobin /Hgb/ and ability of solving oxygen in plasma), but also ability to diffuse to the vicinity of capillaries, promote the production of granular tissue, stimulate the synthesis of collagen, epithelium and thus the production of a scar. Oxygen (O2) in an absolute pressure of 2.5–3.0 ATA has a bacteriostatic and even bactericidal effect in relation to some bacteria, and thus contribute to the treatment of infection which is inevitebly present in every chronic wound. The importance of examination of transcutaneous oxymetry (TcpO2) – its value for assessing prognosis – and at the same time effeciency of treatment by hyperbaric oxygenotherapy (HBO) is highlighted. The review of the most frequent causes of chronic, not healing defects and simultaneously increasing number of patients treated by HBO as an adjuvant method for osteomyelitis or osteoradionecrosis are presented. Many not healing defects are hypoxic with oxygen tension from 5 to 15 mm Hg. In these cases, the normal healing of the defect is problematic even none because the ability of phagocytosis of leucocytes is decreased and other parametres necessary for healing of the wound are paralyzed. Additional use of 100 % oxygen in an absolute presssure of 2.5–3.0 ATA with basic classical complex treatment (medicaments, local, incl. surgical) using HBO may help (and is necessary for starting the healing process) treating the defect completely. It is evident that unless patients have a basic TcpO2 below 30 mm Hg, there is no improvement, resp. treatment of a defect in all patients but only in some of them. If the TcpO2 is above 50–100 mm Hg, defects of all patients treated with HBO will get healed. However, healing of the wound is influenced by other factors presented in the paper. The necessity of complex treatment and still growing importance of HBO as an adjuvant therapy in healing chronic defects are highlighted.

        Key words: chronic skin defects, osteoradionecrosis, osteomyelitis