When undergoing Hyperbaric Oxygen Therapy, the patient breathes 100% Oxygen while being at increased ambient pressure. At the tissue level, Oxygen partial pressure ranges 50-80 mmHg. Inhaling 100% Oxygen raises that at 400-500 mmHg. Inhaling 100% Oxygen inside a hyperbaric chamber at a pressure of 2,2 ATA (3,2 times the atmospheric pressure) raises available Oxygen at 1672 mmHg, of which 1000-1500 mmHg reaches the tissues. While final available to the tissues amount of Oxygen is lower than this for various reasons, it is still much higher compared to what the patient gets when breathing ambient air.
Macrophages and fibroblasts need partial pressure of Oxygen above 30 mmHg to function and this is often difficult to achieve at the hypoxic – diabetic ulcer. Production of necessary growth factors by the cells can be accomplished either at low oxygen levels (hypoxia) or at very increased ones – levels achieved during HBOT. However, hypoxia may lead to cell death and production of collagen is oxygen-dependant. It has been shown that maximal collagen synthesis occurs at Oxygen partial pressure of 250 mmHg. This “amount” of Oxygen can only be offered with the use of HBOT.