What difference does extra pressure create?
Hemoglobin (in red blood cells) holds 97% of its maximum amount of oxygen from normal air or holds 100% when breathing pure oxygen. One gram of hemoglobin can only combine with 1.34 ml of oxygen. Therefore, red blood cells can only deliver a limited level of oxygen to tissue cells, a pO2 of 39 mmHg or less. This is called oxygen tension (or oxygen partial pressure, “pO2”) and is measured in units labeled “mmHg” (the amount of pressure able to raise the equivalent weight of a liquid mercury column. Injuries, infections and diseases can drop this vital tissue oxygen level down to almost zero! As we age we can loose vital lung capacity and the ability to effectively obtain adequate oxygen. Some disease conditions impair oxygen utilization. Also, injuries or conditions with swelling can cause pressure that cuts off circulation flow. This loss of blood flow, called ischemia, cuts off oxygen circulation to the affected areas of the body. This problem drops the pO2 gravely low, destroys tissue, and slows healing. Research has shown optimal tissue healing occurs if pO2 rises to between 50 and 80 mmHg. Oxygen given in a normal room is not sufficient to raise tissue oxygen levels to that level because red blood cells cannot carry the extra oxygen. The answer is to deliver the oxygen in a pressurized chamber to raise oxygen tension beyond red blood cell saturation.