Oxygen which accounts for about 21% of earth’s atmosphere is essential for the survival of all living forms on earth. Under normal situation, we breathe oxygen from the surrounding air which is combination of many gases (78% Nitrogen and 1% other gases). Surprisingly pure oxygen is actually not very good for health. Researchers have discovered that pure oxygen (100%) could actually hinder with the functioning of the lungs. Inhalation of pure oxygn can also harm the brain. How exactly pure oxygn kills the body cells is not known yet. 100% oxygen at normal air pressure would accumulate water in the lungs. A highly reactive form of oxygen molecule called oxygen free radical destroys membranes in the cells.
Inhaling pure oxygn in a low pressure atmospheric environment could lead to breathing problems. It is learnt that astronauts could breathe pure oxygn at reduced pressure for up to two weeks. Also when pure gas is breathed at very high pressure, acute oxygen poisoning can occur. Even in the case of resuscitation, it is advised that oxygn mixed with carbon dioxide be provided for the patients rather than pure gas. This will actually help preserve the brain function in them. As per the new guideline, healthcare providers are strongly encouraged to add carbon dioxide for oxygn dispensation especially when resuscitating infants. In many hospitals, patients are resuscitated with room air which is a mixture of oxygn, nitrogen and carbon dioxide.
When pure oxygn is provided to the patients, it has been found that part of the brain overreacts causing a heavy flow of hormones in the bloodstream. These hormones interfere with the heart’s ability to pump blood and deliver oxygn to other parts of the body. On the other hand, addition of carbon dioxide relaxes the blood vessels carrying oxygen to all parts of the body including heart and brain and regulates the release of hormones.