Because breathing is largely an unconscious process, it’s only when breathing becomes difficult that a person begins to take notice. The earth’s atmosphere is 21 percent oxygen, which is enough to support human life until problems arise. When disease or injury compromises the body’s use of oxygen, supplemental oxygen is necessary; however, too much oxygen can be toxic. Patients on supplemental oxygen in a health care setting will be monitored by pulse oximetry to make sure oxygen levels stay within established guidelines.
Receptors in the brain arteries near the heart detect chemical changes that can alter the rate and depth of respiration. If the level of carbon dioxide in your blood begins to rise, the chemoreceptors send out nerve signals that stimulate breathing. Receiving oxygen can “quiet’ these signals by supplementing a low oxygen level. Too much oxygen in body tissues is called hyperoxia, and too little oxygen is called hypoxia. Oxygen reduces peripheral circulation, so it needs to be prescribed by a physician.
Oxygen therapy supplements a person’s oxygen level when it is lower than what is needed to sustain life. Receiving low concentrations of oxygen-enriched, humidified air continuously through a nasal cannula or mask will compensate for low oxygen levels due to respiratory failure, asthma and a range of disease states. Receiving non-humidified oxygen can be irritating to the lining in the upper airway. According to the American Association of Respiratory Care, the target oxygen level for patients suffering from chronic obstructive pulmonary disease is a saturated blood oxygen level of 88 to 92 percent, and 94 to 98 percent in an otherwise healthy person.
Oxygen in large concentrations is toxic when inhaled for more than a few hours, particularly for infants. According to the American Association of Respiratory Care, supplemental oxygen should be high enough to treat a low blood oxygen level, but not so high that it suppresses breathing. Concentrations of oxygen greater than 50 percent, is generally used short-term for critically ill and acute care patients as the effects are giving high levels of supplemental oxygen to patients with chronic and severe emphysema will reduce their respiratory drive, which can cause respiratory distress, failure and death.