What is a Pulse Oximeter?

A pulse oximeter is one of many electronic devices used by health care providers and laypeople to measure the amount of oxygen circulating in the bloodstream. This measurement is known as oxygen saturation percentage (SpO2). Knowing the SpO2 of someone is important because a determination of whether he or she is hypoxic dictates the medical interventions needed. What is hypoxia? Hypoxia simply means that the tissues of the body lack sufficient oxygen; when they are deprived of oxygen, they begin to die. This is why a person in respiratory and cardiac arrest must be given rescue breaths, usually performed with a pocket face mask (PFM) or a bag valve mask (BVM). He must also receive cardiopulmonary resuscitation (CPR) if he's going to have a chance at survival. The rescue breathing provides him with oxygen and the CPR ensures that the oxygen is delivered to all parts of the body so that hypoxia doesn't develop.

Although the readings of a pulse oximeter aren't considered a vital sign (sign of life/activity in the body) such as pulse, respirations, skin color, temp, and condition; blood pressure, and the pupils of the eyes; the device is employed by some health care providers. When functioning properly, it does aid in determining whether hypoxia has set in or not. The pulse oximeter reading for a normal healthy individual should fall between 96 and 100. That might sound high, but it only indicates what is normal. A reading between 91 and 95 indicates hypoxia. One that is between 86 and 90 is troubling and usually prompts aggressive medical management of the patient.

The pulse oximeter, however helpful it might be, certainly isn't without flaw. Its readings can't be trusted if a person is hypothermic, in shock, has carbon monoxide (CO) poisoning, is a chronic smoker, used on a patient wearing nail polish or on one who is excessively moving around. The reason why it can't be trusted in cases of CO poisoning is because CO binds with hemoglobin, a protein in blood, which causes a red color detected by a pulse oximeter. Cigarette smoke contains deadly CO, causing the reading for smokers to be inaccurate.

Fortunately, the detection of hypoxia in a person isn't dependent on the readings of a pulse oximeter. Signs of hypoxia, depending on the severity, can include cyanosis (bluish or gray color caused by cells being starved for O2), and an altered mental status. To prevent the development of severe hypoxia, O2 is generally administered to patients even in the pre-hospital setting, particularly those who've suffered any kind of trauma (injury).

Many people who've dedicated themselves to exercise in the fresh air, particularly if they live in the country, have noticed improvement in their health and memory retention. Some even reap benefit from practicing deep breathing while in the car with the windows rolled at least slightly down to get fresh air. Those who are in heavily polluted area don't benefit near as much as those who live where the air is till fairly clean.

Source:

EMT Training (Lecture/Text): Emergency Care (11th Edition) by Daniel Limmer, Michael F. O'Keefe, Medical Editor: Edward T. Dickinson MD, FACEP