Oximeter Basics
Medical personnel use a pulse oximeter to measure the oxygenation of the blood. An acceptable range is 95 to 100 percent. The pulse oximeter is widely used to measure blood oxygen levels because it is noninvasive; the medical staff is not required to draw blood to test oxygen levels. In modern medical facilities, the nursing staff attaches the pulse oximeter to a monitor that provides continual monitoring of the blood oxygen levels.
Diodes
A pair of diodes makes up the sensing unit of the pulse oximeter. One of the diodes emits a red light and the other emits an infrared light. A clip holds one light on either side. The clip is attached to a translucent area of the body, such as the fingertip, across the nail bed or the earlobe. The diodes send pulses of light, which is absorbed at a different rate, depending on whether the blood is oxygenated or deoxygenated.
Measuring Oxygen Levels
The pulse oximeter uses an established ratio to determine the percentage of blood oxygenation, depending on the amount of oxygenated and deoxygenated blood. The pulse oximeter only measures the oxygen levels in the blood, ignoring skin and tissue, because the wavelengths from the light respond to the pulse. As the heart beats, the walls of the arteries expand and contract. The light responds to this pressure. For this reason, the patient must have a pulse for the pulse oximeter to work properly. This is also the reason it will not work properly if the clip housing the lights slips out of place.
Limitations
There are some occasions where a pulse oximeter will not function properly. A patient with circulation issues may have such an irregular or weak pulse rate that the pulse oximeter will not function properly. A patient that is in a brightly lit room may receive inaccurate readings from the pulse oximeter, due to disruption between the light sources. Finally, a patient experiencing who is experiencing shock or is very cold may shiver uncontrollably. This shivering can interfere with the pulse oximeters ability to provide an accurate reading.
Other Functions
Hospital and other medical facilities use pulse oximeters in a wide range of situations. Pulse oximeters monitor patients during surgery and recovery as well as patients in intensive care and other critical care situations. Pulse oximeters are a valuable piece of hospital equipment. Most are able to not only monitor blood oxygen levels, but the pulse as well. The monitors provide a constant stream of data for the healthcare professional. Typically, a pulse oximeter provides a digital readout of the percentage of oxygen saturated blood, an audible sound that measures the pulse and provides a calculated display of the patient's heart rate.
