The oximeter measures blood oxygen saturation by measuring the specific wavelengths of oxygenated (saturated) and deoxygenated (desaturated) red blood cells (hemoglobin). The percentage of blood oxygen saturation is calculated based on the proportion of the two measurements.
The readings for blood oxygen saturation and blood flow are displayed on a monitor, and a beep signals the pulse rate. Oximeters are accurate in the range of 70 to 100 percent saturated blood oxygen, and low readings or unusual pulse rates can trigger alarms on the device.
External conditions may affect accuracy and validity of the readings, including altitude, temperature, lighting, involuntary movements and nail polish.
Internal conditions affect the accuracy and range of the pulse oximeter, including the patient's age, cardiovascular condition, respiratory status and use of diagnostic dyes.
Since the device is designed to measure two wavelengths for hemoglobin, hemoglobin that is saturated with carbon monoxide will yield a similar value as oxygenated hemoglobin.
Medical facilities employ pulse oximeters because they provide clinicians with fast, indirect monitors for hypoxia.
A pulse oximeter is a medical device that indirectly measures levels of hypoxia. The device senses levels of oxygen saturation in arterial blood using spectral analysis, along with pulse rate. Pulse oximeters are attached to an external body part such as a finger or earlobe for readings.