Finger pulse oximeters are tools that allow medical professionals to quickly measure, and constantly monitor, the amount of oxygen being carried by your blood. You can also purchase these tools for your own use through medical suppliers and pharmacies, although it's a good idea to consult your physician for help in correctly interpreting the readings.
Definition
A finger pulse oximeter measures your blood's oxygen saturation or "sats" by shining two different wavelengths of light through the your finger. The device measures how much light the oxygen in your blood absorbs over a circulation period of five to 20 seconds, depending on the device and settings, and renders this as a percentage reading.
Reading
A finger pulse oximeter's percentage reading indicates what percentage of the maximum possible amount of oxygen your blood is carrying. The readings for most healthy individuals will range between 96 and 99 percent. Some patients, particularly those with chronic pulmonary or cardiovascular diseases, may have readings lower than 90 percent, which is defined as acute respiratory failure.
Uses
Finger pulse oximetry readings on any individual may vary over time. The pulse oximeter can chart these readings over time, including an your response to the stress of exercise, or they may be used to monitor vital signs, specifically giving the alert for insufficient oxygen in the blood (hypoxia) before you show other physical signs, and monitoring your pulse at the same time.
Checklist
If you're having problems getting accurate or consistent readings with your finger pulse oximeter, check to make sure that the oximeter is fully calibrated (it should do this automatically when you turn it on), make sure you're using a probe that the appropriate size for the finger, and make sure that the finger is clean---remove all nail polish or vanish. Other problems that may keep you from getting an accurate reading include shivering or repeated movement of the finger the sensor is on, venous congestion in an arm or leg, and reduced peripheral pulsatile blood flow.
Alarms
Most finger pulse oximeters allow you to set the ranges at which alarms for low oxygen saturation will be set. Oximeters will also sound a "Pulse Not Detected" alarm if the subject's pulse rate falls below a threshold that, once again, you can modify.
