Pulse oximetry is a way of measuring the oxygen saturation in arteries. Determining your arterial blood oxygen saturation is important because it can identify low blood oxygen, or hypoxemia. Hypoxemia can be caused by a number of medical problems in which you need to receive prompt medical intervention. According to MayoClinic.com, a normal pulse oximetry reading is 95 percent to 100 percent. A reading of less than 90 is too low and alerts caregivers to a hypoxic state.
About Pulse Oximetry
Pulse oximetry is a noninvasive way of measuring the percentage of hemoglobin -- the oxygen carrying component of red blood cells -- that is oxygen-saturated. The test is commonly done in a hospital and involves placing a measuring device on your finger. A light shines through your finger and determines the oxygen saturation based on its color. The measurement is based on the fact that blood cells are bright red when they are oxygen saturated and blue when they are oxygen-deprived.
Limitations of Pulse Oximetry Measurement
Having a pulse oximetry test is a fairly accurate way of measuring your blood oxygen saturation, though the most accurate and comprehensive way is by having a blood gas test, which involves a small sample of blood to be withdrawn from an artery. A doctor can order a blood gas test if he doesn't believe a pulse oximetry reading is a completely accurate measurement of hypoxemia symptoms. According to information about pulse oximetry on the EndonurseInstitute website, results can be skewed by nail polish, abrupt movements, incorrect attachment, circulation problems and certain types of light and electromagnetic waves.
Causes of Hypoxemia
If you are in the hospital with symptoms of hypoxemia and require frequent pulse oximetry monitoring, several potential causes can exist. According to MayoClinic.com, common hypoxemia causes include an airway obstruction, lung diseases such as emphysema, illnesses such as pneumonia, some medications such as narcotics, conditions such as a collapsed lung or a pulmonary embolism, shock or sleep apnea. These are some examples but the exact cause of hypoxemia needs to be diagnosed by your doctor.
Considerations
Pulse oximetry might not provide a complete measure of your respiratory health. For example, you might be short of breath and on oxygen so a pulse oximetry test indicates that you have an adequate blood oxygen level. In addition to your pulse oximetry reading, your caregiver records your respiratory rate and the amount of oxygen being given, if applicable, to assess your respiratory status. You might still have an arterial blood gas test if your doctor has additional concerns about your respiratory status.
