Your physician may also recommend pulse oximetry if you use a ventilator to support breathing, suffer from sleep apnea or have a serious medical condition, such as heart attack, congestive heart failure, chronic obstructive pulmonary disease (COPD), anemia, lung cancer, asthma, or pneumonia. [4] X Trustworthy Source University of Rochester Medical Center Leading academic medical center in the U. S. focused on clinical care and research Go to source
A device called a probe has a light source, light detector, and microprocessor, which compares and calculates the differences in oxygen-rich versus oxygen-poor hemoglobin. [5] X Trustworthy Source Johns Hopkins Medicine Official resource database of the world-leading Johns Hopkins Hospital Go to source One side of the probe contains a light source with two different types of light: infrared and red. These two types of light are transmitted through the body’s tissues to the light detector on the other side of the probe. Hemoglobin that is more saturated with oxygen absorbs more of the infrared light, while hemoglobin without oxygen absorbs more of the red light. [6] X Trustworthy Source Johns Hopkins Medicine Official resource database of the world-leading Johns Hopkins Hospital Go to source The microprocessor in the probe calculates the differences and converts the information to a digital value. This value is then assessed to determine the amount of oxygen being carried in the blood. [7] X Trustworthy Source Johns Hopkins Medicine Official resource database of the world-leading Johns Hopkins Hospital Go to source Measurements of relative light absorption are made multiple times every second. These measurements are then processed by the machine to give a new reading every 0. 5-1 second. The readings of the last 3 seconds are then averaged out. [8] X Research source
If using the oximeter for a prolonged time, you may experience tissue breakdown at the site where the probe is applied (e. g. , finger, ear). Skin irritation can sometimes occur when using adhesive-containing probes. [10] X Trustworthy Source University of Rochester Medical Center Leading academic medical center in the U. S. focused on clinical care and research Go to source There may be other risks depending upon your medical health and any specific conditions you may have. Consult your doctor if you have any concerns before beginning the procedure.
Portable pulse oximeters can be purchased from a wide array of stores, including drugstores like Walgreens and CVS, big-box stores like Walmart, and even online. Most pulse oximeters are clip-like and look like a clothespin. There are also adhesive probes that can be placed on your finger or forehead. [11] X Trustworthy Source University of Rochester Medical Center Leading academic medical center in the U. S. focused on clinical care and research Go to source Appropriately sized probes should be used for children and infants. [12] X Research source
Probes can also be placed on the earlobe and forehead, although research suggests that the earlobe is not a reliable site for the measurement of oxygen saturation. [17] X Research source Haynes JM; The ear as an alternative site for a pulse oximeter finger clip sensor. Respir Care. 2007 Jun;52(6):727-9. If a finger probe is used, the hand should be rested on the chest at the level of the heart rather than the affixed digit held in the air (as patients commonly do). This helps to minimize any motion. [18] X Research source Minimize movement. The most common cause of inaccurate oximeter readings is excessive movement. One way to make sure that motion isn’t affecting the reading is to check that the displayed heart rate matches the heart rate when you check it manually. The two rates should be within 5 beats/minute of each other. [19] X Research source
Make sure there is no interference (environmental or on the probe site directly). Warm and rub skin. Apply a topical vasodilator that will help open the blood vessels (e. g. , glyceryl trinitrate (GTN) cream). Try an alternative probe site. Try a different probe and/or oximeter. If you’re still uncertain whether the oximeter is functioning properly, consult your physician.
