Possibly at some point during a doctor exam you had a little “thingie” put on your finger. It was to check your blood oxygen level. There are two main ways to measure or test blood oxygen levels: through a blood draw test and through pulse oximetry (using an oximeter). A blood draw test provides much more information about your oxygen levels than an oximeter does, but it is more invasive. If the doctor feels the oximetry reading gives him/her enough information, a ‘stick’ is not needed.
Your blood oxygen level, or oxygen saturation (Sp02), tells you how much oxygen you have in your blood. When you breathe, oxygen moves into your lungs and binds to hemoglobin/Hb. a protein in your red blood cells. In your bloodstream, hemoglobin carries oxygen from your lungs to your body’s cells used for energy production and organ function. Generally, 92% or more of your blood should carry oxygen to keep your body running smoothly. Most healthy adults have oxygen saturation levels between 95% and 100%, though people with lung problems or those who live at high altitudes (where there is less oxygen in the air) may have lower levels. Prolonged or repeated periods of low blood oxygen levels (hypoxemia) can lead to low oxygen levels in your tissues (hypoxia) which can strain or damage your body’s vital organs, including your brain and heart. Having an acceptable oxygen level is important for managing chronic lung conditions and maintaining optimal health. Regular measuring of your blood oxygen levels helps monitor how well your lungs are functioning, especially if you have any kind of chronic cardiac/lung medical condition, including chronic obstructive pulmonary disease/COPD.
When your blood oxygen levels fall below the normal range, you may experience symptoms such as: shortness of breath/dyspnea, dizziness, restlessness, anxiety, fatigue, confusion, bluish-colored lips, fingernails, or skin/cyanosis, rapid heartbeat, unexplained headaches.
Many factors can influence blood oxygen levels causing hypoxemia that affect lung or heart function: (a) respiratory infections impairing breathing, i.e. pneumonia, Covid, etc.; (b) chronic lung conditions – asthma, COPD/chronic obstructive pulmonary disease, cystic fibrosis, lung cancer, etc.; (c) Anemia – low red blood cells/hemoglobin/Hb reduces blood’s oxygen-carrying capacities; (d) heart diseases/heart failure – reducing the heart’s ability to pump oxygenated blood efficiently through body; (e) sleep apnea – breathing disruptions during sleep can cause periodic drops in oxygen levels; and, (f) pulmonary embolism – a blood clot lodged in a lung’s artery can reduce or block the flow of oxygen within the body.
Other factors that may affect blood oxygen levels: (a) higher altitudes have less oxygen in the air, especially affecting people not acclimated to high altitudes; (b) exercise – recent strenuous physical activity increases your body’s demand for oxygen, especially those who have an underlying lung or heart condition may experience temporary drops in blood oxygen levels; (c) smoking – tobacco damages your lungs and airways; and, (d) some medications such as opioids and benzodiazepines can suppress breathing or affect your body’s oxygen-carrying capacity. Benzodiazepines are a class of medications that slow activity in the brain and nervous system. They’re most often used for treating anxiety and related mental health conditions as well as brain-related conditions like seizures.
Pulse oximetry is a non-invasive small device that clips onto your fingertip, earlobe, or other body part (i.e., nose, toe) and sends infrared and red light through your soft tissues. A sensor attached to the pulse oximeter clip measures how much light passes through the tissues and blood and how much is absorbed. The oximeter then measures how much light is reflected off the hemoglobin molecules in your blood. Oxygenated blood absorbs more infrared light, and de-oxygenated blood absorbs more red light. Deoxygenated blood means the blood which is received to the heart and has greater concentration of carbon dioxide as compared to oxygen.
How to use a pulse oximeter to help ensure an accurate reading: (a) wash your hands, including fingernails –no nail polish/acrylics; (b) sit in a comfortable seated position and relax for a few minutes; (c) apply oximeter to tip of your index or middle finger – it should feel snug but not painful; (d) sit still while taking the measurements. If the number fluctuates, remain still until the device provides a steady, consistent number; and, (e) note the device’s numbers – one is your heart rate, and the other is the blood oxygen level.
When using the pulse oximeter at home, several factors can influence the oxygen levels and/or the device’s measurement, including: (a) skin temperature – very cold hands; (b) artificial nails and fingernail polish; (c) smoking; (d) high altitude; (e) skin pigmentation – pulse oximeters may not give accurate readings on people with darker skin tones; (f) skin thickness; and, (g) poor circulation.
While occasional fluctuations in blood oxygen levels are normal, persistent drops or concerning symptoms require medical attention. Ignoring low oxygen levels can impact your health and increase the risk of complications, especially if you have a condition affecting lung function. Please see your health care provider if you are experiencing any of these things.
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