Platform
Company
Immunology & Autoimmune
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Currently under review
Pending specialist review and validation.
Arterial oxygen saturation measures the proportion of hemoglobin in your arterial blood that is carrying oxygen. It reflects how effectively your lungs load oxygen onto hemoglobin and how well that oxygen is being delivered into the bloodstream.
This measurement is commonly obtained as part of an arterial blood gas test. It is related to, but not the same as, fingertip pulse oximetry; pulse oximetry estimates oxygen saturation noninvasively, while an arterial sample allows direct analysis in a laboratory instrument and can be paired with other results such as pH and carbon dioxide.
Your arterial oxygen saturation helps clinicians evaluate how your lungs, heart, and blood are working together to provide oxygen to your body. It is used in emergency and critical care settings, during surgery and anesthesia, and in the assessment of breathing problems from conditions like pneumonia, asthma, chronic obstructive pulmonary disease, pulmonary embolism, or heart failure. It can also help guide oxygen therapy and ventilator settings.
Doctors may order this test if you have shortness of breath, chest problems, confusion, bluish lips or fingertips, or if you are receiving oxygen. It can identify problems with gas exchange and can signal the need for timely treatment. Collecting an arterial sample involves a small needle into an artery, which can cause brief discomfort, bruising, or rarely persistent bleeding, especially if you are on blood thinners.
If your arterial oxygen saturation is lower than expected for you, it suggests that your blood is not carrying as much oxygen as needed. This can happen when airflow is limited, when areas of the lung are not exchanging gases well, or when blood is bypassing oxygenated regions. It can also be influenced by the type or condition of hemoglobin present.
Your care team will interpret this result alongside other measurements, your symptoms, and your medical history. Depending on the context, next steps may include supplemental oxygen, breathing treatments, imaging, or repeat testing. If you already use oxygen or have a chronic lung condition, your clinician may adjust your therapy and set individualized targets that balance benefits and risks.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Breathing extra oxygen can raise saturation, while high altitude can lower it by reducing the oxygen available in the air. Tell your clinician about recent travel or oxygen use.
Using a true arterial sample, removing air bubbles, and prompt analysis are important. Air contamination, delays, or using venous blood by mistake can distort the result.
Carboxyhemoglobin from smoking or carbon monoxide exposure, and methemoglobin from certain drugs or chemicals, can alter measured saturation and oxygen delivery.
Changes in blood pH, carbon dioxide, body temperature, and 2,3-DPG shift hemoglobin’s affinity for oxygen, which affects saturation at a given oxygen pressure.
Opioids, sedatives, and anesthetics can suppress breathing and lower oxygen levels. Nitrates and some local anesthetics may increase methemoglobin, affecting accuracy.
Conditions like COPD, interstitial lung disease, pulmonary hypertension, or heart failure can reduce saturation and may require individualized targets and monitoring.
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