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Company
Electrolytes
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Currently under review
Pending specialist review and validation.
The pO2 CL test measures the partial pressure of oxygen dissolved in your blood, which reflects how effectively oxygen moves from the air you breathe into your bloodstream. It is commonly performed as part of a blood gas panel along with pH, carbon dioxide, and oxygen saturation.
The CL label indicates the sample is not arterial. It may be drawn from a venous or central line, or from a capillary source. Because the source is different from an arterial sample, clinicians interpret the result in the context of where and how the blood was collected.
This test helps assess how well your lungs transfer oxygen into your blood and how your heart and circulation deliver it to tissues. It is used when there are breathing problems, suspected lung or heart conditions, during monitoring in the hospital, and to guide oxygen therapy or ventilator settings. It can also help check your response to treatments for breathing or circulation issues.
Results can influence decisions about oxygen delivery, inhaled medications, and other supportive care. Your clinician considers your symptoms, examination, pulse oximetry, and other labs or imaging to decide on next steps and whether additional testing is needed.
Your result is interpreted alongside your symptoms, the sample type, and other blood gas values. A lower than expected value may point to reduced oxygen transfer in the lungs, shallow breathing, problems with blood flow through the lungs, or issues with the heart and circulation. A higher than expected value can occur with supplemental oxygen, rapid breathing, or occasionally from sample handling issues.
Because this measurement comes from a non‑arterial source, values naturally differ from a typical arterial blood gas. Altitude, body temperature, hemoglobin level, and ventilator or oxygen settings also influence interpretation. Your clinician may repeat the test, adjust oxygen or medications, or request an arterial sample if more precise assessment is needed.
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.
Non‑arterial samples such as venous, central line, or capillary blood yield different oxygen values than arterial blood. The draw site and whether the capillary was properly warmed influence interpretation.
Air bubbles in the syringe, inadequate sealing, or delays before analysis can alter the measured oxygen level. Rapid, airtight handling and prompt testing reduce these pre‑analytic effects.
Breathing supplemental oxygen or changes in ventilator settings can raise the measured oxygen level. Documenting the inspired oxygen and recent changes is important for correct interpretation.
Higher altitude and lower ambient oxygen reduce the amount of oxygen available to the lungs, which can lower measured values even in otherwise healthy people.
Drugs that slow breathing, such as opioids or sedatives, can reduce oxygen levels, while bronchodilators and steroids may improve them. Recent dosing and timing matter.
Samples from intravenous lines can be diluted or contaminated by flush solutions or residual fluids if the line is not properly cleared, which can distort results.
Diseases such as COPD, asthma, pneumonia, heart failure, or shunts can change oxygen transfer or delivery. Baseline status and recent exacerbations guide interpretation.
References