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Oxygen End-Expiration Concentration (Serum/Plasma)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of oxygen present in your blood at the end of a normal breath cycle. It helps assess how well your lungs deliver oxygen to your bloodstream.

Quick summary

["This test evaluates lung function and oxygen exchange efficiency in your blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
60943-8
Short code
O2 end exp VFr/PPres Away adap
Synonyms
O2 end exp VFr/PPres Away adap
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What This Test Measures

Oxygen end-expiration concentration reflects the partial pressure of oxygen in your arterial blood after exhalation. It is often used in specialized settings like pulmonary function testing or monitoring for conditions affecting oxygen delivery.

Why It Might Be Ordered

Your healthcare provider may request this test if you have symptoms like shortness of breath, chronic lung conditions (e.g., COPD), or suspected oxygen imbalance. It can also be part of broader evaluations for respiratory disorders or pre-surgical assessments.

How the Test Works

A small blood sample is taken from a vein, usually in your arm. The sample is analyzed to determine the oxygen concentration at the end of exhalation, which is compared to standard values for your age and health status.

What to Expect Before the Test

No special preparation is needed, but you may be asked to sit quietly for a few minutes before the blood draw. Avoid smoking or caffeine for 30 minutes before testing if instructed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

O₂ End-Expiration Level

Frequently asked questions

How long will I need to prepare for this test?
Generally, no special preparation is required, but follow any specific instructions your healthcare provider gives you, such as fasting or avoiding certain medications.
What does a low or high oxygen level mean?
Low levels may signal lung problems or reduced oxygen delivery, while high levels could indicate overbreathing or other metabolic factors. Your results will be interpreted by a healthcare professional based on your overall health and symptoms.
Will I feel any discomfort during the blood draw?
You may feel a slight pinch when the needle is inserted, but most people describe it as mild discomfort. The area may feel sore briefly afterward, but it typically resolves quickly.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy