Carbon Dioxide (Partial Pressure) in Exhaled Breath
This test measures the amount of carbon dioxide released naturally during breathing, which can help assess lung function and breathing efficiency.
["Measuring exhaled CO₂ helps doctors evaluate how well your lungs are working and your breathing pattern."]
Key facts at a glance
- LOINC
- 76095-9
- Short code
- CO2 during expir VFr/PPres Gas DS.EL
- Synonyms
- CO2 during expir VFr/PPres Gas DS.EL
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 22
- Ref high
- 28
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82374
- 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 Does This Test Measure?
Your breath contains carbon dioxide, which your body produces as a byproduct of using oxygen. This test measures the partial pressure of CO₂ in your exhaled breath, often used to evaluate lung function and ventilation efficiency. It can also be part of studies on respiratory health or metabolic processes.
Why Might You Need This Test?
Doctors may order this test to check for conditions affecting breathing, such as chronic obstructive pulmonary disease (COPD), asthma, or other lung disorders. It can also be used in research or clinical settings to monitor breathing patterns during sleep studies or other respiratory assessments.
How Is This Test Done?
You’ll likely exhale into a special device that captures your breath. The device measures the CO₂ levels in your exhaled air. This is a quick, non-invasive test with no preparation needed beyond breathing normally.
What Does the Result Mean?
Results are typically compared to a baseline or reference range for your age, sex, and health status. Higher than expected levels may suggest poor lung function or conditions like hyperventilation, while lower levels could indicate issues like hypoventilation or certain metabolic disorders.
Reference range
Adult: 22-28 mmol/LN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: This test is primarily used to assess respiratory function, diagnose or monitor lung-related conditions, and evaluate breathing patterns. It can also be part of broader metabolic or research studies to understand how the body processes gases during breathing.
Short name
Exhaled CO₂ Pressure (PCO₂)
Frequently asked questions
Why would my doctor ask for this test?
Is there any preparation needed before this test?
What are the possible risks or side effects of this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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