An important function of the lungs is to transfer gases. They allow oxygen to pass into the bloodstream, and carbon dioxide to pass from the blood to your lungs. 

If these gases don’t pass normally, it could indicate lung disease such as emphysema, asthma, interstitial lung disease (or scarring of the lungs) and pulmonary embolism (or a blood clot in the lungs).

What is Single-Breath Carbon Monoxide Uptake in the Lung?

This test, also known as lung diffusion capacity, checks to see how well your lungs are getting oxygen to your bloodstream and removing carbon dioxide.
During this test, you’ll be connected via mouthpiece and tube to a machine. You'll breathe in a harmless tracer gas and hold your breath for about ten seconds, then exhale. The amount of tracer gas you breathe out will then be measured.

How to Prepare for Your Test

On the day of your test, it’s important to:

  • Stop smoking or other exposure to carbon monoxide (a colorless, odorless gas produced by burning gas, wood, charcoal, propane or other fuel)

  • Avoid heavy exercise immediately before the test

  • Stop drinking alcohol at least four hours before the test

  • Wear loose clothing to allow for chest expansion (no tight belt or vest)

  • Avoid having a large meal two hours prior to your test

Your appointment may be rescheduled if you haven’t prepared according to these criteria.
Call us ahead of time if you:

  • Have an inability to follow instructions*

  • Have had a heart attack in the last month

  • Have chest or abdominal pain

  • Have excessive pain while using a mouthpiece

  • Have stress incontinence, or an unintentional loss of urine during movement or physical activity

  • Have had recent eye surgery (1 week to 6 months depending on surgery)

  • Have had recent brain surgery or an injury (3 to 6 weeks)

  • Have had a collapsed lung (2 weeks)

  • Are spitting up blood

*If a patient is unable to follow instructions due to a confused state, young age or dementia, then a parent, caregiver or guardian may call on their behalf.

Need More Information?

A white woman with blond hair sits upright in a hospital bed and breathes into a lung diagnostic tool

Download additional information on your test procedure.

If you have any questions about your test, please call us: 

Adult Testing

(559) 459-3947 

Pediatric Testing  

(559) 459-2327

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