Skip to content

Cardiopulmonary Oxygen Transport Function Index (Maximal Oxygen Uptake Ratio)

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

This test measures how efficiently your heart, lungs, and blood work together to deliver oxygen to your body during exercise. It helps assess overall cardiovascular and respiratory health.

Quick summary

["Evaluates your body’s ability to use oxygen during physical activity."]

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

Key facts at a glance

LOINC
20293-7
Short code
Pulmonic/Systemic DOP.VMAX+AO
Synonyms
Pulmonic/Systemic DOP.VMAX+AO
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-doppler-vmax-aorta-calculated
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

Your doctor may order this test to evaluate how well your cardiovascular and pulmonary systems work together to transport oxygen. It combines measurements of oxygen consumption (VO₂) and arterial oxygen saturation (AO₂) to create an index of functional capacity. This can be useful in diagnosing or monitoring conditions affecting heart, lungs, or circulation.

How the Test Works

The test typically involves graded exercise on a treadmill or stationary bike while oxygen levels and heart rate are monitored. Blood samples may be taken to assess oxygen delivery and utilization at different intensities. The results are compared to expected values based on your age, sex, and fitness level.

Common Uses

Doctors may use this test to diagnose or monitor conditions like heart failure, lung diseases (e.g., COPD), or chronic kidney disease. It can also help assess fitness levels, recovery after surgery, or the effectiveness of treatments for cardiovascular or respiratory conditions.

Preparation

No special preparation is usually needed, but you may be asked to avoid caffeine or heavy meals before the test. Wear comfortable clothing and shoes suitable for exercise. Bring any medications you’re currently taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cardiopulmonary VO₂ Max Ratio

Frequently asked questions

How long does this test take?
The test itself typically takes about 30 to 60 minutes, including preparation and recovery. The full evaluation, including blood draws and monitoring, may extend this time.
What should I expect during the test?
You’ll start with a baseline assessment, then exercise at increasing intensities while your heart rate, blood oxygen levels, and breathing are monitored. Blood samples may be taken at different points to measure oxygen-related markers. You’ll gradually increase effort until you reach your maximum capacity.
Will I need to fast before this test?
No fasting is required, but avoid heavy meals or caffeine within a few hours before testing to ensure accurate results.
  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