Cardiopulmonary Function Assessment Scores (CPET)

Oxygen Pulse (O2 Pulse Index) Calculator

Clinical calculation support · Verify results before clinical use

Calculate oxygen pulse

Enter oxygen uptake and heart rate measured at the same exercise stage. Use VO₂ in mL/min.

—mL/beat

Clinical interpretation

Oxygen pulse (O₂ pulse) is calculated as oxygen uptake divided by heart rate and expressed in mL/beat. From the Fick relationship, it reflects the product of stroke volume and the arteriovenous oxygen-content difference.

O₂ pulse is sometimes used as an indirect clue to the stroke-volume response during cardiopulmonary exercise testing (CPET), but it is not a direct measurement of stroke volume. A low value or a flattening/downward trajectory during increasing workload may be clinically relevant, but neither finding is specific on its own.

Important limitations

Interpret the value alongside the exercise stage, workload, VO₂ response, heart-rate response, symptoms, ECG, oxygen saturation, hemoglobin status, and the full CPET pattern.
Age, sex, body size, fitness, medications (including beta-blockers), pacing, anemia, hypoxemia, and peripheral oxygen extraction can affect interpretation.
A single value cannot establish a universal normal/abnormal classification. The original template's approximate 10–15 mL/beat range is not used as a diagnostic cutoff here.

Formula and references

Formula

O₂ pulse (mL/beat) = VO₂ (mL/min) ÷ heart rate (beats/min)

Example: VO₂ 1,800 mL/min ÷ heart rate 150 bpm = 12.00 mL/beat.

American Thoracic Society / American College of Chest PhysiciansATS/ACCP Statement on Cardiopulmonary Exercise Testing. Describes O₂ pulse as VO₂/HR and explains the modified Fick relationship and interpretation cautions. Official statement (PDF)

Whipp BJ, Higgenbotham MB, Cobb FC.Estimating exercise stroke volume from asymptotic oxygen pulse in humans. Journal of Applied Physiology. 1996;81(6):2674–2679. DOI: 10.1152/jappl.1996.81.6.2674.

Petek BJ, et al.Utility of the oxygen pulse in the diagnosis of obstructive coronary artery disease in physically fit patients. Physiological Reports. 2021;9(21):e15105. DOI: 10.14814/phy2.15105.

Claessen G, et al.Does oxygen pulse represent a reliable surrogate for stroke volume during exercise? Insights from CPET combined with echocardiography or invasive measurements. European Journal of Preventive Cardiology. 2025;32(Suppl 1):zwaf236.316. DOI: 10.1093/eurjpc/zwaf236.316.

Clinical disclaimer: This calculator performs arithmetic only. It does not provide an age-, sex-, or body-size-adjusted reference range, diagnose cardiovascular disease, or replace expert interpretation of the complete CPET. Interpret results in the appropriate clinical context.