Formula used
1) Heart rate and stroke volume
- CO = HR × SV
- CO in L/min when SV is in L/beat and HR in beats/min.
2) Fick principle
- CO = VO2 ÷ (CaO2 − CvO2)
- Use consistent oxygen-content units; the calculator converts to mL O2/L blood internally.
- Cardiac Index = CO ÷ BSA (if BSA is provided).
How to use this calculator
- Select a calculation method based on available measurements.
- Enter values and choose the correct units for each input.
- Optionally add body surface area to compute cardiac index.
- Click Calculate to show results under the header.
- Use Download CSV or Download PDF to save your history.
Example data table
| Scenario | HR (bpm) | SV (mL) | VO2 (mL/min) | CaO2 (mL/dL) | CvO2 (mL/dL) | CO (L/min) |
|---|---|---|---|---|---|---|
| Resting (HR × SV) | 72 | 70 | — | — | — | 5.04 |
| Light exercise (HR × SV) | 110 | 90 | — | — | — | 9.90 |
| Fick sample | — | — | 250 | 20 | 15 | 5.00 |
Cardiac output in practice
1) What cardiac output represents
Cardiac output (CO) is the blood volume the heart pumps each minute. In physics terms, it is a flow rate: volume per time. Because CO links pressure generation to flow delivery, it helps summarize how effectively the cardiovascular system transports oxygen and nutrients to tissues. In research settings, CO supports energy and transport models.
2) Typical values you can benchmark
For many resting adults, CO is roughly 4–8 L/min, while exercise can push it far higher depending on fitness. Stroke volume is often near 60–100 mL/beat, and heart rate commonly spans 60–100 bpm at rest. Use these as rough checks, not diagnoses.
3) Understanding the units
This tool reports CO in L/min, plus convenient conversions to mL/min and L/s. Remember: 1 L = 1000 mL and 1 min = 60 s. If stroke volume is entered in mL/beat, it is converted internally to L/beat before multiplying by beats/min.
4) HR × SV method: direct and intuitive
The HR × SV approach uses two measurable quantities and mirrors the definition of a pump: beats per minute times liters per beat. It is sensitive to measurement quality; for example, a 10% error in stroke volume produces about a 10% error in CO. Keep units consistent across scenarios.
5) Fick principle: flow from oxygen balance
The Fick method estimates CO from oxygen consumption (VO2) divided by the arteriovenous oxygen-content difference (CaO2 − CvO2). At rest, VO2 around 250 mL/min is a common reference, and an O2 content difference near 5 mL/dL is often seen.
6) Cardiac index for body-size normalization
Cardiac index (CI) adjusts CO by body surface area (BSA): CI = CO ÷ BSA. Many references cite CI near 2.5–4.0 L/min/m2 in adults at rest. Enter BSA only if you have a reasonable estimate, because CI inherits any BSA uncertainty.
7) Built-in checks and common pitfalls
The calculator flags values that fall outside typical ranges to help catch unit mix-ups (for example, entering stroke volume in mL while selecting liters). For the Fick method, CaO2 must exceed CvO2 to produce a positive difference. Recheck decimals and unit drop-downs when warnings appear.
8) Using saved runs for comparison
Every calculation is stored in the session history table so you can compare rest vs. activity, different unit choices, or alternative assumptions. Export CSV for spreadsheets, or generate a PDF for reports. This calculator is for learning and analysis, not medical decision-making.
FAQs
1) Is this calculator for clinical diagnosis?
No. It is an educational tool for exploring relationships between heart rate, stroke volume, oxygen use, and flow. Always rely on qualified clinicians and validated instruments for medical decisions.
2) What units should I use for stroke volume?
Most references use milliliters per beat. Enter SV in mL when your value is around 60–100. Switch to liters only if your source reports SV in L/beat, then keep heart rate in bpm.
3) Why does the calculator warn about unusual ranges?
Range checks help catch unit mix-ups and data-entry errors. For example, confusing mL with L can inflate output by 1000×. Warnings do not block calculation; they prompt you to verify measurements and context.
4) How do I estimate body surface area (BSA)?
If you do not have BSA, you can leave it blank and still compute CO. For study purposes, typical adult BSA values are often near 1.6–2.2 m², but use the value appropriate to your dataset.
5) When should I use the Fick method?
Use Fick when you have oxygen consumption (VO2) and arterial/venous oxygen contents. It is common in physiology labs and catheterization settings. Accuracy depends on synchronized sampling and consistent oxygen-content units.
6) Which oxygen-content unit should I select?
Select mL/dL if your report gives oxygen content per deciliter. Select mL/L if values are already per liter. The calculator converts internally so the arteriovenous difference matches VO2 units.
7) Why might my value differ from a bedside monitor?
Different methods measure different signals and time windows. CO can vary with posture, breathing, arrhythmias, and instrument averaging. Also check whether the monitor reports indexed values, thermodilution outputs, or values adjusted by proprietary algorithms.