How to Calculate Cardiac Output
What is Cardiac Output?
Cardiac output is the volume of blood pumped per minute. It's calculated from heart rate and stroke volume, crucial for shock assessment.
Formula
Calculate: CO = HR × SV (in mL)
- CO
- CO/BSA — CO/BSA
- HR
- HR value — Variable used in the calculation
- SV
- SV value — Variable used in the calculation
Step-by-Step Guide
- 1Calculate: CO = HR × SV (in mL)
- 2Normal CO ≈ 5 L/min; normalize to body surface area: CI = CO/BSA
- 3Normal CI ≈ 2.5-3.5 L/min/m²
Worked Examples
Input
HR 100, SV 50 mL
Result
CO = 5 L/min (normal)
Normal cardiac output
Common Mistakes to Avoid
- ✕Confusing cardiac output with blood pressure
- ✕Using SV values from different populations without BSA normalization
Frequently Asked Questions
What decreases cardiac output?
Decreased heart rate, decreased stroke volume (due to reduced preload, afterload, or contractility).
How is stroke volume measured?
Echocardiography, cardiac catheterization, or non-invasive methods. Not directly measured from vital signs.
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