The Stroke Volume Index (SVI) calculator is an essential tool in the medical field, particularly in cardiology and critical care. It measures the volume of blood pumped by the heart with each beat relative to the body surface area, providing a normalized measure of heart performance. This metric is crucial for assessing cardiac function and guiding therapeutic decisions.
Formula of Stroke Volume Index Calculator
The Stroke Volume Index is calculated using the following formula:
SVI = SV / BSA
- SVI: Stroke Volume Index (unit: ml/beat/m²)
- SV: Stroke Volume (unit: ml/beat) – the amount of blood pumped by the heart with each beat
- BSA: Body Surface Area (unit: m²)
Important to Note:
- This formula calculates SVI based on previously obtained Stroke Volume (SV) and Body Surface Area (BSA) values.
- You cannot directly calculate SVI without knowing either SV or BSA.
For calculating Stroke Volume (SV), you can use a separate formula:
SV = CO / HR
- SV: Stroke Volume (unit: ml/beat)
- CO: Cardiac Output (unit: L/min or ml/min) – the amount of blood pumped by the heart per minute
- HR: Heart Rate (unit: beats per minute)
General Terms Table
| SVI Range (ml/beat/m²) | Interpretation | Clinical Implications |
|---|---|---|
| < 35 | Low SVI | Potential indication of decreased cardiac function, |
| which might be due to heart failure, hypovolemia, | ||
| or other conditions leading to reduced stroke volume. | ||
| 35 – 45 | Normal SVI | Considered within normal range, indicating |
| adequate cardiac function relative to body size. | ||
| > 45 | High SVI | May indicate increased cardiac output due to conditions |
| like sepsis, anemia, or hyperthyroidism, or | ||
| could be seen in athletes with a trained heart. |
This table provides a general guide to interpreting SVI values. It’s important to understand that SVI, while valuable, is just one piece of the puzzle in cardiac assessment.
Example of Stroke Volume Index Calculator
To illustrate, consider a patient with a Stroke Volume (SV) of 70 ml/beat and a Body Surface Area (BSA) of 1.9 m². Applying the formula:
SVI = SV / BSA = 70 ml/beat / 1.9 m² = 36.84 ml/beat/m²
This example demonstrates how to calculate the Stroke Volume Index using real-world values, providing a clear understanding of the process.
Most Common FAQs
The Stroke Volume Index is a measure of the amount of blood the heart pumps with each beat, adjusted for body surface area. It’s a critical parameter for assessing heart performance.
Body Surface Area is used to normalize the Stroke Volume, allowing for comparisons between individuals of different sizes, providing a more accurate assessment of heart function.
No, you must know both the Stroke Volume and the Body Surface Area to calculate the Stroke Volume Index accurately.