1. What is Stroke Volume Index?

Stroke Volume Index (SVI) is a hemodynamic parameter that represents the volume of blood pumped by the left ventricle per beat, indexed to body surface area. It provides a normalized measure of cardiac function that accounts for patient size.

2. How Does the Calculator Work?

The calculator uses the SVI formula:

Where:

• \( SVI \) — Stroke Volume Index (mL/m²)
• \( SV \) — Stroke Volume (mL)
• \( BSA \) — Body Surface Area (m²)

Explanation: This calculation normalizes stroke volume to account for differences in patient body size, allowing for more accurate comparisons between individuals.

3. Importance of SVI Calculation

Details: SVI is crucial for assessing cardiac function, guiding fluid management, evaluating response to therapy, and monitoring patients in critical care settings. It helps differentiate between various types of shock and guides appropriate treatment strategies.

4. Using the Calculator

Tips: Enter stroke volume in milliliters (mL) and body surface area in square meters (m²). Both values must be positive numbers. BSA can be calculated using various formulas (Mosteller, Du Bois, etc.) based on height and weight.

5. Frequently Asked Questions (FAQ)

Q1: What is the normal range for SVI?
A: Normal SVI typically ranges from 35-65 mL/m² in adults. Values below 35 mL/m² may indicate impaired cardiac function.

Q2: How is stroke volume measured?
A: Stroke volume can be measured using echocardiography, thermodilution (via pulmonary artery catheter), or pulse contour analysis. It can also be calculated as SV = CO / HR (cardiac output divided by heart rate).

Q3: Why index to body surface area?
A: Indexing to BSA accounts for differences in body size, allowing for more accurate comparisons between patients of different sizes and establishing standardized normal values.

Q4: What factors affect SVI?
A: SVI is influenced by preload, afterload, contractility, heart rate, and various pathological conditions affecting cardiac function.

Q5: When is SVI most commonly used?
A: SVI is particularly valuable in critical care, cardiology, and anesthesiology for monitoring cardiac performance and guiding therapeutic interventions.