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Doppler Echo Cardiac Output Calculator

Doppler Echo Cardiac Output Calculator Diagram

beats/min

1. What is a Doppler Echo Cardiac Output Calculator?

Definition: This calculator uses Doppler echocardiography measurements to compute Cardiac Output (CO), Cardiac Index (CI), Stroke Volume (SV), Cross-Sectional Area (CSA) of the Left Ventricular Outflow Tract (LVOT), and Body Surface Area (BSA). It requires inputs for height, weight, heart rate, LVOT Velocity Time Integral (VTI), and LVOT diameter.

Purpose: It provides a non-invasive method to assess cardiac function, helping clinicians evaluate heart performance in conditions like heart failure, shock, or during perioperative care.

2. How Does the Calculator Work?

The calculator performs the following calculations:

  • Body Surface Area (BSA):
    • Formula: \( \text{BSA (m}^2\text{)} = \sqrt{\frac{\text{Height (cm)} \times \text{Weight (kg)}}{3600}} \) (Mosteller formula).
    • Calculates BSA, with selectable output units (m², cm², in²).
  • Cross-Sectional Area (CSA) of LVOT:
    • Formula: \( \text{CSA (cm}^2\text{)} = \pi \times \left(\frac{\text{LVOT Diameter (cm)}}{2}\right)^2 \).
    • Assumes the LVOT is circular, with selectable units (cm², mm², in²).
  • Stroke Volume (SV):
    • Formula: \( \text{SV (mL)} = \text{CSA (cm}^2\text{)} \times \text{LVOT VTI (cm)} \).
    • Represents the volume of blood ejected per heartbeat, with selectable units (mL, L, fl oz).
  • Cardiac Output (CO):
    • Formula: \( \text{CO (L/min)} = \frac{\text{SV (mL)} \times \text{Heart Rate (beats/min)}}{1000} \).
    • Measures total blood flow per minute, with selectable units (L/min, mL/min, fl oz/min).
  • Cardiac Index (CI):
    • Formula: \( \text{CI (L/min/m}^2\text{)} = \frac{\text{CO (L/min)}}{\text{BSA (m}^2\text{)}} \).
    • Normalizes CO for body size, with selectable units (L/min/m², mL/min/m², fl oz/min/in²).

Unit Conversions:

  • Height: cm, m, in, ft, ft + in (e.g., 1 m = 100 cm, 1 ft = 30.48 cm).
  • Weight: kg, lb (e.g., 1 kg = 2.20462 lb).
  • LVOT VTI and Diameter: cm, in (e.g., 1 in = 2.54 cm).
  • BSA: m², cm², in² (e.g., 1 m² = 1550 in²).
  • CSA: cm², mm², in² (e.g., 1 cm² = 6.4516 in²).
  • SV: mL, L, fl oz (e.g., 1 mL = 0.033814 fl oz).
  • CO: L/min, mL/min, fl oz/min (e.g., 1 L/min = 33.814 fl oz/min).
  • CI: L/min/m², mL/min/m², fl oz/min/in².

Steps:

  • Input your height, weight, heart rate, LVOT VTI, and LVOT diameter with chosen units.
  • Compute BSA, CSA, SV, CO, and CI, displaying results with selectable units.

3. Importance of Doppler Echo Cardiac Output Calculations

These calculations are useful for:

  • Cardiac Assessment: Evaluates heart function non-invasively, aiding in diagnosis of conditions like heart failure or shock.
  • Critical Care: Monitors hemodynamic status in intensive care settings.
  • Perioperative Management: Guides fluid and inotropic therapy during surgery.

4. Using the Calculator

Examples:

  • Example 1: Height = 5 ft 7 in (170.18 cm), Weight = 154 lb (69.853 kg), Heart Rate = 70 beats/min, LVOT VTI = 7.874 in (20 cm), LVOT Diameter = 0.787 in (2 cm)
    BSA: \( \sqrt{\frac{170.18 \times 69.853}{3600}} \approx 1.8177 \, \text{m}^2 = 2817.4350 \, \text{in}^2 \).
    CSA: \( \pi \times \left(\frac{2}{2}\right)^2 = 3.1416 \, \text{cm}^2 = 20.2681 \, \text{in}^2 \).
    SV: \( 3.1416 \times 20 = 62.8320 \, \text{mL} = 2.1248 \, \text{fl oz} \).
    CO: \( \frac{62.8320 \times 70}{1000} = 4.3982 \, \text{L/min} = 148.7234 \, \text{fl oz/min} \).
    CI: \( \frac{4.3982}{1.8177} \approx 2.4195 \, \text{L/min/m}^2 = 0.0528 \, \text{fl oz/min/in}^2 \).
  • Example 2: Height = 170 cm, Weight = 70 kg, Heart Rate = 75 beats/min, LVOT VTI = 22 cm, LVOT Diameter = 2.1 cm
    BSA: \( \sqrt{\frac{170 \times 70}{3600}} \approx 1.8198 \, \text{m}^2 \).
    CSA: \( \pi \times \left(\frac{2.1}{2}\right)^2 = 3.4636 \, \text{cm}^2 \).
    SV: \( 3.4636 \times 22 = 76.1992 \, \text{mL} \).
    CO: \( \frac{76.1992 \times 75}{1000} = 5.7149 \, \text{L/min} \).
    CI: \( \frac{5.7149}{1.8198} \approx 3.1405 \, \text{L/min/m}^2 \).

5. Frequently Asked Questions (FAQ)

Q: What is LVOT VTI?
A: LVOT VTI (Velocity Time Integral) is the distance blood travels through the LVOT during one heartbeat, measured in cm or inches using Doppler echocardiography.

Q: Why is BSA used in CI calculations?
A: BSA normalizes CO for body size, allowing standardized comparisons across individuals of different heights and weights.

Q: What are typical values for these measurements?
A: Normal ranges include CO (4–8 L/min or 135–270 fl oz/min), CI (2.5–4 L/min/m²), SV (60–100 mL or 2–3.4 fl oz), LVOT VTI (18–22 cm or 7–8.7 in), and LVOT Diameter (1.8–2.2 cm or 0.71–0.87 in). Values outside these ranges may indicate cardiac dysfunction.

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