Qp/Qs Calculator
Calculate pulmonary to systemic flow ratio for cardiac shunt assessment
Qp/Qs Calculation
Calculation Method
Echocardiographic Parameters
Qp/Qs Assessment Results
⚠️ Medical Disclaimer: This calculator is for educational purposes only. Qp/Qs ratios should be interpreted by qualified cardiologists in conjunction with clinical assessment and other diagnostic tests. Always consult your doctor for cardiac evaluation and treatment decisions.
Normal Values
Quick Reference
Qp/Qs > 1: Left-to-right shunt
Qp/Qs < 1: Right-to-left shunt
Used for ASD, VSD, PDA assessment
Helps guide surgical intervention
Understanding Qp/Qs Ratio
What is Qp/Qs?
The Qp/Qs ratio represents the ratio of pulmonary flow (Qp) to systemic flow (Qs). This measurement helps quantify cardiac shunts and assess the severity of congenital or acquired heart defects that cause abnormal blood flow patterns.
Clinical Applications
- •Assess severity of cardiac shunts
- •Guide surgical intervention decisions
- •Monitor treatment effectiveness
- •Evaluate congenital heart defects
Calculation Methods
Echocardiography
Uses RVOT and LVOT measurements with velocity time integrals to calculate flow volumes.
Fick Principle
Uses oxygen saturation differences to calculate the shunt ratio based on oxygen content.
Direct Values
Direct calculation when pulmonary and systemic flow values are already known.
Common Cardiac Shunt Conditions
| Condition | Shunt Direction | Typical Qp/Qs | Clinical Significance |
|---|---|---|---|
| ASD (Atrial Septal Defect) | Left-to-right | > 1.0 | Volume overload of right ventricle |
| VSD (Ventricular Septal Defect) | Left-to-right | > 1.0 | Pulmonary overcirculation |
| PDA (Patent Ductus Arteriosus) | Left-to-right | > 1.0 | Left heart volume overload |
| Tetralogy of Fallot | Right-to-left | < 1.0 | Cyanosis and reduced oxygen |