Qp:Qs (Shunt Ratio)

Name: Qp:Qs (Shunt Ratio)
Creator: Daniel Diaz-Gil, MD
Keywords: Qp:Qs, shunt ratio, pulmonary blood flow, systemic blood flow, cardiac catheterization, intracardiac shunt, ASD, VSD, PDA, left-to-right shunt, right-to-left shunt

Calculates pulmonary-to-systemic blood flow ratio from oxygen saturation data to quantify intracardiac shunts

Clinically Verified· 5 tests

For educational and informational purposes only. Verify all results before clinical application.

Systemic Arterial O2 Saturation (SaO2) *

Aortic or systemic arterial oxygen saturation (%)

Mixed Venous O2 Saturation (MvO2) *

Mixed venous oxygen saturation — typically from SVC or calculated (3 SVC + 1 IVC) / 4

Pulmonary Venous O2 Saturation (PvO2) *

Pulmonary venous oxygen saturation — assume 95-100% if no pulmonary vein sampling

Pulmonary Artery O2 Saturation (PaO2) *

Pulmonary artery oxygen saturation (%)

References

Grossman W, Baim DS. Cardiac Catheterization, Angiography, and Intervention. 8th ed. Lippincott Williams & Wilkins; 2014.
Lock JE, Keane JF, Perry SB. Diagnostic and Interventional Catheterization in Congenital Heart Disease. 2nd ed. Springer; 2000.[DOI]

Reviewed by Daniel Diaz-Gil, MD · Last updated March 2026

Medical disclaimer

This tool is for educational and informational purposes only. It is not a substitute for professional clinical judgment. Always independently verify results before making clinical decisions.

Professional Resources — Tools used by pediatricians for shunt calculation

Grossman's Cardiac Catheterization HandbookEssential hemodynamic assessment and cath lab reference~$70via Amazon Hemodynamic Rounds, KernCase-based hemodynamic interpretation for the cath lab~$70via Amazon Park's Pediatric Cardiology for Practitioners, 7th EdComprehensive reference for pediatric cardiology evaluation and management~$95via Amazon