Background

Pulmonary shunt refers to the passage of venous blood into the arterial blood system bypassingthe alveoli-blood gas exchange. Pulmonary shunt is defined by a drop in the physiologic coupling of lung ventilationand lung perfusion. This may consequently lead to respiratory failure.

Main body

The pulmonary shunt assessment is often neglected. From a mathematical point of view, pulmonaryshunt can be assessed by estimating the degree of mixing between oxygenated and deoxygenated blood. To com-pute the shunt, three key components are analyzed: the oxygen (O2) content in the central venous blood before gasexchange, the calculated O2 content in the pulmonary capillaries after gas exchange, and the O2 content in the arte-rial system, after the mixing of shunted and non-shunted blood. Computing the pulmonary shunt becomes of furtherimportance in patients on extracorporeal membrane oxygenation (ECMO), as arterial oxygen levels may not directlyreflect the gas exchange of the native lung.

Conclusion

In this review, the shunt analysis and its practical clinical applications in different scenarios are discussedby using an online shunt simulator.