Background: Accurately quantifying blood flow through a shunt vessel is vitally important, because
shunt prevents gas exchange and can provide a pathway for emboli that bypass the pulmonary
microcirculation. Some current techniques allow an approximate estimate of the pulmonary shunt
and present technical and evaluative difficulties that can compromise the result.
Objectives: To develop a mathematical model, based on important chemical-physical laws, for the
precise calculation of pulmonary blood flow (Qp), intrapulmonary arteriovenous anastomoses blood
flow (QIPAVA) and then validate it.
Methods: Some experimental data, obtained from healthy subjects, were input into the model.
Results: Qp and QIPAVA were precisely calculated at rest and at moderate (50% of VO2max) and heavy exercise (90% of VO2max) in both normoxia (FIO2 = 0.2093) and acute hypoxia (FIO2 = 0.125).
In normoxia under heavy exercise, Qp decreased slightly (97.56% of Qt), and QIPAVA represented
2.44% of Qt.
Instead, in hypoxia at heavy exercise, Qp decreased significantly (85.25% of Qt), and QIPAVA
increased significantly (14.75% of Qt).
It was possible to demonstrate a negative contribution of QIPAVA directly to gas exchange efficiency
and identify incorrect Qt measurements.
Conclusions: This model is precise because composed of equations which describe the real
representation of gas exchange and therefore of universal application.
Qp differs significantly from Qt under some physiological conditions already in healthy subjects.
The use of this model will allow research a general advance in the understanding of this critical
biological function and in clinical practice a precise and early detection of the pathology.