RESUMO
In patients with Bidirectional Glenn who have undergone surgery, the superior caval venous flow provides the only pulmonary blood supply. This is the effective pulmonary flow and at the same time its volume is not enough to overflow the single ventricle. The unsaturated, inferior vena cava flow is not oxygenated, since it goes across the interatrial septal communication and gets mixed in the left ventricle with the pulmonary venous blood. In this work, a bidirectional Glenn case is analyzed. The hemodynamic data before and after the operation are shown. It was evident from this case that the use of the Fick method to measure pulmonary flow in patients with bidirectional Glenn operation is not appropriate. Alternative methods, such as Doppler echocardiography and Magnetic Resonance Imaging, are recommended. A literature review on this subject was carefully done.