How does the knee-to-chest maneuver help a patient with Tetralogy of Fallot?

The knee-to-chest maneuver is a useful technique for patients with Tetralogy of Fallot, particularly during a tet spell, which is characterized by cyanotic episodes. This maneuver helps improve blood flow to the lungs, which is crucial for these patients who experience a right-to-left shunt due to the structural abnormalities present in Tetralogy of Fallot.

When a patient assumes the knee-to-chest position, it increases intrathoracic pressure and decreases venous return to the heart, effectively raising systemic vascular resistance. This shift can help redirect blood flow through the right ventricular outflow tract into the pulmonary artery rather than across the ventricular septal defect and into the aorta. Consequently, this maneuver enhances the right ventricular blood flow to the lungs, facilitating better oxygenation of blood and alleviating the hypoxia experienced during a tet spell.

This understanding of increased right ventricular blood flow to the lungs is pivotal in managing acute episodes in these patients, making the knee-to-chest maneuver an important intervention in the acute care of those with Tetralogy of Fallot.