Acute normovolemic hemodilution (ANH) is a widely used blood conservation strategy in cardiac surgery aimed at reducing intraoperative blood loss and the need for allogeneic blood transfusion. However, inadequate or excessive fluid replacement during ANH may lead to hemodynamic instability and other complications. The Pleth Variability Index (PVI) is a noninvasive dynamic parameter that can predict fluid responsiveness and guide goal-directed fluid therapy during surgery. This study aims to evaluate whether performing ANH under intraoperative PVI guidance in cardiac surgery allows more precise fluid management and reduces allogenic blood transfusion and the risk of perioperative complications.