Goal-directed Fluid Therapy During Deep Inferior Epigastric Perforator (DIEP) Free Flap Breast Reconstruction

Adequate free flap perfusion during Deep Inferior Epigastric Perforator (DIEP) flap breast reconstruction surgery requires maintaining blood pressure above 100 mmHg and avoiding excessive fluid administration. This study aims to determine whether the use of a measurement of preload dependency (Pulse Pressure Variation = PPV), can guide fluid therapy and if it decreases the risk of flap oedema. For this purpose, two fluid management strategies will be compared: * Static intraoperative fluid management: Administration of crystalloid fluids is limited to 5ml/kg/h * Dynamic intraoperative fluid management: Crystalloid fluids are only administered if PPV exceeds 12% The purpose of this study is to compare the static and dynamic (= targeted) fluid strategy and to evaluate the effect on flap oedema and flap perfusion.