Effect of Phenylephrine Versus Norepinephrine on Venous Return

In consecutive patients scheduled for DIEP flap surgery, all hemodynamic and respiratory variables are recorded electronically for subsequent off line analysis. A systolic blood pressure of minimal 100 mmHg will be maintained during surgery by optimization of the cardiac preload and titrated norepinephrine (1.5 µg/kg/h) or phenylephrine (15 µg/kg/h) administration. Cardiac preload optimization will be based on pulse pressure variation (PPV) measurement, which is calculated by pulse contour analysis of the radial arterial pressure curve. Following the international goal‐directed fluid therapy guidelines, plasmalyte will be administrated if the PPV>11%. The tricuspid annular plane systolic excursion (TAPSE) will be measured by transthoracic echocardiography (TTE) to evaluate the inotropic effect of norepinephrine and phenylephrine. In addition, TTE will be used to measure the cardiac output to calibrate the PPV measurements.