The trial groups will be: 1. Routine fluid management. Clinicians will be blinded to RI monitoring and use clinical judgement to determine how much fluids should be given, and when. Clinical judgement will be according to their standard practice and may include interpretation of blood pressure, and heart rate. 2. RI-guided fluid administration. RI fluid guidance will be initiated before anesthesia induction and will maintain until end of anesthesia. Clinicians will titrate fluids with the goal of keeping RI above 90- always using good clinical judgement for individual patients which may include avoiding fluid when RI is \<90 or giving additional fluid when RI \>90. For RI scores below 90, 1 cc/kg actual body weight fluid bolus of any crystalloid solution (normal saline or Ringer's lactate) will be given; colloids and blood products can also be given if clinically indicated. The target will be maintained until end of anesthesia. Anesthesia will be maintained for the entire surgical procedure per clinical routine. At the end of the surgical procedure, patients will be extubated and transferred to the post anesthesia care unit (PACU).