The purpose of this study is to evaluate the feasibility of a closed-loop (automated) fluid administration system to deliver fluids using feedback from standard operating room hemodynamic monitors. In standard anesthesia care the rate of IV fluid administration to the patient is determined by the anesthesiologist caring for the patient. In this study protocol, the rate of fluid administration will be determined instead by the closed-loop (automated) control system under the supervision of the anesthesiologist. The system will independently decide when to give fluid and at what rate; the supervising anesthesiologist will monitor the system to ensure appropriate volumes are being delivered and to intervene if necessary.