In addition to the effect of crystalloids and colloids on the patient, the amount of each fluid administered is also under debate. Goal-directed fluid therapy (GDFT) strategies based on cardiac output (CO) optimization have been shown to benefit moderate- to high-risk surgery patients and have recently been recommended by professional societies in the UK, in France, and in Europe. However, despite the growing evidence, these strategies are often not implemented in current practice. One of the reasons for this lack of implementation is that GDFT strategies, like any other complex clinical protocol, require significant provider attention and vigilance for consistent implementation and it is well known that even under study conditions protocol compliance rates are often not greater than 50% In another hand, one of the chief complicating factors in fluid administration studies is variation in provider administration practices, even when attempting to follow a protocol. Previous studies have used closed-loop (automated) systems to deliver fluid by a standardized protocol, removing variation between providers as one of the confounders of the study. Dr. Cannesson and Rinehart (UC Irvine, California, USA) have recently developed and used a closed-loop system for the provision of GDFT in clinical studies at UC Irvine and La Pitie hospital in France. The closed-loop system is beneficial because it involves the standardization of fluid management and all patients are treated equivalently. This system will thus provide consistent GDFT for all cases in the protocol and remove inter-provider variability as a confounder between groups.