Following cardiac surgery, patients receive large amounts of fluid in the intensive care unit. This may cause problems with wound healing and delay hospital discharge. A planned randomised controlled trial of a restrictive fluid regime as compared to a more liberal approach utilising advance hemodynamic monitoring, aims to reduce the amount of fluid patients receive and reduce hospital length of stay. This feasibility study aims to determine whether this nurse-led protocol is practicable and feasible and will help answer the research question. This study is simple and inexpensive and if it demonstrates a decreased length of hospital stay then this will represent a significant benefit for both individual patients and the health system.