The present disclosure describes embodiments of a patient monitoring system and methods that include the measure and display of hemoglobin statistics, cardiac output statistic and vessel volume statistics. In an embodiment, total hemoglobin trending, cardiac output, or vessel volume is displayed over a period of time. Statistics can include frequency domain analysis, differences between measurement sites, or further calculations based on concentrations and volume of fluids added to a patient which may be unique for each patient monitored. The total trending and/or statistics can further be used to help control the treatment of a patient, such as being used to control IV administration.