Abstract: A patient monitoring unit is used to follow the actual changes in a patient's weight during the course of a surgical procedure. A patients' fluid inventory is vital to the patients' well being and any significant additions to or losses in body fluids are very significant in the proper management of the patient during surgery. Real time changes in a patient's weight are monitored throughout the surgical procedure. A weighing system utilizing strain gauges or other transducers is built into the operating platform and the output from the transducers is communicated into a computer controller. Angle sensors are provided to measure the tilt at which the operating table may be placed thereby causing an apparent change in weight. The apparent weight change is corrected to the true weight. In the event various portions of the operating table are individually articulated, separate weighing systems and angle sensors are provided for each articulated portion.