Intravenous fluid flow monitor

An improved system for monitoring the fluid flow through a fluid delivery system to a patient wherein the fluid flow rate is varied in a predetermined sequential manner. Corresponding changes in pressure in the line (14) connecting the vein of a patient (16) and the pump (12) are detected and are used to derive signals indicative of the resistance or impedance in the line, which in turn can be used to determine whether the vein is normal, whether it is phlebitic, whether it is occluded, whether infiltration of the cannula into the patient's soft tissue has occurred, or whether the continuity of tubing to the vein has been interrupted.