Abstract: An infusion system includes fluid-delivery components for delivering a fluid from a separate source of the fluid into a patient, transducer components for producing a signal related to the pressure of the fluid in the fluid-delivery components, and identification components responsive to the signal for identifying pressure artifacts characteristic of patient activity. Gravity-fed infusion may be employed as well as infusion with a flow control device, and identification may be accomplished with a microprocessor for examining the waveform of the signal and identifying pressure artifacts characteristic of patient activity amidst pressure changes caused by fluid-delivery components so that site checking can be conducted during quiet periods, i.e., times of little patient acitivity.