Ambulatory patient infusion apparatus

Abstract

A modular ambulatory patient infusion apparatus including a control module and an infusion fluid or solution-containing interlocking cassette. The control module includes thumbwheel presettable electronic circuitry and display means in the form of windows for viewing the preset numerical values. In accordance with these settings, the circuitry drives a motor-operated reciprocable piston actuator terminating in a finger-like flange engaging portion. The motor shaft drives a worm and worm gear arrangement for reciprocating the piston actuator, with each of the worm and worm gear interoperatively associated with light cells for determining both motor speed and worm gear revolution. These, in turn, provide signals to the circuitry to vary the duty cycle of a pulse width modulated motor controller, while providing an indication of a complete revolution of the worm gear (which correlates to one cycle of the piston actuator) and providing an indication of motor speed which is utilized to detect occlusions by motor speed slowdown or stall. A flexible solution bag is retained within the cassette with the discharge tube thereof in fluid communication with a fluid pumping means within a block having a chamber therein and valve arrangement therein. The fluid pump includes a piston communicating with the chamber and having a flanged end configured for coacting engagement with the finger-like flange engaging portion of the piston actuator of the control module. The valve arrangement includes first and second check valves in fluid flow communication with the chamber, the first valve being in flow communication with the tube from the bag and the second valve being in flow communication with a passage leading to an IV tube set for connection to the patient.