Abstract: Automated dispensing apparatus is disclosed for administering intravenous fluid to a patient at a controlled volumetric rate such that deviations from the desired fluid volumetric flow rate are automatically corrected. In accordance with the invention, the width and silhouette of each drop of fluid are measured and give rise to representative signals of each such parameter. These signals are then multiplied to obtain a signal proportional to the volume of the drop. This drop volume signal is combined with a rate control signal to modify the latter to reflect deviations in the measured drop volume from a nominal value. The thus modified control signal is compared against the actual rate of drop administration, and any necessary adjustment made in the constriction of a fluid-passing tube. The rate at which intravenous fluid is supplied to the patient is thus maintained at the desired volumetric rate.

Abstract: Automated intravenous fluid dispensing apparatus regulating intravenously administered electrolyte solution, nutrient or other fluid flow employs a bidirectionally motor-driven clamp for selectively constricting a fluid passing conduit, typically a tube. The apparatus employs a relaxation oscillator, or timing circuit, having a variable period dependent upon whether fluid is being administered at a specified rate, or too rapidly or too slowly. When either of the latter two conditions obtain, the tube pinch-off motor is excited in an appropriate corrective direction to cause the desired fluid flow rate.In accordance with varying aspects of the present invention, motor and timing circuit modulation (i.e., speed of system correction response) varies for excess/deficient flow rate conditions depending upon the specified flow rate and upon the constrictive state of the fluid delivery tubing. Also, audio/visual alarming is provided for defined conditions.