Apparatus for Controlled Volume and Rate Administration of Liquids

Abstract

Apparatus for selective controlled volume and rate administration of parenteral solutions, blood and the like, wherein sight and flow control problems caused by splashing and foaming of fluids having high surface tension such as blood are substantially diminished, and flow rates during different time phases of operation are optimized due to an arrangement of structure providing an increased head pressure on flow of fluid to a measuring chamber. Administration sets for delivery of parenteral solutions, blood and the like, have been heretofore available to the medical profession, which included volumetric chambers that allowed accurately measured volumes of solution to be administered to a patient. Volumetric sets of this type are especially essential for delivering discrete small volumes to infants and young children who could not tolerate larger, unregulated volumes of fluids. Volumetric control sets of this type are disclosed in prior U.S. Pat. Nos. 3,216,418 and 3,216,419. With volumetric control sets of this type, precise small volumes of fluid can be delivered but they cannot, however, be used for direct flow from a supply container through the volumetric chamber when such a flow is desired since the fluid can flow faster into the chamber than flow from the chamber so that the chamber will fill completely and tend to leak from the airway. U.S. Pat. No. 3,625,211 discloses another type of apparatus for providing delivery of a small, precise volume of solution. In the apparatus of this patent, fluid is introduced by means of a special two-way stopcock into the bottom of the volumetric chamber to fill it to the desired volume. The stopcock has a fail-safe configuration so that fluid can be delivered to the patient from the chamber, but never directly from the supply container. The inability of using these prior constructions for a direct fluid flow from a supply container is overcome in the volumetric administration set disclosed in U.S. Pat. No. 3,776,229 by the simple expedient of providing an on-off at the airway. When the airway is closed, the chamber functions as an extension of the conduit joining the chamber to the supply container so that larger volumes of fluid can flow at a pre-set rate into the patient. With the airway valve open, a precise volume can be introduced into the measuring chamber and subsequently delivered to the patient. This apparatus, accordingly, is useful for accomplishing two functions and separate administration sets are not required. While the apparatus of this latter patent constitutes an improvement over prior apparatus, it has certain drawbacks which are also present in U.S. Pat. Nos. 3,216,418 and 3,216,419. In these prior devices, when fluids with high surface tension, such as blood, flow or drip from the drip tube at the top of the measuring chamber into the chamber, a considerable amount of frothing develops which not only obscures and makes reading of a meniscus difficult or impossible, but frequently a float member of a valve at the bottom of the chamber is rendered inoperative after the blood drains from the chamber. The float member rides on top of the froth and will not seal the discharge opening. Additionally, blood and other solutions falling from the drip tube cause splashing of the liquid which clings to the walls of the chamber and obscures the vision of a technician when reading a meniscus. Another problem of substantial significance is present in the prior known administration sets, particularly in those sets where the effective head pressure is rather small as a consequence of existence of a somewhat short column of fluid between the top of the supply fluid and the drip tube. If this head pressure is rather low, then the flow rate into the measuring chamber will be unacceptably slow when one desires to fill the chamber to a certain level. The present invention provides an administration set wherein these problems existing in the prior known apparatus as disclosed in the aforementioned patents have been overcome. The present invention provides apparatus for administration of parenteral solutions, blood and the like, operable for selective controlled volume and rate administration. The apparatus substantially eliminates problems arising through splashing and foaming of fluids having high surface tension such as blood which cause sight and flow control problems. This is accomplished by the point of introduction of the fluid from a supply container to the measuring chamber, i.e., to the bottom of the measuring chamber. This arrangement of introduction of the fluid to the measuring chamber also eliminates to a substantial extent deleterious flow rates during different time phases of operation by providing an increased head pressure on fluid flow to the measuring chamber.

Patent Drawings (2 sheets)

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