Drip Meters

Abstract

A drip meter that is an integral part of a flexible parenteral solution container.

Description

Intravenous feeding of solutions other than whole blood or plasma has become very common. The usual solutions are normal saline, 5 percent glucose, Ringer's lactate, and the like. When any of these solutions are fed, it is imperative that it be fed in at a controlled pre-determined rate. For each solution there is a maximum rate that must not be exceeded. If this maximum rate is exceeded, the bloodstream at the infusion point will become diluted due to the over-concentration of solution at that point and serious damage could result. Likewise, there is a minimum desirable rate, since damage could result from a too leisurely rate of infusion of the solution into the patient. Thus, it can be seen that there is a range of infusion rates for each solution, and that the actual rate must be kept somewhere in this range.

The method of maintaining the proper infusion rate is to employ the use of a device called a drip meter. Reduced to its most basic terms, a drip meter is simply a variable area restriction somewhere in the flow path from parenteral solution container to patient, followed immediately by a large chamber where the individual drops of solution coming through the drip meter can be seen and counted. The nurse or other person administering the solution adjusts the variable area restriction to get an approximation of the correct flow rate, and then obtains the correct flow rate by counting the number of drops per unit of time and either increasing or decreasing the amount of restriction in the line to respectively decrease or increase the flow rate. While this method is satisfactory, it is time-consuming; it would be preferable to have a drip meter that could be set to the proper flow rate without requiring that the nurse go through a tedious trial and error process.

Prior art drip meters have the additional drawback of being a separate unit. That is, they consist of a unit that is separate and distinct from both the solution container and the tubing that leads to the patient. This latter feature means that not only must the hospital inventory and stock a separate item, it also means that the nurse who is about to administer a parenteral solution must pick up and carry to the patient's room the drip meter as well as the container of solution, tubing, needle, etc. With many separate items required, it is inevitable that there are occasions when one of the items is either lost or forgotten, which causes a delay while the nurse retraces her steps to obtain another. Thus, it can be seen that a combined container - drip meter will reduce the burden on the nurse and the administrative staff by reducing the number of items that each must handle.

Furthermore, the present trend is toward the use of plastic (generally polyethylene) bags as containers for the parenteral solutions rather than glass bottles; the plastic bags are disposed of after use, saving the costs of returning the empty bottle and sterilizing it before re-use. A drip meter that is capable of being made an integral part of such a plastic bag, to be disposed of with the bag, would further enhance the use of such plastic bags.

Accordingly, it is an object of this invention to provide a drip meter that can be integrally molded into a disposable plastic bag used to hold parenteral solutions.

A further object is to provide a drip meter that is composed of only two parts adapted for relative sliding motion.

A further object is to provide a drip meter that includes provision for setting a desired flow rate without time-consuming adjustment procedures on the part of the user.

Other objects and advantages will be apparent from the following specification and drawings.

SUMMARY

Briefly, the drip meter of the present invention comprises two elements designed for sliding motion relative to each other. Each element is joined to its adjacent sidewall to prevent leakage past the drip meter. One element is grooved, the second element is shaped to slide within this groove. The element having the groove also has flow passages in it, these flow passages being perpendicular to the groove. When the second element is slid fully into the groove, the flow passages are closed off; progressively withdrawing the second element from the groove exposes increasing areas of the flow passages to flow therethrough.

The drip meter of the present invention can be thought of as a modified gate valve with flow passages in the element in which the gate seats. Gate valves in general are not new, and gate valves having flow passages in the translating element which must be in registration with other flow passages before flow can occur are also not new (see U. S. Pat. No. 3,517,697). However, all prior art gate valves require actuating mechanisms that are external to the flow path. Thus, these gate valves are not only complicated and bulky, they offer leakage paths both into and out of the valve. By contrast, the modified gate valve of the present invention consists of only 2 parts, both of which are entirely within the walls of the parenteral solution bag, thereby precluding the possibility of any leakage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation of the lower half of a flexible parenteral solution container that is hung vertically in its normal use position, showing the drip meter in profile;

FIG. 2 is a cross section through the drip meter, taken along the line 2--2 in FIG. 1;

FIG. 3 is taken along line 3--3 in FIG. 2;

FIG. 4 shows an additional set of flow passages that may be incorporated;

FIG. 5, taken along line 5--5 of FIG. 3, shows detent means for setting pre-determined drip rates;

FIG. 6 is a perspective view of the present invention applied to a conventional glass container.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The parenteral solution bag, generally indicated at 1, includes a body portion 2 and a neck portion 3, the latter containing the drip meter 4. Since parenteral solution bags of this type are generally made of two sheets of plastic joined to each other at their peripheries, a cross section of the neck portion 3 perpendicular to the centerline of the bag is approximately oval in shape. As can be seen in FIG. 1, the drip meter 4 has a curved profile. This curve assures that all of the solution that goes through the meter will collect at a common point and fall into collection chamber 5 in a single series of drops rather than from several points along the meter.

In cross section (FIG. 2) the drip meter can be seen to consist of two elements: member 6, which as can be seen has a rather deep groove 8 running the length of one side, and member 7, which forms a tongue that is disposed in groove 8 of member 6. Members 6 and 7 may be molded integrally with the respective sidewalls of the neck portion of the bag; or the drip meter (elements 6 and 7) may be molded separately, assembled in tongue and groove relationship, and then each half of the unit bonded to its respective sidewall by any suitable means. In the center of each member 6 and 7 and projecting through the sidewall of the bag is a tab 9, which tab is the means of operating the drip meter. These tabs 9 are not essential to the operation of the drip meter, since the base of each member can be grasped through the flexible sidewalls 12. However, the inclusion of tabs 9 facilitates the opening of the drip meter as will be explained later. The material which comprises members 6 and 7 can be any plastic that is compatible with the solutions to be administered, but it must possess a certain amount of flexibility and resilience, as will be explained later.

FIG. 3 is a view looking down on the drip meter with the drip meter closed to flow. As can be seen, member 7 is seated fully in groove 8 of member 6, thereby blocking flow through slots 10 of member 6.

It is imperative that all of the flow into collection chamber 5 be through slots 10 in member 6 (see FIG. 3). Therefore, it is necessary that the juncture of the ends of drip meter 4 with the sides of the neck portion 3 (these juncture points being designated 4') be sealed to prevent leakage at this point. Of course, this problem is obviated if the two parts of the drip meter are molded into their respective side-walls.

If desired, additional flow passages 11 could be provided in member 7' as shown in FIG. 4. These passages would be exposed when member 7' is withdrawn from groove 8, thereby providing increased flow area for a given amount of withdrawal of member 7'.

The operation of the drip meter is as follows: Before the bag is filled, member 7 is pushed all the way into groove 8 in member 6 thereby closing off the flow passages 10. However, it is not necessary that these passages be completely blocked since the bag is sealed around its outer periphery; any solution that gets past the drip meter merely fills up the collection chamber 5. If parenteral solution has filled up the collection chamber, all that is necessary is that the bag be inverted, the meter opened, and the solution drained back into the main portion of the bag. With the collection chamber empty and the drip meter closed, the bag is allowed to hang with the collection chamber at the bottom. The needle on the infusion tubing is inserted through the wall of the bag which forms the bottom of the collection chamber. Each tab 9 is then grasped between the thumb and forefinger of one hand, and the tabs are gently pulled apart. As the tabs are pulled apart, member 7 is pulled out of the groove in member 6, exposing passages 10 to the flow of solution therethrough. As the solution flows through the slots 10, it collects at the low point on the curved surface of the drip meter and then falls into the collection chamber 5 in easily seen and counted drops. Member 7 is designed to be held in groove 8 by a friction fit. That is, while member 7 can be easily moved in groove 8, it will remain in position when tabs 9 are released. Thus a given flow rate can be set and it will not vary due to slippage of member 7 in groove 8.

If desired, detent means can be incorporated into the drip meter to lock member 7 in relation to member 6 at points corresponding to the most commonly used drip rates. As shown in FIG. 5, this can take the form of a series of hemispherical depressions 12 in member 6 and a corresponding projection 13 on member 7. Withdrawing member 7 from groove 8 until projection 13 is felt to "snap" into the first of depressions 12 will thus set a known flow rate without the need for any other checking or adjustments. Note that there is also a depression 14 for locking the drip meter in the closed position.

It will be noted that since members 6 and 7 are joined at each end, when tabs 9 are pulled apart, members 6 and 7 must bend along their length; for this reason members 6 and 7 must be made of a relatively flexible plastic or other material. However, the slots in member 6 will increase its flexibility; further, if the slots are wide, only a limited amount of relative movement will be necessary to expose the required flow area.

Up to this point the invention has been described with regard to a flexible bag; however, it can also be used in conjunction with a glass container, as shown in FIG. 6. In this latter configuration, the only modification that is required is not to the drip meter per se but to the sidewalls that enclose it and form the collection chamber. These sidewalls must be contoured so that they go from the circular neck of the bottle to the narrow, somewhat rectangular, section of the bottom of the collection chamber, with the drip meter disposed in the middle as in the flexible bag. The sidewalls can be secured to the neck of the bottle by any convenient means, resulting in a cover for a glass parenteral solution container that has sealed within it an integral drip meter.

Claims

I claim:

1. Parenteral fluid administering equipment comprising: a flexible walled container having means integral therewithin for setting a variable predetermined fluid administration rate.

2. Parenteral fluid administering equipment as in claim 1 wherein said means comprises interdigitated elements, alternate ones of said elements being associated with the same flexible wall.

3. Parenteral fluid administering equipment as in claim 2 wherein said interdigitated elements have at least one flow passage in at least one of said interdigitated elements.

4. Parenteral fluid administering equipment as in claim 3 having detent means associated with said interdigitated elements for holding said interdigitated elements in any one of a plurality of relationships.

5. A flexible walled fluid container comprising: sheets of flexible material placed in overlying relationship to one another and sealed at their peripheries to form a fluid reservoir therewithin, said reservoir being subdivided by adjustable valve means into two reservoirs, said adjustable valve means controlling the rate of flow of fluid between said reservoirs.

6. A container as in claim 5 wherein said valve means comprises interdigitated elements, alternate ones of said interdigitated elements being associated with the same fluid reservoir wall.

7. A container as in claim 6 wherein said interdigitated elements have at least one flow passage in at least one of said elements.

8. A container as in claim 7 having detent means associated with said interdigitated elements for holding said interdigitated elements in any one of a plurality of relationships.