Intravenous fluids administration apparatus

Abstract

Apparatus for parenteral fluid administration to a patient wherein a pliant bag containing the liquid to be administered is supported between two pressure pads having mutually-confronting, spaced-apart, pressure-applying faces. A side edge and the bottom edge of one of the pads is offset from the corresponding side and bottom edge of the other pad. As one pressure pad approaches the other, pressure is applied to the pliant bag and the liquid is forced therefrom through a bottom outlet disposed below the pressure plates. When the pliant bag is fully squeezed and its side-walls are in contact, portions of the pliant bag adjacent the offset bottom edges and the offset side edges of the pressure plates form a lateral duct at the bottom of the bag for the remaining liquid and a riser duct which is in communication with the lateral duct and extends for the full height of the bag interior. Any gases present in the pliant bag rise to the top of the riser duct while the liquid remains at the bottom of the bag in the lateral duct. Thus no gas is ever administered to the patient.

Description

This invention relates to apparatus for the subcutaneous administration, to humans or animals, of intravenous and like fluids such as blood, nutrient liquids and the like, hereinafter mainly referred to simply as "fluids."

In early stages of the prior art, gravity-feed glass bottles were used as containers in the reception, storage and administration of fluids. Glass bottles for the uses indicated are becoming obsolete, and now the more usual way of administering fluids is by subcutaneous injection of the fluid from a pliant bag which, until required for use, is usually included, with necessary needles, tubing and the like, in a kit known (where blood is the fluid) as a "donor pack."

The pliant bag is usually made of plastics film material such as polyvinylchloride, and is formed with end ears or flaps which are holed for suspension of the bag on a peg, a hook or the like. At one end of the bag (the lower end when the bag liquid content is being administered to a patient) it is furnished with an outlet tube which usually includes a puncturable diaphragm or membrane through which the needled end of a delivery tube may be pierced. The delivery tube usually includes observable drop-feed devices and an adjustable flow delivery valve as well understood. In use, the contents of the bag can be expelled (for positive flow-control) under squeeze pressure applied to the bag externally.

The prior administration apparatus for emptying pliant bags has proved satisfactory at least to the extent indicated by bags having largely superseded glass bottles and other containers intended to serve the same purposes, but nevertheless the prior apparatus is open to objection in several respects.

Among the more serious defects are the occasional injection of air into the patient, sometimes with fatal result, and the occurrence of what is known as "bag strangulation." Strangulation occurs when the bag walls come flatly together below the upper surface of the liquid content so that liquid flow from the upper reaches of the bag is halted or impaired. Other defects of the prior pliant bag squeezing devices involve such aspects as: unreliability of feed-rate control, difficulty of immediately ceasing fluids flow when required, and necessity for frequent inspection during use to ensure sustained proper functioning of the apparatus; and above all, to ensure that when the bag is empty of liquid, air is not then injected into the patient.

The object of this invention is to overcome or ameliorate the disabilities referred to above in a simple but highly effective manner.

The invention provides:

Means for applying squeeze pressure to a pliant bag having an outlet, a gaseous content and a liquid content being a fluid for subcutaneous or other administration to a patient; said pressure-applying means comprising:

a. two pressure pads each supported in relation to the other and having mutually-confronting spaced-apart pressure-applying faces;

b. means to support a fluid-stocked bag sandwiched between said faces so that its liquid content may drain through said outlet; and,

c. loading means operable to cause relative mutual approach of said faces;

said faces being so formed and sized that when, by mutual approach, they bring opposed side-walls of a bag therebetween into contact, portions of said side-walls remain bulged apart sufficiently for the fully squeezed bag still to contain virtually all of said gaseous content.

An example of the invention is illustrated in the drawings herewith.

FIG. 1 is a perspective showing of the apparatus as it is when in use.

FIG. 2 is an end elevation of the apparatus shown in FIG. 1 but with its door open.

FIG. 3 is a side elevation taken on line 3--3 in FIG. 2; that is, with certain frontal parts removed.

FIG. 4 is a sectioned elevation of an air-flow control valve shown (un-sectioned) near the top of FIG. 3.

FIG. 5 virtually repeats FIG. 4, but with some parts differently positioned.

FIG. 6 is a sectional end elevation taken on line 6--6 in FIG. 3.

FIG. 7 is a sectional plan taken on line 7--7 in FIG. 6.

In the illustrated embodiment, a small cupboard-like cabinet is provided. This cabinet is divided into two compartments; an upper, normally-closed compartment 8, and a lower fluids bag squeezing compartment 9. Compressed air is the preferred medium for applying bag-squeezing pressure, and in that case the upper compartment is a convenient housing for a manually operable air pump 10, an air-flow control valve or regulator 11, and the body of an air pressure gauge 12. The front wall 13 of the upper compartment then constitutes a convenient mounting panel for displaying the dial portion 14 of the pressure gauge. The air-pump 10, the valve 11, and the pressure gauge 12 may be of conventional kind.

The cabinet may simply stand on the floor, or on a table near the patient, but for preference it is provided with hanger hooks or lugs, clamping means or other mounting means whereby it may be securely mounted on a wall, a rack, a stand, a rail or other member forming part of a bedstead, or other suitable support. For preference these mounting means consist of a channel bracket 15 fixed to the cabinet, a clamping plate 16 hinge-mounted at 17, and a thumb-screw 18 (threading in nut 19 fixed on bracket 15) able to tighten against a bed post or other upright member as indicated at 20 in FIG. 7.

The lower compartment of the cabinet is open-fronted. The open front is closable by a door 21 hinged, at 22, about an upright axis, at one side of the lower compartment. Latch means are provided to keep the door closed during fluid administration. The latch means need consist in no more than a plate 23 hinged on the door (at 24) having a headed pin 25 and a finger-knob 26 fixed on it. The headed end of pin 25 is able freely to enter a latch-hole 27 in the cabinet wall. It is found that when the apparatus is under inflation pressure (as described later herein) the pressure on the door 21 loads it sufficiently to restrain withdrawal of pin 25 from hole 27 and thus ensures against unwanted door opening.

For descriptive convenience the two previously mentioned pressure pads are distinguished herein as "back" and "front."

In the embodiment under description, the back pad is constituted by the rear wall 28 of the lower compartment and an inflatable bag 29 which stands uprightly within the lower compartment just in front of the rear wall so to extend for virtually the full width and full height of that wall.

The inflatable bag 29 is closed except for intrusion of an air supply tube 30. This tube 30 extends through a hole 31 in front wall 13 to one leg 32 of a coupling elbow 33. This arrangement is convenient when it is required to put a new inflation bag into the cabinet. The new bag (door 21 being open) is simply placed in the cabinet, and its tube (30) is passed upwardly through hole 31 from inside the cabinet. The emergent end of the tube is then simply attached to coupling leg 32.

The other leg 34 of the elbow 33 is connected, by pipe 35, to a tubular nipple 36 which opens to the inside of valve chamber 37. Two other nipples 38 and 39 also open to chamber 37. Nipple 38 leads, by pipe 40, to the pressure gauge 12. Nipple 39 is connected, by pipe 41, to the foot valve 42 of air pump 10.

Chamber 37 houses valve head 43 fixed on stem 44. Head 43 is able to close seating 45 and is constantly influenced to do so by compression spring 46. Below seating 45 exhaust ports 47, which open to atmosphere, are provided.

Stem 44 carries a follower cap 48. This cap resiliently rides a cam 49 forming part of, and a spherical journal for, an operating finger-piece 50. When the finger-piece is in the raised position shown in FIG. 5, valve head 43 is clear of seating 45 and therefore the interior of bag 29 is open to atmosphere by way of pipe 40 and ports 47. When the finger-piece is in the lowered position shown in FIG. 4, valve head 43 is closed relative to its seating 45. In FIG. 4 it will be seen that finger-piece 50 could be further depressed by the very small amount indicated at 51 (in FIG. 4). Any such further depression will move head 43 by a very small amount off its seating 45 thus permitting bleed escape of air from bag 29 to atmosphere for working bag-pressure adjustment purposes.

The front pressure pad is preferably constituted by a plate 52 adhered or otherwise secured to the inside surface 53 of a door panel 54 so that its side and bottom edges form steps 55 (whereof the depth is equal to the thickness of the plate 52) relative to the rear face 53 of the door panel 54. The disposition of these steps relative to a fluids bag 56 placed in the lower compartment is of considerable importance as explained below.

The lower compartment, near its top, is furnished with a support hook or pin 57 upon which a fluids bag (56) may be hung, with its outlet 58 lowermost, for administration of its contents to a human or animal patient. The floor of the lower compartment has an opening 59 in it through which the bag outlet, or a supply tube connected to that outlet, may freely extend.

When a transfusion or other fluids administration is to be carried out, the closure 43, if not already in exhaust position, is turned to that position as shown in FIG. 5. A loaded fluids bag 56 is then placed in the lower compartment, and the door 21 is closed and latched. While the inflatable bag is not inflated there is no substantial pressure on the fluids bag. When the administration is to go forward, the closure 43 is closed, as shown in FIG. 4, and the inflation bag pressure required is that generated by operation of the pump 10, as manifested by the pressure gauge 12.

As the inflation bag swells under pressure, the bag surface 60 in touch with the fluids bag 56 becomes the pressure applying face of the back pad, and the stepped inner surface of the panel on the closed door becomes the pressure applying face of the front pad; the pump and the air flowing from it into the inflation bag become the loading means operable to reduce the distance between the two faces so to cause expulsion of the fluids bag's liquid content.

The fluids bags, as supplied fully stocked with liquid, invariably have a small gaseous content; usually air. This gaseous content is very much a minority content because obviously, it is at best a useless content by comparison with the liquid content, and can even be a seriously detrimental content so far as the patient is concerned, as previously explained. Even so, some small fraction of air (or other gas) is included in a normally liquid-stocked bag otherwise there is grave danger of bag bursting in the event of rough handling or abrupt temperature rise. It is this air which involves the danger of being injected into a patient. An essential aspect of the present invention is to ensure that at all times of use a fluids bag, even when fully squeezed, still has sufficient volumetric capacity or "gas space" to contain the air (or other gas) originally in the bag, or at least as much of that air as will ensure none of it reaching the patient. It is also essential to ensure that during injection, the bag outlet at 58 is liquid immersed, and that any gas bubbles in the liquid be freely able to rise to the gas space. It follows that at all times a freeway duct is required throughout the height of the fluids bag so that liquid can always freely proceed to the outlet, and so that gaseous matter just as freely can travel to or remain in the gas space; that space, as previously explained, being large enough to hold all of the bag's original gaseous content or at least sufficient of that content to ensure that none of it reaches the patient.

Early in the expulsion process the entire interior of the fluids bag constitutes a freeway duct through which liquid may proceed, without obstruction, to the fluids bag outlet; but as the expulsion process nears its end the two pressure applying faces come flatly together, being eventually separated by no more than the double thickness of the fluids bag walls tightly and flatly sandwiched therebetween. Thus an important aspect of the present invention (as already indicated) is that one (or both) of the pressure applying faces is or are so formed, by the mentioned stepping 55 of the front pad face for example, that part of the fluids bag remains uncompressed (to the point of flat contact) to an extent sufficient to ensure retention in the fluids bag of such air (or other gases) as may have been included in it when it was charged; and also, to define a fluid-flow or freeway duct through which the bag interior, throughout its height, remains in communication with the fluids bag outlet and with the gas space above the liquid level. This is effected by making the plate 52 on the cabinet door, of such dimensions as will allow portions 61 of the fluids bag to remain bulged apart so that the bag walls in those portions remain separated by an amount substantially equal to the depth or thickness of the steps 55.

This is preferably arranged by making and positioning the plate or panel 52 so that its lower edge is above the bottom of the fluids bag (as shown) thus defining a freeway duct portion 62 which extends laterally of and along the bottom of the fluids bag, and which therefore remains in communication with the bag outlet 58; and by arranging for at least one of the two side edges of the panel or plate not to reach to the adjacent upright side of the fluids bag, thus defining at least one upright or riser freeway duct portion 63 which extends vertically of the bag and has its lower end opening to the lateral duct portion 62 at the bottom of the bag. Thus, the incompletely compressed bag portions defining the duct will be L-shaped, if the plate or panel provides for only one riser portion, and U-shaped if the plate or panel has both of its side (and stepped) edges falling short of the fluids bag sides, as shown in the drawings.

It will be seen that the riser portion or portions 63 will provide a channel whereby any air bubbles at the bottom of the fluids bag can rise to the top, and similarly any liquid tending to remain at the top of the bag can freely run to the outlet 58. Of importance however, is the necessity for the pressure pads or one of them to be so sized that when the pads are fully approached one towards the other sufficient of the fluids bag remains uncompressed, and thus ducted, to a degree such that the bag is still able to contain virtually all the air (or other gas) originally in it.

It will be understood that the invention, as described above, may be extensively modified without departure from the essence of the invention.

For example, the pressure pad which defines a freeway duct when the two pads are fully approached, each or either towards the other, need not consist in the stepped edge or edges of a plate or panel applied to the inside surface of a door. The duct could be constituted by a sunken groove or grooves in the inside surface of the door provided the groove or grooves is one or more which leaves an incompletely compressed duct extending from the fluids bag outlet to the upper reaches of that bag; and provided also that when the pressure pads are fully approached, one toward the other, sufficient of the fluids bag remains uncompressed for the bag still to contain virtually all of the air originally in it.

One of the pressure pads, instead of being in the form of an inflatable bag (such as 29) backed by a cabinet wall, could be in the form of a rigid plate which is spring loaded so as to bear flatly against a fluids bag placed between it and its companion pressure pad.

Where air (or other gas) under pressure is relied upon to enforce mutual approach of the pressure pads, a hand operated pump such as 10 is preferred as it renders the apparatus self-contained and hence readily portable as may be desirable for on-the-spot fluids administration to accident victims, battle-field casualties and the like. However, an appropriate air pump could be power driven; and, if desired, particularly in large hospitals and the like, pressure gas could be used from any source thereof, for example an oxygen or nitrogen cylinder, or a compressed air reticulation, in such case the pump (such as 10) can be replaced by a simple "on-off" valve, or a flow regulator valve of (for example) needle type.

Reverting to the illustrated embodiment of the invention, plate 52 and panel 54 are preferably made of transparent material, and the door 21 furnished with a sighting aperture 64, so that the extent to which a fluids bag has been emptied, or markings on the bag, may be observed without having to open the door. Plate 52 and panel 54 could, of course, be moulded as a one-piece element; indeed, plate 52, panel 54, and the door itself could be so formed.

It will be appreciated that although the apparatus subject hereof is primarily intended for use in administering a liquid to a patient subcutaneously, it can be usefully employed for other administrations; for example; in the administration of enema liquids; oral, nasal and other spray liquids; and in the spray application of plastic dressing liquids in surgery.

Claims

I claim:

1. Apparatus for parenteral fluid administration to a patient comprising:

a. two pressure pads having mutually confronting spaced apart pressure applying faces, a side edge and bottom edge of one face being offset from the corresponding side edge and bottom edge of the other face;

b. a pliant bag having a bottom outlet, a gaseous content and a liquid content;

c. means to support said pliant bag sandwiched between said faces so that its liquid content may drain through said outlet, the outlet extending beneath one of said pads;

d. loading means operable to cause one of said pressure pads to approach the face of said other pressure pad;

e. said faces being so sized that when, by said approach, they bring opposed side-walls of said pliant bag therebetween into contact thereby to halt further said approach of said faces, portions of said side-walls remain bulged apart sufficiently for the squeezed bag still to contain said gaseous content thereby to avoid its reaching the patient; and said pressure-applying faces being formed that the said bulged apart side-wall portions form a lateral duct in and at the bottom of the bag to which said outlet opens, and also forms at least one riser duct which opens to said lateral duct and extends for the full height of the bag interior.

2. Apparatus according to claim 1 wherein said pressure pads comprise a first pad having a pressure-applying face able to bear evenly against a fluid-stocked bag over substantially the entire area of one of its sidewalls, and a second pad having a pressure-applying face which is stepped to provide a projecting portion able to bear evenly against the opposite side-wall of the bag over an area less than its entire area.

3. Apparatus according to claim 1 which includes an open-fronted cabinet within which a fluid-stocked bag may be suspended, wherein said first pad consists of the rear wall of said cabinet and an inflatable bag placed in front of that wall, and wherein said second pad consists of a door adapted to be closed and held closed relative to the open front of said cabinet.

4. Apparatus according to claim 1 wherein said second pad is made of transparent material.

5. Apparatus according to claim 1 which includes a cabinet within which a fluid-stocked bag may be suspended, and wherein said loading means include a manually operable air pump housed inside said cabinet.