Title:
DRIP CHAMBER
United States Patent 3744492


Abstract:
A drip chamber for use in an infusion set for feeding blood, saline solution or other liquids from a container to a catheter or needle for administration to a patient. The drip chamber comprises an inlet section and a larger volume outlet section, liquid filling the latter section before it can escape from the chamber outlet and, when in use, covering the outlet irrespective of the orientation of the drip chamber, such that air bubbles can not escape from the drip chamber to the catheter or needle of the infusion set and thence to the patient.



Inventors:
LEIBINSOHN S
Application Number:
05/132789
Publication Date:
07/10/1973
Filing Date:
04/07/1971
Assignee:
LEIBINSOHN S,IL
Primary Class:
International Classes:
A61M5/14; (IPC1-7): A61M5/16
Field of Search:
128/214R,214C,214.2 21
View Patent Images:
US Patent References:



Primary Examiner:
Truluck, Dalton L.
Claims:
I claim

1. A drip chamber for determining the rate of flow of a liquid comprising:

2. A drip chamber for determining the rate of flow of a liquid comprising:

3. The device of claim 2, further comprising a sheet of porous filter material disposed between the outlet tube and the inner surface of the disc-shaped member which is adapted to close off the open end of the cylindrically shaped element.

Description:
BACKGROUND OF THE INVENTION

The present invention relates to infusion apparatus and more particularly to a novel drip chamber for use there-with to prevent the passage of air through its exit opening.

Drip chambers are typically used in conjunction with infusion sets to determine liquid flow. A major disadvantage in conventional drip chambers is their failure to prevent air bubbles from exiting therethrough. In addition, drip chambers comprising parts of infusion sets employed in the field (e.g., on a battlefield or during disasters) must be adapted to withstand rough handling while preventing air from passing through the infusion set into the patient's body.

SUMMARY OF THE INVENTION

The present invention is characterized by providing a drip chamber for use with an infusion set which is designed to prevent the passage of air through its exit chamber and which is ruggedized to withstand rough handling without suffering any damage.

In one preferred embodiment, the tubing interconnecting the container for the liquid to be infused and the hypodermic needle or catheter used, for example, for administration to the patient is provided with a drip chamber of a design which is uniquely adapted to prevent air from entering into the liquid flow, regardless of any change or deviation in the orientation of the drip chamber. The drip chamber, which may be made of glass, plastic or any other suitable transparent material, comprises a hollow housing having an inlet at its narrower end and an outlet at its wider end. The inside of the housing defines a first, inlet section adjacent the inlet end of the chamber and a second, outlet section of greater volume adjacent the outlet end of the chamber. An outlet tube extends into and through at least the outlet section of the drip chamber, the inner end of the tube having an outlet opening communicating with the inlet section of the housing. The interior walls defining the principal inside surfaces of the inlet section taper inwardly from at least the portion of such section adjacent the outlet tube opening toward the inlet end of the drip chamber, such that liquid fed into the drip chamber fills at least the outlet section thereof prior to overflowing through the outlet tube opening and exiting through such tube. The liquid in the drip chamber thus provides a liquid seal preventing the escape of air bubbles from the drip chamber through the outlet tube, irrespective of the orientation of the drip chamber.

Any disruption or deviation in the orientation of the drip chamber, whether deliberate or accidental, will have no effect upon the flow or direction of flow of the infusion liquid. This results from the fact that the volume of the inlet section of the drip chamber is significantly less than the volume of the outlet section of the drip chamber, thereby assuring that the opening of the outlet tube from the chamber will remain covered by the liquid so as to absolutely prevent the escape of air bubbles through such opening.

The outer ends of the inlet and outlet tubes may be connected with appropriate tubing to the container for the infusion liquid, the administering needle or catheter and, if desired, to a suitable stopcock or other valve. In order, however, to provide a drip chamber which is adaptable for use in a wide variety of applications, the drip chamber housing, in one preferred embodiment, is provided with reinforcing ribs arranged in a starburst fashion about each of the outwardly extending inlet and outlet tubes to prevent breakage thereof during storage or handling. As another alternative embodiment, the housing is designed to provide for recessed tubular interconnections to prevent breakage or separation of the several components of the infusion set during storage, handling or use.

It is, therefore, among the objects of the present invention to provide a simple, ruggedly designed drip chamber for use with infusion sets and the like to determine the flow rate of a sterile liquid, while simultaneously preventing air bubbles from passing through the drip chamber to the patient being treated.

THE DRAWINGS

The preceding as well as other objects and advantages of the invention will be apparent from the following description of a number of preferred embodiments of the drip chamber hereof shown in the accompanying drawings, in which:

FIG. 1 shows a sectional view of a drip chamber designed in accordance with the principles of the present invention;

FIGS. 2a and 2b are sectional and plan views, respectively, showing an alternative arrangement for the drip chamber of FIG. 1;

FIG. 3 is a sectional view of a portion of a drip chamber showing a further modification of the embodiment of FIG. 1;

FIG. 4 is a sectional view showing another alternative embodiment of the present invention;

FIG. 5 is a sectional view showing an alternative embodiment of the drip chamber; and

FIGS. 6a, 6b and 6c are schematic views, partially in section, showing a drip chamber as a component of an infusion set (with the drip chamber enlarged for purposes of clarity), and illustrating the liquid levels maintained in the drip chamber when its orientation is changed, whether accidentally or otherwise, during use.

THE PREFERRED EMBODIMENTS

A sectional view of a drip chamber 11 designed in accordance with the principles of the present invention is shown in FIG. 1. The drip chamber comprises a hollow housing indicated generally at 12 and defining an upper or inlet section 13 and a lower, larger volume outlet section 14. The housing inlet section 13 has inwardly tapering walls 15 extending toward inlet wall portion 16 of the drip chamber housing. An inlet tube 17 extends through such wall portion 16 and into the inlet section 13 of the drip chamber.

The outlet section 14, on the other hand, is defined by generally cylindrically shaped walls 18 and an adjoining outlet wall portion 19. An outlet tube 21 is formed integrally with such wall portion extending into and through the outlet section 14 of the drip chamber. Outlet tube 21 has an outlet opening or port 22 communicating with the interior of the drip chamber housing 12. The outlet tube is of a length such that the outlet port thereof communicates with inlet section 13 of the chamber housing. Thus, the tube may extend to the interface 23' between the inlet and outlet sections 13 and 14 (FIG. 4) or to some further plane 23 intersecting the inwardly tapering interior walls 15 of the drip chamber inlet section.

Inlet and outlet tubes 17 and 21 which may, as shown, be aligned with one another, suitably possess relatively small internal diameters such that the liquid passed through the inlet tube will form discrete droplets which may be counted as they pass from the inlet tube into the drip chamber housing. The internal diameters of both such tubes may, for example, be of the order of 2 mm. When the tubes are formed with these diameters the liquid droplets pass through the inlet section and are collected in the outlet section 14 of the drip chamber housing rather than passing directly into the outlet portion 22 of the outlet tube.

As the droplets collect in the outlet section 14, no liquid thus escapes from the drip chamber through the outlet tube. Rather, it is not until the liquid level reaches plane 23 (FIG. 1) or 23' (FIG. 4) that any liquid can overflow through the outlet port 22 and exit from the drip chamber via outlet tube 21. During continuous operation the discrete droplets of the liquid whose rate of flow is to be counted pass into the drip chamber housing, the liquid continuously overflowing through outlet port 22 and exiting from the drip chamber.

The normal orientation for the drip chamber is as shown in FIG. 1 with the inlet port being positioned directly above the outlet port so that their openings are substantially vertically aligned. If the orientation of the drip chamber 11 is either deliberately or accidentally altered from the vertical alignment as shown, the configuration of the drip chamber is such as to prevent the air which may have collected in the inlet section 13 of the drip chamber housing (i.e., in the region above the level 23 or 23') from exiting from outlet port 22. By providing adjoining inlet and outlet sections within the drip chamber housing, the former of which is of smaller volume and which is defined by inwardly tapering (conical, as shown in the drawings) wall surfaces, and extending the outlet tube into and through the outlet section such that the outlet opening communicates with the inlet section of the drip chamber housing, the liquid which overflows through the outlet opening acts as a liquid seal preventing the escape of air therefrom. Moreover, by incorporating inwardly tapering inlet section wall surfaces 15, air bubbles such as might form with orthogonally directed wall surfaces are not produced. Thus, any disorientation of the drip chamber merely displaces the liquid level without permitting air to escape through outlet port 22. Such is the case whether the drip chamber is either momentarily disturbed or is disturbed for longer intervals of time.

FIG. 4 shows a slightly modified embodiment from that shown in FIG. 1 wherein like components are designated by like numerals. The basic difference between the arrangement of FIG. 4 and that shown in FIG. 1 is that the outlet section 14 of the drip chamber 11' is open ended and that the outlet or base wall portion 19 is provided with an upwardly extending circular flange 19a which may be press fitted into the interior of outlet section 14 in the manner shown. This arrangement simplifies the production techniques employed in producing the drip chamber. Alternatively, the inlet section 13 of the housing 12 may be designed in a similar fashion with the upper or inlet wall portion 16 being provided with a similar flange to be fitted into an open-ended inlet section.

FIG. 5 shows still another alternative embodiment in which the outlet tube assembly 21' incorporates a separate member 24 having a slightly tapered hollow conical portion 21a integral with a hollow conical skirt 21b of greater taper. This member is preferably press fitted into the outlet surface 19 having an upwardly extending flange 19a. A porous filter sheet 25 is positioned between the lower edge of member 24 and the outlet surface 19. Sterile liquid is collected in the embodiment of FIG. 5 in a manner similar to that described hereinabove with regard to the embodiment of FIG. 1 until the liquid level reaches the height of the outlet port 22' of the member 24, at which time the liquid is then free to pass therethrough and through porous member 25 outwardly from the drip chamber. The porous filter member 25 acts to prevent any foreign matter from exiting through the outlet tube assembly and may be replaced at any time by a fresh filter member, if desired.

FIGS. 2a and 2b show a portion of a drip chamber, including the inlet section 13, incorporating a modified structure which may be employed with any of the drip chambers shown in FIGS. 1, 1a or 4. As shown therein, the inlet section 13 of a drip chamber 11'" is provided with a plurality of radially aligned ribs 26 each having a triangular configuration. The lower horizontal edge of each rib 26 is integrally joined to the upper surface of inlet wall portion 16. Each of the vertically aligned edges 26a of ribs 26 lies a spaced distance from the outer surface of the inlet tube 17. The vertically aligned edges 26a, together with the outer surface of the inlet tube 17, form a hollow annular region surrounding the inlet tube wherein a flexible connector 27 may be force fitted to provide a tight fitting between members 17 and 27. The radially aligned ribs 26 serve the dual functions of protecting the inlet tube 17 against undue bending and/or breakage, while simultaneously providing an improved fitting. Whereas six ribs are shown as illustrative in the embodiments of FIGS. 2a and 2b, it should be understood that greater or lesser numbers of reinforcing ribs may be provided, if desired.

It should further be understood that a substantially similar arrangement may be employed to protect the outlet tube 21 and to provide an improved fitting therewith. In a preferred embodiment, both the inlet and outlet tubes 17 and 21 are preferably so designed.

FIG. 3 shows another alternative embodiment for providing an improved fitting between the drip chamber and external connectors 27. In this form of the invention the inlet wall portion 16 of the drip chamber housing comprises a tapered surface which defines an annular opening together with the outer surface of the inlet tube 17 recessed within the opening. In this manner, the inlet tube is protected against undue bending and/or breakage which may occur as a result of rough handling. In addition thereto, the annular opening provides a press fit between the flexible connector 27 and inlet tube 17.

The outlet wall portion 19 of housing 12 (see FIG. 1) may be tapered in a fashion similar to that shown in FIG. 4 so as to provide a recessed arrangement for protecting and coupling the outlet tube 21 to an internal connector.

The use of a typical drip chamber 11 of the present invention as part of an infusion set is illustrated in FIGS. 6a, 6b and 6c. In these drawings there is schematically illustrated an infusion set comprising a bag, bottle or other container 28 for the blood, saline solution or other infusion liquid, a catheter or needle 29, and flexible connectors 27 coupling the liquid container, the drip chamber, and the administering needle or catheter. Preferably, the infusion set additionally includes a valve 31 for regulating the flow of the liquid infused consistent with the desired drip rate determined by periodic inspection of the feed of droplets through the drip chamber. Any conventional stopcock may be used as such valve means; preferably, however, infusion sets incorporating the novel drip chamber hereof additionally include stopcocks of the type described in my application Ser. No. 714,644 filed Mar. 20, 1968, entitled "Stop Cock", now abandoned and the continuation-in-part thereof, Ser. No. 48,807 filed June 8, 1970, now Pat. No. 3,678,960 granted on July 25, 1972.

The drip chamber hereof may be advantageously employed in the novel infusion set described in my copending application Ser. No. 132,516 filed Apr. 8, 1971 entitled "Non-Gravitational Infusion Set". The rugged construction of the drip chamber of this invention and the fact that such prevents air leakage through the administering needle or cannula irrespective of the orientation thereof makes it particularly useful in the infusion set described in the said application, which set is particularly useful for battlefield or like application in which it may be subjected to adverse conditions.

In FIGS. 6a, and 6b and 6c the drip chamber 11 is diagrammatically shown in three varying orientations to illustrate the liquid seal formed therein during use which prevents the escape of air bubbles from the chamber irrespective of the orientation thereof. Since the outlet tube 21 of the chamber extends into the inlet section of the chamber housing and such section possesses a smaller volume than the outlet section 14 thereof, more than half of the chamber volume is filled with liquid before any can overflow through the outlet port and through the connector 27 to the administering needle or catheter 29. The liquid levels 23a, 23b or 23c illustrated in the respective views are thus above the level of the outlet port 22, irrespective of the orientation of the drip chamber. In this manner the desired liquid seal is maintained and air bubbles cannot escape from the inlet section 13 of the drip chamber through the connecting tube to the administering needle or other device.

It may be seen from the foregoing description that the present invention provides a novel drip chamber for determining the flow of a liquid to be administered to a patient by means of an infusion set incorporating the same. Such drip chamber is both simple and rugged in design and construction and may, therefore, be utilized in a wide variety of applications. Moreover, the drip chamber design is such as to prevent the escape of air bubbles from the drip chamber and into the administering needle or catheter, irrespective of the accidental or intentional disorientation of the drip chamber from the vertical. It will be understood that other modifications of the preferred embodiments of the drip chamber described hereinabove may be made without departing from the scope of the present invention. The preceding description should, therefore, be construed as illustrative and not in a limiting sense.