US 3604420 A
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United States Patent ["21 lnvcntor Vincent L. Vaillancourt Livingston. NJ.
[21 I Appl No 792.565
[22 Filed Jan. 21.1969
 Patented Sept. 14, 1971 173] Assignee C. R. Bard, Inc.
Murray Hill, NJ.
 CLOSED SYSTEM DRAINAGE DESIGN 7 Claims, 7 Drawing Figs.
 References Cited UNITED STATES PATENTS 1,596,754 8/1926 Moschelle 128/350 3.428.046 2/1969 Remer et al. 128/349 1,928,992 10/1933 Clark et al. 128/349 2,749,913 6/1956 Wallace 128/295 3,190,290 6/1965 Alley et a1... 128/348 3,270,790 9/1966 Clark 128/275 3,332,422 7/1967 Jinkens et a1. 128/275 3,417,750 12/1968 Carson 128/349 3,429,314 2/1969 Ericson 128/295 X 3,430,631 3/1969 Abramson 128/350 Primary ExaminerCharles F Rosenbaum At!orneyW. Saxton Seward ABSTRACT: Means for eliminating the negative pressure problem in a closed urinary (or other) drainage system by shaping or conditioning the interior surface of the drainage tube to overcome differentially the surface tension of the liquid in the tube, permitting air to enter and release the column of liquid, such means comprising making the lumen of the tube noncircular (ridged or grooved), and, where needed. providing a slanting cut opening at the lower end of the tube.
PATENTEI] SIEPI 4m: 3.604.420
INVENTOR Vincent LVxiHam court BYhomWnlh-om ATTOR N EY-S CLOSED SYSTEM DRAINAGE DESIGN A major problem in the operation of a closed urinary drainage system is the hand-up of the liquid column in the drainage tube, which tube normally extends generally downward from the level of the patient's bladder to a receptacle some distance lower. The weight of such a column results in the development of negative pressure in the bladder, not only emptying it, but also tending to draw the bladder wall against the end of the catheter and even partly into the eyes thereof, with serious adverse effects on the patient.
Methods heretofore proposed to alleviate or eliminate this condition include venting the system at a suitable point in its upper portion and use of abnormally large diameter tubes. As for the latter a tube of more than I l/32-inch ID. will release its liquid column if vigorously shaken and it is believed that tubing larger than one-half inch will allow free flow of the liquid as air enters the outlet and bubbles up through the descending liquid, but most closed systems actually use tubing in the range of 3/l6-inch to 9/32-inch I.D. and substitution of larger tubing is not considered practical or convenient.
The entry of air into the lower end of a small tube is prevented by the surface tension of the liquid column at that point. It has been discovered that the provision of a tube having a noncircular lumen, i.e., longitudinally ridged or grooved, so increases the wetted perimeter of the tube lumen that the surface tension can no longer hold the end of the liquid column together to prevent entry of air. As a result the liquid will descent in discontinuous slugs or drops as air bubbles ascend, and the negative pressure, if any, developed in the bladder remains within tolerable limits.
Practical embodiments of the invention are shown in the accompanying drawings, wherein:
FIG. 1 represents an elevation of a complete closed urinary drainage system;
FIG. 2 represents an elevation of a drainage bag and holder having an ordinary drop chamber;
FIG. 3 represents a detail vertical sectional view of the upper part of the drip chamber of FIG. 1, the vent being enlarged out of proportion for illustrative purposes;
FIG. 4 represents a transverse section on the line IVIV of FIG. I;
FIG. 5 represents a section corresponding to FIG. 4 showing an alternative form;
FIG. 6 represents a detail horizontal section on the line VI- VI of FIG. 3 through the vent and cap only, and;
FIG. 7 represents a detail vertical section of the upper portion ofa drip chamber with straight-cut tube end.
Referring to the drawings, a urinary drainage system is shown as comprising the normal elements of catheter 1, drainage tube 2, drip chamber 3 and collection receptacle 4, in the form a bedside bag supported in any customary manner. With the catheterv installed in a patient the flow of liquid through the tube 2 would, in the case of a plain tube having an ID. less than one-half inch, create undesirable negative pressure in the bladder due to the weight of the downwardly moving liquid column. This is overcome in the present case by forming the drainage tube 2 in a special configuration, as indicated in FIGS. 4 and 5, the interior having longitudinally extending ridges or splines 5 (FIG. 4) or grooves 6 (FIG. 5). It is found that the noncircular cross section of the tube lumen has a disorienting effect on the surface tension at the lower end of the liquid column, permitting air to bubble up through the liquid and effectively counteracting the negative pressure at the upper end.
The commencement of such bubbling action can be assured by the provision of a bevel tip 7 at the lower end of the drainage tube, within the drip chamber. If a liquid column (or slug of any length) reaches this point substantially intact, it will be broken up immediately by the entry of air at the upper portion ofthe bevel opening.
Air is permitted to enter the drip chamber (or leave it) through a vent 8, shown as including a collar 9 projecting upward from the top of the chamber 3, a venthole 10 passing through said top, a small wad of cotton 11, acting as a filter, and a cap 12 with inwardly projecting fins 13 between which air may pass. The form of the recess within the collar 9 permits easy insertion of the cotton filter.
Liquid enters the drip chamber from the tube 2 with a head which may be as much as two or three feet (plus pressure from the bladder) so that there is likely to be a rapid flow, whereas the head in the drip chamber, vented to atmosphere, is only the depth of the pool which may collect in the drip chamber. The base 24 of the chamber must therefore be substantially larger than the inlet; it is fitted with a wide flutter valve 15 within the bag 4, designed to permit emptying of the drip chamber at a rate fast enough to prevent flooding.
The drip chamber 3, bag 4' outlet 14' and flutter valve 15, shown in FIG. 2 are substantially in scale for a nonvented drip chamber, in comparison to the enlarged drip chamber, outlet and flutter valve of FIG. 1.
The flutter valve 15 physically closes off the drainage bag 4 from the drip chamber 3 and the drainage tube 2 so that there is no open-air path for airborne bacteria to ascend from the bag into the drip chamber, tube and eventually the patient. The drip chamber breaks the liquid path but no provisions have been made heretofore to break also the air path.
The cap 12 over the vent protects the cotton 11 from becoming wet in the event that the patient takes the bag into a shower. If wetted, the cotton would close the vent.
In the alternative form of FIG. 7, the lower end 16 of the drainage tube is shown as being cut straight across, without the bevel. While the provision of a noncircular cross-sectional form in the tube lumen tends to permit entry of air bubbles, even without the beveled end, more reliable operation can be achieved when the tube end is bevel cut. In fact, the provision of a beveled end on a tube of circular cross section will ensure entry of air bubbles into the tube, particularly in the larger sizes, e.g. 9/32-inch I.D., but the combination of the bevel with the noncircular section gives the best assurance of satisfactory operation.
What I claim is:
l. A closed system for drainage of liquid from a body cavity comprising a tubular conduit having a liquid inlet opening in the cavity and a downwardly extending section, a drip chamber, and a drainage receptacle in a position to receive liquid from said conduit, the lumen of at least part of the downwardly extending section being noncircular in cross section, the lower end of said noncircular part of .the downwardly extending section projecting into the drip chamber, and said lower end, being bevel cut.
2. A system according to claim I in which the air vent is constituted by a hole through the top of the drip chamber, a collar surrounding said hole and a cap fitting over said collar with provision of an air passage between the collar and the cap.
3. A closed system for drainage of liquid from a body cavity comprising a tubular conduit having a liquid inlet opening in the cavity and a downwardly extending section, a drip chamber, and a drainage receptacle in a position to receive liquid from said conduit, the lumen of at least part of the downwardly extending section being noncircular in cross section, the lower end of said noncircular part of the downwardly extending section projecting into the drip chamber, and the drip chamber being provided with a flutter valve on its outlet.
4. A closed system for drainage of liquid from a body cavity comprising a tubular conduit having a liquid inlet opening in the cavity and a downwardly extending section, a drip chamber, and a drainage receptacle in a position to receive liquid from said conduit, the lumen of at least part of the downwardly extending section being noncircular in cross sec tion, the lower end of said noncircular part of the downwardly extending section projecting into the drip chamber, the drip chamber being provided with an air vent, and the lower portion of the drip chamber being enlarged and provided with a wide-flaring flutter valve on its outlet.
5. A drip chamber for use in a body fluid drainage system comprising a hollow closed container, an inlet tube extending into the upper part of the container and terminating at a point below the container wall through which the tube passes, an outlet at the bottom of the container the cross-sectional area of said outlet being substantially larger than the cross-sectional area of the inlet tube and an air vent in the upper part of the container at a level above the termination of the inlet tube.
6. A drip chamber according to claim 5 in which the outlet is provided with a flutter valve of a size sufficiently large to permit the flow of fluid outward through the outlet at a rate at least equal to the rate of flow into the container through the inlet tube.