Title:
BLOOD DRIP CHAMBER
United States Patent 3834386


Abstract:
A blood drip chamber is provided with a cap having a large penetration area which includes a self-sealing rubber supported by a layer of stiffer material. The inner surface of the stiffening material is at the same general level as the remainder of the inner surface of the cap so that blood is not held by capillary action in the penetration area. The blood drip chamber includes a reservoir having a sidewall, a lower discharge port and an upper end. A blood inlet port is positioned centrally in the cap so that the inflow of blood is maintained away from the sidewalls of the reservoir.



Inventors:
SISLEY J
Application Number:
05/286857
Publication Date:
09/10/1974
Filing Date:
09/07/1972
Assignee:
SWEDEN FREEZER,US
Primary Class:
Other Classes:
215/309, 604/86, 604/415, D24/117
International Classes:
A61M1/36; A61M5/14; (IPC1-7): A61M5/16
Field of Search:
128/214R,214C,214D,214.2 215
View Patent Images:
US Patent References:



Primary Examiner:
Truluck, Dalton L.
Attorney, Agent or Firm:
Seed, Berry, Vernon & Baynham
Claims:
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows

1. A blood drip chamber for hemodialysis or the like comprising a reservoir for holding a quantity of blood and having a lower end with a discharge port, an upper end, and sidewalls extending between said ends; and a cap covering said upper end, said cap having a generally centrally located inlet port means for directing blood into said reservoir inwardly away from the sidewalls of the reservoir and for forming a pool of blood at the bottom of the reservoir, and penetration means in said cap for introducing a syringe needle into said reservoir and including a self-sealing medium for closing the penetration means when the needle is withdrawn, said penetration means extending approximately at least a third of the way around said inlet port means for providing a large penetration area for a syringe needle, said penetration means including a layer of stiffening material bonded to the underside of the self-sealing material for avoiding contaminable air gaps between the self-sealing material and for supporting the self-sealing material when a syringe needle is inserted or withdrawn by strengthening the self-sealing material for withstanding the stress resulting from multiple insertions of the syringe needle, said stiffening material being bonded to said self-sealing medium over substantially the entire area of contact between said self-sealing medium and said stiffening material.

2. The blood drip chamber of claim 1, said penetration means including an inner surface at generally the same level as the inner surface of the remainder of said cap.

3. A blood drip chamber for hemodialysis or the like comprising a reservoir for holding a quantity of blood and having a lower end with a discharge port, an upper end, and sidewalls extending between said ends; and a cap covering said upper end, said cap having an inlet port means for directing blood into said reservoir away from the sidewalls of the reservoir and for forming a pool of blood at the bottom of the reservoir, and a penetration area covering a substantial region of said cap for the insertion of a syringe needle through said cap, said penetration area including a soft self-sealing material, and a layer of supporting material below said self-sealing material and bonded thereto over substantially the area of contact between said self sealing medium and said supporting material to prevent contamination of the surfaces between the self-sealing material and the supporting material and to support the latter from stress of a syring needle when inserted or withdrawn.

4. The blood drip chamber of claim 3 said supporting material lying generally in the plane of the inner surface of the remainder of said cap.

Description:
BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to blood drip chambers for hemodialysis or the like.

2. Description of the Prior Art

Hemodialysis requires removal of the blood from the circulatory system of the patient and then after dialysis the blood is returned into the circulatory system. Blood drip chambers are added to the arterial and or venous vessels to reduce the possibility of air leakage into the circulatory system. A blood drip chamber generally includes an elongated tubular reservoir having a bottom discharge port and an upper end covered by a cap. The cap is provided with a blood inlet port and a penetration region and generally with some form of optional monitoring port. The blood inlet port directs the blood into the reservoir where the level is maintained at approximately one-half the height of the reservoir so that air bubbles in the blood are free to rise and be released into the air in the top portion of the reservoir. The penetration region is provided for the insertion of a syringe into the reservoir either to remove blood for sampling or for maintaining a proper level in the reservoir or for the introduction of medication into the blood during dialysis.

Blood drip chambers heretofore used in the industry have several shortcomings. One problem with prior art drip chambers is caused by the inherent characteristic of blood to immediately increase its viscosity or coagulate when it loses velocity and to form fibrin. Whenever fibrin formation (clotting) occurs within hemodialysis sets in use, the patient's well-being is jeopardized.

In prior art drip chambers fibrin formation frequently occurs since the blood inlet port generally is near the sidewall of the chamber with the blood being directed against the sidewall before it reaches the pool of blood at the lower end of the reservoir. As the blood touches the sidewall it begins to coagulate frequently leaving a residue on the sidewall. Secondly, non-flowing blood in a small vertical tube will be held in the tube against gravity due to the capillary action of the tube. In prior art drip chambers the penetration region for introducing syringes into the chamber consists of a small tube projecting up from the cap of the chamber. Consequently, blood splashing into the tube is held causing a fibrin build up situation.

An additional shortcoming of prior art blood drip chambers is that the penetration region is a cap secured to a short small diameter tube in the cap of the chamber and is difficult to hit with a syringe needle. The diameter is so small that a non-axially inserted needle will frequently penetrate the side of the tube. Furthermore, because of the small diameter and thus small surface area the selfsealing rubber in the penetration area can only tolerate a relatively few number of needle penetrations before losing its self-sealing capability.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a blood drip chamber in which the blood inlet port is centrally positioned in the cap of the chamber.

It is an object of this invention to provide a blood drip chamber which has a large penetration area for the insertion of hypodermic syringes.

It is another object of this invention to provide a blood drip chamber having a central blood inlet port partially encircled by a large penetration area.

It is an object of this invention to provide a cap for a blood drip chamber in which blood deposits are minimized.

Basically the invention comprises a reservoir having a lower discharge port and an open upper end. A cap is provided over the upper end. The cap has a centrally-located blood inlet port and a large target area covering approximately a third or more of the remainder of the cap. The inner surface of the penetration area is generally aligned with the remainder of the inner surface of the cap. Self-sealing material is provided on the penetration area.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric of the preferred form of blood drip chamber with parts removed for clarity.

FIG. 2 is a fragmentary section taken along the line 2--2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The blood drip chamber 10 includes a reservoir 12 having a smooth sidewall 14 and a lower discharge port 16. The upper end of the reservoir is provided with an open end 18 which is covered by a cap 20. The cap and reservoir are all formed from medical-grade, water-clear, non-pyrogenic, non-toxic polyvinyl chloride. Preferably the polyvinyl chloride material is soft enough to "milk" or squeeze blood from the chamber but stiff enough to withstand negative pressures that are typical in a dialysis system.

The cap 20 is uniquely provided with a centrally positioned blood inlet port 24 which is coupled to a tube 26 in a conventional manner. Blood flowing through the tube 26 is discharged into the reservoir forming a pool of blood B with an air space above it. Since the blood is fed centrally into the reservoir there is less opportunity for blood to strike the sidewall above the level of the pool B where it can coagulate.

A second unique feature of the invention is the provision of a large self-sealing penetration (injection) area or region 28. As best shown in FIG. 1 the penetration area is substantially kidney-shaped extending all the way from the diameter on one side of the inlet port to the diameter on the other side of the inlet port. The penetration region has an upright wall 30 which houses a self-sealing material 32 of a type conventional in this art. A thin layer of polyvinyl chloride 34 is left in the molding process at the inside of the penetration area. The purpose of the thin layer of polyvinyl chloride is to provide stiffening support for the self-sealing material throughout the large surface of the penetration area. During both insertion of a syringe needle through the penetration area and the removal of the needle the self-sealing material clings to the needle. The support 34 holds the self-sealing material from thus pulling out or being pushed in by the needle. Since the polyvinyl chloride is relatively thin it provides little obstruction to the penetration of the needle. The large surface allows the needle to be inserted at variable angles and provides for numerous insertions without the selfsealing material losing its capability to seal.

As is best shown in FIG. 2 the thin polyvinyl chloride layer 34 forming the bottom of the penetration area terminates generally flush (relative to prior art tubes) with the remainder of the inner surface of the cap indicated by the reference character 38. The width of the penetration area above the surface 38 is substantially large so that no capillary action is present to capture and hold blood in the penetration area.

If desired, an optional monitoring inlet 40 (not shown) may be provided as is conventional.

While the preferred form of the invention has been illustrated and described it should be understood that variations and alternatives will be apparent to one skilled in the art without departing from the principals thereof. Accordingly, the invention is not to be limited to the specific embodiment described but rather only by a literal interpretation of the claims appended hereto.