Disposable Blood-warming Container

Abstract

A container for adjusting the temperature of liquids such as blood flowing therethrough, which comprises a plastic envelope, heat sealed to define a tortuous fluid flow conduit therein. The conduit has an inlet and an outlet communicating with the exterior of the container. The outlet communicates with the interior of a drip chamber, the end of the outlet being spaced from the walls of the drip chamber to permit liquid passing from the outlet to fall a short distance through space, to indicate the rate of liquid flow, and to separate and entrap in the drip chamber any gas bubbles present.

Description

BACKGROUND OF THE INVENTION

Between collection and administration, blood is generally kept in refrigerated condition to prolong its useful life. However, when an individual requires the administration of blood, the blood must be warmed prior to administration in order to avoid placing excessive stress upon the metabolism of the individual by administering cold blood.

Conventional blood warmers such as disclosed in the Pins U.S. Pat. No. 3,475,590 are used with a disposable plastic blood flow liner within an electrically operated blood warming apparatus or the like. However, difficulties have been encountered in that as the blood is warmed, its capacity to retain dissolved gases is reduced, and thus gas bubbles are formed which flow along with the blood out of the warming apparatus. Also, bubbles are formed from entrapped air as conventional blood flow liners are filled. It is extremely important that these gas bubbles be removed prior to administration of the warmed blood to the patient, and typically, the blood is directly transferred from the blood warmer to the patient without further storage.

It is also important to determine the rate of blood flow through the blood warmer and the corresponding rate of blood administration to the patient.

DESCRIPTION OF THE INVENTION

The invention of this application provides means for automatically removing gas bubbles from the blood prior to administration, while simultaneously providing a flow rate indicating means in conjunction with a disposable liner which can be used with a conventional blood warmer of, for example, the electrical type or the warm water heat exchange type.

In accordance with this invention, a container or liner for adjusting the temperature of liquids such as blood flowing therethrough comprises a plastic envelope heat sealed to define a tortuous fluid flow conduit therein. The conduit has an inlet and an outlet communicating with the exterior of the container, the outlet communicating with the interior of a drip chamber to permit liquid passing from the outlet to fall a short distance through space. By this, the rate of liquid flow from the blood container is indicated and an opportunity is provided for gas bubbles to be trapped in the drip chamber to prevent bubbles from being swept on into the patient.

Typically, the inlet is spaced below the outlet in the position of use and at one end of the container, while the outlet is spaced at the other end to facilitate the bubble-free filling of the fluid flow conduit by the liquid flowing therethrough. The displaced air in the conduit is swept through the chamber in front of the advancing liquid and out of the exit port, until the system is filled and ready for administration to the patient.

Referring to the drawing, a preferred embodiment of this invention is shown in plan view.

A pair of plastic sheets 10, 12, made of vinyl or the like, are shown laid together in side by side relationship and secured together by sets of heat seals 14, 16 to define a tortuous fluid flow conduit 17 passing through the container. A plurality of tortuous conduits in parallel relation can also be used, if desired. The container has an inlet tube 18 and an outlet tube 20 leading into respective ends of the tortuous fluid flow conduit, both the inlet and the outlet communicating with the exterior of the container.

Outlet 20 communicates with the interior of a drip chamber 22, which is typically made of plastic tubing, heat sealed at both ends. Outlet 20 is disposed in a transverse relation to the drip chamber 22, passing through tubular outer jacket 21, and sidewall 24 of chamber 22, to prevent kinking of outlet 20. An advantage to this construction is that when the container is oriented in its position of use with heat sealed end 26 of drip chamber 22 pointing downward, the fluid flowing through last horizontal leg 28 of the tortuous fluid flow conduit tends to separate any remaining gas bubbles entrapped in the conduit or generated by heating of the liquid upwardly to the top of leg 28 and outlet 20. Then, when the liquid and separated gas bubbles come to the end 30 of conduit 20, the liquid falls downwardly and tends to be further separated from the gas bubbles, which join the entrapped gas portion of the drip chamber.

Typically, for the administration of one unit of blood, only a 15 to 20 cc. drip chamber needs to be used since approximately 1 or 2 cc. of gas are generated during the heating process, and there are only very few, if any, bubbles of air trapped in the system during filling because of the advantageous configuration described above.

The drip chamber 22 is supported by brace 32, which is attached to both the drip chamber and plastic sheets 10 and 12. A liquid exit port 34 is located in heat sealed end 26 of the drip chamber, and typically carries or communicates with flexible tubing 36, which has conventional means 38 for mounting a blood administration needle thereon for administration of blood to the patient. In the embodiment shown, mounting means 38 has a sterile covering 40, a latex supplemental injection site 42, and a roller clamp 44 for adjusting flow through tubing 36.

Inlet 18 communicates with flexible tubing 46, which in turn connects to coupling means 48 for connection to a blood supply, such as a blood bottle or bag. Coupling means 48 is closed with sterile seal means 50.

The container of this invention can be used in a blood warmer of the type disclosed in the above-cited Pins patent by sliding sealed sheets 10 and 12 into the slot of the blood warming device described therein, or it can be utilized in other types of blood warmers, such as those comprising a pair of opposed warming plates hinged to each other to swing open and closed, and having studs for mounting the container of this invention on one of the heating plates. In the embodiment shown, tabs are provided defining holes 52 for emplacement of the container on such studs for proper positioning in such a blood warmer. The holes 52 and studs of such a blood warmer are arranged in an asymmetrical manner to prevent the container from being inserted in improper orientation.

The above description is intended for illustrative purposes only, and it is seen that many modifications of this invention can be readily made which fall within the teachings of this invention.

Claims

What is claimed is:

1. A container for adjusting the temperature of liquid flowing therethrough, which comprises a plastic envelope, heat sealed to define a tortuous fluid flow conduit therein, an inlet and an outlet to said conduit communicating with the exterior of said container, a drip chamber, said outlet communicating with the interior of said drip chamber and disposed in transverse relation to said drip chamber passing through a sidewall of said chamber, the end of said outlet being spaced from the walls of said drip chamber to separate and trap in said chamber any bubbles present.

2. The container of claim 1 in which said inlet is spaced below said outlet in position of use to facilitate the bubble-free filling of said fluid flow conduit by said liquid flowing therethrough.

3. The container of claim 2 in which said drip chamber has a liquid exit port which communicates with flexible tubing having means for mounting a blood administration needle thereon.

4. The container of claim 3 in which said inlet is in fluid communication with flexible tubing having coupling means for connection to a blood supply.

5. The container of claim 4 having a single tortuous fluid flow conduit.