Anticoagulating Blood Suction Device

Abstract

An anticoagulating blood suction device for use in intra-operative autotransfusion operations which removes pools of blood and simultaneously draws a controlled amount of anticoagulant into the stream of blood by means of a metering orifice designed on the Venturi principle. The prescribed amount of anticoagulant is mixed with the volume of blood removed from the wound regardless of blood volume variations per unit of time.

Description

FIELD OF THE INVENTION

The present invention relates to the field of autologous blood reinfusion and, more particularly, to a blood suction device for use in intra-operative autotransfusion which feeds a controlled amount of anticoagulant into the blood stream which amount is dependent upon the flow rate of blood being drawn.

BACKGROUND OF THE INVENTION

Autotransfusion, defined as the return of a patient's blood to his own circulation during an active bleeding episode, has been used sporadically since 1886 for a wide variety of surgical problems. While autotransfusion has been shown to be a safe and effective means of blood replacement in selected surgical cases, its routine use has not been established. One reason for this is the previous lack of practical and efficient methods of processing blood recovered at surgery for reinfusion.

When autotransfusion was initially used, open collection techniques including sponging, ladling and bulb suction were employed. Anticoagulation was achieved with citrate or hemodilution, and blood was filtered through multilayered gauze to remove contaminants. The return of blood was accomplished subcutaneously, intramuscularly, intravenously or even per rectum when grossly contaminated. Later, a closed system using a vacuum suction and tonsil tip suction device was developed. Wall vacuum suction was later replaced by a roller pump device to minimize hemolysis. Many improvements in filtration devices have also been described in the prior art.

While collection and filtration devices for autotransfusion have been modernized, methods of anticoagulation of the blood to be reinfused have changed little in the past 80 years and leave much to be desired. U.S. Pat. No. 3,492,991, to Dyer, Jr. recommends anticoagulation of blood in a collection reservoir or chamber using either citrate or aqueous heparin introduced by "in-line" drip. This method of "chamber anticoagulation" demands constant surveillance and monitoring by an assistant for proper anticoagulation and may allow clot formation to occur in the vacuum line between the suction tip and the collection chamber.

A second method of anticoagulation is systemic heparinization. While this method is satisfactory for peripheral vascular surgery, its use would not be readily acceptable in patients where a significant amount of soft tissue dissection is anticipated or in patients suffering from multiple trauma.

SUMMARY OF THE INVENTION

The present invention eliminates the problems of the prior art by anticoagulating the blood as it is removed from the surgical field. A metering orifice near the vacuum tip, operating on a Venturi principle, draws a controlled amount of anticoagulant into the blood stream immediately after the blood leaves the surgical field. The orifice is designed to permit a predetermined anticoagulant-blood ratio to be achieved regardless of the volume or rate of flow of blood aspirated.

It is therefore an object of the present invention to overcome the above described problems in the prior art.

It is another object of the present invention to provide improved autologous blood reinfusion.

It is another object of the present invention to provide a novel means for anticoagulating blood in an autotransfusion process.

It is still another object of the present invention to provide an autotransfusion device which avoids the need for systemic anticoagulation.

It is yet another object of the present invention to provide an anticoagulating blood suction device with which a controlled ratio of anticoagulant to blood may be maintained regardless of the blood flow rate.

It is another object of the present invention to provide an autotransfusion device in which anticoagulant is introduced within the suction device thus preventing blood clot formation during extra-corporeal flow.

These and other objects will become more clear with reference to the following description and the attached drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an anticoagulating suction device *(*See "Intraoperative Autotransfusion -- Preliminary Report of a New Blood Suction Device for Anticoagulation of Autologous Blood" by Bennett, Hoye and Riggle, Am. J. of Surg., Vol. 123, hereby incorporated by reference.) of the present invention.

FIG. 2 is an enlarged cross-sectional view showing the venturi assembly of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a suction device 5 in accordance with the present invention connected to a suitable vacuum creating device such as a roller-type pump (not shown) via a connector 11 at one end. A suction tip 12 is attached to the other end of the device.

Forming a central portion of the device 5 is a tube 14, soldered at one end 7 to a blood receiving nozzle 10. The nozzle 10 has a gently rounded tip 6 for receiving the entering blood without injuring the blood cells. A filtering housing 9, threaded at its base, is screwed to the nozzle 10. The housing 9 has a perforated or screened portion 13 around its periphery for receiving the blood but keeping out any pieces of tissue or contaminants which may be in the blood. The screen portion 13 of the housing 9 may be made of either screening or perforated metal but the latter is preferred in order to minmize hemolysis. The nozzle 10 and the filtering housing 9 make up the suction tip 12.

From the suction tip 12, the tube 14 leads to a venturi section 15, comprising a venturi element 16 having a flanged portion 27. A sleeve 17 is attached to the end of the tube 14 and the flanged portion 27 of venturi element 16 is compressed against the end of the tube 14 with the tube 14 being press-fitted within the sleeve 17. A tube 22 fits over the venturi element 16 and an externally threaded sleeve 24 fits over the tube 22 and is preferably soldered thereto. The sleeve 24 threads into the sleeve 17 up to the flanged portion 27 of venturi 16. An internally threaded and externally knurled collar 20 threads over the sleeve 24 and is separated from the sleeve 17 by an o-ring 28 which acts as a seal between sleeve 24 and sleeve 17. A tube 21, concentric about the tube 22, is fitted over the end of element 24 and is sealed by an o-ring 29. An o-ring 32 acts as a seal between the venturi element 16 and the tube 22.

A thumb plate 18 is attached to the sleeve 17 and an air vent orifice 19 passes through thumb-plate 18, sleeve 17 and tube 14. The interior of the venturi element 16 narrows to a small-diameter neck or throat 31 and a siphon orifice 30 is located at the neck 31. At least one metering hole 23 is provided in the tube 22 around the location of the siphon orifice 30.

A plug 26 is located at the end of tube 21 and seals the annular space between tube 22 and the end of tube 21. An anticoagulant flow line 25 passes through the plug 26 to communicate with the annular chamber which is formed between tubes 21 and 22. The flow line 25 is connected to a source of anticoagulant (not shown).

In operation, pooled blood is drawn into the tube 14 through the suction tip 12 and passes throuh the venturi throat 31 when the air vent 19 is sealed by the thumb of the operation. Anticoagulant is drawn into the suction device by the Venturi principle. Thus, by narrowing a section of the suction tube, an increase in the velocity of blood flow occurs with a decrease in pressure. This creates a relative vacuum opposite the point of conveyance causing the anticoagulant to be drawn into the suction line at that point. The anticoagulant solution enters the chamber formed between tubes 21 and 22 and is drawn into the stream of blood through the holes 23 in tube 22 and metering orifice 30 in venturi element 16.

The thumb control air vent 19 allows the operator to interrupt suction if the negative pressure at the suction tip 12 has drawn soft tissue or fat around the tip to occlude the openings. This feature prevents the sudden inflow of anticoagulant solution into the system if the tip should become occluded.

It is preferable that a suitable check valve assembly (not shown) be incorporated in the anticoagulant inflow line to prevent the anticoagulant from flowing retrograde from the suction device at the conclusion of each aspiration.

The anticoagulant infusion system of the present invention has been shown to cause minimal hemolysis while introducing controlled amounts of anticoagulant proportionate to the blood flow rate. The ratio of anticoagulant to blood has been shown to remain within satisfactory limits and relatively consant regardless of whether the suction tip is totally immersed in the pool of blood allowing no air to be introduced or whether the suction tip is placed at the air-liquid interface, thereby permitting both fluid and air to enter the system.

In the above-described embodiment of the present invention it is seen that the venturi element 16 is removable and replaceable. The ratio of anticoagulant to blood can be varied by varying the size of the venturi throat 31 and/or the metering holes 23. If the inner diameter of tubing 14 is about 3.4 mm. it has been found that a venturi throat diameter of 1.8 mm. and a single metering hole diameter of 0.4 mm. will draw approximately 30 ml. of heparin per 1,000 ml. of blood.

It is of course necessary that all materials used in the manufacture of the device 5 be compatible with blood and stainless steel is preferred. Furthermore, it is recommended that all surfaces which come in contact with blood be silicone resin coated.

While a full and complete description of the invention has been set forth in accordance with the dictates of the patent statutes, it is to be understood that the invention is not limited to the basic embodiment herein shown. Accordingly, modifications may be made without departing from the invention.

Claims

What is claimed is:

1. An anticoagulating blood suction device comprising:

a tube;

a suction tip at one end of said tube;

vacuum means for creating a partial vacuum in said tube connected thereto at the end remote from said suction tip; and

metering means within said tube for drawing anticoagulant into said tube at a rate proportionate to the flow rate of blood passing said metering means, wherein said metering means comprises

a venturi element with a passageway therein narrowing to a neck and then widening again to the inner diameter of said tube; and

a chamber connected to said tube in the area of said venturi element for maintaining anticoagulant therein;

said venturi having an orifice therethrough in the area of said neck communicating with said chamber whereby the pressure decrease caused by the passage of blood past said neck in said venturi element will draw anticoagulant through said orifice in an amount proportionate to the flow rate of the bood.

2. An anticoagulating blood suction device in accordance with claim 1, further including:

a second tube surrounding said first mentioned tube and coaxial therewith, said chamber for anticoagulant being defined by the annular space between said first mentioned tube and said second tube; and

a metering hole in said tube in the area of said orifice for permitting the flow of anticoagulant from said chamber to said venturi element.

3. An anticoagulating blood suction device in accordance with claim 1 further including:

a housing means connected to said suction tip for preventing pieces of solid material from entering said tube.

4. An anticoagulating blood suction device in accordance with claim 3 wherein:

said housing means includes a screen of perforated metal.

5. An anticoagulating blood suction device in accordance with claim 1 wherein:

all of the surfaces of the device which come in contact with blood are silicon resin coated.

6. An anticoagulating blood suction device in accordance with claim 1, further including:

air vent means comprising a vent through said tube located between said metering means and said suction tip for preventing aspiration from said suction tip when open and permitting aspiration when closed.