Surgery – Means for introducing or removing material from body for... – Treating material applied to or removed from external...
Reexamination Certificate
2000-07-12
2003-05-20
Lo, Weilun (Department: 3761)
Surgery
Means for introducing or removing material from body for...
Treating material applied to or removed from external...
C604S289000, C604S317000
Reexamination Certificate
active
06565544
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a blood removal device particularly useful in medical procedures.
The removal of unwanted fluids during surgical procedures constantly poses a problem for surgeons and surgical assistants. For example, copious amounts of saline solutions are commonly used in eye surgery. Other surgical procedures, although not employing large quantities of irrigating solutions, generate blood from a bleeding source during such surgery.
Reference is made to U.S. Pat. No. 5,599,330 which represents a marked advance in the art of removing surgical irrigating solutions without trauma to surrounding tissues. However, although successful in removing blood atraumatically from a bleeding source during surgery for a short time, clotting of the blood within a few minutes clogs the wicking element found in devices described in U.S. Pat. No. 5,599,330. It is believed such clotting is due to the fine porous openings though the wicking element, which are sized in order to facilitate capillary action. However, such fine pore sizing exacerbates clogging due to clotting by blood and blood containing fluids.
It is known that clotting or coagulation is initiated by thrombin, formed from prothrombin, which facilitates the clotting of blood by catalyzing conversion of fibrinogen to fibrin. Antithrombotic or antithrombogenic materials are known, such as heparin. However, the application of most heparin compounds and/or complexes to wicking elements such as sponges with fine pores, although preventing the clotting of blood, also severely inhibits wicking. This is believed to be due to the naturally hydrophobic nature of such compounds or complexes.
Materials and combinations of materials have been proposed to transport or absorb moisture and blood from wounds. For example, U.S. Pat. No. 5,540,964 describes a moisture transport material which utilizes a hydrophilic synthetic material that is employed beneath a cast to reduce moisture conditions, promoting fungal and bacterial growth.
U.S. Pat. Nos. 5,447,505 and 5,977,428 show absorbent dressings for wounds which are intended to permit the removal of wound exudates, including blood, by the use of imbedded hydrogel particles and the predetermination of pore size with a particular polymeric material.
U.S. Pat. No. 5,928,174 shows a wound dressing device in which removal of moisture in the wound area is enhanced by forming absorbent material into a plurality of free floating strands.
U.S. Pat. No. 3,969,498 describes a wound dressing having a water-soluble body which may be aerated and foamed to adhere to wound tissue and form an artificial eschar or a scab.
U.S. Pat. No. 5,466,231 shows a laminated sponge device in which a polyvinyl acetate sponge body is laminated on multiple sides by a surface layer having perforations of a small pore size to permit fluids to pass through the laminate and be absorbed by the sponge body.
Relatively large diameter catheters have been coated with heparin in the past to prevent clotting or coagulation of blood while the catheters are used to deliver medications, blood components, fluids, hyperalimentation products, and to measure central venus pressure, in surgical situations.
Catheters have also been used in various cardiovascular procedures such as angioplasty and stent insertion. extract blood in surgical situations.
A blood removal device which employs wicking elements which are not clogged by the blood would be a notable advance in the medical field.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention a novel and useful blood removal device is herein provided.
The system of the present invention includes a wicking element having a surface which may be exposed to blood and a zone within the wicking element which is spaced from the blood-contacting surface. The wicking element may take the form of polymeric materials formed into an open-cell configuration, a bundle of fine elongated fibers, a unitary body having a pore structure and the like. For example, low density polyethylene (LDPE), cellulose, polyvinyl acetyl, polyester, polyurethane and generally hydrophilic polymeric materials may be employed in this regard. The wicking element may be formed into a particular shape which is compatible with aspiration or suction devices. As is the case with the surgical wicking device disclosed in U.S. Pat. No. 5,599,330, the suction is normal and does not create a suction force on the surface of the wicking element in contact with the blood.
An antithrombotic material is applied to the surfaces of the wicking element to the extent that coagulation of blood is prevented and the wicking function of the wicking element is not inhibited. In certain cases heparin compounds and complexes may be employed in this regard. Of course other antithrombotic materials may be used. For example, heparin-benzalkoniium chloride (HBAC), 1.5% in isopropanol, heparin-tridodecylmethylammonium chloride (TDMAC), 2% in toluene, sodium or lithium heparin (NaHEP, LiHEP), 2% in deionized water serve as excellent sources of antithrombotic material which pervades the wicking element.
In many instances, the antithrombotic material is applied directly to the wicking element surfaces. In addition, a surfactant or surfactants may be used in conjunction with the antithrombotic material, HBAC, TDMAC, NaHEP, LiHEP and the like to insure wicking through the wicking element without affecting. the anticoagulation function provided by the antithrombotic material. In this regard, one or more surfactants may be employed in conjunction with a particular material used to construct the wicking element. Notably, silicone-glycol copolymer, ethoxylated esters, glycerin, and other hydrophilic surfactants have been found to be satisfactory in many cases in the present invention.
In addition, the surface of the wicking material may be modified using a plasma or corona treatment to provide a surface which readily accepts the antithrombotic, and in certain cases, surfactant material. It is believed that plasma or corona treatments provide an alteration of the surfaces of the wicking element and, in turn, allow better adherence of the antithrombotic material with or without a surfactant or surfactants. In the case of plasma treatment, nitrous oxide gas, oxygen gas, ammonia gas and the like have been proven to be satisfactory in the present invention.
It should be apparent that a novel and useful blood removal device has been herein above described.
It is therefore an object of the present invention to provide a blood removal device which uses a wicking element and an aspiration element which act in concert to remove blood from a surgical site without damaging tissue and at an acceptable rate.
Another object of the present invention is to provide a blood removal device which employs a wicking element that is capable of wicking blood for a relatively long period of time without clogging of the wicking element by coagulated blood.
Another object of the present invention is to provide a blood removal device which is useable in surgical operations in which blood must be removed from the surgical site from a bleeding source.
Another object of the present invention is to provide a blood removal device which is relatively easy to manufacture and employs proven biocompatible materials.
The invention possesses other objects and advantages especially as concerns particular characteristics and features which will become apparent as the specification continues.
REFERENCES:
patent: 3969498 (1976-07-01), Catania et al.
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patent: 5447505 (1995-09-01), Valentine et al.
patent: 5466231 (1995-11-01), Cercone et al.
patent: 5540964 (1996-07-01), Mallen
patent: 5541167 (1996-07-01), Hsu et al.
patent: 5599330 (1997-02-01), Rainin
patent: 5628735 (1997-05-01), Skow
patent: 5846230 (1998-12-01), Osborn, III et al.
patent: 5865794 (1999-02-01), Castro
patent: 5928174 (1999-07-01), Gibbins
patent: 5977428 (1999-11-01), Bozigian et al.
Bielen, Jr. Theodore J.
Bogart Michael
Lo Weilun
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