Surgery – Miscellaneous – Methods
Reexamination Certificate
2001-03-07
2003-05-27
Lo, Weilun (Department: 3761)
Surgery
Miscellaneous
Methods
C424S499000, C424S435000, C428S402240, C264S004000
Reexamination Certificate
active
06568398
ABSTRACT:
This invention relates to methods for bringing about rapid, painless hemostasis intraorally, for dermatological applications or all other hemostasis applications.
A present method for effecting hemostasis intraorally involves the direct application of an astringent solution to the gingival crevice. A problem associated with the use of present astringent solutions is that they generally rapidly flow away from the gingival crevice and do not sustain their astringent action for an adequate period of time. Use of readily washed away astringent solutions is often ineffective for bringing about adequate hemostasis.
For intraoral, dermatological and all other hemostasis applications, present astringent and hemostatic materials for application to body tissues are comprised of active ingredients which immediately react with the body tissues upon contact therewith. If a practitioner applies an excessively large quantity of such material to the tissues, then those tissues are immediately subjected to an excessively large quantity of reactive agent. A problem that may result from such an occurrence is that delicate tissues may be irritated by the excess astringent substances, and excess astringent is wasted.
There are various hemostasis and astringents which have been used to control bleeding. One of the most common hemostatic and retraction agents used in dentistry is an aqueous solution of 25% aluminum chloride marketed under a variety of tradenames including Denti-Care Hemostat, Hemodent, Hemoban, and Gingi Aid. Ferric salts have also been used as astringents, such as Monsel's solution which is based on ferric subsulfate, ferric sulfate, and ferric chloride. U.S. Pat. No. 4,617,950, discloses an astringent gel which includes an astringent salt and a bodying agent such as carboxypolymethylene. U.S. Pat. No. 4,551,100 teaches a aqueous ferric sulfate solution for use in the gingival area as a hemostatic agent having both coagulant and astringent properties. U.S. Pat. No. 5,454,719 provides a sterile gauze dental pack which provides hemostasis by direct pressure. U.S. Pat. No. 4,395,398 deals with an aqueous dental hemostatic composition comprising one or more astringents and a surfactant in a carrier or diluent. U.S. Pat. No. 4,597,960 discloses powdered astringent hemostasis agents microencapsulated with a hemostatic polymer. A variety of different particle size astringent hemostatic agents are encapsulated in capsules having a variety of capsule wall thickness. U.S. Pat. Nos. 5,635,162 and 5,785,955 relate hemostatic compositions for controlling oral bleeding. The compositions includes a hemostatic agent, an agent to reduce the acidic activity of the hemostatic agent, and an aqueous base. U.S. Pat. No. 5,773,033 concerns fibrinogen and chitosan hemostatic adhesive agents which can be topically applied to bleeding wounds or vessels.
Another typically used hemostatic agent is Kaltostat which is composed of the sodium and calcium salts of alginic acid. The dressing is generally in the form of a non-woven pad consisting of absorbent fibrous fleece for application to surface wound or other body fluids. As the fibers absorb liquid and swell the dressing to takes on a gel-like appearance.
The present art of bandages to be applied topically to skin surfaces discloses astringent hemostatic agents impregnated into bandage substrate materials. However, there are problems associated with such bandages which are similar to problems associated with conventionally impregnated gingival retraction cords relating to an excess of astringent agent being applied to delicate body tissues. There are no bandages presently impregnated with astringent agents that are released only upon demand.
The hemostasis action of fibrin glue has been demonstrated. Thrombin is present in the fibrin glues, which are generally prepared from pooled human and bovine blood. The non-human antibodies present, sometimes result in severe anaphylactic reactions and there is a possibility of transmitting infectious disease from the human components. Additionally, purified or biocompatible fibrin compositions are extremely expensive.
In accordance with one aspect of this invention, a novel method is provided for producing rapid, painless hemostasis and which provides a visual color indication upon completion of hemostasis. The methods of the invention may be used for intraoral, dermatological and all other hemostasis applications. The composition is comprised of a powdered astringent hemostatic agent microencapsulated with a polymer that has hemostatic properties, is biologically inert; is compatible with human tissue; and, is non-allergenic. The particle size distribution of the individual microcapsules are preferably in the range of about 100 to 300 micron, more preferably in the range of about 200 to 250 micron, and most preferably containing less than 10% of particle above the upper range limits. In practice the hemostatic granules are applied over the wound or bleeding surface until coagulation occurs, at which point the last layer of granules will remain white and the granules may be washed from the wound or cut. The granules of the invention may be used alone or in combination with other agents or techniques typically used to facilitate hemostasis.
The microencapsulated granules used in the present invention preferably consist of ethyl cellulose encapsulating the astringent. The ethyl cellulose granules accommodate a volume of fluid equal to the volume of the granules. Fluid is both absorbed at the bead interstices and adsorbed at the bead surface. The large surface area of the applied granules fosters coagulation. Within the interior spaces of the ethyl cellulose granules, the aluminum sulfate is dissolved by absorbing fluid. The dissolved astringent diffuses out of the encapsulating granules and produces an astringent action within the wound site which arrests secretion and stops minor bleeding. The granules interacting with the wound appear reddish because of the absorbed exudate and blood. When the hemostatic action is complete the granules remain white and can be rinsed from the tissue. In one preferred embodiment, the astringent is aluminum sulfate, the same as that found in styptic pencils, however the encapsulation of aluminum sulfate with 6% ethyl cellulose reduces the rate of plasma absorption of aluminum by 70% compared to styptic pencil. Extended exposure to the granules of the invention results in negligible increased absorption due to the astringent action of the granules. The product does not cause skin irritation, skin sensitization, acute systemic toxicity, cytotoxicity or hemolysis and does not effect the rate of would healing. Extended exposure to the granules should result in negligible increased absorption of astringent in the plasma due to the astringent action of the granules, however the color change gives the practitioner a visible indication that minor bleeding and secretion have been arrested. The microcapsules can then be irrigated from the wound without subjecting the patient to time delays or wasting astringent microcapsules. Water or any other conventional irrigation solutions and devices such as those found in U.S. Pat. Nos. 5,830,197, 4,778,679, 4,413,987, and 6,050,981, may be used for wound irrigation.
Fine 250 micron, biocompatible granules that contain an astringent such as aluminum sulfate are sprinkled into fresh, minor cuts or superficial wounds to absorb body fluid and to stop minor bleeding in fresh traumatic superficial lacerations or wounds. Once exudation and bleeding has stopped, the outermost layer of microcapsules remain white, are irrigated from the wound and a protective dressing can be applied. For high pressure bleeding, slight pressure may be applied to the microcapsules with gauze pads.
When used intraorally the method of the invention may be used to bring about both gingival retraction and hemostasis. For intraoral applications the preferred microencapsulated astringent hemostatic agent is aluminum sulfate and the preferred encapsulation material is ethyl cellulose. Ot
Cohen Edgar C.
Lo Weilun
Millen White Zelano & Branigan P.C.
Truong Linh
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