Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-09-14
2001-04-10
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C424S423000, C424S431000, C424S445000, C424S486000, C521S078000, C521S141000, C523S122000, C604S036000, C604S037000, C604S358000, C604S363000, C604S369000
Reexamination Certificate
active
06214895
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for making non-sticking or nonadherent nasal, sinus and otic packings and other surgical packing shapes from treated polyvinyl acetal sponge material.
2. Discussion of the Related Art
The literature is replete with references to various types of foam materials including polyurethane, polyisocyanate, polystyrene, polyolefin, polyvinyl chloride, epoxy, urea-formaldehyde, latex, silicone, and fluoropolymer and with methods of controlling the physical properties of the foam or providing surface laminates on the foam surface during manufacture.
Advances in the development of synthetic polymers have produced radical changes in medical sponges. Factors such as water vapor, oxygen permeability, bacterial impermeability, and selective absorption can be incorporated into new formulations. These new formulations also address specific requirements such as conformability, non-adherence, and adhesiveness. Thus, a family of polymeric products has been formed for wound care including polymeric foams, polymeric films, particulate and fibrous polymers, hydrogels and hydrocolloids.
The optimum characteristic for nasal, sinus and otic packings is the ease of removal of the packing from the patient without pain or trauma. Wound dressings and other packing materials used for nasal, sinus and otic packings require a high degree of absorptivity. These packings normally swell as body fluids are absorbed. However, current materials and sponges such as porous foams support the coagulated blood and proteins exuding from the cavity surfaces that have been disrupted by surgery or trauma. These coagulated materials enter the pores of the sponge and dry in place. The coagulated blood and extudate form a mechanical bond with the sponge pores. When it is necessary to remove the sponge, the sponge can stick to the tissue surface via this connection. Removal of the medical sponge then causes debridement of the healing tissue surface causing pain and occasionally causing bleeding.
A number of solutions to the adhesion problem have been attempted. Overlays or coatings of silk, rubber or non-adherent films, such as polyethylene, have been applied to packings before insertion into the nasal cavity. Other techniques have included the application of lubricating gels, creams and ointments on the surface of the sponge packing material to alleviate patient discomfort upon packing withdrawal. None of these solutions have proven effective and adhesion of packing material continues to be a painful problem. There are a number of prior art references disclosing sponge dressings having varied treated surfaces.
A foam sponge product constructed of lyophilized hydrocolloid foam which is capable of absorbing body exudates is shown in U.S. Pat. No. 4,292,972. The wound dressing is preferably constructed with a thin outer oxygen and vapor-permeable film and a layer of an absorbent adhesive such as hydrogel for adhering the wound dressing to the skin and for acting as a reservoir for wound exudate absorbed therein. A layer of collagen, in the form of a sponge or film is adapted for placement directly on the wound, the collagen layer being of smaller dimensions than the absorbent adhesive layer so that areas of the adhesive layer extending beyond the periphery of the collagen layer can be applied to the skin surrounding the wound to adhere the dressing in place.
U.S. Pat. No. 3,934,587 discloses a solid sheet or film of a polymeric compound containing chemically reactable hydroxyl or amine groups that is reacted in a vapor phase mixture of acid chloride and aldehyde to form a product which is water-repellent on the treated side but water-permeable on the opposite, untreated side. The reactant sheet may be constructed of polyvinyl alcohol.
U.S. Pat. No. 4,997,425 discloses using a porous wound dressing including a first sponge layer for contacting a wound and a second surface remote from a wound. The second surface, the surface remote from the wound, has a pore size smaller than the first surface.
U.S. Pat. No. 4,054,141 describes a molded absorptive body including an absorptive layer of hydrophilic fibers and a sheath of the hydrophilic fibers bound together by thermoplastic particles. The absorptive body may be provided with a sheath on all sides or only on part of the body.
Sponges shaped for use as nasal, sinus and otic packings and other surgical packing shapes made from polyvinyl acetal sponge material are well known in the prior art. Polyvinyl acetal sponge packings can be treated and rendered hydrophilic. Such treated sponges have a great affinity for liquids and are soft and strong when moist. Such sponges present a gentle and non-traumatic packing material for use in body cavities or the like. Treated polyvinyl acetal sponge materials can be fabricated into shapes to provide hemostasis resulting from the tamponading effect of expansion from a compressed state. When used as nasal, sinus or otic packings, sponges are compressed and inserted into the nasal, sinus or ear cavity to arrest bleeding or restrain hemorrhage. The sponge is left in to absorb secretions and maintain the general pressure on the interior surfaces of the nasal, sinus or ear passages.
However, a problem that occurs with currently produced treated polyvinyl acetal packings inserted in the nasal, sinus or ear cavities is the mechanical debridement of the surgical site or cavity caused during healing by firm adhesion of the packing to the surgical site or to mucosal linings in the cavities via ingression of blood components serum, mucous and proteins. If the packing is left in situ for sufficient time, adhesions and actual connective tissue ingrowth and attachment will occur. This adhesion is caused by fibrin produced at the surgical site or in the nasal or sinus cavity and subsequent spreading of fibroblasts and capillaries. Although the polyvinyl acetal sponges may be rehydrated before removal, incrustation of the sponge surface with dried blood products and other exudate stiffens the sponge packings, adding to the difficulty of removal. Since the sponge expands to come into intimate contact with the wall of the nasal, sinus or ear passages having variable, asymmetrical spaces, such as are found in the nasal, sinus and ear cavities, the stiffened packings can assume a shape not readily withdrawn and removed without significant discomfort and pain for the patient.
Thus, there exists the need for a nasal packing, sinus packing and ear packing having a soft other surface and being advantageous for insertion into nasal, sinus and ear cavities. There is also another need for an easily removable nasal, sinus and otic packing to eliminate or reduce uncontrolled mechanical debridement of the nasal, sinus and otic cavity wall surfaces while still allowing removal of exudate from these surfaces and maintaining moisture at the packing interface.
Frictional and shear forces required by the physician to remove the device are lessened in the case of the soft, hydrogel surface or interface of the present invention.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a packing sponge for overcoming the adhesion or sticking problem encountered in removal of packing material from nasal, sinus and otic cavities.
It is a further object of the present invention to provide a non-stick, lubricious surface modification of polyvinyl acetal sponge material for use in nasal, sinus and otic packing sponges.
Another object of the present invention is to provide a method for producing a polyvinyl acetal sponge containing a uniformly dispersed interstitial gel of polyvinylpyrrolidone, for use in making nasal, sinus and otic packings, which overcomes the adhesion problem discussed above.
In a first embodiment, a polyvinyl acetal (PVAcl) packing material undergoes a surface modification, imparting a non-adherent hydrogel coating on the surface. The surface modification is accomplished after final processing and fabrication of the nasal pac
Foelak Morton
Xomed Surgical Products, Inc.
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