Resorbable Laparoscopically Deployable Hemostat

Abstract

The present invention is directed to a resorbable hemostatic nonwoven felt suitable for use in laparoscopic procedures and to methods for manufacturing said felt.

1 . A resorbable hemostatic dressing comprising a single layer of three-dimensionally entangled nonwoven felt that is not separable into distinct layers by hand consisting essentially of oxidized cellulose fibers, wherein the felt has sufficient mechanical strength and flexibility to retain its structural integrity when deployed laparoscopically. 
     
     
         2 . The resorbable hemostatic dressing of  claim 1 , wherein said felt has a basis weight of from 70 to 200 grams per square meter 
     
     
         3 . The resorbable hemostatic nonwoven felt of  claim 2 , wherein said felt has a tensile strength of more than 0.89 newtons. 
     
     
         4 . The resorbable hemostatic dressing of  claim 3 , wherein said felt has a Z-direction tensile strength of more than 0.22 newtons. 
     
     
         5 . The resorbable hemostatic dressing of  claim 4 , wherein said felt has a tear strength of greater than 0.22 newtons. 
     
     
         6 . The resorbable hemostatic nonwoven dressing of  claim 5 , wherein the oxidized regenerated cellulose fibers have on average diameters from about 5 microns to about 25 microns. 
     
     
         7 . The resorbable hemostatic nonwoven dressing of  claim 6 , wherein said felt has water absorption up to about 1000% of its weight. 
     
     
         8 . The resorbable hemostatic nonwoven dressing of  claim 1  having rectangular dimensions of 1 inch×2 inches and an insertion force for deployment through a laparoscopic trocar that, for a felt having the basis weight of from about 150 to about 200 grams per meter squared, is less than 89 newtons; that, for a felt having the basis weight of from about 100 to about 125 grams per meter squared, is less than 35.6 newtons; or that, for a felt having the basis weight of from about 70 to about 80 grams per meter squared, is less than 13.3 newtons. 
     
     
         9 . The resorbable hemostatic nonwoven dressing of  claim 1 , wherein said three-dimensionally entangled felt is consists essentially of strands having a crimp of from about 5 crimps/inch to about 12 crimps/inch and a staple length from about 1½ to about 4¼ inches. 
     
     
         10 . A method of manufacturing the resorbable hemostatic nonwoven dressing of  claim 1 , said method comprising the steps of
 a) providing cellulose yarn having filaments of minimal twist;   b) forming a multi-yarn, single feed circular knitted cellulose fabric having minimal twist;   c) scouring the cellulose fabric;   d) oxidizing the scoured fabric;   e) pliabilizing the oxidized fabric;   f) de-knitting the pliabilized fabric to form a continuous strand having a crimp from about 5 crimps/inch to about 12 crimps/inch;   g) cutting the continuous strand to form staples, said staples having length from about 1½ to about 4¼ inches;   h) carding the staples into a carded batt;   i) needle-punching and three-dimensionally entangling the carded batt to form a single layer non-woven felt.   
     
     
         11 . The method according to  claim 10 , wherein the steps of de-knitting and cutting are performed at low tension or minimal time at high tension. 
     
     
         12 . The method according to  claim 10 , wherein the step of de-knitting is performed without subsequent spooling and followed immediately by cutting. 
     
     
         13 . The method according to  claim 10 , wherein the carded batt comprises approximately 10 to 17 layers of carded web. 
     
     
         14 . The method according to  claim 13 , wherein the carded batt comprises about 12 layers of carded web.