Dura Versus Gore-Tex as an Abdominal Wall Prosthesis in an Open and Closed Infected Model By Sam Smith, Nancy Gantt, Marc I. Rowe, and David A. Lloyd Pittsburgh, Pennsylvania 9 Occasionally, it is necessary to use prosthetic material ,, to close large abdominal wall defects in infected, poten-, tially infected, or open wounds. We compared the effec- tiveness of Gore-Tex (PTFE, W.L. Gore & Associates, Flagstaff, AZ) and dura for closing large, full thickness abdominal wall defects in terms of resistance to infection, patch separation, and intraperitoneal adhesion formation. Ninety guinea pigs had full thickness, 2 cm 2, abdominal defects patched with either PTFE or dura. The skin was (A) left open (B) closed over the patch under aseptic condi- tions, or (C) closed after wound contamination with 10 s CFU of staphylococcus aureus. Wounds were examined daily and the wound and peritoneal cavity examined at necropsy (day 45). Patch separation, patch retention, and adhesions were similar in both open (A), and clean closed (B) wounds patched with PTFE or dura. In the infected closed wounds (C) of the PTFE animals, the incision remained intact significantly longer, the time of patch separation and overall patch retention were significantly increased, and bowel adhesions were significantly reduced compared to dura animals. 9 1989 by Grune & Stratton, Inc. INDEX WORDS: Abdominal wall prosthesis; abdominal wall defects; dura; Gore-Tex. p ROSTHETIC MATERIALS have been used to repair the abdominal wall for many years. 1'~ There are many situations when a prosthetic patch is the only possible means of closing large abdominal wall defects. However, problems arise when material must be used (1) in contaminated wounds; (2) where skin closure is impossible, and the material is exposed; (3) when there is a skin breakdown, and the material becomes exposed. If the wound becomes infected it is not clear whether the prosthetic material must be removed to control the infection. If the material must be exposed, or becomes exposed, it is not clear whether the patch will remain attached to the abdominal wall or to underlying viscera. Only one study3has evaluated prosthetic material in the presence of experimental bacterial contamination. In a guinea pig wound model contaminated with Staphylococcus aureus, Gore-Tex (PTFE; W.L. Gore & Associates, Flagstaff, AZ) demonstrated less bacterial adherence and fewer bowel adhesions compared with Marlex mesh. Whereas PTFE has become increasingly popular as an abdomi- nal wall prosthesis, 4 many surgeons including the authors have used human lyophilised dura for repair of large difficult abdominal wall defects,s7 We were impressed with the apparent resistance to infection of dura when placed in an infected field. In a brief clinical report of the use of dura in adults, Quilicis also noted that dura appeared resistant to local infection. To test this "subjective" clinical impression, as well as the efficiency of the use of prosthetic material in the presence of potential or actual infection, we compared PTFE with dura for closing large, full-thickness abdominal wall defects in an animal model. We evalu- ated resistance to infection, long-term outcome of the patch and abdominal wound, and the incidence of intraperitoneal adhesion formation. Open and bacte- ria-contaminated closed wounds were compared. MATERIALS AND METHODS Experimental Procedure Adult female Hartley guinea pigs weighing approximately 300 g were anesthetised with intraperitoneal ketamine (4 mg/kg) and xylozine (5 mg/kg). The abdomen was shaved, and cleaned with Betadine solution. A 5-cm midline skin incision was made down to the linea alba. A 2-cm diameter, full-thickness segment of abdomi- nal wall was excised. The resulting defect was repaired with a 2-cm diameter patch of prosthetic material, using 4-0 running polypro- pylene sutures. The animals underwent reconstruction with the Gore-Tex polytetrafluoroethylene soft tissue patch (PTFE), or pre- served human dura (Miami Tissue Bank, Miami). Animal Study Groups Group A---open wounds. In these animals after the insertion of the patch skin was left open. Group B---clean closed. The skin was closed cleanly over the patch with 4-0 interrupted nylon sutures. Group C--infected closed. Prior to skin closure, 10~ colony forming units of S aureus in 0.5-ml phosphate buffered saline were innoculated onto the surface of the prosthetic patch. Post-Operative Care and Monitoring The animals were fed regular laboratory chow, and given water ad libitum. The incision or wound was examined daily. Both the number of skin closures that opened, and the timing of closure breakdown were noted. The beginning of patch separation was also recorded, On day 45, the animals were sacrificed, and the wound and peritoneal From the Departments of Pediatric Surgery, University of Pitts- burgh School of Medicine and Children's Hospital of Pittsburgh. Supported in part by a research grant from the Human Rights Committee, Children's Hospital of Pittsburgh. Presented at the 35th Annual Congressof the British Association of Paediatric Surgeons, Athens, September 21-23, 1988. Address reprint requests to Sam Smith, MD, Department of Pediatric Surgery, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, 3705 5th Ave at DeSoto St, Pittsburgh, PA 15213-2583. 9 1989 by Grune & Stratton, Inc. 0022-3468/89/2406-0002503.00/0 Journalof PediatricSurgery, Vol 24, No 6 (June), 1989: pp 519-521 519
Transcript
Dura V e r s u s G o r e - T e x as an A b d o m i n a l Wal l P r o s t h e s i s in an Open and Closed I n f e c t e d M o d e l
By Sam Smith, Nancy Gantt, Marc I. Rowe, and David A. Lloyd
Pittsburgh, Pennsylvania
�9 Occasionally, it is necessary to use prosthetic material ,, to close large abdominal wall defects in infected, poten- , tially infected, or open wounds. We compared the effec- tiveness of Gore-Tex (PTFE, W.L. Gore & Associates, Flagstaff, AZ) and dura for closing large, full thickness abdominal wall defects in terms of resistance to infection, patch separation, and intraperitoneal adhesion formation. Ninety guinea pigs had full thickness, 2 cm 2, abdominal defects patched with either PTFE or dura. The skin was (A) left open (B) closed over the patch under aseptic condi- tions, or (C) closed after wound contamination with 10 s CFU of staphylococcus aureus. Wounds were examined daily and the wound and peritoneal cavity examined at necropsy (day 45). Patch separation, patch retention, and adhesions were similar in both open (A), and clean closed (B) wounds patched with PTFE or dura. In the infected closed wounds (C) of the PTFE animals, the incision remained intact significantly longer, the time of patch separation and overall patch retention were significantly increased, and bowel adhesions were significantly reduced compared to dura animals. �9 1989 by Grune & Stratton, Inc.
INDEX WORDS: Abdominal wall prosthesis; abdominal wall defects; dura; Gore-Tex.
p ROSTHETIC MATERIALS have been used to repair the abdominal wall for many years. 1'~
There are many situations when a prosthetic patch is the only possible means of closing large abdominal wall defects. However, problems arise when material must be used (1) in contaminated wounds; (2) where skin closure is impossible, and the material is exposed; (3) when there is a skin breakdown, and the material becomes exposed. If the wound becomes infected it is not clear whether the prosthetic material must be removed to control the infection. If the material must be exposed, or becomes exposed, it is not clear whether the patch will remain attached to the abdominal wall or to underlying viscera. Only one study 3 has evaluated prosthetic material in the presence of experimental bacterial contamination. In a guinea pig wound model contaminated with Staphylococcus aureus, Gore-Tex (PTFE; W.L. Gore & Associates, Flagstaff, AZ) demonstrated less bacterial adherence and fewer bowel adhesions compared with Marlex mesh. Whereas PTFE has become increasingly popular as an abdomi- nal wall prosthesis, 4 many surgeons including the authors have used human lyophilised dura for repair of large difficult abdominal wall defects, s7 We were impressed with the apparent resistance to infection of dura when placed in an infected field. In a brief clinical
report of the use of dura in adults, Quilici s also noted that dura appeared resistant to local infection. To test this "subjective" clinical impression, as well as the efficiency of the use of prosthetic material in the presence of potential or actual infection, we compared PTFE with dura for closing large, full-thickness abdominal wall defects in an animal model. We evalu- ated resistance to infection, long-term outcome of the patch and abdominal wound, and the incidence of intraperitoneal adhesion formation. Open and bacte- ria-contaminated closed wounds were compared.
MATERIALS AND METHODS
Exper imenta l Procedure
Adult female Hartley guinea pigs weighing approximately 300 g were anesthetised with intraperitoneal ketamine (4 mg/kg) and xylozine (5 mg/kg). The abdomen was shaved, and cleaned with Betadine solution. A 5-cm midline skin incision was made down to the linea alba. A 2-cm diameter, full-thickness segment of abdomi- nal wall was excised. The resulting defect was repaired with a 2-cm diameter patch of prosthetic material, using 4-0 running polypro- pylene sutures. The animals underwent reconstruction with the Gore-Tex polytetrafluoroethylene soft tissue patch (PTFE), or pre- served human dura (Miami Tissue Bank, Miami).
Animal Study Groups Group A---open wounds. In these animals after the insertion of
the patch skin was left open. Group B---clean closed. The skin was closed cleanly over the
patch with 4-0 interrupted nylon sutures. Group C--infected closed. Prior to skin closure, 10 ~ colony
forming units of S aureus in 0.5-ml phosphate buffered saline were innoculated onto the surface of the prosthetic patch.
Post-Operative Care and Monitoring The animals were fed regular laboratory chow, and given water ad
libitum. The incision or wound was examined daily. Both the number of skin closures that opened, and the timing of closure breakdown were noted. The beginning of patch separation was also recorded, On day 45, the animals were sacrificed, and the wound and peritoneal
From the Departments of Pediatric Surgery, University of Pitts- burgh School of Medicine and Children's Hospital of Pittsburgh.
Supported in part by a research grant from the Human Rights Committee, Children's Hospital of Pittsburgh.
Presented at the 35th Annual Congress of the British Association of Paediatric Surgeons, Athens, September 21-23, 1988.
Address reprint requests to Sam Smith, MD, Department of Pediatric Surgery, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, 3705 5th Ave at DeSoto St, Pittsburgh, PA 15213-2583.
�9 1989 by Grune & Stratton, Inc. 0022-3468/89/2406-0002503.00/0
Journal of Pediatric Surgery, Vol 24, No 6 (June), 1989: pp 519-521 519
cavity examined. The number of animals with prosthetic patch still present at sacrifice was recorded. The presence and degree of adhesions beneath the patch were subjectively graded by the same observer on the following scale: 0, no adhesions; 1, filmy adhesions; 2, definite omental or bowel adhesions to the patch; 3, dense bowel adhesions to the patch. Student's t test and chi-square were used to evaluate differences in the dura v PTFE groups.
RESULTS
Forty-nine animals received a PTFE patch and 41 had a dura patch. None of the animals developed peritonitis, evisceration from premature patch separa- tion, or enterocutaneous fistulas from bowel injury secondary to the patch. Table 1 is a summary of results.
Group A--Open Wound (13 PTFE, 18 dura)
Patch separation, patch retention, and adhesion formation were not significantly different between the PTFE and dura animals.
Group B~Clean, Closed Wounds (20 PTFE, 11 dura)
A large number of both PTFE and dura incisions broke down (62% v 45%). This appeared to result from the animals gnawing at the sutures. The average time of incision breakdown was significantly longer in the PTFE animals (12 _+ 4 days), compared with the dura animals (7 -+ 4 days). The cause of this difference was not clear. The percent of animals with patch at sacri- fice, and the severity of bowel adhesions at sacrifice were not significantly different.
Group C--Infected, Closed Wounds (16 PTFE, 12 dura)
All of the incisions demonstrated obvious signs of infection with redness, swelling, and subsequent inci- sion breakdown. The pus which drained grew S au- reus. The skin incision remained intact significantly longer in the PTFE animals (16 _+6 v 10 _+ 6 days). The time of patch separation (22 _+ 6 v 9 _+ 2 days) was significantly increased in the PTFE group. None of the dura animals had the patch present at the time
of sacrifice, compared with 25% of the PTFE animals (Figs 1 and 2); thus overall patch retention was significantly increased in the PTFE group. Bowel adhesions were significantly less in the PTFE animals (l.4 ___ .7 grade), compared with the dura animals (2.6 _+ 1.2 grade).
DISCUSSION
The wounds were left open with the patch exposed in group A animals to simulate the clinical situation in which either the skin cannot be closed, or the skin is closed but breaks down, exposing the prosthesis. Sur- prisingly, none of the animals developed an eviscera- tion, or enterocutaneous fistulas. PTFE and dura remained attached until wound contraction, and gran- ulation under the prosthesis allowed secondary heal- ing. The bowel adhesions were mild, and not signifi- cantly different in either the PTFE or dura animals. This suggests that either PTFE or dura would be a satisfactory temporary abdominal wall prosthesis in
Fig 1. View of the abdominal wall from the peritoneal surface of guinea pig in group C repaired with dura. Note absence of dura replaced by granulation tissue (G) filling the fascial defect in the abdominal wall musculature (M). Dense bowel and omental adhe- sions (A) are present.
DURA v GORE-TEX FOR ABDOMINAL WALL REPAIR 521
Fig 2. View of the abdominal wall from peritoneal surface of guinea pig in group C repaired with PTFE. Note presence of patch (P) attached to abdominal wall musculature (M) filmy omental adhesions (A) present to patch.
this clinical setting. Our results also suggest that wound breakdown, and subsequent exposure of either PTFE or dura, can be managed expectantly in place of urgent removal of the prosthetic material.
The skin was closed over the prosthetic material without contamination in the group B animals. We found an exceptionally high incidence of skin incision separation over the prosthesis. Since this appeared to be related to the animals chewing on their sutures, we feel that no definite conclusion can be reached regard- ing the differences in patch material in the clean closed group.
The prosthesis was intentionally contaminated with S a u r e u s in group C animals to compare PTFE with dura in a grossly contaminated closed wound. In the PTFE animals, the incision remained closed, and the patch remained attached to the abdominal wall for a significantly longer time than the dura group. By the
time of sacrifice, 25% of the PTFE animals still had the patch present compared to 0% in the dura group. In the dura group there was a significant increase in severity of bowel adhesions to the edges of the fascial defect, created by the early loss of the dura patch. These findings suggest that with a contaminated abdominal wall defect, in comparison to dura, PTFE has significant advantages in terms of wound stability, and subsequent adhesion formation. The observation that all the contaminated wounds became infected suggests that our "subjective" clinical impression, that dura is more resistent to infection, is not true.
A recent report by the Centers for Disease Control and the Food and Drug Administration may limit the use of dura in the future. 9 A 28-year-old woman died from Creutzfeldt-Jakob Disease (CJD), 22 months after receiving a lyophilysed irradiated human cadaver dura graft. The dura was contaminated with the CJD agent. It was recommended by the FDA that, since the CJD agent would not be inactivated by the current methods used to sterilise dura, that alternative pros- thetic materials be utilised when possible.
In summary both PTFE and dura are comparable temporary abdominal wall prostheses for an open wound or closed clean abdominal wall defect. In the presence of staphylococcal contamination, compared to dura, PTFE demonstrated longer patch retention with less intraperitoneal adhesion formation. Since it has no risk of transmitting Creutzfeld-Jakob Disease, PTFE is preferable to dura for overall use as an abdominal wall prosthesis.
ACK NOWLEDGME NT
We would like to acknowledge W.L. Gore & Associates, lnc, and Dr Theodore Malinin who supplied the Gore-Tex patch and human lyophilised dura, respectively. We also acknowledge the assistance of Ms Patricia Boyle who helped with the animal care and surgical procedures.
REFERENCES
1. Ogilvie WH: The late complications of abdominal war- wounds. Lancet 2:253-256, 1940
2. Usher FC, Fries JG, Oschner JL, et al: Marlex mesh--A new plastic mesh for replacing tissue defects. Arch Surg 78:138-145, 1959
3. Brown GL, Richardson .ID, Malangoni MA, et al: Comparison of prosthetic materials for abdominal wall reconstruction in the presence of contamination and infection. Ann Surg 201:705-711, 1985
4. Hamer-Hodges DW, Scott NB: Replacement of an abdominal wall defect using expanded PTFE sheet (Gore-Tex| J R Coil Surg Edinb 30:65-67, 1985
5. Reid IS, Cummins G: Gastrosehisis treated with lyophilized dura. Arch Dis Child 52:593-594, 1977
7. Hutson JM, Azmy AF: Preserved dura and pericardium for closure of large abdominal wall and diaphragmatic defects in children. Ann R Coll Surg Engl 67:107-108, 1985
8. Quilici P J, Vieta JO, Privitera L: The use of dura matter allograft in the surgical repair of large defects of the abdominal wall. Surg Gynecol Obstet 161:47-48, 1985
9. Possible association between dura matter graft and CJD. FDA Drug Bull 3-4, April 1987
