Annals of Burns and Fire Disasters - vol. Xl - n. 3 - September 1998

TEMPORARY WOUND DRESSING OF BURNS WITH FRESH, STERILE, FROZEN PORCINE SKIN

Becker D.

Department of Emergency, Academic Training Hospital, Bad Hersfeld, Germany

SUMMARY. In 1964 Kohnlein described seven severely burned patients who received a primary wound dressing of fresh porcine skin, with reasonable success. When fresh, frozen, sterile porcine skin became readily available as a dressing, our hospital in Bad Hersfeld (Germany) adopted this primary wound dressing as a regular part of its planning of burns treatment. Today, the use of cadaver skin as a better biological dressing has been discontinued because of the danger of HIV infection, and the expectations raised by the culture of epithelial cells have not been fully realized: the culturing is very expensive and the sheets transplanted become necrotic in most patients after six months. It is thus necessary to revive the use of porcine skin wound dressing. Porcine skin is available as a collagenate (Mediskin), which can be stored without any problems. And pigs are to be found all over the world

Introduction

A burn accident is a most spectacular occurrence, and often the most conspicuous consequence is extensive injury to the integument. The early covering of burn wounds with grafts decisively influences the further clinical course - as well as shock therapy and rapid parenteral fluid supply, according to well-known calculable parameters.
In 1964, for the first time in Europe, Kohnlein produced a report on the heterotransplantation of porcine skin as a therapeutic measure in burn patients. In Kings County Hospital, New York, seven severely burned persons with over 50% body surface burns were successfully treated using primary wound dressings of fresh porcine skin.
The autograft coverage of burn wounds is virtually impossible because of the additional suffering caused to the patients. A combination of auto- and allograft skin transplantation requires a large number of blood donors, who are hard to find in such numbers.
The white skin of pigs seems to be an adequate substitute for skin homografts, for the following reasons:

1. it has a surprisingly similar structure to that of human skin

2. it has an extremely low content of proteolytic enzymes, which accounts for its great resistance capacity

3. there is no connection between the graft and the vascular system of the recipient. Consequently this cannot become the object of an antigenic antibody reaction. Also for this reason there cannot be any local or general toxic reaction

4. there is a distinctive epithelialization effect

Method

On the basis of the above considerations, we have applied early wound coverage in burn victims at the Surgery Department of the Hospital in Bad Hersfeld since 1969.
The first very severely burned patients were seven children with first-, second- and third-degree burns in 6070% body surface area. They were treated with fresh porcine skin and they all survived. This positive result was the reason for our decision to include this measure among our therapeutic protocols as an indispensable lifesaving method.
Necrotic tissue has to be removed after the shock phase has subsided, within the first 48 h, when burns are sterile because of the effect of heat. In the course of the same operation the entire area of the burn wound has to be covered with porcine skin (Fig. 1).

Fig. 1 - Different areas of cutis damaged by heat. These specific areas determine the graduation of the burn status.

Back in 1969 it was rather difficult to obtain fresh porcine skin. In case of need, a team had to be sent to the local slaughterhouse and skin was removed, under sterile conditions, from freshly slaughtered pigs. After repeated washing with penicillin solution, the porcine skin was ready to be placed on the wound. The skin bonded tightly to the wound after only a few minutes, and it was possible to continue with "open wound" treatment (Fig. 2). This complicated manner of obtaining fresh porcine skin has now been considerably facilitated. Fresh sterile porcine skin is now available as Mediskin in a frozen state. It is sealed in plastic packages and can be supplied in the required quantity.

Fig. 2 - Child's face, first- and second-degree burns. Burned areas covered with fresh sterile frozen porcine skin. The immediate adherence of the protein-rich fluid of the wound is visible. We thus have open wound treatment conditions.

After despatch by express mail it can be stored for up to 18 months a normal freezer without any problems. Thus, in the event of an emergency, a sufficient supply of porcine skin can always be guaranteed.
When required, Ringer's or normal saline solution is placed directly into a vessel. After two minutes the porcine skin thaws and is ready for use. The prepared gauze is positioned directly opposite the wound surface and, after adjustment of the graft to establish the contour of the wound, the porcine skin is placed in position without any difficulty.
Subsequent treatment of the wound is similar to that used in open wound treatment.

Results

We have used this kind of early wound coverage in burn victims for nearly 20 years, treating 296 burn victims. The youngest patient, two years old, had extensive first-, second- and third-degree burns in the right hand, arm and thorax due to scalding. The oldest was 72 years old. All the burns treated with Mediskin presented ideal conditions, without severe infection, and good epithelialization effect.
The survival of severely burned middle-aged persons is always difficult, but using this therapy good results can be obtained. When porcine skin has been placed on the wound, it quickly adheres because of the extremely high protein content of the exudate. Nearly total wound closure is thus achieved. The otherwise enormous loss of fluids, electrolytes and proteins can considerably be reduced and more easily controlled. Equally important is the prevention or at least the reduction of the risk of infection in extensive wound areas, which are a perfect base for contamination and a breeding site for infective agents of all kinds. The parenteral supply of antibiotics alone cannot achieve effective levels in the burn area (Fig. 3).

The healing process of burns is accelerated by the use of porcine skin. Comparison with a group of patients receiving the previously used standard local treatment showed a significant reduction in hospital stay and in healing time (Figs. 4, 5). A further advantage of the Mediskin temporary wound dressing is the inexplicable but immediate relief from pain that is much welcomed by the grateful patients. We can therefore significantly reduce the amount of analgesics that have to be used.

Discussion

The advantages of early wound dressing are evident. In addition to its immediate adherence to the wound bed, the use of Mediskin leads to:

• a significant reduction in the loss of proteins, electrolytes and fluids. There is also a significant reduction in the amount of infusions on the basis of laboratory parameters
• a reduction in the risk of infection, due to the considerably smaller contamination area
• the possibility of using open wound treatment conditions, as further wound dressings become unnecessary. After epithelialization of the wound, the porcine skin dries and either comes away by itself or can be peeled off, when another piece of porcine skin can be positioned in the same manner. Permanent changes of wound dressings become redundant 

A considerable relief of pain immediately occurs that allows a reduction in the use of analgesic drugs, and early mobilization - particularly with gymnastic exercises - can be initiated. We have thus been able to treat successfully a number of severely burned hands and restore satisfactory functioning (Figs. 6-8).
Slight cicatrization effects after the healing process have thus been overcome. Particularly disfiguring keloid formations have not been subject to research in our hospital.
Summing up all our experience in the field of primary wound dressing using fresh sterile frozen porcine skins on burns, we can say that our results show the very best local therapy for burned patients at the present time.

Fig. 6 - Local situation of severely burned hand.

Figs. 7a/b - Satisfactory function of burned hand obtained by wound dressing with fresh sterile frozen porcine skin.

Fig. 8 - Right-hand side indicates relationship between "slight cicatrization effecC and keloid formations. Fig. 9 - Face of boy shown in Fig. 2 treated using primary wound dressing consisting of fresh sterile frozen porcine skin (Mediskin).

Conclusion

Today, the use of porcine skin is limited. This is because the skin of cadavers is widely preferred in view of its more biological effect and also because of recent medical expectations with regard to epithelial cultured skin support. However, cultured skin substitutes are very expensive - a sheet measuring 10 x 10 cm costs some thousands of Deutschmark - and after about six months the supports themselves also become necrotic. Also, cadaver skin is no longer available due to Hiv infections.
Some publications have recommended shark skin as an ideal first-time wound dressing. But this means neglecting the advances of Mediskin - a collagenoid of porcine skin - and the excellent results achieved and documented in past decades. And why should an endangered species like the shark be sacrificed when another animal is so widely available?

RESUME. En 1964 Kôhnlein a décrit le traitement de sept patients grâvernent brûlés qui ont reçu un pansement primaire pour leurs lésions constitué de peau fraîche porcine. Les résultats ont été positifs. Quand la peau porcine fraîche et congelée commençait à être facilement disponible comme pansement, notre hôpital à Bad Hersfeld a adopté ce pansement primaire des lésions comme une procédure normale dans le traitement routinier des patients brûlés. Aujourd'hui l'emploi de la peau de cadavre comme pansement biologique préferé a été abandonné a cause du danger de l'infection HIV, et l'espoir une fois suscité par la culture des cellules épitheliales n'a pas été totalement realisé: la culture est très coûteuse et les lambeaux transplantés se nécrotisent dans la plupart des patients après six mois. Il faut donc réexaminer la possibilité d'employer le pansement de peau porcine. La peau porcine est disponible comme collagénate (Mediskin), qui peut être conservé sans difficulté. Et les cochons se trouvent en tout le monde!

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