CRYOPRESERVED ALLOGRAFT SKIN TO COVER 50% DEEP BURNS

Pousa Real F.

Serv. de Cirurgia Plastica, Hospital Juan Canalejo, La Coruna, Espaha

SUMMARY. Cryopreserved allograft skin from cadaveric sources has proved to be an excellent material for burn wound covering, allowing temporary closure of the wound 10 days post-bum. Its use has many advantages in the case of second- or third-degree burns. The methods of obtaining, preserving and applying the skin are described. Two case histories are also given.

Viable human allograft skin from cadaveric sources has proved to be a very effective material to cover ' tangentially excised deep second- or third-degree bum wounds when insufficient amounts of autografts have been present. Allograft cryopreserved skin has performed as both a mechanical and a physiological barrier, and its use has decreased the loss of water, protein and heat through the burn wound, as well as preventing contamination of the wound by enviromental micro-organisms.

From the pioneer works of Baronio etc. up to the latest works of Randolf May more than 300 works have been published on this subject.

Patients and methods

1. Patients with major thermal injuries of secondor third-degree bum wounds, when insufficient amounts of autograft have been present.
2. Request of allograft skin from bank:

• recipient patient's name
• patient's hospital registration number or similar identification
• name of requesting physician
• anticipated time and date of use
• amount of skin required
• part of body to be covered.

Transport and use of frozen skin:
The skin should be maintained at or below -70 'C during transportation (dry ice). The skin should be thawed using the procedures which maintain suitable viability. One such procedure is rapid thawing of the packets in water at 37 'C. This has considerable advantages in that this procedure is simple, inexpensive, and provides the excellent heat transfer needed by skin for rapid warming.
The cryoprotector fluid is eliminated in sterile capsules through repeated washing with isotonic saline solutions. The allograft is applied over the burn wound after being tangentially excised up to 10 days post-burn, being taped on. Then follows clinical study with controls after 5, 10, 15, 20 days. Depending on there being a sufficient amount of autografts the process continues.
In our Burn Care Unit the use of allograft is routine and the only limitation is the availability of reserves in the bank.
We present two cases which we see as being significant among the patients with extensive secondand third-degree bums in above 40% BSA.

A 50-year-old male with 2nd-3rd degree burns which affected 85% BSA, 60% of which could be established as being deep: tangential excision was used and the wounds were covered with a cryopreserved allograft after the eighth, fifteenth and twenty-first days until a total covering of the wound bum was achieved. This was substituted by meshed autografts 1:3 over well-vascularized allogenic dermis. The patient was able to leave hospital after 65 days.

An 18-month-old male child presenting 2nd-3rd degree burns in 40% BSA: our aim was to cover tangentially excised deep second- or third-degree burn wounds with only one surgical operation ten days after being taken into hospital, with grafted allotype skin. It showed signs of rejection in the contact areas after 18 days, being replaced by meshed autograft 1:3, with the result that the burn wound closed. He could leave hospital after 40 days.

Figg. 1-2 Rejection of the allograft after twenty seven days.

Figg. 3-4 Excision tangential skin allograft covered. The allograft is not meshed because we need to make the wound waterproof. The growth of a meshed allograft is very poor.

Figg. 5-6 Head and neck, 3rd degree bums.

Fig. 7-8 Cryopreserved allograft covered the wounds after only one surgical operation.

Cryopreserved allograft is the best material for wound covering. It allows temporary closure of the wound 10 days post-burn. This reduces pain, the number of dressings, and contamination of the bums by germs.

The patient's comfort is increased as also recovery of the haematological factor, platelets, clotting factors, the increase in red blood cells, nitrogen balance, etc.
At the same time there must be available independent work areas and a laminar flow chamber as well as an infrastructure for the finding of donors.

RÉSUMÉ. L'allogreffe de peau cryoconservée d'origine cadavérique s'est montrée un matériau excellent pour la couverture des brûlures parce qu'elle permet la fermeture temporaire de la plaie 10 jours après la brûlure. Elle offre beaucoup d'avantages dans le cas de brûlures de 2éme et de 3ème degré. L'Auteur explique les méthodes pour obtenir, conserver at appliquer la peau, et il décrit deux cas.