AN EXPERIMENTAL TUBE PEDICLE LINED WITH SMALL BOWEL. By J. H. GOLDIN, F.R.C.S.(Edin.) Plastic Surgery Unit, St Thomas' Hospital, London

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1 British Journal of Plastic Surgery (I972), 25, z AN EXPERIMENTAL TUBE PEDICLE LINED WITH SMALL BOWEL By J. H. GOLDIN, F.R.C.S.(Edin.) Plastic Surgery Unit, St Thomas' Hospital, London ONE of the major problems in reconstructive surgery, for example in the region of the head and neck, is the provision of skin cover with a suitable lining to repair full thickness defects. This difficulty is usually overcome by the use of appropriate skin flaps taken locally or from a distance, and sometimes supplemented by the use of a split skin graft. But all these methods have limitations and disadvantages ; some of these would be overcome by providing a tube pedicle with an inner surface of suitable epithelium. Intestine, either colon or jejunum, has been used to repair defects after operation such as pharyngolaryngectomy. It seemed likely, therefore, that a tube pedicle lined with gut might be ideal in cases where both external skin cover and inner mucous lining had to be provided. It had been observed that an established colostomy or ileostomy often has a good blood supply communicating with the surrounding skin. Whether this blood supply would be sufficient to retain the viability of the intestine in the absence of a mesenteric circulation formed the basis of these preliminary studies. MATERIALS AND METHODS Belgian white rabbits of either sex and weighing between 2"o and 4"o kg. were used. The rabbit was deprived of solid food, but not water, for 24 hours before and after the intra-abdominal operation. Anaesthesia was induced using Pentobarbitone Sodium (Nembutal) in a dose of 60 mgs./kg. This was diluted to IO ml. with saline, given into an ear vein at a rate of i ml. per minute for 5 minutes, and supplemented with i ml. every 5 minutes until satisfactory anaesthesia was obtained. Pedicles were constructed in 3 staged operations. Stage I. At the first stage a midline incision was used to open the abdomen, and a 75 ram. length of ileum isolated. Intestinal continuity was restored by an end to end anastomosis using a single layer of everting interrupted 4/0 silk sutures (Fig. I). The isolated ileum with its intact blood supply and intact serosa was then taken through the lower end of the abdominal incision and implanted into a subcutaneous tunnel made about 25 ram. laterally. The ends of the ileal segment were brought through the skin and sutured to it with fine silk. The laparotomy wound was closed with care being taken not to constrict the mesenteric blood supply to the transplanted bowel. The skin was closed using fine wire sutures. Stage z. Three, 6 or i2 weeks after the initial operation, part of the laparotomy wound was re-opened to expose the vascular pedicle of the isolated ileum. This was then divided between ligatures and though visible blanching of the intestine occurred it quickly recovered. Stage 3. Three weeks after the second stage, a longitudinal skin and fat tube pedicle was constructed to surround the isolated ileum. The pedicle and its enclosed

2 AN EXPERIMENTAL TUBE PEDICLE LINED WITH SMALL BOWEL 389 ileum were now completely free from the abdominal wall except by its attachments at each end (Fig, 2). Biopsies of the isolated ileum were obtained at intervals. The mortality rate was high, many of the animals being lost from anaesthesia. Many also died from causes related to the anastomoses, about half being lost from intestinal obstruction, or generalised perkonitis. However in all the animals (IO) submitted to Stage 2, i.e. dividing the mesenteric blood supply, the loop of bowel was observed to survive. FIG. I. Isolated loop of bowel with mesenteric blood supply attached. Thus a viable graft of small bowel, free of any mesenteric blood supply, had been established in the subcutaneous tissues of these animals. Five animals survived Stage 3 of the procedure, i.e. the fashioning of a tube pedicle lined with this free graft of bowel. They were alive and well from 6-9 months after completing all stages of the surgery. The pedicles were viable and the open ends of the ileum appeared normal and well coloured. However, in those tube pedicles allowed to mature for over 6 months there occurred a tendency to stenosis of the mucocutaneous junction. If allowed to progress this stenosis became complete, leaving a well-healed tube pedicle containing a viable but closed loop of bowel.

3 39 B R I T I S H JOURNAL OF PLASTIC SURGERY FIG. 2. T u b e pedicle containing isolated loop of bowel. FIG. 3 Histological section of grafted bowel.

4 AN EXPERIMENTAL TUBE PEDICLE LINED WITH SMALL BOWEL 39 I Three of these composite tube pedicles were cut open throughout their entire length in order to study the whole mucosal surface of the free grafts. The cut edge of the grafts bled profusely and the mucosa looked macroscopically normal. Active peristaltic movements were observed to take place, thus indicating that at least part, if not all, of the muscle coat had survived. The essentially normal architecture as observed macroscopically has been confirmed by histological examination (Fig. 3). There is a generalised decrease in the height of the intestinal villi with a profuse round cell infiltration into them and a gross increase in the vascularity of the submucosa which probably contributed materially to the survival of the grafts. The muscle coats had survived well. DISCUSSION In all these experiments rabbits were used and the diflficuhies encountered when anaesthetising them with Nembutal are emphasised. Rabbits also do not tolerate well resection and anastomosis of bowel. However, one is greatly impressed by the ability of a loop of small bowel to survive in a subcutaneous position even when the mesenteric blood supply has been severed, provided that sufficient time has elapsed to allow the new circulation to develop. In this series the shortest time successfully allowed for maturation of the new circulation was 3 weeks. Division of the mesenteric blood flow at an earlier date was not attempted. The construction of the skin tube around the graft proved to be very simple. In the future it should be possible to construct the skin tube at the first stage and implant the loop of bowel directly into it, leaving a small bridge attached to the abdomen through which the mesenteric blood supply could pass until ready for its division. Such a composite tube pedicle would have many uses in reconstructive surgery but the fact that a multistaged procedure is needed to produce the composite tube pedicle, and further operations necessary to translate the tube to its required site, may prove to be a disadvantage. While these studies were in progress it was noted that essentially similar experiments were carried out 25 years ago at the Johns Hopkins Research Laboratories in Boston, U.S.A. Essentially similar results were obtained and this paper therefore corroborates the findings of Longmire and Ravitch (i946) who were the first to show that bowel could be induced to survive inside a tube pedicle without any mesenteric blood supply. In z959 Fararasanu and co-workers from France, discussing their experiences with antethoracic oesophagoplasties, declare: " The authors draw attention to the possibility of secondary section of the nutritive pedicle of the loop, or gastric tube. The pre-thoracic transplant has always remained viable, thanks to vessels of new formation." This paper thus serves to confirm earlier experience of the feasibility of constructing a composite tube pedicle. SUMMARY It has been proved experimentally that it is possible to establish a graft of small bowel free of any mesenteric blood supply, and without any gross change in the histological appearance of the mucos~, in the rabbit. It has further been possible to incorporate this graft of intestine in a skin tube, thus providing a composite tube pedicle with a mucosal lining which could be used in reconstructive surgery.

5 392 BRITISH JOURNAL OF PLASTIC SURGERY I would like to thank Professor C. G. Clark, M.D., Ch.M., F.R.C.S., Director of the Surgical Unit and Professor of Surgery of the University of London at University College Hospital, for his encouragement and advice in the carrying out of the experiments and in the preparation of this paper. I would also like to thank Mr Peter Luther for his expert technical assistance. REFERENCES FAGARASANU, I., GAVRILIU, D. and ALOMA~q, D. (I959). L'oesophagoplastie par greffes pedicul6es (ou libres) des segments du tube digestif--consid6rations sur une statistique personelle concernant 6o cas oper6s." Comptes rendus XVIII Congr~s de la Societd Internationale de Chirurgie, Munich, 5o6-5o8. LONGMIRE, W. P. and RAvi:rc~, M. M. (I946). A new method for constructing an artificial oesophagus. Annals of Surgery, I23, I.