Experimental Studies on the Repair of Wounds and Defects of the Trachea and Bronchi

¹ The Department of Surgery. Vanderbilt University School of Medicine. Nashville, Tennessee and The Research Laboratory of the Thayer Veterans Administration Hospital.

Full-thickness segments of the trachea have been removed from dogs and the defects bridged by glass or metal tubes. The tubes were tolerated well by most animals. Examination of the tissue about these tubes at intervals of from two weeks to 14 months following operation revealed that small islands and rings of new cartilage were growing in the granulation tissue. It is believed that this cartilage develops from fibroblasts growing in the granulation tissue.

Several other types of operative procedure have been carried out on dogs. The following observations were made:

1) Longitudinal incisions in the dog's trachea heal without residual deformity of the tracheal wall. Complete transverse division of the trachea and end-to-end suture results in healing with rather marked stenosis in the neck whereas firm healing occurs with much less evidence of stenosis in the thoracic trachea.

2) Transplants of patches of tracheal wall, about 1 cm. square and containing parts of three tracheal cartilages were successfully used to fill defects of similar size. These grafts appeared to be tolerated equally well whether taken from the same animal or transplanted from the tracheas of other dogs. The cartilage gradually disappeared from most of these transplants, the grafts finally being composed of fibrous tissue. In two animals the cartilage did not change in appearance and in two others it appeared that new cartilage was being formed.

3) Segments of the entire trachea, 1 cm. long, which contained three cartilage rings were removed from the thoracic trachea of two dogs and then replaced by suture. These animals had no respiratory difficulty after operation and were sacrificed at the end of three weeks. The incisions were found to be well healed and histological examination revealed the tissues in the grafts to be normal in appearance.

Similar transplants in the cervical trachea became partly necrotic and were rapidly replaced by scar, with contracture of the graft and marked stenosis of the trachea. Transplants from one animal to another, in both the cervical and thoracic portions of the trachea, also were replaced by scar and in those animals stenosis developed so rapidly that most of the dogs were sacrificed within two weeks of the operation because of respiratory obstruction.

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