Tracheal allograft replacement. An unsuccessful method.

Abstract

Replacement of the tracheal conduit remains a difficult and unresolved surgical problem. We present an experimental study of 20 pigs undergoing replacement of the cervical trachea using glutaraldehyde (n = 5), glycerol (n = 5), lyophilized (n = 5) and cryopreserved (n = 5) pretreated allogenic grafts (AGs). In the lyophilized group, a stainless steel spiral endoprosthesis was used as stent. A segment of native trachea measuring 3.2 +/- 0.3 cm (range: 1-5 cm) in length and 1.4 +/- 0.02 cm in diameter was resected and replaced with AGs measuring 3.8 +/- 0.2 cm in length and 1.4 +/- 0.2 cm in diameter. Neither immunosuppressive agents nor steroids were given. Animals were followed up with weekly bronchoscopy, and trachea and chest roentgenography. Those receiving glutaraldehyde AG (21.6 +/- 6.4 days) and lyophilized AG (19.5 +/- 7.8 days) had a longer survival than those receiving glycerol AG (6.8 +/- 0.3 days) and cryopreserved AG (5 +/- 0.5 days). At postmortem, grafts were examined grossly and with light microscopy. The cause of death was always airway obstruction, and the underlying processes were: 1) collapse due to cartilaginous microscopic necrosis in cryopreserved and glycerol AGs; 2) necrosis of allograft which crossed the spiral stent for lyophilized AGs; 3) granulation formation, tissue necrosis and anastomosis leakage in glutaraldehyde AGs. Results demonstrate that passage of necrotic tissue across the grafts represent the common failure denominator, making the different AGs studied unsuitable for long-segment tracheal replacement.