Revascularization of tracheal transplants with omentum]

In a series of 6 dogs we performed an autotransplantation of a four-ring segment of the thoracic trachea. In 3 cases the omentum was brought into the chest and wrapped around the transplant (omentum group) and compared with the others (control group). After 20 days or at occurrence of severe tracheal stenosis the study was determined. In the omentum group all tracheal transplants healed with structural integrity. Microfil injection into the gastro-epiploic artery demonstrated revascularization through omental vessels. In the control group all transplants developed a severe stenosis due to chondromalacia within 2 weeks. In conclusion: The omentum can successfully revascularize a transplant of a four-ring segment of the thoracic trachea.     

人工气管腔内气管粘膜上皮再生的实验研究

为了研究气管膜上的皮在人工气管腔再再生的难题，我们将１２只成年犬分为３组，和线组４只，Ａ组采用自体带血管蒂大网包绕在网孔型硅橡胶人工气管外壁行Ⅰ期气管置换术；Ｂ、Ｃ两组采用胎犬气管包绕在部分网孔型炭素纤维人工气管外壁，其外现地包绕自体带血管蒂大网膜，制成所谡人工气管－胎犬气管－大网膜复合体分别施行Ⅰ期吻合Ⅱ期吻合的气管国我实验，结果Ａ、Ｂ、组滑观察到人工气管腔内气管粘膜的再生，Ｃ组可观这以人工气管     

Obliterative airway disease and graft stenting in pig-to-dog tracheal xenotransplantation

OBJECTIVE: Obliterative airway disease occurring in concordant tracheal xenografts in rodent models is histologically similar to obliterative bronchiolitis in human lung allografts. We studied whether obliterative airway disease would occur in a large animal-discordant model. METHODS: Pig and dog tracheas were cryopreserved for 7 to 14 days, and 18 recipient dogs given splenectomy 7 days before transplantation, then seven tracheal rings were removed and a corresponding five-ring donor tracheal segment was transplanted to the excised site. Grafts were wrapped with pedicled omentum and inmmunosuppression was conducted with tacrolimus or deoxyspergualin. Graft status was observed by bronchoscopy. Dogs were classified into three groups. Group 1 consisted of dog-to-dog allotransplantation animals (control group, n = 5), Group 2 of pig-to-dog xenotransplantation animals (n = 8), and Group 3 of pig-dog xenotransplantation animals who also underwent graft stenting immediately after transplantation (n = 5). RESULTS: Grafts healed well in 4 of 5 Group 1 dogs. Tracheal stricture began on day 5 post transplantation and the lumen was obstructed by fibrosis by days 8 to 14 in all Group 2 dogs. All Group 3 dogs remained in good respiratory status until death. CONCLUSION: Obliterative airway disease developed quickly in pig-to-dog discordant tracheal xenografts. Graft stenting is a feasible treatment for managing of tracheal obstruction.     

Removal of cartilage rings prevents graft stenosis in extended tracheal allotransplantation with omentopexy and immunosuppression: an experimental study.

BACKGROUND: One of the serious problems in longer size tracheal transplantation is severe stenosis of the graft, probably caused by an inadequate blood supply. We have previously reported that removal of some cartilage rings of the graft and omentopexy helps to provide sufficient blood flow to the graft mucosal tissue and results in satisfactory survival and non-significant graft stenosis in extended tracheal autotransplantation. However, it is unclear whether this method can be applied to extended tracheal allotransplantation that requires immunosuppression. In this report, we describe midterm results of extended tracheal allotransplantation with the technique. METHODS: Twenty-four adult mongrel dogs were used. In 18 dogs, a nine-cartilage-ring length of the trachea was allotransplanted when five cartilage rings of the graft were removed, leaving two rings intact at both ends of the graft for simple fixing to the recipient. Two artificial tracheal rings outside the graft and a stent inside the graft were used for maintaining the lumen width. Omentopexy was done for sufficient blood supply to the graft. FK 506 (0.1 mg/kg) was given on each day after the operation in Group A (n = 10), but was not given at all in Group B (n = 8). In Group C (n = 6), a nine-cartilage-ring length of the trachea, without removal of any cartilage ring, was transplanted into the recipient dog and covered with an omental pedicle flap. The same dose of FK 506 as that used in Group A dogs was given to Group C dogs. RESULTS: In Group A, 2 dogs died of graft stenosis within 9 weeks after surgery and 1 died of emaciation without tracheal stenosis. Seven dogs (70%) survived until time of killing. Among the 8 dogs in Group B, 6 died of graft stenosis within 9 weeks after surgery, with 1 dying of pneumonia and only 1 (13%) surviving for >1 year until killing. In Group C, all 6 dogs died of graft stenosis within 6 weeks after surgery. Survival at 16 weeks after surgery was 70% in Group A, 13% in Group B and 0% in Group C (p < 0.01, A vs B and C). No significant graft stenosis was found in 6 dogs and mild stenosis was found in 2 dogs at the time of death or killing in Group A (80%), whereas mild stenosis was found in only 2 dogs in Group B (25%) (p < 0.05). Mucosal blood flow of the graft in Group A was higher than that in Group C and was the same as that in Group B within 4 weeks after surgery; however, it remained unchanged to ultimately be higher than in Group B at 6 and 8 weeks after surgery. CONCLUSIONS: Removal of some cartilage rings, omentopexy and immunosuppression improved blood supply to the graft and resulted in good survival and non-significant tracheal stenosis in extended tracheal allotransplantation.     

Tracheal resection and reanastomosis in the neonatal period

BACKGROUND/PURPOSE: Severe congenital tracheal stenosis is rare. Most of these can be managed conservatively before elective repair. Focal tracheal stenosis has been treated with resection of the involved trachea and primary reanastomosis in older infants. The authors found no reports of repair of this lesion in neonates. Two patients are presented with severe respiratory failure on the first day of life that required extracorporeal life support (ECLS) who underwent successful tracheal resection and reanastomosis (TRR) during the first week of life. METHODS: A retrospective review was conducted. RESULTS: Both babies had severe pulmonary hypertension and carbon dioxide retention despite maximal therapy and were placed on ECLS shortly after transfer. One had an isolated stenosis of the upper trachea, and the other had agenesis of the right lung, esophageal atresia with tracheoesophageal fistula, and a tracheal stenosis at the end of a short trachea with a long, narrow left bronchus. Both underwent diagnostic studies and had surgical repair while on ECLS at day 3 and 7 of life without bleeding complications. They were weaned off ECLS 1 and 8 days after surgery. One patient was extubated and did well. The other was extubated transiently, but required a tracheostomy because of left mainstem bronchomalacia. Both are alive and well at 18 and 38 months of age, with no narrowing of the repairs. CONCLUSION: In the setting of severe respiratory failure requiring ECLS support, TRR can be performed safely and successfully in the neonate with focal tracheal stenosis.     

Replacement of a tracheal defect with a tissue-engineered prosthesis: early results from animal experiments

OBJECTIVES: The major problems in the development of tracheal prosthesis are anastomotic dehiscence and stenosis, caused by poor epithelialization of the prosthetic graft. We developed a novel tracheal prosthesis with viable mucosa transplanted from the oral cavity and reported excellent long-term results after thoracic tracheal replacements in dogs. In the current study, we used tissue-engineering techniques to construct a mucosal prosthetic lining from skin cells and evaluated its usefulness in tracheal replacement. METHODS: Abdominal skin patches (5 x 10 cm) were harvested from 10 adult mongrel dogs. The epithelial cells were separated, cultured in vitro for 4 weeks, and then seeded onto a porous polylactic glycolic acid scaffold (6 x 8 cm) to construct a lining mucosa. This was then mounted onto the prosthesis framework, made with polypropylene mesh reinforced with polypropylene rings. The mucosa-lined prosthesis was wrapped with the greater omentum of the same dog and placed in the peritoneal cavity for 1 week. Complete surgical resection and replacement of a thoracic tracheal segment (5 cm in length, just above the carina) was then performed using the prosthesis. RESULTS: The animals regained full activity and survived with normal activity. Bronchoscopy at 1 week and at 1 and 2 months revealed no stenosis in the anastomosis. CONCLUSIONS: This highly biocompatible tracheal prosthesis could prove useful for the reconstruction of large, circumferential tracheal defects.     

Tracheal reconstruction with autogenous jejunal microsurgical transfer

Tracheal defects due to stricture formation, tracheomalacia, and neoplasms can present difficult reconstructive problems. Tracheal defects were surgically created in 6 dogs and primarily reconstructed with microsurgical free tissue transfer of autogenous jejunal segments. Primary healing was accomplished in all dogs without severe air leakage or infection. Bronchoscopy demonstrated no substantial secretions or tracheal narrowing. Gross pathological examination of the trachea revealed no evidence of tracheal disruption or infection. Direct measurements revealed no major tracheal narrowing. Microscopic examination demonstrated normal jejunal mucosa with a minimal amount of inflammatory change at the margins of the reconstruction at 6 weeks. Microvascular free tissue transfer of jejunal segments to correct cervical tracheal defects can readily be accomplished with excellent healing and maintenance of the tracheal lumen in dogs.     

Experimental reconstruction of the trachea with free jejunal graft

To evaluate experimentally the usefulness of the jejunum in the correction of extensive tracheal defect, circumferential tracheal defect was surgically created in 31 mongrel dogs and primarily reconstructed with microsurgical free tissue transfer of autogenous jejunal segment. A silicone T tube was inserted to maintain the lumen of the grafted jejunal segment. First, defect of 7 cervical tracheal rings was repaired with untreated 5 cm free jejunal segment in 12 dogs (group 1). Next, a pilot experiment to examine the quantity of intestinal juices from jejunal segments revealed that abrasion and cauterization of the mucosal surface decreased the secretion of intestinal juices, so defect of 7 cervical tracheal rings was repaired with 5 cm free jejunal segment the surface of whose mucosa was abraded and cauterized in 11 dogs (group 2). In all the dogs except two, primary healing was accomplished without air leakage or infection, and gross pathological examination of the trachea and graft revealed no evidence of disruption, infection or granulation. In group 1, 6 of the 12 dogs died of pneumonia or air way obstruction caused by intestinal juices from free jejunal segment within 20 days after the operation. On the other hand, only one of the 11 dogs died of pneumonia at 9 days in group 2. One of the dogs died of air way obstruction caused by mucus at 3 months. Three dogs died of filariasis at 4 weeks, 3 and 7 months, and 5 dogs were sacrificed at 2, 4, 8 weeks and 3 months. Microscopic examination of the graft demonstrated thin jejunal mucosa. The anastomosis was already covered with epithelium by the end of 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)     

人工气管重建气管的实验研究

目的研制一种新型的人工气管假体，构建犬气管长段环行缺损与重建动物模型。方法实验犬16只，以3种不同类型的人工气管进行颈段气管重建。通过纤维支气管镜、影像学、病理组织学等检查来评价假体置换效果，筛选出最优化人工气管类型。结果Ⅰ型人工气管组(8只犬)中除1只术后96d出现假体移位，1只术后45d出现切口感染、吻合口瘘外，其余均能长期存活(1只术后90d处死，余均生存达180d处死)。术后假体通畅度良好，与宿主气管及其周围组织融合生长达到了生物学固定。假体内腔可见不规则的黏膜上皮生长。假体周围包绕的组织中可见散在的大小不等的新骨形成。Ⅰ型人工气管在普通X线下可以显影。Ⅱ型人工气管对照组(4只)术后均出现不同程度的假体移位、吻合口炎性肉芽肿增生和管腔狭窄等并发症。Ⅲ型人工气管对照组(4只)术后生存时间均未超过1个月，主要死亡原因为来自假体本身的网管裸露、漏气、感染和塌陷。结论Ⅰ型人工气管是一种复合式结构，糅合了无孔型和有孔型人工气管的优点，基本具备了置换和替代气管缺损的重要条件，对进一步应用于临床气管重建领域的研究具有重要的参考价值。     

Removal of cartilage rings of the graft and omentopexy for extended tracheal autotransplantation

BACKGROUND: One of the serious problems in longer-size tracheal transplantation is infection or severe stenosis of the graft, probably caused by an inadequate blood supply even with omentopexy. For obtaining an appropriate blood supply, we experimentally developed a new technique that included removal of some cartilage rings of the graft and omentopexy. METHODS: Twenty-one adult mongrel dogs were used. In group A (n = 11), a nine-cartilage ring length of the trachea in which six of nine rings were removed, leaving one cartilage ring at each end of the graft and another in the center, was autotransplanted with omentopexy. Two artificial tracheal rings outside the graft were used for maintaining the lumen. In group B (n = 10), a nine-cartilage ring length of the trachea was autotransplanted with omentopexy. RESULTS: In group A, all dogs survived until being sacrificed, whereas 5 group B dogs died of graft infection and mediastinitis (p<0.05 versus group A). Mucosal blood flow of the graft in group A was normal and higher than in group B (p<0.05). Grade of the graft stenosis at death or sacrifice was 14%+/-1% in group A and 58%+/-25% in group B (p<0.05). CONCLUSIONS: Removal of some cartilage rings improved blood supply to the graft and resulted in satisfactory survival and nonsignificant tracheal stenosis in extended tracheal autotransplantation.     

Tracheal T-tube treatment following tracheoplasty--post-intubation tracheal obstruction and stenosis

A 26-year-old man with post-intubation tracheal obstruction and stenosis was treated at our department. The lesions were granulomas, showing almost complete obstruction of the tracheal lumen at the stomal level, circumferential cuff stenosis at the cuff level and pressure necrosis on the trachea directly behind the brachiocephalic artery. Circumferential resection of the trachea including 13 tracheal cartilages with end to end tracheal anastomosis was performed. The site of the anastomosis was covered with pedicled omentum retrosternally. Seven days following the tracheal resection, a granulomatous lesion resulting in dyspnea was found at the distal trachea of the anastomosis. Subsequently, a tracheal T-tube was inserted, he had a remarkable improvement of the patient's overall condition. Pedicled omental wrapping of tracheal anastomotic site was found quite useful, particularly in the case of possible anastomotic insufficiency. Treatment of post-intubation stenosis with tracheal T-tube proved effective when the tracheal resection was not possible.     

Evaluation of Antigenicity of Components of Tracheal Allotransplant and Effect of Immunosuppressant Regime in a Rodent Model

Background  Tracheal transplantation seems to be the logical step in the process of reconstruction of the trachea following a long-segment resection, which is usually done to treat malignant disease or benign stenosis of the airway caused by a traumatic, congenital, inflammatory, or iatrogenic lesion. Immunosuppression following transplant is essential but not ideal after oncoresection. Methods  The tracheal allografts, harvested from Sprague Dawley rats, were implanted in the Wistar strain rat. The harvested tracheal grafts were divided into groups and subgroups, based on the layers of trachea, method of decellularization, and immunosuppression. The antigenicity of different layers of trachea and the effect of various decellularization methods were studied within three time frames, that is, day 3, 9, and 15. Result  On structural analysis, the day 3 and day 15 samples showed no meaningful comparison could be made, due to extensive neutrophil infiltration in all three layers. The day 9 tracheal grafts showed loss of epithelium, with no signs of regeneration in most of the allografts. The subepithelial lymphoid infiltration was found to be severe in nonimmunosuppressed allografts. The group in which both inner and outer layers were removed showed moderate-to-severe infiltrate of lymphoid cells in all the allografts, but there was no cartilage loss, irrespective of the method of decellularization. The irradiated specimens retained the cartilage but showed extensive ischemic damage. Conclusion  Rat trachea is a good model for tracheal transplant research but not adequately sturdy to sustain mechanical debridement. Irradiation and chemical decellularization eliminates the immune response but causes intense ischemic damage. Out of the three time frames, day 9 seemed to be the best to study the immune response. To substantiate the results obtained in this study, the immunohistochemical study of the allografts is needed to be performed among a larger group of animals.     

Tracheal allotransplantation in beagle dogs without immunosuppressants

BACKGROUND: The antigenicity of tracheal grafts is still unclear. We investigated the possibility of performing tracheal allotransplantation without immunosuppressants. METHODS: Intrathoracic five-ring tracheal replacements were performed in beagle dogs without immunosuppressants (n = 18). The dogs were divided into 9 pairs, and grafts were exchanged within the pairs. In group 1 (n = 6), the paired dogs were blood relatives, whereas in group 2 (n = 12), the paired dogs were not related. Full-thickness skin transplantation was also performed in both groups. RESULTS: In group 1, 5 animals survived uneventfully for more than 3 months. No stenosis was observed in any of the dogs. In group 2, the grafts were incorporated by the host trachea in 2 dogs. Four animals died of airway obstruction within 3 months. Moderate or slight airway stenosis was observed in 6 dogs. Rejection was confirmed by histologic examination. In both groups, all of the skin allografts were destroyed within 2 weeks. CONCLUSIONS: After tracheal allotransplantation, long-term survival was achieved, especially in recipient dogs that were blood relatives of donors. We conclude that it is possible to perform tracheal allotransplantation using histocompatible matched grafts without immunosuppressants.     

聚酯聚丙烯复合人工气管重建气管的实验研究

探讨微孔孔聚酯聚丙烯复合人工气管重建气管的效果。方法：将１７只犬分成２组,在手术切除术部分颈段气管后,Ⅰ组（１２只）用６ｃｍ长的人工气管作置换,采用可吸收性合成缝线吻合１１只,用聚丙烯缝线吻合１只。Ⅱ组用４ｃｍ长的人工气管作置换,其中３只用ｍａｘｏｎ缝线吻合,２只用ｐｒｏｌｅｎｅ缝线吻合。     

Management of intractable and extensive tracheal stenosis by implantation of cartilage graft

A variety of methods have been developed to solve the problem of extensive tracheal stenosis. Endoscopic resection with injection of steroids was performed with some success. Resection with end-to-end anastomosis has been attempted in localized tracheal stenosis, but it is not practical in extensive tracheal stenosis. As an alternative to the above procedures, we performed a simpler operation to increase the diameter of the narrow trachea. We treated three children (a 7-month-old, a 2-year-old, and a 3-year-old) who had severe tracheal stenosis. The trachea was explored through a cervical transverse incision. The anterior wall of the trachea at the level of the stenosis was opened longitudinally and the scar in the tracheal lumen was resected. A free-cartilage graft measuring 1 X 4 cm was taken from the third costochondral junction and was wedged and sutured in place into the tracheal opening. This resulted in increasing the internal diameter of the stenotic trachea. A nasotracheal tube was left in place at the end of the procedure for 48 hours. The children are still asymptomatic 19, 10, and 8 months postoperatively. The careful selection and preparation of the patients for this procedure is discussed.     

Development of a tracheal stapling device

OBJECTIVE: Recent years have witnessed a multitude of technical advances regarding gastrointestinal and vascular anastomosis. However, difficulties still hamper tracheal and bronchial anastomosis. We have therefore developed a novel set of instruments and performed end-to-end anastomosis of the transected canine cervical trachea to establish the operative procedures. METHODS: A novel set of instruments was developed for tracheal anastomosis including two pairs of forceps for grasping the free tracheal ends, a metal connecting device, and clamping forceps for staple insertion. Briefly, the operative procedure involves fixation of forceps circumferentially to hold the cut trachea. End-to-end anastomosis is completed by joining the forceps with a clamp and stapling the tracheal ends everted outward. End-to-end anastomosis of the cervical trachea was performed on 23 dogs. Animals were monitored on a daily basis, and bronchofiberscopy was performed periodically. Deaths from all causes were evaluated by immediate necropsy. Sixteen dogs were sequentially sacrificed at 1, 2, 3 and at 6 months after surgery. RESULTS: In our dog model, stenosis at the anastomosis of the cervical trachea was found as a complication in 8 of 23 cases. Tracheal rupture occurred in a further 3 cases, slight granulation in another 4, and the remaining 8 showed no complication. Histological findings of anastomotic healing were similar to those reported for hand suture.     

The use of omental pedicle flap for tracheobronchial reconstruction in infants and children

For the surgical repair of long-segment tracheal stenosis, costal cartilage graft or extensive resection with end-to-end anastomosis has often been used. Both procedures have a risk of developing anastomotic leakage, which is potentially a lethal complication, or stenosis resulting from compromised blood supply to the tissue at the anastomosis. We have used omental pedicle flap (OPF) to seal the anastomotic line and to restore the vascularity of the graft and the trachea in an attempt to avoid fatal complications. During the period between 1986 and 1990, OPF technique was used in tracheobronchial reconstruction in six patients aged 4 months to 3 years; cartilage graft for extensive tracheal stenosis (4), tracheal resection and anastomosis (1), and bronchial resection and anastomosis (1). The omentum was separated from the colon to form an OPF with the right gastroepiploic vessels preserved. The OPF was brought to the upper trachea in the mediastinum through the retrosternal space. There was no immediate postoperative death due to anastomotic leak. Endotrachial tubes were removed in all patients. Four of the six are totally free of airway problems. One patient showed persistent stridor because of remaining stenosis at the cervical trachea. The remaining one patient who underwent bronchial resection developed anastomotic stenosis probably due to the compression of the floppy left main bronchus by adjacent aorta. The OPF seems to be an important surgical adjunct in order to eliminate fatal complications in tracheobronchial reconstruction.     

Tracheal dilatation followed by stenosis in Mounier–Kuhn syndrome

A patient with previously undiagnosed Mounier-Kuhn syndrome (tracheobronchomegaly) was admitted with a head injury after a fall. The trachea was intubated with an oral tracheal tube with high-volume low-pressure cuff. The intracuff pressure was within the normal safe range recommended by the manufacturer. However, the patient developed tracheal dilatation on the second day after intubation. The trachea was extubated on the 15th day, and it was noticed 48 hours later that the patient was developing a tracheal stenosis at the site of the previous dilatation. The stenosis was so severe that the patient underwent resection-anastomosis surgery of his stenotic tracheal segment 2 months after extubation. It may be preferable in patients with Mounier-Kuhn syndrome who require mechanical ventilation to intubate the trachea with an uncuffed tube and to pack the throat to decrease the chances of gas leak and inhalation.     

The effects of preoperative irradiation on primary tracheal anastomosis.

Preoperative radiotherapy was used in the management of selected patients with cancer of the lung or trachea who might subsequently require segmental resection of bronchus or trachea and reconstruction by primary anastomosis. This study was designed to determine the effects of varying dosages of preoperative irradiation on anastomotic healing. Two rings were resected from the cervical trachea of 20 dogs following irradiation with varying doses of cesium. There were no important adverse effects on healing of the trachea or adjacent organs in dogs receiving up to 3,500 rads. All dogs receiving a higher dose than this developed some anastomotic stenosis, which was severe in 6 of 8 animals. Similar adverse effects were observed in 2 patients managed by preoperative radiotherapy (4,000 rads in three weeks) and tracheal resection with primary anastomosis.     

记忆合金网二期成形人工气管实验研究

目的寻找一种能与自体气管完全愈合为一体的人工气管。方法将20只犬随机分为带蒂组和不带蒂组，经二期手术成形制成“三明治”式人工气管。置换6cm长颈部气管，观察其生存期、吻合口有无狭窄等。结果带蒂组术后除1只出现吻合口狭窄，2只出现吻合口感染外，其余7只生活质量好。不带蒂组犬术后4周内全部死于吻合口狭窄和感染。结论带蒂记忆合金网二期成形人工气管基本可与自体气管融为一体．成为自体气管的一部分。此种人工气管可以应用到临床。