Tracheal Prosthesis Research Articles

Investigations into tracheal prosthetic reconstruction.

Reconstruction of circumferential tracheal defects may be necessary following trauma or oncologic surgery. For defects up to approximately 6 centimeters in an adult, an end-to-end anastomosis appears to be the method of choice. Larger defects may require utilization of a tracheal prosthesis. In dogs, a tracheal prosthesis constructed of Dacron polyurethane mesh (Osteomesh) was found to well tolerated following a two-stage implantation procedure. Normal confluent respiratory epithelium was identified in the lumen of the prosthesis. Previously reported difficulties with recurrent granulation tissue at the areas of anastomosis appear to have been successfully avoided.

Morphological evaluation of the viability of silicon-lavsan tracheal prostheses

Time course of the healing process in the tracheal wall during silicon-lavsan tracheal grafting was investigated in experiments on 108 dogs with a new model of tracheal prosthesis. The formation of granulation tissue was noted as a result of postoperative inflammatory reaction in the prosthetic area. The tracheal epithelial layer adjacent to the anastomoses was hypertrophic and acquired the features of squamous epithelium. Later, after the implantation the prosthesis was surrounded by a thick fibrous capsula. In anastomoses, at tracheal tissue--implant border there was a poorly expressed inflammatory reaction, which had a local character and was compatible with 3 and more years of life in most experimental animals.

Palliative intubation of the tracheobronchial tree

Sixteen patients with far-advanced neoplastic lesions in the trachea and main-stem bronchi were studied. Ten of them were admitted to the ward in extremely poor general condition with marked cyanosis and dyspnea at rest. Palliative intubation was undertaken with two types of tubes: a Neville tracheal prosthesis and a Tracheoflex tracheostomy tube. Both types of tubes had to be specially prepared, as they had originally been designed for other purposes. The tubes were placed in the stenotic sections of the trachea and, depending on anatomical relations, within the right or left main bronchus as well. Intubation of the bronchus in the case of changes involving only the trachea was necessary to properly position and fasten the tube in the bronchial tree and to prevent displacement of the prosthesis inside the trachea. In two patients the esophagus was intubated as well. An improvement in the general condition of all patients was observed. Intubation resulted in reexpansion of a completely collapsed lung in two patients. The longest time of intubation was 9 months. The method is simple, and every physician experienced in endoscopy can use it. The results obtained encourage its further and wider application.

Circumferential tracheal replacement with costal cartilage

Long-term incorporation of foreign material or tissue in circumferential tracheal replacement will lead to progressive growth of granulation tissue, provoking either airway stenosis or a reduction of subepithelial blood supply and thereby preventing the appearance of functioning ciliated epithelium in the replaced segment. In experience with dogs, a 5 cm length of the thoracic trachea was replaced circumferentially with fresh autogenous untreated circularly positioned cartilage-perichrondrium strips. During the period of strengthening of this neotracheal wall, a temporary tracheal prosthesis made of tubular silicone rubber with absorbable sewing rings of polyglactin 910 placed 3 mm from the end of the tube served as a tracheal replacement. Six months after the cartilage transplantation, the neotracheal wall had stabilized sufficiently for the silicone rubber tube to be extracted with an endoscope. Four weeks after extraction of the silicone rubber tube the neotracheal segment was completely covered with ciliated epithelium over a thin subepithelial, well-vascularized layer. Subepithelial vessels had a diameter of 180 microm. They were a continuation of the intercartilaginous main vessels of the neotracheal wall. The presence of normal cilia on the epithelium was proved through transmission electron microscopy. Even the tubules of the cilia were arranged in the right order. In the ink test, movement of the transport marker across the neotracheal segment at a speed of 18 to 21 mm/min was proof of mucociliary clearance. In a process of migration starting from the margin of the trachea, the ciliated epithelium pervaded and replaced the preexisting temporary one-layer stratified squamous epithelium. This completely new technique of circumferential tracheal replacement with autogenous cartilage, avoiding permanent incorporation of foreign material, succeeds within the observation period of up to 7 months.

Radionuclide study of bronchial aspiration in intensive care newborn children.

Newborn children, fitted with tracheal prosthesis for mechanical ventilation, may present chronic pulmonary complications due to the repetition of silent aspirations following gastroesophageal reflux. We evaluated, in a newborn intensive care population, the frequency of such aspirations and the relationship between the different parameters and pathologies. This particular group of sick neonates cannot be moved, and as the hospital for the newborn is far from the Nuclear Medicine district, the patients cannot be scanned. We used a simple technique: the injection of a solution of 99Tcm-sulphur colloid in their gastric tube, and the measurement of the tracheal aspiration tubes' radioactivity. Thirty one children were tested; thirteen children (42%) had radioactive tracheal tubes. The study of the relationship between several parameters and our results, shows that the examination was generally positive when the maximal insufflation pressure value was low. Our results prove that silent aspirations are very frequent in such a population and that it will be perhaps useful to prevent them in a systematic way in order to save the neonates from developing pulmonary lesions.

Incorporation of microporous Teflon tracheal prostheses in rabbits: Evaluation of surgical aspects

Because tracheal prostheses made of nonporous silicone rubber develop granulation tissue at the anastomoses, we tested a prosthesis made of a microporous material (polytetrafluoroethylene, Teflon) to see whether this problem could be avoided and the prosthesis could be successfully incorporated (luminal side covered by connective tissue and epithelium). At various times after implantation in the cervical trachea of rabbits, the prostheses were inspected macroscopically for obstruction of the prosthesis lumen (lumen reduced by one-third or more) and microscopically for incorporation and inflammatory reaction (concentration of inflammatory cells) of the prosthesis. The prosthesis was successfully incorporated within 2–4 weeks in most rabbits without granulation tissue at the anastomoses. Two complications were infection of the prosthesis before incorporation was completed and obstruction of the lumen in the center of the prosthesis by granulation tissue or a deformed prosthesis wall. Both problems can be overcome, the first by giving an appropriate antibiotic for a longer period and the second by making a stiffer prosthesis. Thus, the microporous Teflon prosthesis is potentially useful as a tracheal prosthesis in rabbits.

Application of new porous hydroxyapatite tube to tracheal prosthesis

Application of new porous hydroxyapatite tube to tracheal prosthesis

Application of porous hydroxyapatite to tracheal prosthesis

Application of porous hydroxyapatite to tracheal prosthesis

The Evaluation of Various Bioabsorbable Materials on the Titanium Fiber Metal Tracheal Prosthesis

A new type of tracheal prosthesis was studied. It consists of a rigid, porous cylinder of titanium fiber metal coated with a polymer that provides an initial air seal and then is absorbed to permit subsequent fibrous tissue ingrowth and reepithelialization. Fifteen such cylinders measuring 50 mm by 26 mm were coated with one of the following polymers: polycaprolactone 700 (3 coated internally and 3 externally); a copolymer of 75% poly- l-lactic acid and 25% polyglycolic acid (3 coated internally and 3 externally); and polyglactin 910 (3 coated externally). Fifteen kennel-conditioned mongrel dogs, each randomly assigned to one of these five groups, underwent implantation of the prosthesis through a right thoracotomy into a 5-cm defect in the distal intrathoracic trachea. There were no immediate postoperative deaths, and no instances of major air leak from the prosthesis. One animal died after two weeks secondary to a lower respiratory tract infection. Bronchoscopic evaluation revealed varying degrees of tissue ingrowth into the prostheses, with no evidence of infection or distal accumulation of secretions. Histological evaluation showed superior tissue ingrowth and reepithelialization with internally coated prostheses; two out of three polymers gave good results.

Neovascularity of a tracheal prosthesis/tissue complex

Permanent bioincorporation of a microporous tracheal prosthesis will require a stable blood supply to connective tissue supporting an epithelial surface. In experience with over 80 tracheal implants in dogs, we have observed that end-on ingrowth and epithelialization does not occur in the absence of lateral ingrowth, epithelialization is marked by the appearance of a subepithelial network of vessels, and this process must be well advanced by 6 to 8 weeks for long-term stability. These observations were extended by using microangiography to delineate the blood supply of the prosthesis/tissue complex. Six implants of bioelectric polyurethane with 10% gentamicin (3 cm length, 2 cm diameter, 1 to 1.25 mm wall thickness, 60 to 120 mu micropore diameter) were interposed in the dog thoracic trachea and wrapped with an omental pedicle. The aorta was perfused with a barium suspension at elective sacrifice between 10 weeks and 21 months. Radiographs of specimens were correlated with bronchoscopic, gross, and histopathological findings. Neovascularity of the prosthesis/tissue complex can be described in three categories: outer capsule, prosthetic wall, and inner lining. Outer capsule vessels were oriented circumferentially immediately adjacent to the prosthetic wall. They resembled arteries up to 75 mu diameter on microscopy and appeared to develop from the omentum with connections developing to the bronchial circulation. Prosthetic wall vessels up to 75 mu with thin muscular walls were noted to traverse the porous prosthetic wall. The inner lining had a network of subepithelial vessels that connected to the lamina propria vasculature of the native trachea across the anastomoses with vessels up to 120 mu in diameter. We conclude that the omentum provides an immediate blood supply and a base for early connective tissue ingrowth. Epithelialization occurs as early as 3 weeks on the favorable bed, accompanied by vascular connections to the existing lamina propria tracheal vessels. This dual organization of blood supply with connections across the prosthetic wall is probably important to long-term stability of healing.

Resorbable materials of poly(L-lactide)

Poly(L-lactide) PLLA materials with various porosity in the range of 5 to 300 Μm were produced by crystallization of the polymer in presence of low molecular weight additives from solution in good solvents, followed by the diluent extraction. For the concentration of diluent in PLLA in the range of 10 to 50 per cent by weight, the pore size increased with increasing concentration of additive, while the additive was easily extracted from the polymer. For the concentration of additive in PLLA in the range of 60 to 80 per cent by weight, the pore size increased or/and decreased with increasing concentration of the additive, while the latter was hardly extractable from the polymer. Porous, resorbable tubes or rods of various diameter well accepted by living organism were produced by this method. Tracheal prostheses, pins or porous reservoirs made from PLLA or modified porous PLLA could be some of many potential application of these materials.

Development of New Tracheal Prosthesis

Development of New Tracheal Prosthesis

Alloplastic tracheal prosthesis with biocarbone. A study of animal experiments (author's transl)

Animal experiments have shown bicarbone to be a suitable material for alloplastic tracheal replacement. So far survival rates have been limited by connective tissue stenoses and by loosening prostheses. Although the transplants are not lined by bronchial mucosa, the movement of secretions is not seriously impaired due to the smooth surface. It is still a matter of speculation as to whether modifying the suture technique with a more elastic transistion from the trachea to the prosthesis would produce better results.

Preliminary Histologic Evaluation of A Biocompatible Mesh for Tracheal Reconstruction

The purpose of this study was to evaluate a porous Dacron - urethane mesh tracheal prosthesis in large dogs with surgically created discontinuous defects of the cervical trachea. Some protheses were carbon coated in an attempt to improve biocompatibility. Histology was performed on 2 dogs. The mucosa regenerated entirely covering the prosthesis. Respiratory epithelium was formed over a large central portion of the tracheas.

Tracheal Regeneration in Long-Term Survivors with Silicone Prosthesis

Dogs that achieved long-term survival (15 to 36 months) following insertion of a silicone tracheal prosthesis exhibited tracheal wall and ring formation around the loosened prosthesis. The new trachea was observed in 6 dogs and fulfilled all the criteria of an ideal tracheal substitute except inner epithelialization.

Compatibility of porous ceramics with soft tissue; application to tracheal prostheses

AbstractThe trachea is a rather simple structure, and partly because of this simplicity, many attempts have been made to effect replacement with various types of prosthetic tubes. Unfortunately, the basic design of the trachea is not easily duplicated, and thus far there is no completely satisfactory prosthetic replacement. A series of porous and non‐porous ceramics implanted in muscle tissue of rabbits indicated that rigid, porous materials can be compatible with soft, viable tissue. A prosthesis of porous ceramic rings and alternate bands of Dacron mesh was constructed and employed to bridge 6‐cm defects created in the tracheas of mongrel dogs. After 6 months an asymptomatic animal was sacrificed. Firm fixation was accomplished and the lumen was completely patent, but histological sections demonstrated that ingrowth and scarring did not satisfactorily contain bacterial infection. Encouragement of epithelial regeneration or some artificial barrier is necessary for successful implants. Work in progress includes devices using both methods to provide this barrier.

Observations in the development of tracheal prostheses and tracheal transplantation.

Observations in the development of tracheal prostheses and tracheal transplantation.

Two Cases of Primary Tracheal Tumors

Two cases of primary tumors of the cervical trachea were presented.A case of adenoma, restricted in the cervical trachea at the level of 4 cm. below the glottis, was successfully removed by tracheotomy with curettment and cauterization.A case of adenoid cystic carcinoma, localized mostly in the cervical trachea but some-what extended to the intrathracic trachea, was operated by complete circumferencial resection of the trachea with mediastinotomy by median sternotomy approach preserving the larynx and esophagus. The tumor, however, could not be removed completely even by this combined surgical approach, and was followed by Co60 irradiation of total amount of 8000 R. The patient passed away from sudden rupture of an intrathoracic vessel 10 months after the operation.The authors came to the conclusion that the tumor of the trachea, although uncommon, should be kept always in mind and early diagnosis made whenever symptomes of respiratory obstruction have developed, and that the tumor should be resected completely by surgical procedure without any addministration of irradiation therapy, if possible.It is hoped that thraugh continued search for a suitable material we will be able to utilize a tracheal prosthesis.

Tracheal prosthesis for stenosis.

The evolution of a suitable tracheal stent to assist in the management of tracheal stenosis has led to the development of this simplified model. It is made of Teflon tubing in three sizes to accommodate teenagers, adult men, and adult women. A collar button stabilizes the stent in the neck thus preventing aspiration or coughing it up. The lumen of the stent rests over a fenestrated tracheostomy tube thus permitting the passage of air and sound during its use. The noncorrosive qualities keep it clean, and its semimalleability permits an adjustment of its length during the operation for insertion. It is well tolerated as an indwelling stent for an interval of 8 to 12 months. Removal is accomplished by releasing of the collar button from the tube and then extracting it by laryngeal exposure or removing it through an incision connecting the tracheostomy wound with the collar button. The stent

Reconstructive Surgery for Tracheal Trauma

1) Referring to a large literature published up to 1963 in the world, 362 tracheo-bronchial plasty cases were commented on statistically. Traumatic injury was the major cause in 113 cases and ranked first. Traumatic injury following a traffic accident has been increasing recently in number. Site of injury was mostly found in the trachea, especially the cervical trachea. Follow-up studies revealed successful recovery in 86% of the cases operated in an early stage and in 72% of that operated rather late. Concerning to the method of surgery, the results of the suture method and the resection-anastomosis method were both satisfactory, that of the transplantation and prosthesis ended mostly in failure except the patch graft method.2) We experienced 22 cases of tracheo-bronchial plasty in Keio University Hospital. Four cases of them who had undergone cervical tracheal plasty were reported in detail.3) In order to study the limitation in length of tracheal resection, Dr. Koizumi of our Surgical Department mesured extensibility of the trachea by means of bronchography. He reported that the physiologically natural extensibility of the trachea was 22.7% of its total length and the trachea of the adult extended 26mm on the average. He also measured extensibility of corpses' resected tracheas and found that the extensibility was definitely in inverse proportion to the age. In this study the extensibility was 41.6% in the teenagers, 17.2% in the sixties, and 24.3% on the average. From the results of his study it is concluded that the standard limitation of tracheal resection is 2.5cm in length and that an amount to be resected has to be decided in accordance to pulmonary lesions and an age of a patient.4) The author, finally, reported the results of his animal experiments on tracheal reconstructive surgery. Reconstruction using “PAIREN” mesh and fascia is the best among other various methods of prosthesis. Satisfactory results were obtained in 60% of the cases using pedicled tracheal cartilages as a support and 56% of the cases using horse-shoe shaped steel wire. These results give us the bright prospects for tracheal prosthesis in clinical use.