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Background: The repair of long-segment tracheal lesions remains an important challenge. Nowdays no predictable and dependable substitute has been found. Decellularized tracheal scaffolds have shown to be a promising graft for tracheal transplantation, since it is non-immunogenic. Objective: Evaluate in vivo decellularized tracheal allografts performance to replace long tracheal segment. Methods: Forty-five swines underwent surgery as follows: Fifteen trachea donors and 30 receptors of decellularized trachea allografts. The receptors were randomly divided in five groups ( n = 6). In groups I and II, donor trachea segment was decellularized by 15 cycles with sodium deoxycholate and deoxyribonuclease, in group II, the allograft was reinforced with external surgical steel wire. Groups, III, IV, and V decellularization was reduced to seven cycles, supplemented with cryopreservation in group IV and with glutaraldehyde in group V. A 10 rings segment was excised from the receptor swine and the decellularized trachea graft was implanted to re-establish trachea continuity. Results: Both decellularization cycles caused decreased stiffness. All trachea receptors underwent euthanasia before the third post-implant week due to severe dyspnea and trachea graft stenosis, necrosis, edema, inflammation, hemorrhage, and granulation tissue formation in anastomotic sites. Histologically all showed total loss of epithelium, separation of collagen fibers, and alterations in staining. Conclusions: Both decellularization techniques severely damaged the structure of the trachea and the extracellular matrix of the cartilage, resulting in a no functional graft, in spite of the use of surgical wire, cryopreservation or glutaraldehyde treatment. An important drawback was the formation of fibrotic stenosis in both anastomosis.

Cryopreserved tracheal grafts have been used in several experimental models of long segment replacement. The clinical application of the procedure has been limited due to the fact that contradictory results have been reported. The purpose of this article is to present a review of the literature on tracheal cryopreservation. Despite the fact that most authors indicate that cryopreserved tracheal allografts retain viability and have a low immunological response, though they continue to function after transplantation with good epithelialization and patency, cryopreservation leads to significant damage to cartilage, the degree of which is based on the freezing-storage methods that affect the function and durability of a graft. The long-term storage of cartilage must therefore be investigated in more detail in basic research models of cartilage viability: the evaluation of chondrocyte apoptosis, and the use of different solutions for tracheal cryopreservation other than RPMI-1640, Dulbecco's modified Eagle's, Eurocollins, and TC-199. Furthermore, problems that involve improving the blood supply to the graft after extensive resection and immunosuppression must be resolved before tracheal cryopreservation can become a clinically established method for tracheal grafts.

Postsurgical tracheal stenosis results from fibrosis formation due to ischemia. There are healing modulators, hyaluronic acid (HA) and collagen polyvinylpyrrolidone (CPVP), which reduce collagen fibers formation. Thus we can hypothesize that the topical application of one of these modulators can diminish postsurgical tracheal scarring and stenosis. The aim of this work was to evaluate the macroscopic, microscopic, and biochemical changes of tracheal healing after the application of HA or CPVP in a canine tracheoplasty model. The study design was prospective experimental investigation in a canine model. Eighteen mongrel dogs underwent three cervical tracheal rings resection and end-to-end anastomosis. They were randomized into three groups according to treatment: group I (control group) (n = 6), topical application of saline solution on tracheal anastomosis; group II (n = 6), topical application of 15 microg HA on tracheal anastomosis; and group III (n = 6), topical application of 2.5 mg CPVP on tracheal anastomosis. They were evaluated clinical, radiological and tracheoscopically during 4 weeks. They were euthanized at the end of the study time. Macroscopic, microscopic, and biochemical changes of tracheal anastomosis healing were analyzed. Collagen formation was quantified by the Woessner method. All the animals survived the surgical procedure and study period. Macroscopic, radiologic, and endoscopic studies showed that animals in group I developed tracheal stenosis, inflammation, and firm fibrous tissue formation, and histological studies also showed severe inflammatory reaction and fibrosis formation. Groups II (HA) and III (CPVP) showed well-organized thin collagen fibers with minimal inflammatory response. Biochemical evaluation revealed a higher collagen concentration in group I animals (analysis of variance [ANOVA] p < .05 and Tukey p < .01). Thus, hyaluronic acid or collagen polyvinylpyrrolidone administered after tracheal anastomosis diminished the degree of stenosis and inflammatory reaction. Both modulators improved tracheal healing.

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BackgroundPhysicians do not routinely recommend smokers to undergo spirometry unless they are symptomatic.ObjectiveTo test the hypothesis that there are a significant number of asymptomatic smokers with chronic obstructive pulmonary disease (COPD), we estimated the prevalence of COPD in a group of asymptomatic smokers.MethodsTwo thousand nine hundred and sixty-one smokers with a cumulative consumption history of at least 10 pack-years, either smokers with symptoms or smokers without symptoms (WOS) were invited to perform a spirometry and complete a symptom questionnaire.ResultsSix hundred and thirty-seven (21.5%) smokers had no symptoms, whereas 2,324 (78.5%) had at least one symptom. The prevalence of COPD in subjects WOS was 1.5% when considering the whole group of smokers (45/2,961) and 7% when considering only the group WOS (45/637). From 329 smokers with COPD, 13.7% were WOS. Subjects WOS were younger, had better lung function and lower cumulative consumption of cigarettes, estimated as both cigarettes per day and pack-years. According to severity of airflow limitation, 69% vs 87% of subjects were classified as Global Initiative for Chronic Obstructive Lung Disease stages I–II in the WOS and smokers with symptoms groups, respectively (P<0.001). A multivariate analysis showed that forced expiratory volume in 1 second (mL) was the only predictive factor for COPD in asymptomatic smokers.ConclusionPrevalence of COPD in asymptomatic smokers is 1.5%. This number of asymptomatic smokers may be excluded from the benefit of an “early” intervention, not just pharmacological but also from smoking cessation counseling. The higher forced expiratory volume in 1 second may contribute to prevent early diagnosis.

Objective. To determine the prevalence of cigarette smoking at the National Institutes of Health in Mexico (NIHM). Material and methods. A survey was performed among workers who voluntarily answered a questionnaire. Smokers were identified with two specific questions, and type of employment was classified as physicians, administrative staff, investigators and support personnel. Results. Total prevalence smoking was 28% (of 4 422 answered questionnaires). It was significantly higher among females, among administrative staff, and common-law and separated workers. It was significantly higher at the Mexican Institute of Psychiatry than at the remaining Institutes, even after adjusting for confounding. The prevalence was also higher among physicians from the same Institute. Of the smokers, 46% do so in their work areas and 78% of them would like to quit. Conclusions. The prevalence of smokers at the NIHM is as high as in the general population and a broad educational program for tobacco control and prevention is needed.