Tracheal Area Research Articles

Tracheal CT morphology: correlation with distribution and extent of thoracic adipose tissue.

To evaluate the relationship between adipose tissue measurements and anterior bowing of the posterior tracheal wall in a large nonselected group of patients undergoing CT pulmonary angiography (CTPA). Consecutive patients undergoing CTPA over a 4-month period were analyzed retrospectively. Using an adapted scoring system (posterior bowing, flattening, mild/moderate or severe anterior bowing of the posterior tracheal membrane), the axial morphology and cross-sectional area of the trachea at the narrowest point and 1cm above the aortic arch were evaluated. Measurements of adipose tissue were taken (anterior mediastinal fat width, sagittal upper abdominal diameter and subcutaneous fat thickness at the level of the costophrenic angle). Relationships between tracheal morphology and measurements of adipose tissue were analyzed. 296 patients were included (120 males, 176 females, mean age 59years, range 19-90). Severe anterior bowing of the posterior tracheal wall correlated with increasing sagittal upper abdominal diameter (p = 0.002). Mild/moderate and severe anterior bowing of the posterior tracheal wall correlated with increasing mediastinal fat width (p = 0.000 and p = 0.031, respectively). Tracheal cross-sectional area was inversely correlated with increasing subcutaneous fat thickness (p = 0.022). The findings demonstrate a statistically significant relationship between CT tracheal morphology and adipose tissue measurements in a large nonselected population. • There is increasing interest in the effects of obesity on the airways. • A relationship between anterior bowing of the posterior tracheal wall and adipose tissue measurements is demonstrated. • This is of clinical relevance in an increasingly obese population. • Further studies with functional correlation are required.

Quantitative Computed Tomography Measurement of Tracheal Cross-Sectional Areas in Relapsing Polychondritis: Correlations with Spirometric Values

Background: Although tracheal stenosis occurs in relapsing polychondritis (RP), no studies exist that have clarified correlations between quantitative airway measurement and spirometry in RP patients. Objectives: The aim of this study was to investigate correlations between the cross-sectional area (CSA) of the trachea and spirometric values in patients with RP. Methods: The institutional review board approved this retrospective study, and written informed consent was waived. Twenty-six patients with RP underwent spirometry and chest computed tomography (CT) at full inspiration and end-expiration. On inspiratory and expiratory chest CT images, CSA at the intrathoracic trachea was measured for all CT slices, and the mean and minimum tracheal CSA were obtained. Correlations between the tracheal CSA and spirometric values were assessed by Spearman's rank correlation analysis. Results: Tracheal CSA measurements for inspiratory and expiratory scans were significantly correlated with FEV₁, FEV_25-75%, and peak flow values (ρ = 0.51-0.86, p < 0.01). During each inspiratory or expiratory phase, the minimum tracheal CSA achieved a higher correlation coefficient with spirometric values than the mean CSA. Conclusion: Tracheal dimensions for both inspiratory and expiratory CT are significant predictors of pulmonary function in patients with RP. The narrowest tracheal dimension likely determines the severity of airflow limitation in RP.

Helical computed tomography scanning of the larynx and upper trachea in rabbits.

BackgroundComputed tomography (CT) is used to evaluate the human tracheobronchial tree because of its unsurpassed ability to visualize the airway and surrounding structures. To establish an ideal animal model for studying subglottic stenosis, we assessed the size and morphology of the normal rabbit’s laryngotracheal airway by helical CT. We measured luminal dimensions at the levels of the arytenoid and cricoid cartilages and the first, third, and eighth tracheal rings. At all levels, the axial slices were used to calculate the maximum anteroposterior (AP) dimension, transverse dimension, and cross-sectional areas. We measured the tracheal length from the cricoid to the third and eighth tracheal rings on sagittal reformation. We assessed the hyoid, thyroid, cricoid, arytenoid, and tracheal rings for the presence of calcific or soft tissue densities. We also addressed the presence or absence of pre-epiglottic and paraglottic fat.ResultsThe mean AP tracheal dimension ± standard deviation (SD) was 8.6 ± 0.5 mm at the arytenoid level, 8.2 ± 0.7 mm at the cricoid level, and 7.7 ± 0.2 mm at the first tracheal ring level. The transverse tracheal dimension ±SD was 5.3 ± 0.1 mm at the arytenoid level, 5.5 ± 0.5 mm at the cricoid level, and 6.1 ± 0.6 mm at the first tracheal ring level. The mean tracheal area ±SD was 35.7 ± 2.2 mm2 at the arytenoid level, 35.8 ± 5.1 mm2 at the cricoid level, and 39.2 ± 4.3 mm2 at the first tracheal ring level. The tracheal length ±SD was 10.7 ± 2.3 mm from the cricoid to the third tracheal ring and 19.1 ± 1.14 mm to the eighth tracheal ring. There was complete calcification of the hyoid in all rabbits. Only two rabbits showed complete thyroid, arytenoid, or tracheal ring calcification. The remaining airway components were otherwise either uncalcified or partially calcified. The uvula, epiglottis, aryepiglottic fold, vallecula, piriform sinus, true/false vocal cords, and pre-epiglottic/paraglottic fat were not seen in any rabbit.ConclusionsHelical CT investigation provides good, highly definitive anatomic details of the larynx and trachea in rabbits. Such results may be used in further evaluation of the normal airway and in cases of subglottic stenosis.

A Rare Presentation of Tracheal Crystal-Storing Histiocytosis as Early Manifestation of Subglottic Mantle Cell Lymphoma

SESSION TITLE: Pulmonary Manifestations of Systemic Disease Student/Resident Case Report Posters II SESSION TYPE: Student/Resident Case Report Poster PRESENTED ON: Tuesday, October 27, 2015 at 01:30 PM - 02:30 PM INTRODUCTION: Mantle Cell Lymphoma (MCL) is a B cell malignancy. Crystal-Storing Histiocytosis (CSH) is a rare, benign entity suggesting the presence of underlying lymphoproliferative disorders. Neither is commonly identified in the trachea. We present a woman with significant dyspnea with CSH in the distal trachea, and co-existing subglottic MCL. CASE PRESENTATION: A 68 year old female avid biker, with a 25 year history of relapse-free CLL, with multiple prior therapies and splenectomy, presented with a six month history of progressive dyspnea, unable to climb 4 stairs. CT angiogram was negative for PE or progressive adenopathy, but upon re-review demonstrated stable thickening of the distal trachea, present since 2009. PFTs suggested a fixed large airway obstructive process. Echocardiogram was negative, and exercise ECG was limited by dyspnea without evidence of cardiopulmonary abnormality. Bronchoscopy revealed an infiltrative process markedly narrowing the subglottic area, as well as a separate lesion involving the distal trachea. Two days after bronchoscopy she was admitted with stridor, placed on steroids and underwent subglottic debulking with dramatic symptomatic improvement. Pathology revealed MCL in the subglottic region and CSH in the distal trachea. Bone marrow biopsy revealed no involvement, and PET CT only demonstrated FDG avidity in the subglottic and distal tracheal areas. She was initiated on rituximab and bendamustine with good response. DISCUSSION: MCL represents 7% of all adult forms of non-Hodgkins Lymphoma with a median age of onset in the 60s. Most patients are in advanced stages at diagnosis primarily presenting with lymphadenopathy, though MCL can present in a single non-lymphoid organ. The disease is typically aggressive with a median survival of 3 years, though a smaller subset of patients survives for years with stable disease. Though CSH is benign, it usually represents the presence of underlying hematologic malignancies, and when discovered necessitates exploration for the malignant source. Lung involvement of CSH is well described. To our knowledge, this is the first case report of CSH associated with MCL, and the first of CSH in the trachea. CONCLUSIONS: It is likely, upon re-review, that our patient has had indolent MCL throughout the course of her disease and not CLL. Her subglottic lesion likely represents a symptomatic recurrence of MCL. Presumably the stable thickening in the distal trachea, previously thought to be inflammation induced from intubation, had long been CSH from her underlying MCL. Had her subglottic lesion been identified first, the distal tracheal lesion would have been considered a metastatic lesion, and the rare CSH-MCL association would have been missed. Reference #1: Guddati AK, et al. Primary mantle cell lymphoma of the trachea. Medical oncology 2012; 29:2385-2387 Reference #2: Lee JS, et al. A challenging diagnosis: crystal-storing histiocytosis in plasma cell myeloma. American journal of clinical pathology 2015; 143:300-304 DISCLOSURE: The following authors have nothing to disclose: Amanda McCambridge, Finbar Foley, Ryan Kern, Timothy Call, Eric Olson No Product/Research Disclosure Information

Expression of high mobility group protein-1 in lung tissue of rats with chronic obstructive pulmonary disease

Objective To study the chronic obstructive pulmonary disease(COPD)in rat airway remodeling and high mobility group protein B1(HMGB1)expression level of correlation. Methods Healthy specific pathogen free(SPF)level 48 Wistar male rats, divided into 3 groups,16 rats in each group.Normal saline control group(group A):in 1st,14 d in aseptic operation down neck trachea puncture, to intratracheal injection sterile water for injection 0.2 ml; COPD model group(group B):1st,14d anisotropic intratracheal injection of lipopolysaccharide(LPS)200μg(200μl), 2- 13 d, 15- 28 d every day in selfmade smoked is passive smoking,2 times a day, 10 cigarettes each time, each lasting 60 min, continuous 28 d;smoking cessation group(group C)16:in 1st,14 days to the airway is injected LPS solution 200μg (200μl),2- 13 d,15- 21 d every day in self- made smoked is passive smoking,2 times a day,10 cigarettes each time, each lasting 60 min, continuous 21 d, the last 1 weeks of normal feeding experiments of broken smoke. Observing the pathological changes of rat airway inflammation, airway remodeling and pulmonary tissue after model establishment, with the expression of HMGB1 protein Western in lung tissue of three groups of blot detection. Results The group B, C of airway remodeling index fine bronchial wall thickness and pipe diameter ratio(MT,%)[group B(9.21±3.54), group C(8.23±3.32)], the Guan Bi area and tracheal total area ratio(MA%)[group B(20.25±3.23), group C(17.44±2.57)] and group A[MT,%(4.62±2.58), MA,%(10.72±1.12)] were significantly increased(P< 0.05), compared with C group lower than group B(P<0.05).The Western blot electrophoresis showed that the expression of B and HMGB1 protein levels in group C[group B(1.621±0.254), group C(1.234± 0.327)]compared with group A(0.462±0.581)(P<0.05), significantly enhanced expression of group C than in group B decreased HMGB1 protein(P<0.05). Conclusion With the COPD disease progression of airway remodeling and the expression of HMGB1,enhance the expression of COPD and HMGB1,illustrate the airway remodeling related. Key words: Chronic obstructive pulmonary disease; Airway remodeling; High mobility group protein B1

Guanylyl cyclase activation reverses resistive breathing-induced lung injury and inflammation.

Inspiratory resistive breathing (RB), encountered in obstructive lung diseases, induces lung injury. The soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP) pathway is down-regulated in chronic and acute animal models of RB, such as asthma, chronic obstructive pulmonary disease, and in endotoxin-induced acute lung injury. Our objectives were to: (1) characterize the effects of increased concurrent inspiratory and expiratory resistance in mice via tracheal banding; and (2) investigate the contribution of the sGC/cGMP pathway in RB-induced lung injury. Anesthetized C57BL/6 mice underwent RB achieved by restricting tracheal surface area to 50% (tracheal banding). RB for 24 hours resulted in increased bronchoalveolar lavage fluid cellularity and protein content, marked leukocyte infiltration in the lungs, and perturbed respiratory mechanics (increased tissue resistance and elasticity, shifted static pressure-volume curve right and downwards, decreased static compliance), consistent with the presence of acute lung injury. RB down-regulated sGC expression in the lung. All manifestations of lung injury caused by RB were exacerbated by the administration of the sGC inhibitor, 1H-[1,2,4]oxodiazolo[4,3-]quinoxalin-l-one, or when RB was performed using sGCα1 knockout mice. Conversely, restoration of sGC signaling by prior administration of the sGC activator BAY 58-2667 (Bayer, Leverkusen, Germany) prevented RB-induced lung injury. Strikingly, direct pharmacological activation of sGC with BAY 58-2667 24 hours after RB reversed, within 6 hours, the established lung injury. These findings raise the possibility that pharmacological targeting of the sGC-cGMP axis could be used to ameliorate lung dysfunction in obstructive lung diseases.

Tracheal section is an independent predictor of asthma in patients with nasal polyposis

Airway anatomy could be a risk factor for asthma in susceptible patients with airway hyperresponsiveness. This anatomy can be described by only two parameters, the tracheal cross-sectional area and the homothety ratio, which describes the reduction of calibre at each subsequent generation. Thus, we hypothesized that the tracheal area would be linked to the risk of asthma presence.Tracheal area (measured by acoustic reflexion method) and airway responsiveness to metacholine (expressed as Dose Response Slope) were evaluated in 71 consecutive adult patients with nasal polyposis and normal baseline lung function.Hyperresponsiveness was evidenced in 30/71 patients (42%), and 20/71 patients (28%) were asthmatics. Forced expiratory flows were related to tracheal areas (mean value: 3.22±1.32cm2). In a logistic multivariate analysis, tracheal area and the degree of responsiveness were independent predictors of asthma.In conclusion, this study suggests that airway anatomy, crudely assessed by tracheal section, is an independent determinant of asthma.

Bioabsorbable Implant as a Tracheal Wall Substitute in Young Developing Canines

This study evaluated a polylactic and polyglycolic acid (PLA/PGA) implant as a partial tracheal substitute in young developing canines. This experimental and longitudinal study included local stray pups that received substitution of a short cervical tracheal segment with a PLA 85%/PGA 15% plaque. We measured clinical, endoscopic, and tomographic variables for 1 year, at which time we performed histomorphological evaluations of the implant using light and electron microscopy. There were no adverse events throughout the clinical progression. On endoscopic evaluation, the implant was covered with mucosal tissue beginning in the first month, without granulation or stenosis, and the circular shape of the trachea was altered. Tomographic images of the tracheal area at the implant site were similar to adjacent healthy areas (p = 0.423). At the end of the follow-up period, the plaque had biodegraded, and the space was covered by pseudostratified epithelium and ciliated cells similar to the neighboring tissue. Implantation of a PLA/PGA plaque constituted an effective (functional) replacement of a short semicircular cervical tracheal segment without limiting the growth of the recipient. Additional studies are required to prove the efficacy of these implants for larger tracheal segment replacements and in subjects at different stages of development.

Larengotrakeal rekonstrüksiyonda kosta kıkırdağıyla Dacron® greftin karşılaştırması: Deneysel çalışma

Amac: Larenks rekonstruksiyonunda Dacron® implant kullanimini degerlendirmek ve bu materyalin bas-boyun cerrahilerinde potansiyel endikasyonlarini tartismak. Yontem: Her biri 12 Wistar albino sicandan ibaret uc grup olusturuldu. Grup 1 kontrol grubu olup bu gruptaki sicanlarda krikoit kikirdaktan 5. trakea halkasina kadar 6 mm uzunlugunda kesi yapilarak elde edilen 5¥5¥5 mm'lik otolog kosta kikirdagi transplantasyonu yoluyla anterior larengotrakeal rekonstruksiyon gerceklestirildi. Grup 2'de, Grup 1'de oldugu gibi trakea esit uzunluklarda bolumlere ayrildi ve ayni buyuklukte homolog kikirdak nakliyle anterior larengotrakeal rekonstruksiyon gerceklestirildi. Grup 3'de trakea, Grup 1'e esit bolumlere ayrildi ve ayni buyuklukte bir Dacron® greftiyle rekonstruksiyon yapildi. Implantasyondan sonraki 12. haftada sicanlar sakrifiye edildi ve hasta gruplar trakea kesit alani, parsiyel oksijen basinci, epitelizasyon, neovaskularizasyon, enflamatuar hucre infiltrasyonu ve yeni kondrosit olusumu acisindan karsilastirildi. Bulgular: Grup 1'de postoperatif 2. gunde pnomotoraks ve Grup 3'de ise 8. gunde granulasyon ve krutlanma nedeniyle birer deney hayvani kaybedildi. Trakea enine kesit alani ve parsiyel oksijen basinci acisindan gruplar arasinda herhangi bir istatistiksel farklilik yoktu. Grup 2 ve Grup 3 arasinda epitel gelisimi ve neovaskularizasyon acisindan istatistiksel bir farklilik yoktu ancak Grup 1, diger iki gruptan anlamli derecede daha iyi idi. Greft reddinde lenfosit infiltrasyonu onemli bir parametre olup gruplar arasinda onemli bir farklilik vardi. Grup 1, diger 2 gruptan daha iyi oldugu gibi Grup 3'un, Grup 2'den hatiri sayilir derecede farkli oldugu belirlendi. Yeni kondrosit gelisimi acisindan Grup 1. ile Grup 2 arasinda anlamli bir farklilik vardi. Sonuc: Epitel, neovaskularizasyon ve kondrosit gelisim skorlari daha iyi oldugu icin otojen kosta kikirdagi trakea ve larenks icin ideal greft materyalidir. Dacron®'un kullanildigi grupta stenoz, enfeksiyon ve rejeksiyon olmadigi, tum deney hayvanlarinda epitel gelisimi ve neovaskularizasyon tatminkâr derecede olustugu icin larenks rekonstruksiyonunda Dacron® implantlari guvenle kullanilabilmektedir.

Homothety ratio of airway diameters and site of airway resistance in healthy and COPD subjects

Our objective was to evaluate whether a decrease in the homothety ratio (h: diameter of child/parent bronchus, constant over generations) explains the shift in airway resistance toward periphery in chronic obstructive pulmonary disease (COPD). Using a validated computational model of fluid motion, we determined that reduced values of h (<0.76) were associated with a shift in resistance toward periphery. The calculated luminal diameters of terminal bronchioles using normal h (0.80–0.85) or reduced h (0.70–0.75) fitted well with measured micro-CT values obtained by McDonough et al. (N. Engl. J. Med., 2011; 365:1567–75) in control and COPD patients, respectively. A semi-analytic formula of resistance using tracheal dimensions and h was developed, and using experimental data (tracheal area and h from patients [Bokov et al., Respir. Physiol. Neurobiol., 2010; 173:1–10]), we verified the agreement between measured and calculated resistance (r=0.42). In conclusion, the remodeling process of COPD may reduce h and explain the shift in resistance toward lung periphery.

Pregnancy is associated with a decrease in pharyngeal but not tracheal or laryngeal cross-sectional area: a pilot study using the acoustic reflection method

BackgroundThe risk of difficult upper airway access is increased during pregnancy, especially in labor. Changes in upper airway calibre have been poorly studied during pregnancy. The acoustic reflection method is a non-invasive technique that allows a longitudinal assessment of the cross-sectional area of the upper airway from the mouth to carina. We used this technique to evaluate upper airway calibre during normal pregnancy. MethodsWe conducted a prospective, single centre, observational study with a clinical and upper airway acoustic reflection method evaluation of healthy women during the first, second and third trimesters of pregnancy, and up to two days and one month after delivery. ResultsFifty women participated to the study. The mean pharyngeal cross-sectional area decreased between the first and third trimesters (P<0.001) with no significant change of the minimal and mean tracheal cross-sectional areas. The Mallampati score increased during pregnancy between the first and third trimesters (P<0.001). ConclusionUsing measurements with the acoustic reflection method, normal pregnancy is associated with a significant reduction in the cross-sectional area of the pharynx and a concomitant increase in the Mallampati score. No change was observed in the minimal and mean tracheal cross-sectional areas.

Lack of CFTR in a cystic fibrosis pig model disrupts airway smooth muscle development

To better understand the pathogenesis of cystic fibrosis (CF) lung disease, we recently generated CFTR‐targeted pigs. CF pigs develop lung disease typical of human CF. An unexpected finding at birth, prior to the onset of infection and inflammation, was that CF tracheas have a reduced lumen area, irregularly developed airway cartilage, and airway smooth muscle (ASM) with prominent appearing bundles. We hypothesized that these abnormal‐appearing ASM bundles were due to differences in ASM proliferation. To test this hypothesis, tracheas were harvested at birth for histological examination. Despite a reduction in tracheal ASM area in CF, we found that ASM cell density was increased in CF (CF: 0.52±0.06 vs. non‐CF: 0.39±0.02 cells/100 μm2). To investigate if cell proliferation was increased in CF, we stained for the proliferation marker Ki‐67 and found reduced Ki‐67 positive cells in CF (CF: 0.04%±0.01 vs. non‐CF: 0.1%±0.01). This decrease was associated with a reduction in CF ASM cell area (197±19 vs. 259±14 μm2). Finally, electron microscopic studies revealed that at birth CF ASM has a contracted appearance, likely accounting for the reduced cell area. These data suggest that CFTR is important in ASM development and might explain, in part, the increased incidence of airway hyper‐responsiveness in human CF.This work was supported, in part, by the American Asthma Foundation (Sandler).

An In Vitro Study to Assess Determinant Features Associated With Fluid Sealing in the Design of Endotracheal Tube Cuffs and Exerted Tracheal Pressures*

To assess the structural characteristics involved in the design of high-volume low-pressure endotracheal tube cuffs that are associated with fluid sealing effectiveness and to determine the extent of transmitted tracheal pressures upon cuff inflation. In vitro study. Pneumology laboratories. Eight high-volume low-pressure cuffs of cylindrical or tapered shape, made of polyvinylchloride or polyurethane, were studied. Cuffs were tested within a tracheal model, oriented 30° above horizontal to assess 1 hr leakage of oropharyngeal secretions simulant at cuff internal pressures of 15-30 cm H2O. The four best performing cuffs were evaluated for 24 hrs using an internal pressure of 30 cm H2O. The extent of transmitted tracheal wall pressure throughout the cuff-trachea contact area was determined using an internal pressure sensor within a tracheal model upon cuff inflation up to 30 cm H2O. Outer diameter, length, and compliance of each cuff were assessed. Multivariate regression analysis was performed to identify the main determinants of simulant leakage rate. The cuff-trachea contact area and the percentage of tracheal wall pressure measurements greater than 50 cm H2O were computed. Cuff design characteristics significantly differ among tubes. The cuffs made of polyurethane showed the best short- and long-term sealing efficacy. Nevertheless, in the multivariate analysis, the cuff outer diameter (n: 288, p = 0.003) and length (n: 288, p < 0.001), along with the internal pressure (n: 288, p < 0.001), were the only predictors of simulant leakage rate. The tapered cuffs showed the lowest tracheal wall contact area (n: 96, p < 0.001). The tracheal wall pressure distribution pattern was heterogeneous, and the percentage of high tracheal wall pressure significantly differs among the cuffs (n: 96, p < 0.001). The high-volume low-pressure cuffs' outer diameter, length, material, and internal pressure are the main determinants of sealing efficacy. Despite internal pressure within the safe range, transmitted tracheal pressure is extremely heterogeneous and differs among cuffs, occasionally reaching localized, very high, unsafe levels.

Age and Sex Dependence of Forced Expiratory Central Airway Collapse in Healthy Volunteers

A recent estimate for the normal range of forced expiratory tracheal collapse differs substantially from that in an earlier study performed with comparable measurement methods. Given differences in subject characteristics between the two samples, we hypothesized that these discrepant findings may reflect a heretofore unrecognized association between forced expiratory tracheal collapse and age or sex. We enrolled 40 female and 41 male healthy volunteers between 25 and 75 years of age who were without respiratory symptoms or known risk factors for tracheomalacia. Subjects underwent low-dose CT scanning at total lung capacity (TLC) and during forced exhalation (Expdyn) with spirometric monitoring and coaching. Percentage forced expiratory collapse was regressed on age for the total sample and separately within sex. Mean tracheal cross-sectional area (CSA) was 2.54 cm(2) ± 0.57 cm(2) at TLC and 1.15 cm(2) ± 0.53 cm(2) at Expdyn. Mean percentage forced expiratory collapse (%collapse) was 54% ± 20%. Men aged 24 to 31 years (n = 12) had mean %collapse of 36% ± 19%, comparable to results previously reported for similarly aged men (35% ± 18%). Men, but not women, showed a significant positive correlation (R(2) = 0.40, P < .001) between %collapse and age. Older men had both greater CSA at TLC (P = .02) and smaller CSA at Expdyn (P = .001) than younger men. Men exhibit positive age dependence of forced expiratory tracheal collapse. The influence of age and sex on forced expiratory tracheal collapse should be considered in the diagnostic evaluation of expiratory dynamic airway collapse and/or tracheomalacia.

Sutures enriched with adipose-derived stem cells decrease the local acute inflammation after tracheal anastomosis in a murine model

Local inflammatory reaction and tension are the main causes of postoperative complications after tracheal surgery. Adipose-derived stem cells (ASCs) are known to have immunomodulatory activity. The exact mechanism of this activity is not known, although it is possible that they modulate the function of different cells involved in the immune response. Little is known of their impact on acute inflammation, especially in the problematic tracheal area. We aimed to study the effect of ASCs applied locally in an animal model of tracheal resection and anastomosis. ASCs from the subcutaneous fat of BDIX rats were infected for expression of the enhanced green fluorescent protein (eGFP) and were cultured with Polyglactin 910 sutures to obtain biosutures (ASC-coated sutures). After tracheal resection, 90 BDIX rats (syngeneic, autologous model) underwent anastomosis with biosutures (1.5 10(6) cells/biosuture [Group 1] or 0.5 10(6) cells/biosuture [Group 2]) or conventional sutures (Group 3). The animals were killed after 1, 4, 10, 30 or 60 days and histological and immunofluorescence studies were performed on the anastomotic areas. Inflammatory cell densities were graded semiquantitatively by the pathologist in a blinded fashion. In the early period (1 and 4 days), the biosuture groups presented an atypical pattern of acute inflammation, characterized by the almost complete absence of neutrophils, and the presence of abundant lymphocytes and plasma cells, compared with the control group (P < 0.05). Moreover, abundant macrophages/monocytes were immunolocated around blood vessels near the biosutures and between biosuture threads 1 day after anastomosis, whereas the presence of macrophages/monocytes in animals treated with conventional sutures was discrete (P < 0.05). No differences were observed in the later period. No side effects in the biosuture groups were found. Biosutures are a comfortable way of stem cell delivery to the surgical field without modification of the operative protocol. ASCs suppress the local acute inflammatory reaction (increased macrophage migration and decreased neutrophil infiltration) in the tracheal anastomosis and cause an early switch from acute to chronic inflammation.

Do Tracheas Grow After Slide Tracheoplasty?

Slide tracheoplasty has become the surgical technique of choice for repair of congenital tracheal stenosis. Despite the initial reluctance regarding the ability of this "reconstructed" trachea to grow, the reduced morbidity and mortality have allowed slide tracheoplasty to be widely adopted. The aim of this study was to evaluate tracheal growth after slide tracheoplasty. This was a retrospective study. In follow-up bronchography performed 1, 6, 12, 18, and 24 months after slide tracheoplasty, we measured the cross-sectional areas of the midtrachea and distal trachea at each investigation and correlated the measurements with the anthropomorphic factors (body weight, height, and body surface). Fourteen patients were enrolled in this study. The midtracheal and distal tracheal cross-sectional areas significantly increased with time (p ≤ 0.0001). The average rates of midtracheal growth were 21.0 mm(2)year in the first 6 months and 8.0 mm(2)/year in the first 2 years, and the distal trachea grew 18.5 mm(2)/year and 8.4 mm(2)/year, respectively. Regression analysis showed that both the midtrachea and the distal trachea increase significantly with weight (r(2) = 0.257, p ≤ 0.0001), height (r(2) = 0.376, p ≤ 0.0001), and body surface area (r(2) = 0.315, p ≤ 0.0001). Balloon dilation did not significantly alter the tracheal growth in the first 2 years after slide tracheoplasty. Slide tracheoplasty does not inhibit tracheal growth. The reconstructed trachea grows faster in the first 6 months and slows in the following 18 months. There is a positive correlation between tracheal cross-sectional area and weight, height, and body surface area.

Evaluation of the trachea and intrathoracic airways by the acoustic reflection method in children with cystic fibrosis

Tracheomalacia has been observed in older patients with cystic fibrosis (CF). The acoustic reflection method (ARM) allows a noninvasive calculation of the longitudinal cross-sectional area of the trachea (MTAv) and the airway resistance (Raw). ARM measurements were performed in 20 CF children and 20 controls during spontaneous breathing (SB), forced inspiration (FI), and forced expiration (FE). The mean MTAv value was comparable in the CF patients and the control subjects during SB, FI, and FE. The Raw was also comparable during SB and FI. However, the Raw during FE was higher in the CF patients than in the control subjects (7.9±2.3 vs. 5.0±1.5 cm H2O l(-1) s(-1), respectively, p<0.001). In the patients with CF, only the Raw during FE correlated with the predicted forced expiratory volume in 1s (R2=0.37, p=0.04). The tracheal cross-sectional area measured by the ARM is normal in children with CF but the increase in Raw during FE suggests an increase in intrathoracic airway distensibility.

Shape and material characteristics of the trachea in the leatherback sea turtle promote progressive collapse and reinflation during dives

The leatherback turtle regularly undertakes deep dives and has been recorded attaining depths in excess of 1200 m. Its trachea is an almost solid, elliptical-section tube of uncalcified hyaline cartilage with minimal connective tissue between successive rings. The structure appears to be advantageous for diving and perfectly designed for withstanding repeated collapse and reinflation. This study applies Boyle's law to the respiratory system (lungs, trachea and larynx) and estimates the changes in tracheal volume during a dive. These changes are subsequently compared with the results predicted by a corresponding finite element (FE) structural model, itself based on laboratory studies of the trachea of an adult turtle. Boyle's law predicts that the lungs will collapse first during the initial stages of a dive with tracheal compression beginning at much deeper depths after complete air mass expulsion from the lungs. The FE model reproduces the changes extremely well (agreeing closely with Boyle's law estimations) and provides visual representation of the deformed tracheal luminal area. Initially, the trachea compresses both ventrally and dorsally before levelling ventrally. Bulges are subsequently formed laterally and become more pronounced at deeper depths. The geometric configuration of the tracheal structure confers both homogeneity and strength upon it, which makes it extremely well suited for enduring repeated collapse and re-expansion. The structure actually promotes collapse and is an adaptation to the turtle's natural environment in which large numbers of deep dives are performed annually.

Mechanical Modulation of Cuff Pressure Reduces Airway Injury

Objective: Test a valve-based mechanical means of modulating endotracheal tube cuff pressure and its efficacy in reducing airway injury. Method: We developed a mechanical valve-based device that modulates endotracheal tube cuff pressure with the respiratory cycle. We tested this device in a previously validated porcine model of accelerated airway injury. Laryngeal specimens from animals intubated with a modulated cuff pressure were compared to those intubated with a constant cuff pressure. Results: We have demonstrated that the valve-based device adequately maintains ventilation. Furthermore, there was a significant reduction in the amount of histologically evident injury to the subglottic and tracheal areas of the airway in those animals that were maintained with a modulated cuff pressure. There was no difference between the 2 animal groups in the degree of supraglottic or glottic injury. Conclusion: This valve-based system is inexpensive, reliable, and effective in reducing airway injury. Validation of this device in the clinical setting would allow its widespread application and potentially result in a significant reduction in airway injury from prolonged intubation.

Management of Anterior Mediastinal Masses in Children

Children with anterior mediastinal masses are at risk for life-threatening airway compromise during anesthesia, and can present a diagnostic and management challenge for pediatric surgeons. We performed a retrospective chart review of all children presenting with an anterior mediastinal mass from 1994-2009. Parameters studied included demographics, historical and physical findings at diagnosis, radiographic evidence of airway compression, diagnostic studies, diagnosis, and complications. There were 26 patients with anterior mediastinal masses over a 15-year period. The mean age was 11.3 years, and there were no gender differences. The diagnoses were lymphoma (62%, 16/26), leukemia (15%, 4/26), and other (23%, 6/26). Diagnosis was made by CBC/peripheral smear in 2/4 patients with leukemia, by bone marrow biopsy in 2/4 patients with leukemia, by thoracentesis in 3/16 patients with lymphoma, by lymph node biopsies in 6/16 patients with lymphoma, and by biopsy of a mediastinal mass in 7/16 patients with lymphoma and in 6/6 patients with other diagnoses. Radiographic evidence of airway compression was seen in 62% (16/26) of children. Only 12% (3/26) had a tracheal cross-sectional area (TCA) <50%. Correlation of symptoms with anatomical airway obstruction or complications was poor. Pulmonary function studies were obtained in 38%, 10/26 children. Only 2 children had a PEFR (peak expiratory flow rate) <50% predicted. This data also correlated poorly with anatomical airway obstruction or complications. 3 patients had anesthesia-related complications: one desaturation during induction prior to median sternotomy, one with significant desaturation and bradycardia during biopsy under local anesthesia with minimal sedation, and one with prolonged (5 days) mechanical ventilation after general anesthesia. 2 of these patients had a TCA <50%, and 2 had SVC obstructions. There were no anesthesia-related deaths, and the overall survival was 85% (22/26). Anterior mediastinal masses in children should be approached in a step-wise fashion with multi-disciplinary involvement, starting with the least invasive techniques and progressing cautiously. The surgeon should have a well-defined and preoperatively established contingency plan if these children require general anesthesia for diagnosis.