Search

Background There is significant pulmonary functional deficit related to obesity, but no prospective CT studies have evaluated the effects of obesity on the lungs and trachea. Purpose To evaluate lung parenchymal and tracheal CT morphology before and 6 months after bariatric surgery, with functional and symptomatic correlation. Materials and Methods A prospective longitudinal study of 51 consecutive individuals referred for bariatric surgery was performed (from November 2011 to November 2013). All individuals had undergone limited (three-location) inspiratory and end-expiratory thoracic CT before and after surgery, with concurrent pulmonary function testing, body mass index calculation, and modified Medical Research Council (mMRC) dyspnea scale and Epworth scoring. Two thoracic radiologists scored the CT extent of mosaic attenuation, end-expiratory air trapping, and tracheal shape. The inspiratory and end-expiratory cross-sectional areas of the trachea were measured. The paired t test or Wilcoxon signed-rank test was used for pre- and postsurgical comparisons. Spearman correlation and logistic regression were used to evaluate correlations between CT findings and functional and symptom indexes. Results A total of 51 participants (mean age, 52 years ± 8 [standard deviation]; 20 men) were evaluated. Before surgery, air trapping extent correlated most strongly with decreased total lung capacity (Spearman rank correlation coefficient [rs] = -0.40, P = .004). After surgery, there were decreases in percentage mosaic attenuation (0% [interquartile range {IQR}: 0%-2.5%] vs 0% [IQR: 0%-0%], P < .001), air trapping (9.6% [IQR: 5.8%-15.8%] vs 2.5% [IQR: 0%-6.7%], P < .001), and tracheal collapse (201 mm2 [IQR: 181-239 mm2] vs 229 mm2 [186-284 mm2], P < .001). After surgery, mMRC dyspnea score change correlated positively with air trapping extent change (rs = 0.46, P = .001) and end-expiratory tracheal shape change (rs = 0.40, P = .01). At multivariable analysis, air trapping was the main determinant for decreased dyspnea after surgery (odds ratio, 1.2; 95% confidence interval: 1.1, 1.2; P = .03). Conclusion Dyspnea improved in obese participants after weight reduction, which correlated with less tracheal collapse and air trapping at end-expiration chest CT. © RSNA, 2020 Online supplemental material is available for this article.

Background Dogs with tracheal stents often have positive airway bacterial cultures. The pathogenicity of these organisms and risk factors for infection have not been investigated. Objective Describe bacterial infection in dogs with tracheal collapse before and after tracheal stent placement. Animals Fifty-three client-owned dogs. Methods Retrospective review of medical records of dogs receiving tracheal stents with thoracic radiographs, tracheoscopy, and endotracheal lavage. Results There was no difference between the overall prevalence of dogs with positive bacterial cultures before (31/38; 82%) or after stent placement (24/31; 77%) (P = .67). An increased number of geriatric (17/28; 61%) and traditional-type collapse (TTC) (16/26; 62%) dogs had positive pathogenic airway infections before stent placement, compared to young (8/25; 32%; P = .04) and malformation-type collapse (MTC) dogs (9/27; 33%; P = .04). After tracheal stent placement, geriatric dogs had a 52% reduction in pathogenic bacteria infection frequency (P = .02) and dogs with TTC had a 56% reduction in pathogenic bacteria infection frequency (P = .01). Significant risk factors for pathogenic infection included a history of pneumonia (OR = 3.6; 95% CI, 0.28-43.36) and cardiac disease (OR = 1.25; 95% CI, 0.16-9.92) in geriatric dogs, and hepatomegaly in young dogs (OR = 1.5; 95% CI, 0.12-19.44). Conclusions and clinical importance Tracheal stent placement does not increase the overall rate of pathogenic bacterial infection in dogs with tracheal collapse and can decrease the rate of subsequent pathogenic infections in geriatric dogs and dogs with TTC that require tracheal stenting. Airway culture and cytology should be performed in all dogs undergoing tracheal stent placement.

BACKGROUND: Tracheal collapse in horses is reportedly uncommon; however, American Miniature Horses are more commonly affected. There is no description of the tracheal luminal diameter of American Miniature Horses, making early detection of tracheal luminal narrowing difficult. OBJECTIVES: To 1) describe radiographic tracheal luminal diameter in clinically normal American Miniature Horses, 2) report the prevalence of subclinical tracheal collapse in a population of American Miniature Horses, and 3) use tracheal videofluoroscopy to quantify variation in tracheal luminal diameter throughout the respiratory cycle in horses with no clinical respiratory disease. STUDY DESIGN: Descriptive observational reference interval study. METHODS: Thirty‐four American Miniature Horses with no reported history of respiratory illness were recruited. Lateral cervical and thoracic radiographs were obtained in unsedated standing horses. Dynamic fluoroscopic images were obtained of the cervical and thoracic trachea throughout the respiratory cycle. Horses were then sedated as needed and tracheoscopy was performed. Twenty‐nine horses were categorised as normal, and five horses were categorised as subclinically affected based on 25% or greater tracheal narrowing using tracheoscopy for visual assessment. Radiographic tracheal lumen to vertebral body measurements were obtained throughout the cervical and thoracic trachea. Maximum and minimum fluoroscopic tracheal diameter at each site throughout the respiratory cycle was recorded. RESULTS: A mean, median, 95% confidence interval and bootstrapped 95% reference interval of radiographic tracheal diameter to vertebral body ratios were generated in normal horses. The prevalence of subclinical tracheal collapse in this population of American Miniature Horses is 14.7%. MAIN LIMITATIONS: Bootstrapped reference range was generated from 29 horses. CONCLUSIONS: Radiographic tracheal measurements and ratios of the tracheal diameter to vertebral body in the normal American Miniature Horse are described herein and can be used as a guideline when screening for tracheal disease in American Miniature Horses. The prevalence of subclinical tracheal collapse in American Miniature Horses may be higher than previously reported.

Introduction Esophageal atresia (EA) is often accompanied by tracheobronchial malformations leading to stridor, recurrent bronchitis, and occasionally to life-threatening obstructive apnea after surgical repair. The aim of this study was to identify the presence of tracheomalacia in patients with EA and tracheoesophageal fistula (TEF) pre- and postoperatively and to find endoscopic correlates leading to clinical airway symptoms. Methods In a cohort of 362 patients with EA-TEF who underwent 595 tracheoscopies at the Children's Hospital of Cologne between January 1983 and December 2002, impaired tracheal lumen, localization of TEF, tracheal pulsations, and corresponding clinical symptoms were retrospectively analyzed. Results The incidence of tracheomalacia was higher in patients with EA and TEF (Gross B–D) compared with patients with EA alone (Gross A) and average tracheal collapse does not significantly change before and after surgical repair of the esophagus in all types. Patients with cyanosis while eating and obstructive apnea presented with an average tracheal collapse of 89%. The presence of respiratory symptoms such as cough, stridor, or bronchitis was not associated with a higher grade of tracheal collapse compared with patients without any airway symptoms (average tracheal collapse of 37% in symptomatic patients vs. 33% in nonsymptomatic patients). Conclusion Tracheomalacia tends to be present independently of surgical procedure. Tracheomalacia should be measured by tracheoscopy (in % of tracheal collapse). Patients with a tracheal collapse of >80%, a ventral pulsation, and obstructive apnea or cyanosis in combination, are at risk for life-threatening situations and further surgical treatment should be considered.

Esophageal atresia (EA) is the most common congenital esophageal malformation. Airway pathology, in particular, tracheomalacia and laryngotracheal anomalies is a major cause of morbidity and mortalilty in patients with EA. The aim of this study was to report the incidence and type of laryngotracheal anomalies seen in a large series of patients with EA, and to evaluate their impact on the management of children with EA. Retrospective study. Retrospective cohort including all patients referred to the EA National Reference Center from January 2002 to December 2014. Airway assessment was based on endoscopy performed before, during and/or after esophageal surgery. One-hundred and fifty-eight patients were included in the study. Endoscopy revealed tracheomalacia in 141 cases (89.2%) and other laryngotracheal anomalies in 43 patients (27.2%). Ninety-six patients (60.7%) presented with persistent respiratory symptoms, including acute life-threatening events in 21 cases, leading to death in 6 cases. A correlation was observed between degree of tracheal collapse and presence of acute life-threatening events. Laryngotracheal surgery was required in 35 cases (22%). Laryngotracheal anomalies are frequently associated with EA and represent an important etiology of morbidity and mortality that can be prevented by early and systematic diagnosis and aggressive management. An early systematic endoscopic evaluation is recommended to coordinate the airway management with the EA surgery.

Introduction As common treatments for long tracheal stenosis are associated with several limitations, tracheal tissue engineering is considered as an alternative treatment. Aim of study This study aimed at preparing a hybrid scaffold, based on biologic and synthetic materials for tracheal tissue engineering. Materials and methods Three electrospun polycaprolactone (PCL) scaffolds, namely E1 (pure PCL), E2 (collagen-coated PCL) and E3 (PCL blended with collagen) were prepared. Allogeneic aorta was harvested and decellularized. A biodegradable PCL stent was fabricated and inserted into the aorta to prevent its collapse. Result Scaffold characterization results revealed that the 2-h swelling ratio of E2 was significantly higher than those of E1 and E3. In the first 3 months, E2 and E3 exhibited almost equal degradabilities (significantly higher than that of E1). Moreover, tensile strengths of all samples were comparable with those of human trachea. Using rabbit's adipose-derived mesenchymal stem cells (AMSCs) and primary chondrocytes, E3 exhibited the highest levels of GAG release within 21 days as well as collagen II and aggrecan expression. Fot the next step, AMSC-chondrocyte co-culture seeded scaffold was sutured to the acellular aorta, implanted into rabbits' muscle, and finally harvested after 4 weeks of follow up. Conclusion Harvested structures were totally viable due to the angiogenesis created by the muscle. H&E and alcian blue staining results revealed the presence of chondrocytes in the structure and GAG in the produced extracellular matrix. Since tracheal replacement using biologic and synthetic scaffolds usually results in tracheal collapse or granulation formation, a hybrid construct may provide the required rigidity and biocompatibility for the substitute.

Rationale and Objectives The opened or closed status of the glottis might influence tracheal size changes in inspiratory and expiratory computed tomography (CT) scans. We investigated if the glottis status makes the tracheal collapse differently correlate with lung volume difference between inspiratory and expiratory CT scans. Materials and Methods Forty patients with chronic obstructive pulmonary disease whose glottis was included in the acquired scanned volume for lung CT were divided into two groups: 16 patients with the glottis closed in both inspiratory and expiratory CT, and 24 patients with the glottis open in at least one CT acquisition. Lung inspiratory (Vinsp) and expiratory (Vexp) volumes were automatically computed and lung ΔV was calculated using the following formula: (Vinsp − Vexp)/Vinsp × 100. Two radiologists manually measured the anteroposterior diameter and cross-sectional area of the trachea 1 cm above the aortic arch and 1 cm above the carina. Tracheal collapse was then calculated and correlated with lung ΔV. Results In the 40 patients, the correlations between tracheal Δanteroposterior diameter and Δcross-sectional area at each level and lung ΔV ranged between 0.68 and 0.74 (ρ) at Spearman rank correlation test. However, in the closed glottis group, the correlations were higher for all measures at the two levels (ρ range: 0.84–0.90), whereas in the open glottis group, correlations were low and not statistically significant (ρ range: 0.29–0.34) at the upper level, and moderate at the lower level (ρ range: 0.51–0.55). Conclusions A closed or open glottis influences the tracheal size change in inspiratory and expiratory CT scans. With closed glottis, the tracheal collapse shows a stronger correlation with the lung volume difference between inspiratory and expiratory CT scans.

BACKGROUND: Tracheal collapse is a weakness of the tracheal wall leading to expiratory central airway collapse of more than 50% compared to inspiration. It has previously been discussed whether the collapsibility of the greater airways is a stable or a dynamic condition. Indeed, other well-known lung diseases such as asthma are characterized by dynamic changes with respect to pulmonary function indices. There are several different morphologies of the trachea related to collapsibility such as the crescent type and the saber-sheath type both involving the tracheal cartilage and excess dynamic airway collapse only involving the posterior membranous part of the trachea. Is the morphology of the trachea important for the course of the disease? The effect or adverse effects of inhaled corticosteroids are thought to play a role in the increasing incidence of the excess tracheal collapse. In this pilot study, we hypothesized that the excess collapsibility of the tracheal wall is dynamic.METHODS: We prospectively examined 20 patients with excessive tracheal collapse on previous CT scans performed primarily due to bronchiectasis. A repeat CT scan was performed in order to evaluate the collapsibility. Before the repeat scan, patients were trained in maximal inspiration, expiration and breathholding. CT was performed in full inspiration and at end-expiration. Image assessment was performed on a dedicated CT workstation using standard lung window display settings. The percentage expiratory collapse based on cross sectional areas from carina to the thoracic inlet was calculated. Pulmonary function tests were performed and analysed in accordance with the American Thoracic Society and the European Respiratory Society guidelines.RESULTS: Repeat CT scan were performed after 24 month +/- 7.2. Six of the 20 participants (30%) were males. Mean age was 67 +/- 11.3 years. Mean FEV1 was 83% of predicted, FVC 96.6 % of predicted and FEV1/FVC-ratio 71%. In 45% of the patients tracheal expiratory collapse improved (by more than 10%) based on percentage change in cross sectional areas in expiration compared to inspiration. 35% of patients showed disease progression with increased collapse and in 20% the collapsibility remained unchanged.CONCLUSION: We demonstrate that the collapsibility in a large fraction of the patients had actually improved at the follow up examination. We do not find any dependency of the change in collapsibility on the morphology of the trachea after end expiration, use of corticosteroid, or recurrent infections. In addition, no correlation between the changes in collapse and changes in the pulmonary function tests and the symptoms is observed.

Objective Suprastomal collapse is a complication of pediatric tracheotomy with a potential impact on decannulation success. The aim of this study was to review the experience in the management of pediatric suprastomal collapse in a tertiary-care center, detailing the surgical technique employed. Methods This study included 12 tracheotomised children with the diagnosis of suprastomal collapse in the last 5 years. All patients of the study underwent surgical intervention to manage suprastomal collapse to achieve tracheotomy decannulation. The surgical procedure entailed dissection of the pre-existing tracheotomy tract down to the trachea, then excision of the tract flush with the anterior tracheal wall. The tracheal opening was closed transversely with 3–4 interrupted absorbable sutures placed in craniocaudal direction. Results At the end of treatment all patients were decannulated successfully. No intraoperative complications were reported. Minor postoperative complications were reported in 3 children in the form of mild surgical emphysema (n = 2) and wound infection (n = 1). Those patients were successfully managed conservatively. Conclusion This technique is a simple and effective procedure enabling immediate decannulation with very low morbidity. In a long term follow up period, no recurrence has been reported and all patients returned to their usual quality of life.

Objective To describe the surgical placement of a continuous extraluminal tracheal prosthesis (CETP) and report the subsequent postoperative clinical outcomes in dogs with tracheal collapse. Study design Retrospective case series. Animals Fifty-four dogs. Methods Medical records of dogs in which cervical and/or thoracic inlet tracheal collapse was diagnosed and treated by placement of a CETP between 2010 and 2017 were reviewed to evaluate postoperative complications, changes in respiratory function, and survival. Histological examinations of tracheal tissues performed in 2 dogs at 51 and 57 months after surgery were also reviewed. Results Fifty-three (98%) dogs survived to discharge. Postoperative complications included laryngeal paralysis (1 dog), disseminated intravascular coagulation (1 dog), and recurrent tracheal collapse (2 dogs). None of the dogs exhibited clinical evidence of tracheal necrosis. Preoperative dry, harsh cough resolved in 87% of the dogs after surgery. Goose honking cough was resolved in 25 of 26 (96%) dogs. Median follow-up time was 30 months (range, 16 days to 76 months). The survival rate at 36 months was 86% (CI: 75%-96%). On histological examination in 2 dogs, the tracheal tissue surrounding the prosthesis was well preserved and without evidence of chronic inflammation. Conclusion Continuous extraluminal tracheal prosthesis placement in dogs with tracheal collapse resulted in low postoperative complication rates and good long-term outcomes. Clinical significance Continuous extraluminal tracheal prosthesis placement provides a viable alternative surgical option for managing dogs with tracheal collapse.

Chondromalacia of the tracheal and bronchial cartilages and redundancy of the dorsal tracheal membrane result in collapse of the large airways, leading to coughing and airway obstruction. It most commonly affects small-breed dogs, although larger-breed dogs, cats, and miniature horses are also sporadically reported. Dynamic airway imaging is used to confirm the diagnosis. The primary goal of medical management is to control clinical signs attributable to coughing and airway inflammation. When this is no longer effective, tracheal stents provide a minimally invasive, rapid way to restore airway patency. Bronchial stenting is in its infancy in veterinary medicine.

Background Tracheomalacia is the most common congenital abnormality of the trachea. Posterior tracheopexy to alleviate posterior intrusion contributing to dynamic tracheal collapse has been reported using thoracotomy or median sternotomy. Here we describe the minimally invasive operative technique of thoracoscopic posterior tracheopexy with bronchoscopic guidance. Operative technique After preoperative computed tomography and bronchoscopy, a right thoracoscopic approach is utilized. The esophagus is mobilized and the membranous trachea is sutured to the prevertebral fascia under direct bronchoscopic visualization. Immediate improvement in tracheal collapse is noted. No major complications are reported and length of stay is short. Aortopexy may also be required to address anterior vascular compression. Conclusion Thoracoscopic posterior tracheopexy is safe and feasible. Further studies with more patients and longer follow-up are needed to assess durability.

Fluid clearance from the respiratory system during developmental transitions is critically important for achieving optimal gas exchange in animals. During insect development from embryo to adult, airway clearance occurs episodically each time the molt is completed by performance of the ecdysis sequence, coordinated by a peptide-signaling cascade initiated by ecdysis-triggering hormone (ETH). We find that the neuropeptide Kinin (also known as Drosokinin or Leukokinin) is required for normal respiratory fluid clearance or "tracheal air-filling" in Drosophila larvae. Disruption of Kinin signaling leads to defective air-filling during all larval stages. Such defects are observed upon ablation or electrical silencing of Kinin neurons, as well as RNA silencing of the Kinin gene or the ETH receptor in Kinin neurons, indicating that ETH targets Kinin neurons to promote tracheal air-filling. A Kinin receptor mutant fly line (Lkrf02594 ) also exhibits tracheal air-filling defects in all larval stages. Targeted Kinin receptor silencing in tracheal epithelial cells using breathless or pickpocket (ppk) drivers compromises tracheal air-filling. On the other hand, promotion of Kinin signaling in vivo through peptide injection or Kinin neuron activation through Drosophila TrpA1 (dTrpA1) expression induces premature tracheal collapse and air-filling. Moreover, direct exposure of tracheal epithelial cells in vitro to Kinin leads to calcium mobilization in tracheal epithelial cells. Our findings strongly implicate the neuropeptide Kinin as an important regulator of airway clearance via intracellular calcium mobilization in tracheal epithelial cells of Drosophila.

We describe the implantation of an absorbable, custom-made stent of polydioxanone to treat tracheomalacia in a 5-month-old patient with extrinsic compression by a double aortic arch. The use of an absorbable, oversized stent treated the tracheal collapse caused by vascular compression, avoided removal procedures, and allowed the infant’s growth. The use of an oversized stent prevented stent migration and gave minimal problems of granulation.

Background Tracheal obstruction resulting from expiratory tracheal deformation has been associated with respiratory symptoms and severe airway exacerbations. In chronic obstructive pulmonary disease (COPD), acute exacerbations (AECOPD) create large intrathoracic pressure swings which may increase tracheal deformation. Excessive central airway collapse (ECAC) may be diagnosed when the tracheal area on expiration is less than 50% of that on inspiration. The prevalence of ECAC in AECOPD and its temporal course have not been systematically studied. Methods We prospectively recruited healthy volunteers (n = 53), stable outpatients with COPD (n = 40) and patients with hospitalised acute exacerbations of COPD (AECOPD, n = 64). 17 of the AECOPD group returned for repeat evaluation when clinically well at 6–12 weeks. All subjects underwent dynamic 320-slice computed tomography of the larynx and trachea during tidal breathing, enabling quantitation of tracheal area and dimensions (mean ± SD). Results No healthy individuals had ECAC. The prevalence of ECAC in stable COPD and AECOPD was 35% and 39% respectively. Mean tracheal collapse did not differ between stable COPD (57.5 ± 19.8%), AECOPD (53.8 ± 19.3%) and in the subset who returned when convalescent (54.9 ± 17.2%). AECOPD patients with and without ECAC had similar clinical characteristics. Conclusions Tracheal collapse in both stable and AECOPD is considerably more prevalent than in healthy individuals. ECAC warrants assessment as part of comprehensive COPD evaluation and management. Further studies should evaluate the aetiology of ECAC and whether it predisposes to exacerbations. Electronic supplementary material The online version of this article (10.1186/s12931-017-0646-2) contains supplementary material, which is available to authorized users.

Background Tracheomalacia (TM) is a condition of excessive tracheal collapse during exhalation. Both acquired and congenital forms of TM are believed to result from morphological changes in cartilaginous, fibrous and/or smooth muscle tissues reducing airway mechanical properties to a degree that precipitates collapse. However, neither the specific amount of mechanical property reduction nor the malacic segment lengths leading to life threatening airway collapse in TM are known. Furthermore, the specific mechanism of collapse is still debated. Methods Computational nonlinear finite element models were developed to determine the effect of malacic segment length, tracheal diameter, and reduction in tissue nonlinear elastic properties on the risk for and mechanism of airway collapse. Cartilage, fibrous tissue, and smooth muscle nonlinear elastic properties were fit to experimental data from preterm lambs from the literature. These elastic properties were systematically reduced in the model to simulate TM. Results An intriguing finding was that sudden mechanical instability leading to complete airway collapse occurred in airways when even a 1 cm segment of cartilage and fibrous tissue properties had a critical reduction in material properties. In general, increased tracheal diameter, increased malacic segment length coupled with decreased nonlinear anterior cartilage/fibrous tissue nonlinear mechanical properties increased the risk of sudden airway collapse from snap through instability. Conclusion Modeling results support snap through instability as the mechanism for life threatening tracheomalacia specifically when cartilage ring nonlinear properties are reduced to a range between fibrous tissue nonlinear elastic properties (for larger diameter airways > 10 mm) to mucosa properties (for smaller diameter airways

Aim To determine the range of tracheal collapse at end-expiration among chronic obstructive pulmonary disease (COPD) patients and to compare the extent of tracheal collapse between static end-expiratory and dynamic forced-expiratory multidetector-row computed tomography (MDCT). Materials and methods After institutional review board approval and obtaining informed consent, 67 patients meeting the National Heart, Lung, and Blood Institute (NHLBI)/World Health Organization (WHO) Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD were sequentially imaged using a 64-detector-row CT machine at end-inspiration, during forced expiration, and at end-expiration. Standardized respiratory coaching and spirometric monitoring were employed. Mean percentage tracheal collapse at end-expiration and forced expiration were compared using correlation analysis, and the power of end-expiratory cross-sectional area to predict excessive forced-expiratory tracheal collapse was computed following construction of receiver operating characteristic (ROC) curves. Results Mean percentage expiratory collapse among COPD patients was 17 ± 18% at end-expiration compared to 62 ± 16% during forced expiration. Over the observed range of end-expiratory tracheal collapse (approximately 10–50%), the positive predictive value of end-expiratory collapse to predict excessive (≥80%) forced expiratory tracheal collapse was Conclusion COPD patients demonstrate a wide range of end-expiratory tracheal collapse. The magnitude of static end-expiratory tracheal collapse does not predict excessive dynamic expiratory tracheal collapse.

Rationale: Tracheobronchomalacia (TBM) refers to the weakening trachea or the trachea loss of structural integrity of airway cartilaginous structures. It causes tracheal stenosis, resulting in significantly high rates of mortality. Bronchoplasty by high-pressure balloon dilation under general anesthesia is a simple but effective and safe method to treat tracheobronchial stenosis. However, recurrent postoperative dyspnea after extubation due to tracheal collapse is still a challenge for anesthetists. Patient concerns: A 52-year-old man weighing 72 kg was scheduled for balloon dilatation surgery under general anesthesia because of breathing difficulties caused by tracheal stenosis. His previous medical history included rheumatoid arthritis, obstructive sleep apnea syndrome (OSAS), chronic bronchitis and a history of tracheal intubation. Laryngeal computerized tomography confirmed the stenosis at the level of thyroid gland. Diagnosis: The tracheal collapse after balloon dilatation for tracheal stenosis therapy. Interventions: Postoperatively, the patient presented with more serious and repetitive symptoms of dyspnea after extubation when compared to that before treatment. So, we had to re-insert the laryngeal mask airway (LMA), and exclude some anesthesia-associated factors, such as laryngospasm, bronchospasm and so on. After a series of treatments, we ultimately found the cause in time (the airway collapsed), and succeeded in tracheal extubation after the stent was inserted. Outcomes: The patient recovered well and reported high satisfaction with anesthesia management. Lessons: In such an emergency even, the anesthesiologist should take valuable treatments to ensure the patient's effective ventilation. If the anesthesia-related factors can be eliminated, tracheomalacia or airway collapse should be considered whenever dyspnea occurs in the patients who unexpectedly fail to be extubated.

Objective—To determine the degree of fluctuation in tracheal dimensions between forced inspiration and passive expiration in healthy dogs of various sizes. Animals—10 client-owned dogs with no evidence of respiratory disease or tracheal collapse. Procedures—Anesthetized dogs underwent a computed tomographic examination during forced inspiration and induced but passive expiration to assess tracheal dimensions. Tracheal height, width, and cross-sectional area were measured at inspiration and expiration, and percentage change in dimension was calculated for each variable. Results—Measurements were acquired in 10 dogs that ranged in body weight from 3.5 to 47.8 kg. Tracheal cross-sectional area at inspiration and expiration was associated with body weight at all 3 tracheal regions. The percentage change in tracheal height and cross-sectional area was associated with body weight in the cervical but not the thoracic-inlet or thoracic regions. The tracheal cross-sectional area changed by as much as 24.2% (mean, 5.5%), 20.0% (mean, 6.0%), and 18.6% (mean, 6.0%) in the cervical, thoracic-inlet, and thoracic regions, respectively. Conclusions and Clinical Relevance—The change in tracheal cross-sectional area from inspiration to expiration was as great as 24% in healthy dogs, and the area was associated with body weight. Respiratory fluctuations appeared to result in changes in tracheal dimension during respiration similar to those reported for humans.

The shape of tracheal cartilage has been widely treated as symmetric in analytical and numerical models. However, according to both histological images and in vivo medical image, tracheal cartilage is of highly asymmetric shape. Taking the cartilage as symmetric structure will induce bias in calculation of the collapse behavior, as well as compliance and muscular stress. However, this has been rarely discussed. In this paper, tracheal collapse is represented by considering its asymmetric shape. For comparison, the symmetric shape, which is reconstructed by half of the cartilage, is also presented. A comparison of cross-sectional area, compliance of airway and stress in the muscular membrane, determined by asymmetric shape and symmetric shape is made. The result indicates that the symmetric assumption brings a small error, around 5% in predicting the cross-sectional area under loading conditions. The relative error of compliance is more than 10%. Particularly when the pressure is close to zero, the error could be more than 50%. The model considering the symmetric shape results in a significant difference in predicting stress in muscular membrane by either under- or over-estimating it. In conclusion, tracheal cartilage should not be treated as a symmetric structure. The results obtained in this study are helpful in evaluating the error induced by the assumption in geometry.

Background Despite being the stiffest airway of the bronchial tree, the trachea undergoes significant deformation due to intrathoracic pressure during breathing. The mechanical properties of the trachea affect the flow in the airway and may contribute to the biological function of the lung. Method A Fung-type strain energy density function was used to investigate the nonlinear mechanical behavior of tracheal cartilage. A bending test on pig tracheal cartilage was performed and a mathematical model for analyzing the deformation of tracheal cartilage was developed. The constants included in the strain energy density function were determined by fitting the experimental data. Result The experimental data show that tracheal cartilage is a nonlinear material displaying higher strength in compression than in tension. When the compression forces varied from −0.02 to −0.03 N and from −0.03 to −0.04 N, the deformation ratios were 11.03±2.18% and 7.27±1.59%, respectively. Both were much smaller than the deformation ratios (20.01±4.49%) under tension forces of 0.02 to 0.01 N. The Fung-type strain energy density function can capture this nonlinear behavior very well, whilst the linear stress–strain relation cannot. It underestimates the stability of trachea by exaggerating the displacement in compression. This study may improve our understanding of the nonlinear behavior of tracheal cartilage and it may be useful for the future study on tracheal collapse behavior under physiological and pathological conditions.

A male mallard duck (Anas platyrhynchos) presented for examination for acute respiratory distress and lethargy. The duck had experienced recurrent episodes of respiratory distress since being attacked by a raccoon the previous year, resulting in neck lacerations. Diagnostic tests, including a complete blood count, plasma biochemical analysis, radiography, and tracheoscopy, revealed a collapsed trachea. Surgical correction of the collapsed tracheal segment resulted in resection of 9% of the total tracheal length and subsequent anastomosis. Tracheoscopy performed 2 and 3 months after surgery revealed a healthy mucosa, minimal reduction of the tracheal lumen in the area of anastomosis, and minimal suture granuloma formation.

This case report describes an unusual presentation of histiocytic sarcoma in a domestic shorthair cat. Initial investigation revealed a haemodynamically insignificant hypertrophic cardiomyopathy, bronchitis and a mild irregularity of the cervical trachea. The cat's disease progressed over a two-week period. Repeat radiography and tracheoscopy revealed a marked dynamic tracheal collapse associated with a raised plaque-like lesion within the cervical trachea. Subsequent post-mortem examination and histopathology revealed disseminated histiocytic sarcoma involving the trachea and kidneys. This is the first reported case of a histiocytic sarcoma involving the trachea in either dogs or cats.

Case Description—An 8-year-old castrated male Yorkshire Terrier was evaluated because of a 1-month history of inspiratory dyspnea that began 2.5 years after placement of extraluminal tracheal ring prostheses for tracheal collapse. Clinical Findings—Physical examination revealed severe inspiratory dyspnea. Cervicothoracic radiography revealed a soft tissue opacity within the lumen of the cervical portion of the trachea at approximately the level of the fifth cervical vertebra. Tracheobronchoscopy revealed 2 prosthetic rings protruding into the tracheal lumen. Treatment and Outcome—The dog was anesthetized, and the 2 protruding tracheal ring prostheses were removed via separate tracheotomies. Tracheoscopy was performed after surgery, and a third prosthetic ring that was found freely floating within the tracheal lumen was removed with an endoscopic grasping forceps. The dog recovered without complications. Dyspnea resolved within the first 2 weeks after surgery. Follow-up examination performed 6 months after surgery revealed that the dog was breathing normally, with no dyspnea or coughing reported by the owner. Clinical Relevance—Migration of extraluminal tracheal ring prostheses should be included in the differential diagnoses for any dog with dyspnea or persistent coughing after surgical correction of cervical tracheal collapse. Surgical removal of the protruding prosthetic rings, without provision of additional tracheal support, was a viable treatment option in this case.

Tracheal collapse is a common problem that is typically observed in middle-aged and older small-breed dogs. It is a structural, obstructive airway disease with a dynamic component that can affect the intra- and extrathoracic portions of the trachea and mainstem bronchi. Many methods of treatment have been suggested, including medical management and provision of extraluminal and intraluminal support. All techniques used to treat intrathoracic and mainstem bronchial collapse have been associated with major complications or limitations. This report describes the implantation of intraluminal nitinol stents to successfully treat intrathoracic as well as extrathoracic tracheal collapse in a dog. The stents are composed of material that has characteristics similar to those of the trachea; nitinol stents may provide a method of supporting intrathoracic tracheal and mainstem bronchial collapse in dogs.

Tracheal transplantation with a long-segment recellularized tracheal allograft has previously been performed without the need for immunosuppressive therapy. Recipients' mesenchymal stromal cells (MSC) and tracheal epithelial cells (TEC) were harvested, cultured, expanded, and seeded on a donor trachea within a bioreactor. Prior techniques used for cellular seeding have involved only static-seeding methods. Here, we describe a novel bioreactor for recellularization of long-segment tracheae. Tracheae were recellularized with epithelial cells on the luminal surface and bone marrow-derived MSC on the external surface. We used dynamic perfusion seeding for both cell types and demonstrate an increase in both cellular counts and homogeneity scores compared with traditional methods. Despite these improvements, orthotopic transplantation of these scaffolds revealed no labeled cells at postoperative day 3 and lack of re-epithelialization within the first 2 weeks. The animals in this study had postoperative respiratory distress and tracheal collapse that was incompatible with life.

Ultrasonographic imaging of the cervical trachea was performed with the neck in both a neutral and a hyperextended position in 10 dogs with tracheal collapse. Tracheoscopy was used to confirm a diagnosis of tracheal collapse. The ultrasound investigation was repeated in 10 dogs of similar size but without tracheal abnormality. The ultrasonographic findings of the affected dogs were compared with those of the normal group and showed an alteration in the shape of the tracheal lumen in the ventrodorsal projection. This study highlights the possibility of identifying changes in the shape of the tracheal lumen during ultrasound investigations as an aid to the diagnosis of tracheal collapse.

Morbid obesity may influence several aspects of airway function. However, the effect of morbid obesity on expiratory tracheal collapse in COPD patients is unknown. We thus prospectively studied 100 COPD patients who underwent full pulmonary function tests (PFTs), 6-minute walk test (6MWT), Saint George's Respiratory Questionnaire (SGRQ), and low-dose CT at total lung capacity and during dynamic exhalation with spirometric monitoring. We examined correlations between percentage dynamic expiratory tracheal collapse and body mass index (BMI). The association between tracheal collapse and BMI was compared to a control group of 53 volunteers without COPD. Patients included 48 women and 52 men with mean age 65 ± 7 years; BMI 30 ± 6; FEV1 64 ± 22% predicted and percentage expiratory collapse 59 ± 19%. Expiratory collapse was significantly associated with BMI (69 ± 12% tracheal collapse among 20 morbidly obese patients with BMI ≥ 35 compared to 57 ± 19% in others, p = 0.002, t-test). In contrast, there was no significant difference in collapse between healthy volunteers with BMI ≥ 35 and35. COPD patients with BMI ≥ 35 also demonstrated shorter 6MWT distances (340 ± 139 m vs. 430 ± 139 m, p = 0.003) and higher (worse) total SGRQ scores (48 ± 19 vs. 36 ± 20, p = 0.013) compared to those with BMI35. In light of these results, clinicians should consider evaluating for excessive expiratory tracheal collapse when confronted with a morbidly obese COPD patient with greater quality of life impairment and worse exercise performance than expected based on functional measures.

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.

Tracheomalacia associated with esophageal atresia (EA) is a well-known condition. However, complete absence of tracheal rings (TRs) is extremely rare. Our aim is to describe a novel triad of conditions and to discuss the best treatment. An expremature male operated for EA presented with severe respiratory distress. The diagnosis of absent cartilage rings, suspected on bronchoscopy, was confirmed by optical coherence tomography. The absence of TRs was localized to a short tracheal segment, and the carina trifurcated into right upper lobe, right intermediate, and left main bronchus. The patient was treated with resection and anastomosis with a completely satisfactory course. Absence of TRs was previously reported by us in 2 other cases, both with associated EA and trifurcation of the carina. One child was treated with tracheostomy and the other with a stent, but the outcome was far from optimal. The patient with tracheostomy eventually underwent resection and anastomosis with tracheostomy closure. Congenital absence of TRs is extremely rare. Although localized, it is responsible for severe symptoms owing to complete tracheal collapse and may be misdiagnosed as tracheomalacia. In our experience, it has been associated with EA and trifurcated carina. Our limited experience suggests resection of the abnormal segment and tracheal anastomosis as the best treatment.

BACKGROUND: Esophageal detector devices (EDDs) impose negative pressure on the trachea or esophagus to verify endotracheal tube (ETT) position. In cardiac arrest, the smooth muscle of the lower esophageal sphincter relaxes in a time-dependent and irreversible manner. If relaxation also occurs in the muscular posterior tracheal wall, it could predispose tracheal invagination or collapse with negative pressure, potentially yielding false-negative (tracheal ETT, EDD indicates esophagus) results. We compared 3 different EDDs in their ability to correctly discriminate tracheal and esophageal intubation. METHODS: ETTs were placed into the trachea and esophagus of 5 domestic swine, and bronchoscopy was used to visualize the trachea while 3 EDDs were tested. Tracheal wall activity was observed before and after induced cardiac arrest. Tracheal ETTs were aspirated with increasing negative force and pressures at initial wall movement and >50% tracheal lumen obliteration were recorded. Measurements were repeated at 4, 8, and 12 minutes postarrest and pressures at tracheal wall collapse pre- and postarrest were determined. EDDs were also tested on esophageal ETTs prearrest and at 6 and 10 minutes postarrest. RESULTS: In a closed system, each EDD generated more than -100 cm H 2 O pressure. Average prearrest pressure at tracheal collapse was -112 cm H 2 O. Average postarrest collapse pressures were -68, -66, and -54 cm H 2 O at 4, 8, and 12 minutes postarrest. One EDD consistently gave equivocal results; the remaining 2 gave accurate results in all subjects. Most observed movement was insufficient to cause device failure although tracheal wall movement was noted in all postarrest EDD trials. Esophageal intubation was correctly determined at all times pre- and postarrest. CONCLUSION: These findings describe a mechanism for false-negative results from decreased posterior tracheal wall tone during cardiac arrest. Further studies are required to elucidate factors contributing to its occurrence and impact on EDD use.

UPPER respiratory tract disease has been described frequently in brachycephalic dogs. Clinical signs include snoring, inspiratory dyspnoea, exercise intolerance, cyanosis and, in the most severe cases, episodes of syncope. These conditions are referred to as brachycephalic syndrome. A hypoplastic

Objective—To describe the clinical and laboratory findings, diagnostic features, and outcome of tracheal collapse in American Miniature Horses at a referral institution. Design—Retrospective case series. Animals—13 American Miniature Horses with tracheal collapse. Procedures—Medical records of American Miniature Horses with tracheal collapse at a referral hospital were reviewed. Data extracted included signalment, history, clinical signs, laboratory data, diagnostic procedures, outcome, and histologic findings. Results—Tracheal collapse was documented in 5.6% of American Miniature Horses admitted to this referral hospital. Median age at onset of clinical signs was 11 years with a range of 2 to 15 years. Common complaints and clinical signs included respiratory distress, tachypnea, inspiratory honking noises, and increased abdominal expiratory effort, which were exacerbated by stressful events, pregnancy, exercise, a dusty environment, and eating. Tracheal collapse was confirmed by use of radiography, endoscopy, fluoroscopy, or postmortem examination. Dorsoventral flattening of the extra- or intrathoracic trachea, or both, was more common than lateral collapse. Tracheal chondromalacia was identified histologically in 4 cases, and mortality rate for affected horses was 10 of 13. Conclusions and Clinical Relevance—Tracheal collapse was relatively common in this study of American Miniature Horses, and outcome was poor. The etiopathogenesis of the disease remains unknown.

In order to study the in vitro mechanical properties of the equine trachea submitted to the compressive pressures observed in vivo, the pressure-volume relationship was determined in intra- and extra-thoracic tracheal segments taken post mortem from 29 healthy horses (one to 15 years old; 352 to 651 kg). At the same time, the cross-sectional lumen area (X-SA) at the mid-point of the segment was measured using a slit-lamp transillumination and photographic measurement by endoscopy. The tracheal specific compliance (Cs) as well as the relative changes in X-SA and in the sagittal and transverse diameters, for intraluminal pressures from 5 to - 5 kPa, were calculated. The extrathoracic tracheal Cs was 0.060 +/- 0.002 kPa-1 and, at an intraluminal pressure of - 5 kPa, X-SA was reduced to about 73 per cent of its resting value. The intrathoracic segments were more compliant and, at similar compressive pressure, their X-SA was more reduced. These data show that the equine tracheal compliance is high and suggest that the increase in pulmonary resistance observed during strenuous exercise may be partly explained by a partial tracheal collapse.

The influence of the age and weight of the animal as well as that of the extension and the shape of the trachea on the mechanical properties of the cervical trachea was studied in 33 isolated tracheal segments obtained from freshly slaughtered horses. The relationship between intraluminal pressure and volume was determined in the cervical tracheal segments positioned firstly under normal longitudinal tension and secondly in hyperextension. At the same time, changes in the area of the cross-section of the lumen (X-SA) at the midpoint of the segment were measured using photographs obtained by slit-lamp transillumination and endoscopy. The sagittal (DS) and transverse (DT) diameters were determined for each segment and the DT/DS ratio was calculated to give an estimate of the shape of the X-SA. The results showed that (i) neither the age nor the weight of the horses had any influence on the mechanical properties of the trachea; (ii) extension decreases the compressibility of the tracheal segment in vitro; (iii) there is a wide variation in the extrathoracic tracheal X-SA shape in horses; and (iv) the shape of the X-SA has a major influence on the mechanical properties of the trachea. It was concluded that (i) hyperextension of the neck will partly facilitate respiration at high levels of ventilation by elongating the trachea and by decreasing its collapsibility; and (ii) the tracheal collapse which may occur during high levels of ventilation will be more or less important depending on the individual X-SA shape.

OBJECTIVES The purpose of this study is to assess the prevalence and severity of expiratory multidetector computer tomography airway abnormalities, including central airway collapse and peripheral air trapping, before and after tracheoplasty, a novel surgical treatment for tracheomalacia. MATERIALS AND METHODS Our hospital information system retrospectively identified all patients with bronchoscopically diagnosed tracheobronchomalacia referred for computer tomography airway imaging pretracheoplasty and posttracheoplasty during a 41-month period. All patients underwent a standard multidetector computer tomography protocol comprised of imaging both at end inspiration and dynamic expiration. Two observers simultaneously reviewed the images. Maximal expiratory tracheal collapse and total air-trapping scores were calculated pretracheoplasty and posttracheoplasty for each patient. Statistical analysis was performed using the paired t test and Wilcoxon signed-ranks test. RESULTS The study cohort was comprised of 16 patients, 12 men and 4 women, with mean age of 60 years (range: 41 to 80). Mean percentage expiratory tracheal collapse pretracheoplasty was 70%+/-28 compared with 36%+/-27 posttracheoplasty (P

A 7-year-old, neutered male, domestic shorthair cat was presented for severe inspiratory dyspnea of 2 to 3 days’ duration. Radiography and tracheobronchoscopy confirmed the diagnosis of primary extrathoracic tracheal collapse. The cat was treated with oxygen, dexamethasone, and terbutaline, but no improvement was seen. Surgical correction was performed using nine prosthetic tracheal ring implants. Clinical signs improved after surgery, and the cat continued to do well 11 months after surgery, despite development of unilateral laryngeal paralysis.

Suprastomal tracheal collapse may interfere with decannulation in tracheostomized patients. The purposes of the study are to evaluate the role of tracheotomy technique in the ethiology of suprastomal cricotracheal collapse and to report our results in the treatment of this complication.A retrospective review of children showing severe suprastomal collapse during the period 1990-2007, in a tertiary care children's hospital, was performed. Medical records were assessed for the following data: sex, age, original indication for tracheotomy, surgical technique, endoscopic findings, type of surgical correction, complications, result, and follow-up.Fourteen patients were included in the study, nine girls and five boys. Average age at tracheotomy was 17 months (range: 21 days-8 years), and prolonged ventilatory support was the most common indication (57%). Horizontal H-type tracheotomy was the most frequent technique in patients with suprastomal collapse (n=9), whereas only one patient with a vertical tracheotomy showed this complication (p0.05). In every case bronchoscopy disclosed a suprastomal tracheal obstruction of at least 50% of the lumen. Mean age at surgical decannulation was 38 months (range: 12-147 months). Two surgical techniques have been used in the treatment of suprastomal collapse: anterior cricotracheal suspension (n=13) and reconstruction with autologous cartilage graft (n=1). All the patients were successfully decannulated although in one case two procedures were required. No recurrence has been observed during long-term follow-up (mean: 8.6 years).Endoscopical examination is essential for the diagnosis of suprastomal collapse and to rule out other causes of decannulation failure. In our experience, the tracheotomy technique seems to have an ethiologic role, and anterior cricotracheal suspension is a simple and effective procedure in the treatment of this tracheostomy related complication.