Study on the rationality of small diameter metallic airway stent in treatment of tracheal stenosis in injured rabbits

BACKGROUND

To observe the occurrence of related complications after self-expandable metallic (SEM) airway stents implantation with different diameters at different time points, and to provide theoretical basis for the optimal chioce of existing airway stents in clinical practice.

METHODS

Healthy New Zealand white rabbits were used to establish benign tracheal stenosis models after chest CT examination. Forty-fivemodel rabbits with more than 50% of airway stenosis were divided into two groups. Small-diameter SEM stents (The ratio of stent diameter to airway diameter is nearly 1.0) were implanted in Group A in 21 rabbits, and large-diameter tracheal stents (The ratio of stent diameter to airway diameter is more than 1.2) were implanted in Group B in 24 rabbits. Stent-related complications were observed after stent implantation in 2nd,4th,8th, and 12th week by bronchoscopygross anatomy, pathological and the expressions of IL-1RA, IL-8 and MMP9 in involved tracheal.

RESULTS

The incidence rate of tracheomalacia of stent was significantly higher in group B (24/24 100%) than that in group A (1 /21,4.8%) (P < 0.05). The incidence rate of scar contracture at both ends of stent was significantly higher than in group B (11 / 24,45.8%) that in group A (2 /21, 9.5%) (P < 0.05). The pathological results of both A and B showed that the columnar epithelium of bronchial mucosa began to damage and detach, inflammatory cells infiltrated after 2nd and 4th week of stenting, The epithelium was repaired, the lamina propria glands almost disappeared, collagen fiber proliferation was obvious, and scars were formed after 8th and 12th week of stenting. ELISA results revealed that the expressions of IL-1RA, IL-8, and MMP9 were increased in the stent group than in model rabbit with benign tracheal stenosis. IL-1RA and MMP9 increased at different periods in group B, but the expression of IL-1RA and MMP9 showed a tread of increasing in the early stage and then decreasing in group A.

CONCLUSION

Metal stents can cause different degrees of stent-related complications in rabbits with benign tracheal stenosis. The incidence of stent-induced tracheomalacia and scar contracture were higher in Group B than that in Group A. IL-1RA, IL-8 and MMP9 may be involved in the development of complications after stentimplantation and peak value of group B movered backward. ing.

Flexible bronchoscopy findings and management impact in children with oropharyngeal dysphagia

INTRODUCTION

Flexible bronchoscopy (FB) and bronchoalveolar lavage (BAL) are frequently performed in children with known or suspected aspiration, however, the additive value of FB in conjunction with direct laryngoscopy and rigid bronchoscopy (DLB) has not been previously quantified. This study details the common endoscopic/cytological findings and associated management impact of FB and BAL in pediatric Aerodigestive patients undergoing combined airway evaluation (FB and DLB) for oropharyngeal dysphagia.

MATERIALS AND METHODS

A retrospective chart review was performed in children <3 years of age followed through a large Aerodigestive center undergoing outpatient, combined airway endoscopy for dysphagia. Patient and procedural characteristics, endoscopic and BAL findings, and management metrics were collected and analyzed. A secondary analysis evaluated the association between endoscopic findings and medication changes.

RESULTS

Ninety-one procedures (median patient age, 15 months) were identified. All procedures included both FB and DLB, and just over half (52.7%) included esophagogastroduodenoscopy. Common endoscopic findings included bronchitis (73.6%), adenoidal hypertrophy (31.9%), and tracheomalacia (10.8%). BAL cytology frequently identified neutrophilic inflammation (mean 39.6% neutrophils [interquartile range 6.5%-71%)]. Cultured pathogens commonly included Streptococcus viridans (46.6%), Hemophilus influenzae (36.3%), Moraxella catarrhalis (30.1%), and Streptococcus pneumoniae (25.0%). FB and BAL results contributed to clinical decisions in 65 of 91 (71.4%) patients. Endoscopically-diagnosed bronchitis (odds ratio [OR] 7.27, 95% confidence interval [CI] 2.4-21.99) and tracheomalacia (OR 5.79, 95% CI 1.20-27.85) were significantly associated with increased odds of medication adjustments following FB.

CONCLUSION

In pediatric Aerodigestive patients undergoing combined airway evaluation for oropharyngeal dysphagia, FB and BAL are high-yield and clinically impactful procedures.

Tracheomalacia Reduces Aerosolized Drug Delivery to the Lung

Rationale: Neonates with respiratory issues are frequently treated with aerosolized medications to manage lung disease or facilitate airway clearance. Dynamic tracheal collapse (tracheomalacia [TM]) is a common comorbidity in these patients, but it is unknown whether the presence of TM alters the delivery of aerosolized drugs. Objectives: To quantify the effect of neonatal TM on the delivery of aerosolized drugs. Methods: Fourteen infant subjects with respiratory abnormalities were recruited; seven with TM and seven without TM. Respiratory-gated 3D ultrashort echo time magnetic resonance imaging (MRI) was acquired covering the central airway and lungs. For each subject, a computational fluid dynamics simulation modeled the airflow and particle transport in the central airway based on patient-specific airway anatomy, motion, and airflow rates derived from MRI. Results: Less aerosolized drug reached the distal airways in subjects with TM than in subjects without TM: of the total drug delivered, less particle mass passed through the main bronchi in subjects with TM compared with subjects without TM (33% vs. 47%, p = 0.013). In subjects with TM, more inhaled particles were deposited on the surface of the airway (48% vs. 25%, p = 0.003). This effect becomes greater with larger particle sizes and is significant for particles with a diameter >2 μm (2-5 μm, p ≤ 0.025 and 5-15 μm, p = 0.004). Conclusions: Neonatal patients with TM receive less aerosolized drug delivered to the lungs than subjects without TM. Currently, infants with lung disease and TM may not be receiving adequate and/or expected medication. Particles >2 μm in diameter are likely to deposit on the surface of the airway due to anatomical constrictions such as reduced tracheal and glottal cross-sectional area in neonates with TM. This problem could be alleviated by delivering smaller aerosolized particles.

Tracheostomy in Mechanically Ventilated Patients With SARS-CoV-2-ARDS: Focus on Tracheomalacia

BACKGROUND

The SARS-CoV-2 pandemic increased the number of patients needing invasive mechanical ventilation, either through an endotracheal tube or through a tracheostomy. Tracheomalacia is a rare but potentially severe complication of mechanical ventilation, which can significantly complicate the weaning process. The aim of this study was to describe the strategies of airway management in mechanically ventilated patients with respiratory failure due to SARS-CoV-2, the incidence of severe tracheomalacia, and investigate the factors associated with its occurrence.

METHODS

This retrospective, single-center study was performed in an Italian teaching hospital. All adult subjects admitted to the ICU between February 24, 2020, and June 30, 2020, treated with invasive mechanical ventilation for respiratory failure caused by SARS-CoV-2 were included. Clinical data were collected on the day of ICU admission, whereas information regarding airway management was collected daily.

RESULTS

A total of 151 subjects were included in the study. On admission, ARDS severity was mild in 21%, moderate in 62%, and severe in 17% of the cases, with an overall mortality of 40%. A tracheostomy was performed in 73 (48%), open surgical technique in 54 (74%), and percutaneous Ciaglia technique in 19 (26%). Subjects who had a tracheostomy performed had, compared to the other subjects, a longer duration of mechanical ventilation and longer ICU and hospital stay. Tracheomalacia was diagnosed in 8 (5%). The factors associated with tracheomalacia were female sex, obesity, and tracheostomy.

CONCLUSIONS

In our population, approximately 50% of subjects with ARDS due to SARS-CoV-2 were tracheostomized. Tracheostomized subjects had a longer ICU and hospital stay. In our population, 5% were diagnosed with tracheomalacia. This percentage is 10 times higher than what is reported in available literature, and the underlying mechanisms are not fully understood.

Mammalian tracheal development and reconstruction: insights from in vivo and in vitro studies

The trachea delivers inhaled air into the lungs for gas exchange. Anomalies in tracheal development can result in life-threatening malformations, such as tracheoesophageal fistula and tracheomalacia. Given the limitations of current therapeutic approaches, development of technologies for the reconstitution of a three-dimensional trachea from stem cells is urgently required. Recently, single-cell sequencing technologies and quantitative analyses from cell to tissue scale have been employed to decipher the cellular basis of tracheal morphogenesis. In this Review, recent advances in mammalian tracheal development and the generation of tracheal tissues from pluripotent stem cells are summarized.

Evaluation of pulmonary complications and affecting factors in children for repaired esophageal atresia and tracheoesophageal fistula

INTRODUCTION

Recurrent pulmonary infections, wheezing and stridor due to swallowing dysfunction, esophageal dysmotility, gastroesophageal reflux, tracheomalacia and bronchomalacia are frequently seen complications after esophageal atresia and tracheo-esophageal fistula (EA-TEF) surgeries. This study aimed to investigate the frequency and causes of respiratory problems and to evaluate the factors that affect respiratory morbidity in patients who had undergone EA-TEF repair in a tertiary referral center.

METHODS

Preoperative and postoperative records of patients with EA, TEF + EA and isolated EA were examined retrospectively. Accompanied diseases and swallowing dysfunction symptoms were questioned. Bronchoalveolar lavage results were investigated if the patient had flexible bronchoscopy.

RESULTS

A total of 71 children with EA were included in the study, and seven patients who did not have follow-up after surgery were excluded. 46 of the 64 patients continue regular follow-up visits in our department. Male sex, primary EA repair in another center, EA type C, accompanying genetic anomalies, severe tracheomalacia, late per oral feeding (1 year after surgery), and severe GER were found to cause significantly higher incidence of coughing, recurrent wheezing, recurrent pneumonia, and bronchiectasis despite surgical and medical treatments (p = 0.048, p = 0.045, p = 0.009, p = 0.029, p = 0.025). CONCLUSİON: Even if anatomical anomalies are corrected by surgery in patients who underwent EA repair, precautions can be taken for GERD, laryngotracheomalacia, and swallowing dysfunction, and effective pulmonary rehabilitation can be initiated with early multidisciplinary approach before the development of respiratory tract symptoms.

Increased Work of Breathing due to Tracheomalacia in Neonates

Rationale: Dynamic collapse of the tracheal lumen (tracheomalacia) occurs frequently in premature neonates, particularly in those with common comorbidities such as bronchopulmonary dysplasia. The tracheal collapse increases the effort necessary to breathe (work of breathing [WOB]). However, quantifying the increased WOB related to tracheomalacia has previously not been possible. Therefore, it is also not currently possible to separate the impact of tracheomalacia on patient symptoms from parenchymal abnormalities.Objectives: To measure the increase in WOB due to airway motion in individual subjects with and without tracheomalacia and with different types of respiratory support.Methods: Fourteen neonatal intensive care unit subjects not using invasive mechanical ventilation were recruited. In eight, tracheomalacia was diagnosed via clinical bronchoscopy, and six did not have tracheomalacia. Self-gated three-dimensional ultrashort-echo-time magnetic resonance imaging (MRI) was performed on each subject with clinically indicated respiratory support to obtain cine images of tracheal anatomy and motion during the respiratory cycle. The component of WOB due to resistance within the trachea was then calculated via computational fluid dynamics (CFD) simulations of airflow on the basis of the subject's anatomy, motion, and respiratory airflow rates. A second CFD simulation was performed for each subject with the airway held static at its largest (i.e., most open) position to determine the increase in WOB due to airway motion and collapse.Results: The tracheal-resistive component of WOB was increased because of airway motion by an average of 337% ± 295% in subjects with tracheomalacia and 24% ± 14% in subjects without tracheomalacia (P < 0.02). In the tracheomalacia group, subjects who were treated with continuous positive airway pressure (CPAP) using a RAM cannula expended less energy for breathing compared with the subjects who were breathing room air or on a high-flow nasal cannula.Conclusions: Neonatal subjects with tracheomalacia have increased energy expenditure compared with neonates with normal airways, and CPAP may be able to attenuate the increase in respiratory work. Subjects with tracheomalacia expend more energy on the tracheal-resistive component of WOB alone than nontracheomalacia patients expend on the resistive WOB for the entire respiratory system, according to previously reported values. CFD may be able to provide an objective measure of treatment response for children with tracheomalacia.