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.
CONCLUSIONS: 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.

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Tracheal stenosis and tracheomalacia in patients with congenital scoliosis are serious and rare conditions caused by congenital dysplasia, postintubation injury, trauma, and tracheal tumor. Anesthesia of a child with tracheal stenosis is challenging for anesthesiologists. We describe an 8-year-old female patient developed severe tracheal stenosis and tracheomalacia after growing rod implantation for congenital scoliosis. Comprehensive assessment of preoperative pulmonary function and airway morphology, which can be neglected clinically, should be performed in congenital scoliosis patients.

Severe tracheomalacia (TM) patients with respiratory symptoms need surgical intervention, including aortopexy, internal stents or external splint. While some patients continue to have respiratory symptoms after tracheal relief, and there is no evidence to support any one surgery therapy over another. Here we introduce a clinical safety and efficacy of the three-dimensional (3D)-printed bioresorbable airway external splints in treating congenital heart disease (CHD) patients with severe TM. From May 2019 to September 2020, nine patients with severe TM were enrolled. The median age was 5 months (range, 3-25 months), and the median weight was 7.5 kg (range, 3-15 kg). All patients had wheezing, and two patients were assisted by machine ventilation (MV) preoperatively. The median length of TM was 1.5 cm (range, 1.0-3.0 cm). All patients underwent suspension of a \"C\"-shaped lumen airway external splint, which were designed in SOLIDWORKS and made of polycaprolactone (PCL). The airway external splint could provided effective support for at least 6 months and was completely degraded into carbon dioxide and water within 2-3 years. The median time of postoperative machine assisted ventilation was 23.7 h (range, 3.3-223.4 h), and the median time of ICU stay was 9 days (range, 4-25 days). The median follow-up time was 18 months (range, 12-24 months). Respiratory symptoms were all relieved, and no external splint-associated complications occurred. The 3D computed tomography reconstruction showed no airway stenosis. Personalized 3D-printed bioresorbable airway external splint can not only limit external compression and prevent airway collapse but also ensure the growth potential of the airway, which is a safe, reliable and effective treatment for CHD with TM.

The tracheal epithelium is a primary target for pulmonary diseases as it provides a conduit for air flow between the environment and the lung lobes. The cellular and molecular mechanisms underlying airway epithelial cell proliferation and differentiation remain poorly understood. Hedgehog (HH) signaling orchestrates communication between epithelial and mesenchymal cells in the lung, where it modulates stromal cell proliferation, differentiation and signaling back to the epithelium. Here, we reveal a previously unreported autocrine function of HH signaling in airway epithelial cells. Epithelial cell depletion of the ligand sonic hedgehog (SHH) or its effector smoothened (SMO) causes defects in both epithelial cell proliferation and differentiation. In cultured primary human airway epithelial cells, HH signaling inhibition also hampers cell proliferation and differentiation. Epithelial HH function is mediated, at least in part, through transcriptional activation, as HH signaling inhibition leads to downregulation of cell type-specific transcription factor genes in both the mouse trachea and human airway epithelial cells. These results provide new insights into the role of HH signaling in epithelial cell proliferation and differentiation during airway development.

OBJECTIVE: Vascular rings are rare anomalies of congenital heart disease that cause respiratory and gastrointestinal symptoms. This study assessed the long-term outcomes of patients with vascular ring division.
METHODS: A multi-institution retrospective review of 371 patients with vascular rings undergoing surgical division at 3 paediatric cardiac institutions between November 2007 and October 2019 was performed.
RESULTS: The complete vascular rings consisted of a double aortic arch (24.5%), right aortic arch with left ligamentum arteriosum (36.7%) and left aortic arch, with right ligamentum arteriosum (0.5%). The incomplete vascular rings consisted of a pulmonary artery sling (22.9%), left aortic arch with aberrant right subclavian artery (15.1%) and innominate artery compression syndrome (0.3%). Respiratory symptoms included stridor (71.4%), wheezing (49.1%), coughing (31.5%), gastrointestinal symptoms included choking (12.4%), dysphagia (3.2%) and emesis (1.9%). Only one patient died after discharge, yielding a late mortality rate of 0.3% (1/360). The 10-year overall survival rate was 96.8%. Postoperative complications were reported in 51 patients, 15 of whom required reoperation. The 10-year freedom from reoperation rate was 95.9%. Follow-up was completed in 95.4% (354/371) of patients, with a mean follow-up time of 4.3 ± 2.9 years (range from 1 to 13 years). Twenty patients (5.6%) experienced residual symptoms during long-term follow-up.
CONCLUSIONS: The outcomes of vascular ring division are excellent. A Kommerell diverticulum >1.5 times the aberrant left subclavian artery origin is an operative indication for primary resection. Tracheomalacia is a risk factor for reoperation and residual symptoms, and preoperative fibrobronchoscopy is important for evaluation.

Flexible bronchoscopy (FB), developed in the 1960s, is widely used in the clinical practice of pediatrics and has demonstrated fundamental value in clinical diagnoses and treatment. However, as an invasive procedure, the use of FB is limited due to concerns regarding the tolerance of the procedure and the possible complications in neonatal units. Thus, the present study aimed to investigate the clinical safety and efficacy of flexible bronchoscopy (FB) in a neonatal intensive care unit (NICU). Neonates (n=54) who received FB in the NICU of Shanghai Children\'s Hospital between January 2012 and December 2016 were enrolled as the experimental group and another 54 neonates who required nebulization and tracheal secretion suction treatments were the control group. Indicators including blood gas, complete blood count, C-reactive protein (CRP), X-ray, patient breathing rate, temperature and blood pressure were monitored prior to and following the procedure. No significant differences in sex, gestational age, birth weight or postnatal age were observed between the experimental group and the control group (P>0.05). Among the 54 FB patients, several cases with side effect were identified, including 18 (33.3%) with respiratory tract stenosis, nine (16.7%) with malacia and stenosis and six (11.1%) with esophagotracheal fistula. Among the 54 members of the control group, 44 neonates (81.4%) were discharged with improved condition, five (9.3%) succumbed and five patients (9.3%) abandoned the treatment and left the hospital. Bronchoalveolar lavage demonstrated consistent results with respiratory secretion culture or tracheal tube culture. In comparison between the experimental and the control groups, no significant difference in pH, partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2) and HCO3 - was observed, while there were no statistical differences in the values of pH, PCO2 and HCO3 - (P>0.05). However, PO2 was significantly increased, and CRP was significantly reduced, following FB procedure compared with prior to FB (P<0.05). No pneumothorax, shock, other severe complications, fever or diffused pneumonia were observed during or after FB. The data from the present study demonstrated that FB is a safe and effective strategy for the diagnosis and differentiation of neonatal respiratory diseases in NICU.

BACKGROUND: Tracheomalacia may be caused by long-standing compression of retrosternal goitre because of destruction of support of tracheal cartilages. Life-threatening airway collapses may occur after surgical removal of goitre. However, available literature on management methods of tracheomalacia is sparse. Our study highlights prolonged endotracheal intubation as a feasible treatment method.
METHODS: This retrospective study analysed 106 thyroidectomies for retrosternal goitre performed between 1994 and 2019. We recorded each patient\'s clinical profile. Severe tracheomalacia was confirmed through the following: soft and floppy trachea on intra-operative palpation and the collapse of cross-sectional tracheal area measured in computed tomography (CT) images by >80%. We assessed the extent of airway stenosis of these cases. All severe cases were treated by prolonged endotracheal intubation.
RESULTS: Surgical treatment was successfully performed in all 106 retrosternal goitre patients with no mortality. Seventeen severe tracheomalacia cases were confirmed. The extent of airway stenosis was assessed: the minimal tracheal diameter of compressed trachea was 0.2-0.4 [mean 0.31, standard deviation (SD) 0.06] cm, and the narrow tracheal length was 4-6.7 (mean 5.1, SD 0.6) cm. These patients underwent endotracheal intubation for 17-47 h after surgery. All patients were transferred to the general ward after extubation and successfully discharged. There were no cases of tracheal stenosis on follow-up.
CONCLUSIONS: Tracheomalacia is a rare but serious complication of retrosternal goitre surgery. Based on our experience, prolonged endotracheal intubation is a feasible treatment for tracheomalacia after retrosternal goitre surgery.

This study is to investigate the status and clinical significance of respiratory viruses in bronchoalveolar lavage fluid (BALF) of children with PBB.
Sixty-eight children with PBB aged from 3 months to 5 years were enrolled and retrospectively reviewed from January 2014 to December 2017. Thirty-five children with persistent pneumonia or chronic pneumonia were matched as controls. Bronchoalveolar lavage fluid samples were collected for respiratory virus detection and bacterial culture.
The detection rate of bacteria in BALF of children with PBB was 61.8%, which was significantly higher than that of control group (20%) (P < 0.001). The detection rate of virus in BALF of children with PBB was 23.5%, including 6 (8.8%) of rhinovirus, 4 (5.9%) of parainfluenza virus type 3, 2(2.9%) of bocavirus, 2 (2.9%) of respiratory syncytial virus 1 (1.5%) of human metapneumonia virus and 1 (1.5%) of influenza virus A. 10 cases (28.6%) of virus were detected in the control group, including 3 (8.6%) respiratory syncytial virus, 3 (8.6%) rhinovirus and 2 (5.7%) bocavirus. There was no significant difference of viral detection rate between the two groups (P = 0.577).
Respiratory viruses can be detected in BALF of children with PBB, However, there is no evidence that PBB is virus-induced.

BACKGROUND: Tracheomalacia (TM), caused by anterior mediastinal tumorectomy, most likely to deteriorate condition of patient life.
METHODS: A 63-year-old patient felt serious dyspnea diagnosis as TM caused by the recurrent cervical schwannoma. The narrowest diameter of the TM was only 0.446 cm and the length of malacic segment was 7.47 cm. Here we designed a novel tracheal suspension technique by using autogenous rib cartilage graft to treat severe TM. The obvious effect was observed that the inner diameter increased from 0.446 cm to 1.390 cm,and the airway symptom was alleviated.
CONCLUSIONS: The autogenous rib cartilage graft used for suspending the malacic trachea was safe and effective.