BACKGROUND: Patients with airway stenosis (AS) are associated with considerable morbidity and mortality after lung transplantation (LTx). This study aims to develop and validate machine learning (ML) models to predict AS requiring clinical intervention in patients after LTx.
METHODS: Patients who underwent LTx between January 2017 and December 2019 were reviewed. The conventional logistic regression (LR) model was fitted by the independent risk factors which were determined by multivariate LR. The optimal ML model was determined based on 7 feature selection methods and 8 ML algorithms. Model performance was assessed by the area under the curve (AUC) and brier score, which were internally validated by the bootstrap method.
RESULTS: A total of 381 LTx patients were included, and 40 (10.5%) patients developed AS. Multivariate analysis indicated that male, pulmonary arterial hypertension, and postoperative 6-min walking test were significantly associated with AS (all P < 0.001). The conventional LR model showed performance with an AUC of 0.689 and brier score of 0.091. In total, 56 ML models were developed and the optimal ML model was the model fitted using a random forest algorithm with a determination coefficient feature selection method. The optimal model exhibited the highest AUC and brier score values of 0.760 (95% confidence interval [CI], 0.666-0.864) and 0.085 (95% CI, 0.058-0.117) among all ML models, which was superior to the conventional LR model.
CONCLUSIONS: The optimal ML model, which was developed by clinical characteristics, allows for the satisfactory prediction of AS in patients after LTx.

Cicatricial pemphigoid (CP) is a rare, chronic, vesiculobullous disease characteristically affecting the mucous membranes and healing with cicatrization. Laryngeal involvement is rare and leads to airway stenosis. We present a 74-year-old Caucasian woman with CP, affecting the oral cavity, esophagus, lower eyelids, and larynx. Regardless of regular treatment with hydrocortisone and azathioprine, she developed bilateral cicatrization of the aryepiglottic folds and ovoid stenosis of the laryngeal introitus, leading to dyspnea. To avoid tracheostomy, we were able to utilize infraglottic high-frequency jet ventilation under total intravenous anesthesia to perform a CO2 laser supraglottoplasty with sectioning of the aryepiglottic folds. Post-operatively, her dyspnea at rest resolved; there was no progression at the six- and 12-month follow-up, and she was satisfied with the result.

This study aimed to design a standardised bronchoscopic holmium laser ablation continuous cryoablation for the treatment of airway stenosis caused by tissue hyperplasia after tracheal intubation and to retrospectively analyse its safety and feasibility. We collected the data of patients who had undergone bronchoscopic holmium laser ablation continuous cryoablation due to airway stenosis caused by tracheal mucosal tissue hyperplasia after tracheal intubation. The patients\' baseline characteristics, ablation effects, surgical complications and other data were analysed. In total, 16 patients were enrolled in this study. On average, airway stenosis occurred 96.00 (interquartile range, 69.75-152.50) days after tracheal intubation and bronchoscopic holmium laser ablation continuous cryoablation took an average of 90.38 minutes (standard deviation: 16.78). After the first continuous cryoablation, 75.0% (12/16) of the patients had complete ablation of hyperplastic tissue, and 25.0% (4/16) had most of the hyperplastic tissue (>50%) removed. Altogether, 18.75% (3/16) and 6.25% (1/16) of the patients had complete ablation of hyperplastic tissue after the second and third cryoablation, respectively. Moreover, one patient (6.25%) had minimal wound bleeding postoperatively, and no other surgical complications occurred. No airway stenosis was found in all enrolled patients during follow-up 1 and 6 months after the last cryoablation. According to the above results of our small sample study indicated that bronchoscopic holmium laser ablation continuous cryoablation seems safe and effective for treating airway stenosis caused by tissue hyperplasia after tracheal intubation.

A woman in her mid-50s was admitted to our hospital with airway stenosis secondary to mediastinal lymph node enlargement. An AERO stent was placed under rigid bronchoscopy. Immediately after stent placement, tissue sampling was performed on the lymph nodes. Metastatic lesions were found to have an EGFR mutation (exon 19 deletion). Consequently, osimertinib treatment was initiated 15 days after stent placement. The tumour partially responded to osimertinib, and the airway stenosis improved. The patient underwent stent removal 66 days after stent placement. Our findings indicate that temporary oncological emergencies due to airway stenosis may be bridged by airway stenting.

BACKGROUND: IgG4-related disease is a systemic fibroinflammatory disease that is mainly seen in older men, and involves multiple organs, such as the pancreas and lungs. However, 75% of patients with IgG4-related lung disease are asymptomatic (if they are symptomatic, they mainly complain of nasal congestion, rhinorrhoea, chest pain, and cough) and are incidentally diagnosed through chest computed tomograph. Although, nodules in the airway and bronchial wall thickening are criteria for diagnosis, it is important that nodules have been reported in peripheral airways in several cases and rarely in the central airway.
METHODS: A 74-year-old woman previously diagnosed with Mikulicz\'s disease presented with swelling of the eyelid margin on both sides and visual disturbances. Computed tomography revealed extensive multiple nodules and mucosal oedema of the trachea and both bronchi. On flexible bronchoscopy under local anaesthesia, extensive lesions were observed from the middle of the trachea to the carina, extending into both segmental bronchi. The nodules were continuous with the normal respiratory tract mucosa, and the surfaces were smooth with minimal neovascularisation. Due to the solid nature of the lesion, obtaining an adequate amount of specimen was challenging. Therefore, we used a 1.9 mm cryoprobe under intubation, resulting in minimal bleeding. Subsequently, the patient was diagnosed with IgG4-related lung disease.
CONCLUSIONS: The present case is very rare because of the presence of multiple nodules, severe mucosal edema of the central airway and the absence of mediastinal lymphadenopathy, ground glass nodules, and lung masses. Therefore, it is important to consider differential diagnoses. Thus, we emphasise the importance of endobronchial cryobiopsy for obtaining an adequate number of tissue specimens in such cases to establish a definitive pathological diagnosis.

Idiopathic pulmonary arterial hypertension is a progressive and life-threatening disease with pulmonary vasculature remodeling, leading to right-sided heart failure. Epoprostenol (prostaglandin I2) is highly recommended for patients with severe pulmonary arterial hypertension (PAH) categorized by the World Health Organization as functional class III or IV. It has been reported that prostaglandin I2 analogs can cause thyroid gland swelling and abnormal thyroid function. A 34-year-old woman was diagnosed with idiopathic pulmonary arterial hypertension and started receiving continuous intravenous epoprostenol. Three years after starting epoprostenol, she began complaining of neck swelling and was diagnosed with Graves\' disease. The patient\'s thyroid function was controlled by thiamazole and levothyroxine; nevertheless, her thyroid gland enlargement worsened as the epoprostenol dose was titrated. After 20 years, she developed respiratory failure with a giant goiter leading to airway stenosis, and she passed away. The pathological autopsy confirmed a massive goiter associated with hyperthyroidism and airway stenosis. We experienced a case of idiopathic pulmonary hypertension with a giant goiter and airway stenosis after long-term intravenous epoprostenol therapy.

There is no standard method of bronchoscopic local therapy for tracheal tumours. We herein present a case involving a 61-year-old woman who was diagnosed with tracheal mucosa-associated lymphoid tissue lymphoma and underwent resection by a bronchoscopic high-frequency electrosurgical snare. Few reports to date have described such use of high-frequency electrosurgical snares; however, they are effective for the treatment of tracheal tumours, especially pedunculated tumours.

Primary adenoid cystic carcinoma (ACC) of the upper anterior mediastinum is rarely encountered in clinical practice, and no standard treatment has been established. We performed palliative radiotherapy to improve airway narrowing in a patient with primary ACC of the mediastinum who presented with respiratory distress as their main complaint. As a result of radiotherapy, the ACC was reduced in size, the narrowed airway was opened due to compression by the ACC, and the patient\'s general condition improved. We present the results of this case with a review of the relevant literature.

We encountered a case of sudden respiratory failure during treatment of catatonia that required intensive care. Electroconvulsive therapy (ECT) was administered in the intensive care unit while the patient was under systemic control. The catatonia symptom was relieved, and respiratory failure improved. Although a proximal venous thrombus was observed, anticoagulation therapy was continued during ECT, and the patient was successfully treated without causing a pulmonary embolism. It is crucial to monitor the patient\'s physical and psychological symptoms because respiratory status may deteriorate rapidly in a catatonic state.

Endobronchial ultrasound (EBUS)-guided tissue acquisition (TA) performed by transbronchial needle aspiration (TBNA) is the main diagnostic procedure in mediastinal and hilar lymph node (LN) biopsy. EBUS-guided intranodal forceps biopsy (EBUS-IFB) and EBUS-guided cryobiopsy can achieve higher diagnostic yield of lymphomas, uncommon tumors, and benign diseases. However, these techniques require the creation of a tract to insert biopsy devices, which may result in critical complications. Here, we report a rare case of airway stenosis (AS) that occurred after EBUS-TA for mediastinal LN biopsy. An 80-year-old man had multiple pulmonary nodules and an enlarged mediastinal LN. EBUS-TBNA and EBUS-IFB were performed for histological diagnosis. Cutaneous adnexal carcinoma (CAC) was diagnosed. The patient underwent chemotherapy. Four months later, he was hospitalized for AS due to a tracheal tumor with dyspnea. Chest computed tomography and bronchoscopy revealed that the tracheal tumor was caused by invasion from the biopsied LN into the tracheal lumen by tract seeding (TS) caused by EBUS-TA. Cryotherapy was performed. The tracheal tumor was pathologically consistent with CAC and is currently under control with radiotherapy. TS-associated EBUS-TA is rare but may increase in frequency with aggressive tissue sampling techniques. Bronchoscopists should perform EBUS-TA with awareness of the potentially serious complications.