A rabbit model of tracheal collapse for optimal self-expanding metal stents.

Investigating the characteristics of tracheas can help the understanding of diseases related to the trachea, particularly tracheal collapse (TC) in dogs. This study aimed to compare the mechanical properties of tracheas from New Zealand White (NZW) rabbits and dogs and to introduce a method for inducing a model of TC in the normal trachea. Tracheal samples were obtained from NZW rabbit cadavers (n=5) weighing 3.62-3.92 kg and from dog cadavers (n=5) weighing 2.97-3.28 kg. Three live NZW rabbits weighing 3.5-4.0 kg were used to establish the model. The radial forces of both sample sets were measured using a digital force gauge and statistically compared. Subsequently, TC was surgically induced in three female NZW rabbits by physically weakening their tracheal cartilage under general anesthesia. Their clinical signs were monitored for 3 months, and radiographic examinations were performed monthly for 3 months. The mean radial forces of the two sample sets were comparable (P>0.05). The clinical signs, radiographic examinations, and macroscopic examinations were all comparable to those of dogs with TC. The cadaveric study between the rabbits and dogs demonstrated that the surgically induced rabbit model of TC is an excellent candidate for the experimental study of dogs with TC. This study also provides a reference of tracheal radial force values to enable selection of appropriate mesh types and wire diameters of self-expanding metal stents.

[Treatment of post-intensive care tracheal stenosis after previous covid-19 pneumonia]. / Lechenie postreanimatsionnykh rubtsovykh stenozov trakhei posle perenesennoi koronavirusnoi pnevmonii Covid-19.

OBJECTIVE: To analyze postoperative outcomes and perioperative management of patients with post-intensive care tracheal stenosis and previous COVID-19 pneumonia. MATERIAL AND METHODS: There were 8 patients with post-intensive care tracheal stenosis and previous COVID-19 pneumonia aged 34-61 years between January 2021 and April 2021. Lung damage CT-3 was observed in 2 (25%) patients, CT-4 - in 5 (62.5%) patients. In one case, COVID-19 pneumonia with lung damage CT-2 joined to acute cerebrovascular accident. Post-tracheostomy stenosis was detected in 7 (87.5%) cases, post-intubation stenosis - in 1 patient. Duration of invasive mechanical ventilation ranged from 5 to 130 days. In 75% of cases, tracheal stenosis was localized in the larynx and cervical trachea. Two patients admitted with tracheostomy. In one case, an extended tracheal stenosis was combined with atresia of infraglottic part of the larynx. One patient had tracheal stenosis combined with tracheoesophageal fistula (TEF). Length of tracheal stenosis was 15-45 mm. Tracheomalacia was observed in 4 (50%) patients. All patients had severe concomitant diseases. RESULTS: To restore airway patency, we used circular tracheal resection with anastomosis, laryngotracheoplasty and endoscopic methods. Tracheal resection combined with TEF required circular tracheal resection with disconnection of fistula. Adequate breathing through the natural airways was restored in all patients. There was no postoperative mortality. Three patients with baseline tracheal stenosis had favorable postoperative outcomes after circular tracheal resection. Four patients are at the final stage of treatment after laryngotracheoplasty and tracheal stenting. CONCLUSION: Patients after invasive mechanical ventilation for COVID-19 pneumonia are at high risk of cicatricial tracheal stenosis and require follow-up. Circular tracheal resection ensures early rehabilitation and favorable functional results. Laryngotracheoplasty is preferred if circular tracheal resection is impossible. This procedure ensures adequate debridement of tracheobronchial tree and respiratory support. Endoscopic measures are an alternative for open surgery, especially for intrathoracic tracheal stenosis and intractable tracheobronchitis.

[Treatment of cicatricial tracheal stenosis and tracheoesophageal fistula in patients with COVID-19 pneumonia]. / Lechenie rubtsovogo stenoza trakhei i trakheopishchevodnogo svishcha u bol'nykh, perenesshikh COVID-19-pnevmoniyu.

OBJECTIVE: To describe treatment of cicatricial tracheal stenosis and tracheoesophageal fistula in patients with COVID-19 pneumonia. MATERIAL AND METHODS: There were 91 patients with cicatricial tracheal stenosis for the period from August 2020 to April 2022 (21 months). Of these, 32 (35.2%) patients had cicatricial tracheal stenosis, tracheoesophageal fistula and previous coronavirus infection with severe acute respiratory syndrome. Incidence of iatrogenic tracheal injury following ventilation for viral pneumonia in the pandemic increased by 5 times compared to pneumonia of other genesis. Majority of patients had pneumonia CT grade 4 (12 patients) and grade 3 (8 patients). Other ones had pulmonary parenchyma lesion grade 2-3 or mixed viral-bacterial pneumonia. Isolated tracheoesophageal fistula without severe cicatricial stenosis of trachea or esophagus was diagnosed in 4 patients. In other 2 patients, tracheal stenosis was combined with tracheoesophageal fistula. Eight (25%) patients had tracheostomy at the first admission. This rate was almost half that of patients treated for cicatricial tracheal stenosis in pre-pandemic period. RESULTS: Respiratory distress syndrome occurred in 1-7 months after discharge from COVID hospital. All patients underwent surgery. In 7 patients, we preferred palliative treatment with dilation and stenting until complete rehabilitation. In 5 patients, stent was removed after 6-9 months and these ones underwent surgery. There were 3 tracheal resections with anastomosis, and 2 patients underwent tracheoplasty. Resection was performed in 3 patients due to impossible stenting. Postoperative course in these patients was standard and did not differ from that in patients without viral pneumonia. In case of tracheoesophageal fistula, palliative interventions rarely allowed isolation of trachea. Four patients underwent surgery through cervical approach. There were difficult surgeries in 2 patients with tracheoesophageal fistula and cicatricial tracheal stenosis. One of them underwent separation of fistula and tracheal resection via cervical approach at primary admission. In another patient with thoracic fistula, we initially attempted to insert occluder. However, open surgery was required later due to dislocation of device. CONCLUSION: Absolute number of patients with tracheal stenosis, tracheoesophageal fistula and previous COVID-19 has increased by several times compared to pre-pandemic period. This is due to greater number of patients requiring ventilation with risk of tracheal injury, non-compliance with preventive protocol for tracheal injury including anti-ischemic measures during mechanical ventilation. The last fact was exacerbated by involvement of allied physicians with insufficient experience of safe ventilation in the «red zone¼, immunodeficiency in these patients aggravating purulent-inflammatory process in tracheal wall. The number of patients with tracheostomy was 2 times less that was associated with peculiarity of mechanical ventilation in SARS-CoV-2. Indeed, tracheostomy was a poor prognostic sign and physicians tried to avoid this procedure. Incidence of tracheoesophageal fistula in these patients increased by 2 times compared to pre-pandemic period. In subacute period of COVID-associated pneumonia, palliative measures for cicatricial tracheal stenosis and tracheoesophageal fistula should be preferred. Radical treatment should be performed after 3-6 months. Absolute indication for circular tracheal resection with anastomosis is impossible tracheal stenting and ensuring safe breathing by endoscopic methods, as well as combination of cicatricial tracheal stenosis with tracheoesophageal fistula and resistant aspiration syndrome. Incidence of postoperative complications in patients with cicatricial tracheal stenosis and previous mechanical ventilation for COVID-19 pneumonia and patients in pre-pandemic period is similar.

Subglottic and tracheal stenosis associated with coronavirus disease 2019.

BACKGROUND: Coronavirus disease 2019 critical care patients endure prolonged periods of intubation. Late tracheostomy insertion, large endotracheal tubes and high cuff pressures increase their risk of subglottic and tracheal stenosis. This patient cohort also often appears to have co-morbidities associated with laryngotracheal stenosis, including high body mass index and laryngopharyngeal reflux. METHODS: This paper presents three coronavirus disease 2019 patients who were intubated for a mean of 28 days before tracheostomy, leading to complex multi-level stenoses. RESULTS: All patients underwent multiple endoscopic tracheoplasty procedures and two required tracheal resections. There was a mean of 33.9 days between interventions. Coronavirus disease 2019 patients do not appear to respond as well to steroid, laser and balloon dilatation as other adult stenosis patients. CONCLUSION: Intubated coronavirus disease 2019 patients have an increased risk of laryngotracheal stenosis, as a result of multiple factors. Otolaryngology teams should be vigilant in investigating for this complication. International guidelines on time to tracheostomy should be followed, despite a diagnosis of coronavirus disease 2019.