The role of tracheal wall injury in the development of benign airway stenosis in rabbits

Abstract

To investigate the role of tracheal wall injury in the development of benign airway stenosis in rabbits. Prospective study. We injured the tracheal walls of 28 New Zealand white rabbits using four different methods. Experimental group: Group A (n = 7, mild injury of tracheal mucosa by ordinary brush under bronchoscopy); Group B (n = 7, severe injury of tracheal mucosa by nylon brush under tracheotomy); Group C (n = 7, tracheal cartilage was injured by vascular clamp after tracheotomy); Group D (n = 7, the tracheal cartilage was injured with vascular forceps and the tracheal mucosa was injured with a nylon brush after tracheotomy). Bronchoscopy was performed on each experimental rabbit at 1, 2, 3 and 4 weeks after operation. High-resolution computed tomography (HRCT) and endobronchial optical coherence tomography (EB-OCT) were performed at 4 weeks, and the rabbits were sacrificed after the examination. Their gross and histological findings were comparatively determined whether the experimental rabbit stenosis was established. No airway stenosis was observed in group A. In group B, 28.57% of experimental rabbits developed tracheal stenosis (granulation tissue proliferation was observed in rabbits No. 2 and No. 6 at 1, 2 and 3 weeks after operation, and the tracheal scar contracture was observed in No.6 rabbit at 4 weeks after operation). Fourteen rabbits in group C and group D had tracheal stenosis caused by granulation tissue proliferation at 1, 2 and 3 weeks after operation. At the fourth week after operation, 71.43% of experimental rabbits had tracheal stenosis due to granulation tissue hyperplasia, 7.14% of experimental rabbits had tracheal stenosis due to scar contracture and granulation hyperplasia, and 21.43% of experimental rabbits had tracheal stenosis due to scar contracture. EB-OCT scan showed that the cartilage layer with low signal reflection band was discontinuous. The injury of cartilage is the key factor of benign airway stenosis. Acute injury of airway mucosa alone is unlikely to cause airway stenosis, but combined with cartilage injury may aggravate airway stenosis. EB-OCT can clearly identify the airway layers of rabbits, which is helpful to evaluate the damage of tracheal cartilage and mucosa. The diagnostic potential of this technique makes EB-OCT a promising approach for the study and monitoring of airway diseases.

Single‐center review on safety of biodegradable airway stenting in pediatric population

“…Our extensive experience with metallic stents over the past two decades has greatly influenced our strategy, especially the approach of downsizing stents thereby minimizing the risk of stent granuloma. There is experimental data supporting this technique 23 . Conversely we did not find a high risk of stent migration especially if stents covered the length of the trachea or bronchus.…”

“…There is experimental data supporting this technique. 23 Conversely we did not find a high risk of stent migration especially if stents covered the length of the trachea or bronchus. We experienced only one major tracheal stent migration which required suturing to keep in place.…”

“…However, our approach was to intentionally downsize the stents to reduce granulation tissue formation which is driven by excessive stent pressure on airway mucosa and cartilage (Figure 1). 23 Typically airway symptoms occur when a significant fraction of the airway is occluded (>75%). We hypothesized that only 50%–75% of the normal bronchial diameter would be necessary to improve symptoms and allow adequate secretion clearance and gas exchange.…”

External beam radiotherapy inhibits stent related granulation hyperplasia in rabbit trachea

“…Post-stenting healing process is a complicated condition that affects by inflammation, immune response, and mechanical stress. The injury of musca and cartilage are the key factors of benign airway stenosis formation 8 . There are three overlapping wound healing process, inflammation, proliferation, and remodelling 9 .…”

Comparative Evaluation of Mechanical Injury Methods for Establishing Stable Tracheal Stenosis Animal Models

“…This simple and cost-effective method gained favor among many researchers, although it yielded varied results. Zhang J and others attempted a similar modeling technique but using a 5.5mm nylon brush for 20 scrapings, resulting in a stenosis rate of only 28.57% [25]. On the other hand, Steehler MK and colleagues utilized a 5.0mm nylon brush for scraping, yet failed to induce stable stenosis [15].…”