Effect of Bronchoscopic Spray Cryotherapy and Ultra-low Temperature on Physical Properties of Metallic and Silicone Airway Stents

Background:Bronchoscopic spray cryotherapy (SCT) is utilized in the field of interventional pulmonology for treating benign and malignant airway stenosis as a standard tool to maintain airway patency. Stent-related complications include tumor overgrowth, granulation tissue, and epithelialization. Thermal ablation can have a limited role in such scenarios due to the risk of airway fire and damage to the existing stent. SCT is a potential therapy using ultra-low temperatures that can allow stents to remain in place during treatment. However, there has been no study demonstrating the safety of SCT on the integrity and physical properties of tracheobronchial stents. We report the results of the first study demonstrating the safety of SCT utilized to treat stent-associated granulation or malignant airway disease. The aim of this study was to demonstrate the effects of SCT on the physical properties of airway stents in an ex vivo environment. Methods:Various types of airway stents were subjected to multiple intervals of SCT for up to 30 seconds, and then the cycle was repeated 3 times. After every cycle, we compressed the stents to 60% of their original size, and compression and expansion force data was collected immediately after, at 3-minute and 5-minute intervals, and compared with the baseline readings. Results:There was no significant change in the association between diameter and compression/expansion force, including any derangement in returning to the original diameter or any physical damage to any of the stents even after 3 prolonged SCT sessions of 30 seconds. Conclusion:Our study provides the first evidence that the use of SCT in conjunction with existing silicone/metal stents is feasible and does not cause any physical damage to the stents or alters their ability to maintain the original diameter.