An open-label, single-arm study of CRYO2 for tissue removal at the site of central airway obstruction or stenosis: study protocol

Argon-plasma coagulation, high-frequency electrosurgical snare, laser therapy, and microwave treatment are therapeutic options to reduce tumor-related stenosis of the central airway. These treatments may cause airway fire under a high concentration of oxygen, so FiO2 levels must be ≤40%. This restriction may be dangerous when treating patients with respiratory failure. The cryosurgery unit, ERBE-CRYO2, facilitates treatment under an FiO(2) level of 100%, safely reducing this risk. In Japan, CRYO2 has been approved for cryobiopsy and foreign body removal, but not for tissue removal at the site of obstruction or stenosis due to lack of sufficient evidence. Since CRYO2 may be useful for reducing airway stenosis, the present study was designed to increase indications for this unit in Japan.