Impact of Balloon Diameter on Dilation Outcomes in a Model of Rabbit Subglottic Stenosis.

OBJECTIVE: To determine the appropriate balloon size for dilation using a previously described reproducible survival animal model of subglottic stenosis. STUDY DESIGN: Prospective animal study. METHODS: We conducted a prospective study including 16 New Zealand White rabbits. The airway of each animal was sized with an endotracheal tube (ETT), and subglottic stenosis (SGS) was endoscopically induced using Bugbee electrocautery to 75% of the circumference of the subglottis, followed by 4-hour intubation. Two weeks postoperatively, the rabbits' airways were sized and then dilated using a 6-, 7-, 8-, or 9-mm balloon, with four animals in each experimental group. Following dilation, animals were again sized and subsequently euthanized. The cricoid lumen was measured microscopically in each animal. RESULTS: Prior to inducing stenosis, all animals were sized with a 3.5 ETT. After inducing injury but prior to dilation, airways showed grade 2 SGS that sized with a 2.5 ETT with no leak. Postdilation, animals dilated with 6- or 7-mm balloons (n = 8) sized with a 3.0 ETT, and animals dilated with an 8- or 9-mm balloon (n = 8) sized with a 3.5 ETT. Postdilation median cricoid lumen measurements were 12.5 mm2 (6-mm balloon), 13.92 mm2 (7 mm), 16.83 mm2 (8 mm), and 17.15 mm2 (9 mm); two cricoid fractures occurred in the 9-mm group. CONCLUSION: The postdilation cricoid lumen diameter increased with increased balloon size, and the use of an 8-mm balloon achieved the largest cricoid lumen diameter without causing fracture. Further research is necessary to determine the ideal duration of dilation and optimal intervals between dilations. LEVEL OF EVIDENCE: NA Laryngoscope, 129:2409-2413, 2019.

Endoscopic posterior cricoid reduction: A surgical method to improve posterior glottic diastasis.

OBJECTIVES/HYPOTHESIS: Describe the preoperative evaluation of patients with glottic diastasis who are candidates for endoscopic posterior cricoid reduction (EPCR) and their perioperative and postoperative surgical and voice outcomes, and validate the aerodynamic benefit of EPCR using computation fluid dynamics (CFD)-based modeling from computed tomography (CT) scans. STUDY DESIGN: Retrospective case series. METHODS: Thirteen patients who underwent EPCR were followed from 2013 to 2017. They received a preoperative voice evaluation, microlaryngoscopy and bronchoscopy, dynamic voice CT (performed on patients seen from 2014 to study completion), and postoperative voice evaluation (n = 12). Postoperative inpatient days, complications, and postoperative endoscopic intervention were collected. To validate the aerodynamic benefit of EPCR, CFD modeling was carried out on one patient. RESULTS: Thirteen patients (nine females, nine with intubation injury, and four with post-airway reconstruction dysphonia) underwent EPCR at a mean age of 11.0 years. The mean preoperative and postoperative Pediatric Voice handicap Index scores were 53.8 and 33.8, respectively (P = .006). Mean maximum phonation time preoperatively and postoperatively was 5.3 and 6.7, respectively (P = .04). Of eight patients who underwent preoperative CT imaging, all demonstrated a posterior gap. Modeling demonstrated a change in flow and pressure. The mean hospital stay was 2.4 days. Nine patients underwent postoperative endoscopic intervention, and one experienced a complication that resolved with intervention. CONCLUSIONS: Patients who underwent EPCR for dysphonia following intubation or airway reconstruction showed improvements in vocal efficiency, loudness, and perceived voice handicapping. Their hospital stay was brief, with few complications. CFD modeling corroborated these clinical findings. EPCR thus warrants consideration in the management of patients with posterior glottic diastasis. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:S1-S9, 2019.

Development of a survival animal model for subglottic stenosis.

OBJECTIVE: To develop a reproducible survival animal model for subglottic stenosis. STUDY DESIGN: Prospective study. METHODS: We evaluated five methods of inducing airway injury in 30 New Zealand white rabbits to produce a subglottic stenosis model. Experimental groups comprised: group 1 (n = 5), which underwent 4-hour intubation; group 2 (n = 5), which underwent induced subglottic injury with a nylon brush; group 3 (n = 10), which underwent subglottic injury with a nylon brush, followed by 4-hour intubation; group 4 (n = 5), which underwent subglottic injury with Bugbee cautery in 50% of the subglottic circumference, followed by 4-hour intubation; and group 5 (n = 5), which underwent subglottic injury with Bugbee cautery in 75% of the subglottic circumference, followed by 4-hour intubation. Five animals were used as controls. Endoscopy of the airway and sacrifice of animals were planned at an interval of 14 days postinjury. Histologic measurements were analyzed. RESULTS: No animals in groups 1 or 2 developed stenosis. In group 3, 50% of animals developed symptomatic grade 3 subglottic and tracheal stenosis, necessitating early endoscopy and sacrifice in three animals. Four animals in group 4 developed grade 1 subglottic stenosis, and four in group 5 developed grade 2 subglottic stenosis. Histologic measurements of lumen areas within each of these two groups were similar; all animals survived the follow-up period. CONCLUSION: We successfully developed a reproducible survival model for induced subglottic stenosis using a combination of cautery-induced subglottic injury followed by 4-hour intubation. This model lays the foundation for future studies that evaluate endoscopic interventions for the management of subglottic stenosis. LEVEL OF EVIDENCE: NA Laryngoscope, 129:989-994, 2019.