Objectives/Hypothesis To develop a reproducible and consistent chronic subglottic stenosis (SGS) in an endoscopic animal model. Study Design Prospective study. Methods We conducted a prospective study using New Zealand white rabbits. Chronic SGS was induced endoscopically by Bugbee electrocautery to 50% to 75% of the subglottic area's circumference, followed by 4‐hour endotracheal intubation. The rabbit airways were endoscopically assessed and sized with uncuffed endotracheal tubes (ETTs) before the injury, during follow‐up, and at the endpoints. There were four endpoints: 2, 4, 6, and 8 weeks post SGS induction. Animals were humanely euthanized for histopathological examination of the subglottic injury site and microscopic measurement of the cricoid lumen. Results Twenty‐two rabbits reached the endpoints, and 18 rabbits developed chronic SGS. ETT size significantly decreased by 0.5 from preinjury to the endpoint in all groups, P < .001. Control median cricoid lumen measurements were 20.48 mm2, the median cricoid lumen measurement for the 2 weeks endpoint was 14.3 mm2, 4 weeks 11.69 mm2, 6 weeks 16.03 mm2, and 8 weeks endpoint median was 16.33 mm2. Histopathological examination showed chronic scar tissue and new cartilage formation at the cricoid level, mainly at the posterior subglottic injury site starting from 4 weeks postinjury. Collagen staining revealed substantial amounts of organized collagen and different collagen orientation starting 4 weeks postinjury lasting until 8 weeks postinjury. Conclusion We developed an animal model to study chronic SGS. This model will be utilized to compare different endoscopic treatment interventions in acute SGS versus chronic SGS and further define the molecular basis of SGS. Level of Evidence NA Laryngoscope, 132:1909–1915, 2022
Summary Sleep‐disordered breathing is an important health issue for children. The objective of this study was to develop a machine learning classifier model for the identification of sleep apnea events taken exclusively from nasal air pressure measurements acquired during overnight polysomnography for paediatric patients. A secondary objective of this study was to differentiate site of obstruction exclusively from hypopnea event data using the model. Computer vision classifiers were developed via transfer learning to either normal breathing while asleep, obstructive hypopnea, obstructive apnea or central apnea. A separate model was trained to identify site of obstruction as either adeno‐tonsillar or tongue base. In addition, a survey of board‐certified and board‐eligible sleep physicians was completed to compare clinician versus model classification performance of sleep events, and indicated very good performance of our model relative to human raters. The nasal air pressure sample database available for modelling comprised 417 normal, 266 obstructive hypopnea, 122 obstructive apnea and 131 central apnea events derived from 28 paediatric patients. The four‐way classifier achieved a mean prediction accuracy of 70.0% (95% confidence interval [67.1–72.9]). Clinician raters correctly identified sleep events from nasal air pressure tracings 53.8% of the time, whereas the local model was 77.5% accurate. The site of obstruction classifier achieved a mean prediction accuracy of 75.0% (95% confidence interval [68.7–81.3]). Machine learning applied to nasal air pressure tracings is feasible and may exceed the diagnostic performance of expert clinicians. Nasal air pressure tracings of obstructive hypopneas may “encode” information regarding the site of obstruction, which may only be discernable by machine learning.
We appreciate Dr. Healy's comments regarding our article. The work Dr. Healy and his mentors had performed at that time were exceptional. 1 Our group described several methods for creating an endoscopic subglottic injury and found that cauterization with prolonged intubation achieved a reproducible and safe model, 2 which was sustainable during our study. We believe that prolonged intubation had a role in creating that injury.Although it is correct that CO 2 laser could be beneficial, and some surgeons utilize it in airway endoscopic surgery our study's objective was to create a subglottic scar tissue endoscopically and not to treat it. Nevertheless, we performed the subglottic injury with cauterization and prolonged intubation and not CO 2 laser. 3 Dohar and Hebda's group had described in several articles their work in the wound healing process at the subglottic area after injury with CO 2 laser 4-6 their work is fascinating and highly recommended to review.We agree that a thorough and updated literature review is key in every study performed. Thank you for recommending reviewing Maggio's article. 7 FUNDING INFORMATIONThis study was supported by donations from Celestial Ball Fundraiser.
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