A Simple Endoscopic Technique for Measuring the Cross-Sectional Area of the Upper Airway in a Rabbit Model

Wistermayer, Paul R.; McIlwain, Wesley; Ieronimakis, Nicholas; Rogers, Derek J.

doi:10.1177/0003489418759361

Cited by 4 publications

(4 citation statements)

References 12 publications

(33 reference statements)

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“…All endoscopic airway images had identifying information removed, and 3 blinded independent reviewers measured each image for cross-sectional area (CSA) of the subglottis using ImageJ software (National Institutes of Health) per our previously validated method. 19 By placing an object with a known size at the level of the stenosis to scale the image, we used ImageJ to calculate the CSA of any point in the airway perpendicular to the endoscope ( Figure 2 ). 19 Reviewer measurements were then averaged for each image.…”

Section: Methodsmentioning

confidence: 99%

“…19 By placing an object with a known size at the level of the stenosis to scale the image, we used ImageJ to calculate the CSA of any point in the airway perpendicular to the endoscope ( Figure 2 ). 19 Reviewer measurements were then averaged for each image. The Cotton-Myer subglottic stenosis grading system was used to assign grades of stenosis to the raw CSA values (grade I, 0%-50%; grade II, 51%-70%; grade III, 71%-99%; grade IV, 100%).…”

Section: Methodsmentioning

confidence: 99%

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Randomized Controlled Trial of Balloon Dilation in Treatment of Subglottic Stenosis With a Rabbit Model

Wistermayer

McIlwain

Escalante

et al. 2020

Otolaryngol.--head neck surg.

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Objectives Identify the effects of balloon dilation duration and topical ciprofloxacin-dexamethasone application in treatment of subglottic stenosis. Study Design Randomized controlled trial. Setting Animal research facility. Subjects and Methods Forty-four rabbits underwent subglottic injury in an Institutional Animal Care and Use Committee–approved study. One week after injury, the subglottis of each rabbit was measured and treated with endoscopic balloon dilation for 2 rounds of short duration (SBD; 3 seconds), long duration (LBD; 30 seconds), or LBD with topical ciprofloxacin-dexamethasone application (LBD+C). The subglottis of each rabbit was remeasured at the study endpoint: 1 month postdilation or following development of life-threatening respiratory distress. Results Of 44 rabbits, 35 (80%) survived to endoscopic balloon dilation, with 21 rabbits developing a grade III Cotton-Myer stenosis. Prior to dilation, there was no difference in stenosis rates among groups (all subjects, P = .99; grade III stenosis only, P = .52). Among grade III subjects, improvement in stenosis after dilation was –1% (SD, 21%) for SBD, 27% (SD, 38%) for LBD, and 58% (SD, 29%) for LBD+C ( P = .01). Early euthanasia/death rates among grade III subjects were 85% for SBD, 63% for LBD, and 17% for LBD+C ( P = .03). Time to early euthanasia/death was 5.0 days for the SBD group and 8.4 days for the LBD group ( P = .04). Conclusion SBD was inferior to LBD or LBD+C in multiple metrics. LBD+C offered significant improvements in stenosis size and mortality over the SBD group and had the lowest rate of early mortality. Further research is needed to identify optimal balloon dilation treatment duration.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Randomized Controlled Trial of Balloon Dilation in Treatment of Subglottic Stenosis With a Rabbit Model

Wistermayer

McIlwain

Escalante

et al. 2020

Otolaryngol.--head neck surg.

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“…All endoscopic airway images had identifying information removed, and three blinded, independent reviewers measured each image for cross-sectional area (CSA) of the subglottis with ImageJ software (NIH, Bethesda, MD, USA) using our previously validated method. 6 By placing an object with a known size at the level of the stenosis to scale the image, we utilized ImageJ to calculate the crosssectional area of any point in the airway perpendicular to the endoscope ( Figure 2). Reviewer measurements were then averaged for each image.…”

Section: Methodsmentioning

confidence: 99%

A Randomized Controlled Trial of Dexamethasone as a Prophylactic Treatment for Subglottic Stenosis in a Rabbit Model

Wistermayer

Escalante

McIlwain

et al. 2020

Ann Otol Rhinol Laryngol

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Objective: Iatrogenic injury is a common cause of subglottic stenosis (SGS). We investigated the role of pre-injury dexamethasone as a preventive treatment for iatrogenic subglottic stenosis. Methods: 16 New Zealand White rabbits were used in an IACUC approved study. Subjects were divided into two groups: intramuscular dexamethasone (DEX) at a dose of 2 mg/kg 15 minutes prior to an endoscopic injury to create SGS, and the same injury creation with a preoperative intramuscular saline (SAL) injection. Three independent, blinded raters evaluated endoscopic images to obtain cross sectional area (CSA) airway measurements. Rabbit airways were measured just prior to injury and at one week post-injury. All subjects were provided as-needed postoperative steroids and buprenorphine for symptoms of respiratory distress. Data analysis was performed using Student t-test. Intraclass correlation coefficients were used to assess inter-rater agreement. Results: All subjects survived to the one-week post-injury airway evaluation. There was no difference in airway size between groups prior to injury ( P = .28). Subjects in the DEX group demonstrated an average stenosis of 20.3% (95% CI 10.2-30.5) at one week compared to 60.6% (95% CI 40.3-80.9) in the SAL group ( P = .01). Subjects in the control group required significantly more doses of postoperative dexamethasone ( P = .02). Inter-rater agreement for between raters was excellent (ICC = .88). Conclusion: This is the first study to examine the role of pre-injury glucocorticoids in preventing iatrogenic subglottic stenosis. In our model, a single dose of intramuscular dexamethasone given prior to a subglottic injury resulted in a statistically significant reduction in airway stenosis. This research suggests that administering systemic dexamethasone should be considered prior to any procedure that may injure the subglottis, including traumatic intubation, to prevent iatrogenic subglottic stenosis.

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“…Endoscopic images were examined with ImageJ (National Institutes of Health, Bethesda, Maryland) to evaluate the degree of SGS. 12,25-27 The percentage of stenosis was defined as [1 – ( s / S )] × 100, where s is the cross-sectional area of the stenotic area and S is the cross-sectional area of the native airway. Grade of SGS was designated according to Myer-Cotton classification: grade 1, <50%; grade 2, 51%-70%; grade 3, 71%-99%; grade 4, 100%.…”

Section: Methodsmentioning

confidence: 99%

Subglottic Stenosis: Development of a Clinically Relevant Endoscopic Animal Model

Mady

Criado

Park

et al. 2020

Otolaryngol.--head neck surg.

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Objective Develop a clinically relevant and reproducible endoscopic animal model for subglottic stenosis amenable to testing of minimally invasive therapeutic modalities. Study Design Cohort study. Setting Division of Laboratory Animals Research, University of Pittsburgh. Subjects and Methods Subglottic stenosis was induced endoscopically via microsuspension laryngoscopy in 26 New Zealand white rabbits. A trimmed polypropylene brush connected to a novel electronic stenosis induction apparatus was used to create circumferential trauma to the subglottis. By using open source image analysis software, the cross-sectional areas of the stenotic and native airways were compared to calculate the percentage of stenosis and the Myer-Cotton classification grade. Results Of the 26 rabbits, 24 (92%) exhibited stenosis after the first attempt. The mean percentage of airway stenosis was 57% (range, 34%-85%; SD, 15%). Five rabbits (19.2%) died on the day of stenosis induction from procedural complications. Of the 21 rabbits, 2 demonstrated no stenosis 7 days after initial injury and so underwent reinduction of airway injury, upon which they developed stenosis. Overall, 14 of the 21 rabbits (67%) exhibited moderate to severe stenosis (grade 2 or 3). Conclusion The stenosis induction apparatus reliably induced stenosis with a low mortality rate as compared with that of other methods in the literature. The device could be improved to generate a predetermined potentially reproducible grade of stenosis as desired by the operator. This method sets the stage for a clinically relevant and reproducible subglottic stenosis disease model that is amenable to testing of minimally invasive treatment modalities.

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A Simple Endoscopic Technique for Measuring the Cross-Sectional Area of the Upper Airway in a Rabbit Model

Abstract: We validate a simple, accurate, and reproducible method of measuring the CSA of the airway that can be used in a clinical or research setting.

Cited by 4 publications

References 12 publications

Randomized Controlled Trial of Balloon Dilation in Treatment of Subglottic Stenosis With a Rabbit Model

Randomized Controlled Trial of Balloon Dilation in Treatment of Subglottic Stenosis With a Rabbit Model

A Randomized Controlled Trial of Dexamethasone as a Prophylactic Treatment for Subglottic Stenosis in a Rabbit Model

Subglottic Stenosis: Development of a Clinically Relevant Endoscopic Animal Model

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