Assess percent airway obstruction based on endotracheal tube size
Based on Cotton-Myer Grading System for Subglottic Stenosis
| Age | ETT 2.0 | ETT 2.5 | ETT 3.0 | ETT 3.5 | ETT 4.0 | ETT 4.5 | ETT 5.0 | ETT 5.5 |
|---|---|---|---|---|---|---|---|---|
| Pre-term (younger) | 40% | No obstruction | - | - | - | |||
| Pre-term (older) | 58% | 30% | No obstruction | - | - | - | ||
| 0-3 months | 68% | 48% | 26% | No obstruction | - | - | - | |
| 3-9 months | 75% | 59% | 41% | 22% | No obstruction | - | - | - |
| 9 months - 2 years | 80% | 67% | 53% | 38% | 20% | - | - | - |
| 2 years | 84% | 74% | 62% | 50% | 35% | 19% | - | - |
| 4 years | 86% | 78% | 68% | 57% | 45% | 32% | 17% | - |
| 6 years | 98% | 81% | 73% | 64% | 54% | 43% | 30% | 16% |
0-50% obstruction
Mild stenosis - Usually well tolerated
51-70% obstruction
Moderate stenosis - May cause respiratory symptoms
71-99% obstruction
Severe stenosis - Significant airway compromise
No detectable lumen
Complete obstruction - Critical airway emergency
Assessment Method: The percentage of obstruction is determined by comparing the size of ETT that can pass through the stenotic area with age-appropriate normal ETT sizes
Clinical Application: This grading system is widely used for pediatric subglottic stenosis assessment and treatment planning
Tube Variability: The grading may depend on the style and outer diameter of the specific ETT used
Limitations: This is an estimation tool. Direct visualization via endoscopy and imaging studies are essential for accurate diagnosis