Prediction of post-extubation stridor using ultrasound measurement of subglottic airway diameter

BACKGROUND: Post-extubation stridor (PES) is a common complication in children in the pediatric intensive care unit (PICU). Despite the evaluation of various predictive tests, no single method has consistently demonstrated strong predictive value for PES. We evaluated the diagnostic utility of subglottic diameter ultrasonography for predicting PES within 48-h post-extubation in children. MATERIAL AND METHODS: The prospective observational study in university-affiliated PICU was done in children aged 1 month to 15 years who successfully passed a spontaneous breathing trial (SBT) and were scheduled for extubation were enrolled between January 2024 and January 2025. During SBT and cuff deflation, subglottic ultrasonography was performed at a peak inspiratory pressure (PIP) of 15 cmH2O, and the subglottic ratio (SR) and intracricoid peritubular free space (IPFS) were calculated. Leak percentage was calculated as the ratio of the difference between inspiratory and expiratory volumes over inspiratory volume at each PIP level. RESULTS: PES occurred in 33 of 176 (18.75%) patients. In children aged ≥1 year, SR was significantly associated with PES (adjusted OR, 3.78; 95% CI: 1.28-12.21). An SR <1.30 showed 70% sensitivity, 65% specificity, and 66% accuracy. IPFS <2.08 mm demonstrated 80% sensitivity, 65% specificity, and 68% accuracy. A leak percentage <36.77% at 25 cmH2O yielded 80% sensitivity, 47% specificity, and 53% accuracy. AUC values for SR, IPFS, and leak percentage were 0.664, 0.691, and 0.648, respectively. CONCLUSION: Among the evaluated parameters, IPFS showed the highest diagnostic performance for predicting PES, slightly outperforming the subglottic ratio in patients aged ≥1 year.