J Med Assoc Thai 2023; 106 (4):411-5

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Laryngeal Ultrasonography and Percent Leak Volume in Predicting Post-Extubation Stridor in The Pediatric Intensive Care Unit Patients
Jetanachai P Mail, Benjasupattananan N

Background: Endotracheal tube intubation can be associated with laryngeal edema, which may present as post-extubation stridor (PES). PES may prolong length of stay in pediatric intensive care unit, particularly if reintubation was necessary.

Objective: To evaluate the efficacy of laryngeal ultrasonography and percent leak volume (PLV) in predicting PES in pediatric patients.

Materials and Methods: A prospective study of 43 pediatric patients admitted to pediatric intensive care unit was conducted. Laryngeal ultrasonography was performed to measure air column width (ACW) within 24 hours after intubation. Within four hours before extubation, laryngeal ultrasonography was repeated. Air column width ratio (ACWR) was calculated by ACW before extubation divided by ACW after intubation. PLV was calculated by the difference between inspiratory and expiratory tidal volume divided by inspiratory tidal volume. Both of ACWR and PLV were analyzed to determine the optimal cut-off value for predicting PES.

Results: Twenty-two patients (51%), developed PES. Receiver operating characteristics curve (ROC) analysis showed that ACWR at cut-off point ≤0.94 had a sensitivity of 72.7%, specificity of 61.9%, positive predictive value (PPV) of 66.7%, and accuracy of 67.4% in predicting PES. A cut-off point of PLV of less than 9.74% had 59.1% sensitivity, 57.1% specificity, 59.1% PPV, and 58.1% accuracy in predicting PES. ACWR and PLV had an area under the ROC curve (AUC) of 0.722 (p=0.013, 95% CI 0.56 to 0.87) and 0.602 (p=0.253, 95% CI 0.43 to 0.77), respectively.

Conclusion: ACWR measured by laryngeal ultrasonography of 0.94 or less may be helpful in predicting PES. ACWR is more accurate than PLV in predicting PES.

Keywords: Laryngeal ultrasonography; Percent leak volume; Post-extubation stridor

DOI: 10.35755/jmedassocthai.2023.04.13839

Received 1 February 2022 | Revised 27 October 2022 | Accepted 7 November 2022

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