From: Prediction of Pediatric Endotracheal Tube Size by Ultrasonography Anesthes. 2010;113(4):819-824. doi:10.1097/ALN.0b013e3181ef6757 Figure Legend: The relationship between the outer diameter of optimally sized endotracheal tubes (ETT) in mm and subglottic diameter, also in mm: the outer ETT diameter = 0.46 × (subglottic diameter) + 1.56, R 2= 0.90 for cuffed ETTs, and the outer ETT diameter = 0.55 × (subglottic diameter) + 1.16, R 2= 0.90 for uncuffed ETTs (n = 48 in each group). Date of download: 10/24/2017 Copyright © 2017 American Society of Anesthesiologists. All rights reserved.