Sir.—The recent study of Rotschild et al1 provides useful data for predicting the length of endotracheal tube required in neonates from external measurements. In common with other studies in both adults2 and neonates,3-5 Rotschild et al found that correct endotracheal tube positioning is dependent on the state of flexion or extension of the neck. Whether endotracheal tube position is confirmed with radiography, palpation,6 ultrasonography,7 bronchoscopy,8 transtracheal illumination,9 or magnetic detection,10 the position of the head and neck relative to the trunk is crucial to the interpretation of these estimations. Rotschild et al conclude their article by recommending that the infant's head be held in the "neutral position" when localizing of the tip of the endotracheal tube is attempted. The problem is ensuring that this "neutral position" is maintained from one examination to the next.
We have addressed this question in our