The Correlation Between Ultrasound-measured Styloid Process of the Distal Radius and the Outer Diameter of the Best-fitting Endotracheal Tube in Pediatrics

Various formulas are used to predict the inner diameter (ID) of the ETT tube whether uncuffed or cuffed based on weight, age, height, and finger size. The accuracy of these formulas is questionable. These formulas depend on the child's demographic characteristics assuming that he/she has normal growth and development and cannot be applied to children with altered growth and development. Moreover, these formulas predict the ID of the ETT ignoring the tube thickness and the OD of the selected tube.

ultrasound has recently been identified as an accurate alternative to these formulas. The US-measured epiphyseal diameter of the distal radius is a method that has been recently introduced as a surrogate for the tracheal diameter. The issue is that the size of the airway can be considered a reflection of the body's growth, assuming that the growth rates of the cartilage all over the body are closely related to each other. Therefore, the measurement of the growth of the bony cartilage of the hand can be considered a surrogate marker of the tracheal diameter.9 The extent to which ultrasonography by this method can succeed in predicting the optimal pediatric ETT size remains under investigation.