EMT Airway Management Practice Test 2026 - Free EMT Airway Management Practice Questions and Study Guide

Estimating pediatric ETT size is about matching the tube’s inner diameter to the child’s airway based on size and age. A quick, widely used rule of thumb is that the uncuffed tube size in millimeters equals (age in years divided by 4) plus 4. So, a 4-year-old would get about a 5.0 mm uncuffed tube. If you’re using a cuffed tube, subtract about 0.5 mm to account for the cuff’s impact on fit. The Broselow tape provides a length-based, quick cross-check that ties a child’s height/length to a recommended tube size and depth.

These methods work better than weight-based or height-only guesses because airway size correlates with overall body size and age rather than weight alone or height in isolation. Size-by-random is unsafe, since the airway dimensions can vary and an improper size risks injury or inadequate ventilation. Use the formula as your starting point and confirm with clinical checks such as a capnography/ventilation assessment and, if possible, a cuff leak test to ensure an appropriate fit.