Paramedic National Registry Practice

How is the appropriate tube size determined for an infant?

1. (Age + 4)/2

2. (Age/4) + 3

3. (Age/4) + 4

4. (Age/2) + 2

The correct answer is: (Age/4) + 4

The appropriate tube size for an infant is determined by the formula (Age in years/4) + 4. This equation is specifically designed to estimate the internal diameter of the endotracheal tube (in size French or mm) based on the child's age. This method takes into account the physiological differences in airway size as infants grow. The formula provides a practical way to calculate a tube size that balances the risk of airway obstruction versus trauma from using a tube that is too large. It is crucial for the paramedic to have a proper fit for the tube to ensure effective ventilation and minimize complications. In this context, the other formulas presented would not yield an appropriate tube size for infants. For instance, formulas that do not include the same factors of age division may lead to miscalculations, either resulting in inadequate airway management or potential injury to the delicate structures of an infant’s airway. Understanding this formula is essential for paramedics to perform their duties effectively when dealing with pediatric patients.