What is the most commonly used endotracheal (ET) tube size for adults?

The most commonly used endotracheal (ET) tube size for adults is typically 7.5mm in diameter. This size is often considered standard because it is generally suitable for the average adult airway, balancing ease of insertion with sufficient airway size to ensure adequate ventilation.

Selecting the appropriate ET tube size is crucial, as using a tube that is too small can lead to insufficient airflow and potential respiratory complications, while a tube that is too large might cause trauma to the airway structures and increased resistance to airflow. The 7.5mm size offers a good compromise for most adults, allowing for effective ventilation while minimizing the risk of airway injury.

In clinical practice, you may also encounter 8.0mm as a common size for larger adults, but 7.5mm is widely accepted as the standard in many emergency and critical care settings. The sizes on either side—6.0mm and 9.0mm—are less commonly used for standard adult intubations, as they cater to patients with smaller or larger airways, respectively.