The ratio of the anteroposterior diameter to the transverse diameter of the chest is 1:1. Which finding best supports this conclusion?

• A. Older adult
• B. History of smoking
• C. Chronic lung disease
• D. Athletic build

Answer: (A)

A1: The front-to-back (AP) diameter increasing to match the side-to-side (transverse) diameter indicates a barrel-shaped chest. As people age, the chest wall stiffens and costal cartilages calcify, which shifts the chest toward a 1:1 AP to transverse ratio. That aging change is the best support for this finding. While smoking or chronic lung disease can lead to hyperinflation and a larger AP dimension, the question’s best match among these options is the older adult, whereas an athletic build is not typically associated with a 1:1 ratio.