During pediatric CPR, the chest compression depth is approximately proportional to which measurement?

• A. About one-third of the chest's AP diameter
• B. About half the chest's AP diameter
• C. About one-quarter of the AP diameter
• D. Full chest recoil

Answer: (A)

In pediatric CPR, how deep you push down should scale with the size of the chest. The guideline is to depress the chest about one-third of the chest’s anterior-posterior (front-to-back) diameter. This proportion keeps the heart compressed enough to generate blood flow without causing excessive injury, and it naturally accommodates the wide range of chest sizes from infants to larger children.

For example, a small infant’s chest AP diameter is narrower, so about a 1.5–4 cm depth corresponds to one-third of that diameter. In an older child, the same fraction translates to a larger actual depth, around 5 cm or so. It’s also important to allow full chest recoil between compressions to maximize venous return, but that recoil is separate from the depth guideline.