A pulsus paradoxus greater than 10 mm Hg in a child with pericarditis is an indicator of cardiac tamponade in the supplied material.

This statement is **true** according to the lecture. **Pulsus paradoxus** is an exaggerated fall in systolic arterial pressure during inspiration; the material identifies a value greater than 10 mm Hg in a child with pericarditis as an indicator of tamponade. It should be interpreted with the full clinical picture and other findings rather than as an isolated substitute for assessment. **Key takeaway:** An inspiratory systolic-pressure fall above 10 mm Hg is a significant clue to tamponade in the context described. **Glossary:** **Systolic pressure**: arterial pressure during ventricular contraction. **Inspiration**: drawing air into the lungs.