Final answer:
During a respiratory examination of an infant diagnosed with laryngotracheobronchitis, the nurse may hear a characteristic sound called stridor.
Step-by-step explanation:
When caring for an infant diagnosed with laryngotracheobronchitis, a nurse may hear a characteristic sound during a respiratory examination. This sound is called stridor. Stridor is a high-pitched, crowing sound that occurs due to the narrowing of the upper airway. It is caused by inflammation and swelling of the larynx and trachea, which are the structures affected by laryngotracheobronchitis.