Which symptom may indicate severe respiratory distress in a child with croup?

The use of accessory muscles is a clear indication of severe respiratory distress in a child with croup. When a child is struggling to breathe, the body compensates by recruiting additional muscles to aid in respiration. This includes muscles in the neck, shoulders, and abdomen, which become more prominent during inhalation. The presence of accessory muscle usage suggests that the child's normal respiratory effort is inadequate, indicating a higher level of respiratory distress that may require immediate medical attention.

In contrast, a slowed respiratory rate may indicate fatigue or an impending respiratory failure, which is concerning but does not necessarily represent active distress. Fever alone, while it may be associated with infection, does not indicate the severity of respiratory difficulty. An absent cough could suggest other issues; while a cough is common in croup, its absence does not specifically reflect the level of respiratory distress. Thus, the visible struggle to breathe and the recruitment of accessory muscles are the most telling signs of severe respiratory distress in this context.