Which symptoms indicate an impending respiratory failure in a child with asthma exacerbation?

In a child experiencing an asthma exacerbation, the presence of agitation and confusion, particularly in conjunction with hypoxemia, suggests the onset of respiratory failure. Agitation can be a significant indicator of hypoxemia, as the brain's demand for oxygen increases. When the child's oxygen levels drop, it can lead to neurological manifestations such as confusion, altered mental status, and changes in behavior. This combination signals a more severe condition that requires immediate intervention.

Persistent coughing and wheezing often accompany asthma exacerbations but are common symptoms and do not necessarily indicate impending respiratory failure. Difficulty in swallowing is not characteristic of asthma exacerbation and may indicate a different condition. Palpitations and chest pain can occur but are less specific to the respiratory failure context in asthma, making agitation and confusion with hypoxemia the more critical signs to monitor for impending respiratory failure.