Which of the following is a physiological sign of an apparent life-threatening event in infants?

An apparent life-threatening event (ALTE) refers to a sudden episode in an infant characterized by a combination of symptoms that can include respiratory distress, changes in color, and unresponsiveness. Unresponsiveness is a critical physiological sign because it indicates a potential compromise in the infant’s neurological function. When an infant is unresponsive, it suggests that they are not adequately responding to their environment, which can be a result of serious underlying issues such as airway obstruction, cardiac problems, or severe infection.

In the context of ALTE, unresponsiveness is significant because it often necessitates immediate medical intervention to assess and stabilize the infant. The other options—abdominal pain, fever, and high blood pressure—may indicate other conditions but do not reflect the immediate life-threatening nature of an event related to airway or neurological compromise that is characteristic of ALTEs. Therefore, unresponsiveness in an infant should be treated as an urgent concern requiring further medical evaluation and potential resuscitation.