Certified Pediatric Nurse (CPN) Practice Exam 2025 - Free CPN Practice Questions and Study Guide

The presence of decreased capillary refill time is a significant clinical sign indicating that an infant has progressed from early to severe dehydration. In infants, normal capillary refill time is typically less than 2 seconds. As dehydration worsens, perfusion to the peripheral tissues is compromised, leading to a slower return of blood to the capillaries, which results in an increased capillary refill time, often noted as greater than 2 seconds. This reflects a more serious level of dehydration, as the body struggles to maintain adequate blood flow to the skin and other tissues.

In contrast, while increased heart rate, sunken fontanels, and dry mucous membranes can also be signs of dehydration, they do not exclusively indicate a progression to a severe state. Increased heart rate can occur in various conditions, and dry mucous membranes may be present in less severe cases. A sunken fontanel is certainly a more specific sign of dehydration but does not necessarily indicate that the dehydration has progressed to a severe stage compared to the critical change observed in capillary refill time.