Certified Pediatric Emergency Nurse (CPEN) Exam 2025 – 400 Free Practice Questions to Pass the Exam

Cyanosis is a primary symptom indicating respiratory failure because it reflects a decreased level of oxygen in the blood. In respiratory failure, the lungs are unable to effectively exchange gases, which leads to hypoxemia, or low oxygen levels in the bloodstream. This insufficient oxygen can cause the skin and mucous membranes to take on a bluish hue due to inadequate oxygenation, particularly evident in the lips, fingertips, and toes.

In contrast, increased appetite and frequent urination typically do not relate to respiratory issues and may reflect other conditions unrelated to respiratory function. Lethargy can occur in many medical scenarios but is especially significant in respiratory distress, as it may indicate compromised oxygen delivery to the brain, yet the distinct presentation of cyanosis makes it a more definitive and immediate sign of respiratory failure. Thus, cyanosis serves as a clear and urgent marker that demands further assessment and intervention for potential respiratory failure.