Final answer:
Retractions, grunting, and nasal flaring in infants and children are signs of respiratory distress and indicate an increased effort to breathe. These phenomena necessitate swift medical evaluation to determine the underlying cause, which could range from respiratory infections to other serious health concerns.
Step-by-step explanation:
In infants and children, retraction of the muscles, grunting, and nasal flaring are indicators of respiratory distress. These signs suggest that the child is working harder to breathe. Retraction occurs when the muscles between the ribs pull inward with each breath, which is a sign of increased respiratory effort. Grunting is a sound made by infants and children when they forcefully exhale through a partially closed glottis; this helps to maintain airway pressure and keep the airways open. Nasal flaring involves the outward movement of the nostrils during breathing, indicating that the child is trying to take in more air. Given Olivia's symptoms, such as excessive crying, irritability, sensitivity to light, unusual lethargy, and vomiting, as well as physical signs like swollen lymph nodes and a tender, swollen abdomen, a healthcare professional needs to evaluate her for potential causes of her distress, which may include respiratory infections or other serious conditions.