In children with RSV, BEST predictor of disease severity?

• A. Pulse Ox
• B. CXR
• C. WBC count
• D. Blood pH

Answer: (A)

Oxygen saturation measured by pulse oximetry best reflects how well the lungs are delivering oxygen to the blood, making it the most reliable predictor of how severe RSV bronchiolitis is in a child. If an infant’s SpO2 drops, it signals significant gas exchange impairment from airway inflammation and obstruction and indicates a higher risk of needing supplemental oxygen, closer monitoring, or hospitalization. Pulse oximetry is noninvasive, continuous, and directly tied to the patient’s respiratory status, which is why it outperforms other measures.

Chest X-ray findings can be variable and often do not correlate with severity, so imaging isn’t a reliable predictor of how sick a child is. WBC count can be influenced by many factors in viral infections and does not reflect the degree of respiratory compromise. Blood pH indicates acid-base status but is not a practical or consistent predictor of severity in typical RSV bronchiolitis; ABG is reserved for specific concerns for respiratory failure. Continuous oxygen saturation monitoring provides the most direct, actionable gauge of illness severity.