Pulse oximetry findings in respiratory failure in children
Yes. Hypoxemia is not always obvious from the physical examination. Most children who are hypoxemic from a respiratory illness have signs of respiratory distress, but in many cases mild to moderate hypoxemia is clinically inapparent. Hypoxemia is a less potent stimulator of the respiratory center than is hypercarbia. Thus, the increase in minute ventilation that occurs with mild hypoxemia is very modest and may be difficult to detect by physical examination. In patients with acute exacerbations of asthma there is very poor correlation between asthma score, a measure of respiratory distress, and oxygen saturation.
Also, cyanosis requires 3 to 5 g of unsaturated hemoglobin per deciliter to be visible. If a child has a total hemoglobin of 12 g/dL, cyanosis is not apparent until the oxygen saturation drops below 75%. Most clinicians believe it is useful to be aware of hypoxemia before it is severe enough to cause visible cyanosis