13y male. Headache, severe cyanosis. SpO2 ~80% (pulse oximetry). No response to 100% FiO2. Normal Lung/Heart US. Here the arterial blood gas.

13y male. Headache, severe cyanosis. SpO2 ~80% (pulse oximetry). No response to 100% FiO2. Normal Lung/Heart US. Here the arterial blood gas.