Unexpected Increase in Arterial to End-Tidal CO2 Gradient in a Child Undergoing Embolization of MAPCAs

A 17-month-old infant with multiple aorto-pulmonary collateral arteries (MAPCAs) and pulmonary hypertension presented for diagnostic catheterization. On the day of the procedure, the infant was asymptomatic with oxygen saturation in the 90’s on 1.0 L/min O2 nasal cannula. His parents denied any recent illness. During the procedure, one coil was inadvertently embolized into the right lung resulting in markedly increased pulmonary artery pressures. The Pa-etCO2 gradient increased to 25 mmHg from a baseline of 2 mmHg. Therapy was initiated to reduce the PaCO2. The patient could not be weaned from mechanical ventilation due to elevated PA pressures.