An infant of 5 kg of body weight was being ventilated with a conventional ventilator with a tidal volume of 40 mL and respiratory rate of 35 rpm, maintaining an expired CO2 of 37 mm Hg and a transcutaneous PCO2 of 43 mm Hg. For transfer, an Oxylog 3000 ventilator (Dräger, Lübeck, Germany) was set to intermittent positive-pressure ventilation mode with a tidal volume of 50 mL and the same respiratory frequency. After connecting, the expired CO2 increased rapidly to 75 mm Hg; the inspired CO2, to 27 mm Hg; and the transcutaneous PCO2, to 82 mm Hg, despite good chest expansion. The respirator was checked and found to be correct. On changing to the conventional ventilator, a rapid decrease was found in the expired CO2 and transcutaneous PCO2 values and the inspired CO2 fell to 0. The Oxylog 3000 ventilator should not be used for the transport of small children because the dead space rise to a significant reinhalation in these patients. Capnography and transcutaneous PCO2 are useful for the early detection of hypercapnia and the dead space during the transfer of pediatric patients.