METHODS	The criteria for trial entry were : an oxygenation index of > 40 or arterial partial pressure of carbon dioxide ( PaCO2 ) > 12 kPa for at least 3 hours ; gestational age at birth of 35 completed weeks or more ; a birth weight of 2 kg or more ; < 10 days high-pressure ventilation ; an age of < 28 days ; and no contraindication to ECMO such as previous cardiac arrest or intraventricular hemorrhage .\