Objective To compare the gas and heat exchange performance of membrane oxygenator DDMO-100S and membrane oxygenator Terumo SX-10 in cardiopulmonary bypass(CPB)in children.Methods 39 children aged 3-12 yrs who suffered from congenital heart disease were selected,and the repair of ventricle septal defect or/and atrial septal defect was performed under cardiopulmonary bypass.The 39 children were randomly divided into Group DD(n =21)and Group SX(n = 18).Membrane oxygenator DDMO-100S(Made by Xi'an Daidai,China)was used in Group DD and Membrane oxygenator Terumo SX-10(Made by Terumo,Japan)in Group SX,respectively.The hypothermic cardiopulmonary bypass with high perfusion flow and the cool crystalloid cardioplegia were applied in all children.The artery blood samples were taken for measuring PO2 and PCO2 and the oxygenating index(OI)was calculated by the formulae(OI = PaO2/FiO2).The temperature at nasal pharynx was monitored and the rewarming time was recorded.Results The total priming volume in Group DD was bigger than in Group SX [(742.5 ± 107.3)ml vs(531.3 ± 84.3)ml,P ＜ 0.05].The PO2,OI and PCO2 at 15 min after CPB or at 5 min before cease of CPB had no differences in both group(P ＞0.05).The rewarming time had no difference in both group [(31.5 ± 10.2)min vs(30.61 ± 8.2)min,P ＞0.05].Conclusions Under our observation condition,the gas and heat exchange performance of membrane oxygenator DDMO-100S were the same as membrane oxygenator Terumo SX-10,when it was used in cardiopulmonary bypass in children,but it had a little bit more priming volume.