Forty children were randomly allocated into @ groups according to the ventilation of their lungs by a circle breathing system in a Drger Primus anesthesia workstation with low ( @ Lmin ) or high ( @ Lmin ) FGF without an HME ( @L and @L groups ) or with an HME ( Pall BB@FS , Pall Biomedical , East Hills , NY ; HME@L and HME@L groups ) .