During craniosynostosis surgery , children in the early substitution group received significantly less RBCs ( median , 28 ml kg ( -1 ) ; IQR , 21 to 50 ml kg ( -1 ) ) compared with the conventional fibrinogen trigger of < 8 mm ( median , 56 ml kg ( -1 ) ; IQR , 28 to 62 ml kg ( -1 ) ) ( P = 0.03 ) .