The hypotensive and standard groups appeared similar , with no statistically significant differences in mean age ( 46.5 months versus 46.5 months ) , weight ( 19.25 kg versus 19.49 kg ) , procedure [ anterior remodeling ( 34 versus 31 ) versus posterior ( 19 versus 16 ) ] , or preoperative hemoglobin level ( 13 g/dl versus 12.9 g/dl ) .