On the third postoperative day , daily drainage remained 250 ml in 22 ( 65 % ) patients , among whom , 17 ( 77 % ) would have their chest tubes removed on the PrRPl/B value in Group C. However , drains could not be removed due to the high protein content of draining fluid despite the acceptable volume of daily drainage in only three ( 27 % ) of 11 cases in Group S ( McNemar 's paired proportions test , P = 0.009 ) .