Patients were randomized into two groups : group A included 30 patients ( 23 males and 7 females , mean age 41.116.29 y , range 17-71 y ) in which digital drainage system was used , group B with 30 patients ( 22 males and 8 females , mean age 40.315.74 y , range 18-72 y ) in which traditional suction drainage system was applied.The following variables were evaluated : intensity of AL , duration of the chest tube drainage , delay in surgery , length of stay , and the overall hospitalization costs .