Patients were randomized into two groups : group A included @ patients ( @ males and @ females , mean age @ y , range @-@ y ) in which digital drainage system was used , group B with @ patients ( @ males and @ females , mean age @ y , range @-@ 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 .