text: [Assessment of mechanical efficiency of coughing in pre- and post-operative lung cancer patients].
  Mechanical efficiency of coughing (MEC) is assessed from the integral calculus of a square of expiratory flow rate divided with a square of tracheal transectinal area. Patients whose FEV1.0% was less than 60% had significantly low MEC, compared with patients whose FEV1.0% was more than 75%. esophageal pressure simultaneously measured at coughing was almost the same in both groups. Pre-operative MEC was corrected in 82 lung cancer patients with the same manner as the prediction of expiratory flow rate after pulmonary resection. In 10 patients who needed bronchofiberscopic aspiration of sputum at post-operative days, corrected MEC was significantly lower than others who did not need it. MEC correlated closely with FEV1.0% divided with body surface area (correlation coefficient = 0.85). MEC was useful for assessment of post-operative difficulty of sputum drainage.