[Physiological function of the lung; fundamentals on inspiratory capacity]

Inspiratory capacity (IC) is recently highlighted in the clinical field of chronic obstructive pulmonary disease (COPD). Generally, IC is positively associated with exercise capacity and survival prognosis. Since chest surgery generally results in restive change in vital capacity, the decrease in IC potentially causes dysfunction of exercise capacity and dyspnea on exertion, which frequently results in disuse syndrome and deterioration in the quality of life. Although IC seems to be less appreciated, it has more important clinical implementation in terms of exercise capacity and dyspnea than one second forced expiratory volume (FEV1.0). In this aspect, surgical strategies to prevent unnecessary decrease in IC should be cared. Also, appropriate treatments such as chest physiotherapy or exercise training are needed to increase IC for the post-operative patients.