Maximal respiratory pressure was measured as an index of respiratory muscle strength in lung cancer patients. Maximal inspiratory pressure (MIP, index of inspiratory muscle strength) and maximal expiratory pressure (MEP, index of expiratory muscle strength) were both significantly low in the lung cancer patients and seemed to be mainly influenced by aging. MIP and MEP correlated well with each other and with FVC, FEV(1.0) and MVV, as seen in the normal adults. MIP usually dropped to about 50% of the preoperative value in lung cancer patients who underwent surgery. MIP increased gradually during the postoperative period, and returned to almost the preoperative value about 6 months after surgery. On the contrary, MEP remained low even 6 months after surgery. Sustainable inspiratory pressure, which was measured using a resistance device designed to produce a load at the inspiratory phase as an index of endurance of respiratory muscles, was significantly low in the lung cancer patients. We also evaluated the effect of preoperative respiratory training using an incentive spirometer. Respiratory training significantly increased inspiratory muscle strength. Evaluation of respiratory muscle strength and endurance in lung cancer patients was quite useful in obtaining information on respiratory function, judging the effect of respiratory training and understanding the pathophysiology of respiratory failure.
Maximal Inspiratory Pressure
Maximal Expiratory Pressure
Sustainable Inspiratory Pressure