Differences of Respiratory Function According to Level of the Gross Motor Function Classification System in Children with Cerebral Palsy

[Purpose] The current study was designed to investigate the difference in lung capacity and muscle strengthening related to respiration depending on the level of the Gross Motor Function Classification System (GMFCS) in children with cerebral palsy (CP) through tests of respiratory function and respiratory pressure. [Subjects and Methods] A total of 49 children with CP who were classified as below level III of the GMFCS were recruited for this study. They were divided into three groups (i.e., GMFCS level I, GMFCS level II, and GMFCS level III). All children took the pulmonary function test (PFT) and underwent respiratory pressure testing for assessment of respiratory function in terms of lung capacity and respiratory muscle strength. [Results] The GMFCS level III group showed significantly lower scores for all tests of the PFT (i.e., forced vital capacity (FVC), forced expiratory volume at one second (FEV1), and slow vital capacity (SVC)) and testing for respiratory pressures (maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP)) compared with the other two groups. The results of post hoc analysis indicated that the GMFCS level III group differed significantly from the other two groups in terms of FVC, FEV1, MIP, and MEP. In addition, a significant difference in SVC was observed between GMFCS level II and III. [Conclusion] Children with CP who had relatively low motor function showed poor pulmonary capacity and respiratory muscle weakness. Therefore, clinical manifestations regarding lung capacity and respiratory muscle will be required in children with CP who demonstrate poor physical activity.