Chronic Pseudomonas aeruginosa infection and respiratory muscle impairment in cystic fibrosis.

BACKGROUND: Chronic infection with Pseudomonas aeruginosa in patients with cystic fibrosis (CF) is associated with increased morbidity. Chronic infection can cause limb and respiratory muscle compromise. Respiratory muscle function can be assessed via maximal inspiratory pressure (P Imax ), maximal expiratory pressure (P Emax ), and the pressure-time index of the respiratory muscles (PTI mus ). We studied the effect of chronic P. aeruginosa infection on respiratory muscle function in patients with CF. METHODS: This cross-sectional study assessed P Imax , P Emax , PTI mus , FEV 1 , FVC, maximum expiratory flow during the middle half of the FVC maneuver, body mass index, and upper arm muscle area in 122 subjects with CF, in 4 subgroups matched for age and sex at different stages of P. aeruginosa infection, according to the Leeds criteria. We compared respiratory muscle function in the subgroups according to P. aeruginosa infection state. RESULTS: Median P Imax was significantly lower in CF subjects with chronic P. aeruginosa infection (P Imax = 62 cm H 2 O), compared to subjects who were never infected (P Imax = 86 cm H 2 O, P = .02), free of infection (P Imax = 74 cm H 2 O, P = .01), or intermittently infected (P Imax = 72 cm H 2 O, P = .02). Median PTI mus was significantly increased in CF subjects with chronic P. aeruginosa infection (PTI mus = .142), compared to subjects who were free of infection (PTI mus = .102, P = .006). Median upper-arm muscle area was significantly lower in CF subjects with chronic P. aeruginosa infection (upper-arm muscle area = 2,219 mm 2 ), compared to subjects who were never infected (2,754 mm 2 , P = .03), free of infection (2,678 mm 2 , P = .01), or intermittently infected (2,603 mm 2 , P = .04). Multivariate logistic regression revealed P. aeruginosa state of infection as a significant determinant of PTI mus ( P = .03) independently of sex, upper-arm muscle area, and FEV 1 . CONCLUSIONS: CF subjects with chronic P. aeruginosa infection exhibited impaired respiratory muscle function and decreased inspiratory muscle strength, and chronic P. aeruginosa infection independently impacts respiratory muscle function in subjects with CF.