Impact of <b><i>Pseudomonas aeruginosa</i></b> Infection on Respiratory Muscle Function in Adult Cystic Fibrosis Patients

Abstract

Background:Pseudomonas aeruginosa infection impairs respiratory muscle function in adolescents with cystic fibrosis, but its impact on adult patients has not been characterised. Objectives: To investigate respiratory muscle function in adult cystic fibrosis patients according to P. aeruginosa status (repetitive samples over 12 months). Methods: The pressure-time index of the respiratory muscles (PTI_mus), a measure of their efficiency, served as the primary outcome. In addition, respiratory load and maximal respiratory muscle strength were assessed. Results: In 51 patients examined (65% female; median age 32 years, IQR 24-40), a median of 3.0 (IQR 2-4) different pathogens was found in each patient. The PTI_mus was 0.113 and 0.126 in Pseudomonas-positive (n = 33) and -negative (n = 18) patients, respectively (p = 0.53). Univariate analysis showed a lower PTI_mus in male than in female patients (p = 0.006). Respiratory muscle load and strength were otherwise comparable, with the exception of higher nasal sniff pressures in Pseudomonas-positive patients who were chronically infected (>50% of positive samples). Quality of Life (according to the Cystic Fibrosis Questionnaire-Revised) was higher if both respiratory load and the PTI_mus were low (high respiratory muscle efficiency). Conclusions: Chronic P. aeruginosa infection does not influence respiratory muscle efficiency in adult cystic fibrosis patients with otherwise multiple co-infections. In addition, patients with reduced respiratory muscle efficiency had worse Quality of Life.

On the Relation of Pseudomonas aeruginosa Infection and Respiratory Muscle Function in Adolescents and Adults with Cystic Fibrosis

“…The study used similar methodology and contrasted the results of a previous study of ours in adolescents with CF, where we found that chronic Pa infection was an independent determinant of PTI mus [2]. Magnet et al [1], thus, suggested that the findings in adolescent CF patients cannot be extrapolated to the adult CF population.…”

“…We read with interest the study by Magnet et al [1] which evaluated the impact of Pseudomonas aeruginosa (Pa) infection on respiratory muscle function in adult cystic fibrosis (CF) patients. The authors studied 51 adults with CF and used the pressure-time index of the respiratory muscles (PTI mus ) to evaluate respiratory muscle efficiency.…”

“…In an effort to address these concerns in our study, we only studied patients with mild to moderate airway obstruction and excluded patients on steroids and patients with co-existing pathogens other than Staphylococcus aureus and Haemophilus influenzae; hence, we included 122 patients [2]. Although previous studies have described that airway obstruction [3] and reported aerobic exercise [7] are determinants of respiratory muscle function in CF patients, in the multivariate regression analysis of Magnet et al [1], FEV 1 and the 6MWT were not independent contributors to alterations of PTI mus . One might, thus, wonder whether a sample size calculation that would have taken into account the known confounders and their interactions might have had an impact on the reported lack of association of PTI mus with the known determinants of respiratory muscle function in CF.…”

Sexual dimorphism in bacterial infections

“…In contrast to the mentioned respiratory tract infections, there are bacterial infections that affect more females than males. These gender differences have been clearly demonstrated in cystic fibrosis disease (CF) that is characterized by a dysregulated inflammatory response and an altered cytokine profile in the lungs that is associated with a higher prevalence of bacterial infections (mainly due to P. aeruginosa ) and poorer lung and respiratory muscle function in females than in males [ 142 – 144 ]. Differential estradiol levels between females and males have been proposed as a factor that explains the sexual dimorphism in CF-associated infections because differences in gender lung function are observed after puberty and are correlated with estrogen levels during the menstrual cycle [ 145 ].…”

Força muscular respiratória e qualidade de vida em crianças e adolescentes com fibrose cística

“…Entretanto a literatura aponta resultados divergentes sobre os efeitos que as infecções por patógenos podem apresentar na FMR. Enquanto alguns estudos mostram que a presença de infecção por Pseudomonas aeruginosa propicia um aumento da carga do trabalho respiratório, exercendo, assim, um efeito de condicionamento da FMR 6,23,24 . Outras pesquisas 25,26 sugerem que as características da doença crônica, como a desnutrição, infecção recorrente e a hiperinsuflação pulmonar, acabam limitando e diminuindo a FMR.…”