Effect of Systemic Inflammation on Inspiratory and Limb Muscle Strength and Bulk in Cystic Fibrosis

The Perception of the Diaphragm with Ultrasound: Always There Yet Overlooked?

Diaphragm ultrasound makes it possible to diagnose diaphragmatic atrophy and dysfunction. Important indications include unclear dyspnea; diaphragmatic elevation; assessment of diaphragm dysfunction in pulmonary, neuromuscular and neurovascular diseases; and in critically ill patients before noninvasive and mechanical ventilation and follow-up of diaphragm thickness and function during mechanical ventilation with potential prediction of prolonged weaning. In patients with respiratory insufficiency and potential diaphragm dysfunction, it is possible to objectify the contribution of diaphragm dysfunction. In addition, assessment of diaphragmatic hernias, tumors and diaphragmatic dysfunction in COVID-19 and diaphragmatic ultrasound in sports medicine have been described. This narrative review includes the sonomorphology of the diaphragm, standardization of ultrasonographic investigation with transducer positions and ultrasound techniques, normal findings and diagnostic criteria for pathological findings. The correct sonographic measurement, calculation and evaluation can ultimately influence further therapeutic procedures for the patient suffering from diaphragm dysfunction in various diseases.

A New Frontier in Cystic Fibrosis Pathophysiology: How and When Clock Genes Can Affect the Inflammatory/Immune Response in a Genetic Disease Model

Cystic fibrosis (CF) is a monogenic syndrome caused by variants in the CF Transmembrane Conductance Regulator (CFTR) gene, affecting various organ and systems, in particular the lung, pancreas, sweat glands, liver, gastrointestinal tract, vas deferens, and vascular system. While for some organs, e.g., the pancreas, a strict genotype-phenotype occurs, others, such as the lung, display a different pathophysiologic outcome in the presence of the same mutational asset, arguing for genetic and environmental modifiers influencing severity and clinical trajectory. CFTR variants trigger a pathophysiological cascade of events responsible for chronic inflammatory responses, many aspects of which, especially related to immunity, are not ascertained yet. Although clock genes expression and function are known modulators of the innate and adaptive immunity, their involvement in CF has been only observed in relation to sleep abnormalities. The aim of this review is to present current evidence on the clock genes role in immune-inflammatory responses at the lung level. While information on this topic is known in other chronic airway diseases (chronic obstructive pulmonary disease and asthma), CF lung disease (CFLD) is lacking in this knowledge. We will present the bidirectional effect between clock genes and inflammatory factors that could possibly be implicated in the CFLD. It must be stressed that besides sleep disturbance and its mechanisms, there are not studies directly addressing the exact nature of clock genes' involvement in inflammation and immunity in CF, pointing out the directions of new and deepened studies in this monogenic affection. Importantly, clock genes have been found to be druggable by means of genetic tools or pharmacological agents, and this could have therapeutic implications in CFLD.

Musculoskeletal aspects of respiratory function in cystic fibrosis: a cross-sectional comparative study

Background

Respiration is an intricate interaction between visceral and musculoskeletal structures. In cystic fibrosis (CF), the airways and lungs are subject to progressive obstruction and destruction. However, knowledge about the musculoskeletal aspects of respiratory function and symptoms is still limited in this patient group.

Methods

In a cross-sectional comparative study, 21 adults with CF enrolled at the Gothenburg CF Centre were matched with 42 healthy controls. The two groups were examined and compared in terms of thoracic mobility, respiratory muscle strength, lung function, and musculoskeletal pain in accordance with a predefined protocol.

Results

Significant differences were observed between the groups in the number of tender points, thoracic excursion, forced vital capacity (FVC), and forced expiratory volume (FEV). The CF group also demonstrated a tendency toward reduced function in other measurements, although these were not statistically significant.

Conclusion

This cross-sectional study revealed that people with CF have reduced thoracic mobility and an increased prevalence of muscular tender points, alongside decreased lung function, compared to healthy controls. These findings stress the need for greater emphasis on the often-overlooked musculoskeletal aspects of CF care, especially as people with CF are living longer and may require more musculoskeletal health support.

Prevalence of diaphragm dysfunction in patients with interstitial lung disease (ILD): The role of diaphragmatic ultrasound

BACKGROUND

Diaphragm ultrasound (DUS) has been extensively used in critically ill patients while data on outpatients with interstitial lung disease (ILD) are limited. We hypothesized that diaphragm function, assessed by ultrasound, could be impaired in patients with ILD, considering both Idiopathic Pulmonary Fibrosis (IPF) and Connective Tissue Disease (CTD-ILD), compared to healthy subjects. Moreover, this impairment could impact clinical and functional parameters.

METHODS

All consecutive CTD-ILD and IPF patients followed in our center (March-October 2020) were screened. Diaphragm displacement (DD), inspiratory thickness (Ti), expiratory thickness (Te), thickening fraction (TF), and respiratory functional parameters were collected. The prevalence of diaphragmatic dysfunction (TF <30%) was then recorded.

RESULTS

Eighty-two consecutive patients (41 CTD-ILD, 41 IPF) and 15 age- and sex-matched controls were enrolled. In the overall population, 24 out of 82 (29%) presented diaphragmatic dysfunction. In CTD-ILD, DD and Ti were lower as compared to IPF (p = 0.021 and p = 0.036, respectively); while diaphragmatic dysfunction was more prevalent compared to controls (37% vs 7%, p = 0.043). TF positively correlated to patients' functional parameters in the CTD-ILD group (FVC%pred: p = 0.003; r = 0.45), while not in the IPF group. Diaphragmatic dysfunction was associated with moderate/severe dyspnea in both CTD-ILD and IPF (p = 0.021).

CONCLUSION

The prevalence of diaphragmatic dysfunction was 29% in patients with ILD and was associated with moderate/severe dyspnea. CTD-ILD presented lower DD compared with IPF and a higher prevalence of diaphragmatic dysfunction (TF<30%) compared with controls. TF was associated with lung function only in CTD-ILD patients, suggesting its potential role in the comprehensive patient assessment.

Physical activity and liver disease affect the fat-free mass in adolescents with cystic fibrosis

Cystic fibrosis (CF) is predominantly a lung disease but is also characterised by impaired skeletal muscularity and a reduction in fat-free mass. We aimed to test the hypothesis that clinical and anthropometric parameters would determine fat-free mass impairment in adolescents with CF. We measured the fat-free mass index (FFMI) using bioelectrical impedance, the lung function using spirometry, the number of shuttles as a measure of exercise tolerance and the reported physical activity in children and young people with CF in a tertiary centre at King's College Hospital, London, UK. CF-related liver disease was diagnosed by abnormal liver enzymes and/or ultrasonography. We studied 28 children and young people (11 male) with a median (interquartile range (IQR)) age of 15 (13-17) years. They had a median (IQR) FFMI of 13.5 (11.6-15.1) kg/m². The FFMI significantly correlated with age (rho = 0.568, p = 0.002), number of shuttles (rho = 0.691, p < 0.001) and reported hours of activity per day (rho = 0.426, p = 0.024). The median (IQR) FFMI was significantly higher in male [15.1 (13.1-18.6) kg/m²] compared to female participants [12.7 (11.6-14.1) kg/m², p = 0.008]. The median (IQR) FFMI was significantly lower in the 10 (36%) participants with liver disease [11.9 (11.5-13.4) kg/m²] compared to the FFMI in the remaining 18 participants without liver disease [14.4 (12.5-15.9) kg/m², p = 0.027].

CONCLUSION

Fat-free mass increases with increasing age and growth in adolescents with CF. Physical activity exerts a beneficial effect on fat-free mass, and CF-related liver disease negatively affects fat-free mass in adolescents with CF.

WHAT IS KNOWN

• Health behaviours in adolescence influence lifelong health in cystic fibrosis (CF). • A normal body mass index in CF might fail to reveal a low fat-free mass (FFM), and quality of life in CF is strongly associated with a reduced FFM.

WHAT IS NEW

• FFM increases with increasing age and growth in adolescents with CF. • Physical activity exerts a beneficial effect, and liver disease negatively affects FFM in adolescents with CF.

Characterization of skeletal muscle wasting pathways in diaphragm and limb muscles of cystic fibrosis mice

BACKGROUND

Cystic fibrosis (CF) patients often suffer from skeletal muscle atrophy, most often attributed to physical inactivity and nutritional factors. CF is also characterized by abnormally elevated systemic inflammation. However, it is unknown whether the lack of a functional CF transmembrane conductance regulator (CFTR) gene predisposes to exaggerated inflammation-induced muscle proteolysis.

METHODS

CF mice (CFTR-/-) and their wild-type (WT=CFTR+/+) littermate controls were systemically injected with Pseudomonas-derived lipopolysaccharide (LPS). After 24 hours, the diaphragm and limb muscles (fast-twitch tibialis anterior, slow-twitch soleus) were assessed for induction of inflammatory cytokines (TNFa, IL1b, IL6), oxidative stress, canonical muscle proteolysis pathways (Calpain, Ubiquitin-Proteasome, Autophagy), muscle fiber histology, and diaphragm contractile function.

RESULTS

At baseline, CF and WT muscles did not differ with respect to indices of inflammation, proteolysis, or contractile function. After LPS exposure, there was significantly greater induction of all proteolysis pathways (Calpain activity; Ubiquitin-Proteasome: MuRF1 and Atrogin1; Autophagy: LC3B, Gabarapl-1, BNIP3) in CF mice for the diaphragm and tibialis anterior, but not the soleus. Proteolysis pathway upregulation and correlations with inflammatory cytokine induction were most prominent in the tibialis anterior. Diaphragm force normalized to muscle cross-sectional area was reduced by LPS to an equivalent degree in CF and WT mice.

CONCLUSIONS

CF skeletal muscles containing a high proportion of fast-twitch fibers (diaphragm, tibialis anterior) exhibit abnormally exaggerated upregulation of multiple muscle wasting pathways after exposure to an acute inflammatory stimulus, but not under basal conditions.

Body functions and structure, activity, and participation limitations of adult cystic fibrosis patients under the international classification of functioning, disability, and health framework

Objective: There is no study in the literature evaluating impairments and functional limitations in adults with cystic fibrosis (CF) under the framework of the International Classification of Functioning, Disability, and Health (ICF). To evaluate the adults with CF using ICF model. Methods: Twenty-three adults with CF and 23 age-sex matched healthy individuals included in this cross-sectional study. The participants evaluated according to the selected items for domain b, domain s, and domain d from the Obstructive Pulmonary Diseases (OPD) Comprehensive Core Set. The body composition, pulmonary functions, respiratory and peripheral muscle strength/endurance tests and anxiety/depression level were evaluated for domain b and s. For domain d, the Incremental Shuttle Walk Test (ISWT) and Short Form-36 (SF-36) Health Survey were used. Results: The fat-free mass (p = .044), pulmonary functions (p < .05), respiratory muscle endurance (p = .010), absolute and %quadriceps muscle strength (p = .001, p = .025, respectively), number of sit-ups (p = .020), walking speed (p = .035), ISWT and ISWT% distance (p < .001) and peak oxygen consumption (p < .001) were significantly lower in adults with CF compared to healthy individuals (p < .05). There were only significant differences in SF-36 physical functioning and role physical subdimension scores between groups (p = .009, p = .045 respectively). Conclusions: The ICF framework is applicable to comprehensively evaluate limitations of adults with CF among rehabilitation professionals. Especially age, respiratory function, respiratory muscle strength and endurance, dyspnea perception, peripheral muscle endurance were related to activity and participation limitation.

Comparison of quadriceps muscle size and quality in adults with cystic fibrosis with different severities of cystic fibrosis transmembrane conductance regulator protein dysfunction

Background

Cystic fibrosis (CF) is characterized by CF transmembrane conductance regulator (CFTR) dysfunction. CFTR protein is expressed in human skeletal muscle; however, its impact on skeletal muscle is unknown. The objectives of this study were to compare quadriceps muscle size and quality between adults with various severities of CFTR protein dysfunction.

Methods

We conducted a prospective, cross-sectional study comparing 34 adults with severe versus 18 with mild CFTR protein dysfunction, recruited from a specialized CF centre. Ultrasound images of rectus femoris cross-sectional area (RF-CSA) and quadriceps layer thickness for muscle size, and rectus femoris echogenicity (RF-ECHO) (muscle quality) were obtained. Multivariable linear regression models were developed using purposeful selection technique.

Results

People with severe CFTR protein dysfunction had larger RF-CSA by 3.22 cm², 95% CI (1.03, 5.41) cm², p=.0049], after adjusting for oral corticosteroid use and Pseudomonas aeruginosa colonization. However, a sensitivity analysis indicated that the result was influenced by the specific confounders being adjusted for in the model. We did not find any significant differences in quadriceps layer thickness or RF-ECHO between the two groups.

Conclusion

We found no differential impact of the extent of diminished CFTR protein activity on quadriceps muscle size or quality in our study cohort. Based on these findings, CFTR mutation status cannot be used differentiate leg muscle size or quality in people with CF.

Exercise intolerance in cystic fibrosis-the role of CFTR modulator therapies

Exercise intolerance is common in people with CF (pwCF), but not universal among all individuals. While associated with disease prognosis, exercise intolerance is not simply a reflection of the degree of lung disease. In people with severe CF, respiratory limitations may contribute more significantly to impaired exercise capacity than in those with mild-moderate CF. At all levels of disease severity, there are peripheral factors e.g., abnormal macro- and micro-vascular function that impair blood flow and reduce oxygen extraction, and mitochondrial defects that diminish metabolic efficiency. We discuss advances in understanding the central and peripheral mechanisms underlying exercise intolerance in pwCF. Exploring both the central and peripheral factors that contribute to exercise intolerance in CF can help inform the development of new therapeutic targets, as well as help define prognostic criteria.

Rethinking physical exercise training in the modern era of cystic fibrosis: A step towards optimising short-term efficacy and long-term engagement

Exercise is considered as an important component of the package of care delivered to people with cystic fibrosis (pwCF). However, despite the well-known short-term physiological and psychological benefits, training effects are heterogenous and the transfer of structured exercise programmes to the daily life of pwCF is challenging. Training concepts and strategies developed over the last decades must be adapted to consider the aging population of pwCF with associated comorbidities, and also a new generation of young pwCF that are healthier than ever. In the present review we propose a new framework for optimising the choice among available exercise training procedures and we provide a theoretical and scientifically justified rationale for considering and testing new exercise training modalities. We propose a multidisciplinary approach, considering various physiological, psychological and logistical factors, with the aim to increase effects of exercise training and build positive long-term exercise behaviour.

Transcriptomic analysis of CFTR-impaired endothelial cells reveals a pro-inflammatory phenotype

Cystic fibrosis (CF) is a life-threatening disorder characterised by decreased pulmonary mucociliary and pathogen clearance, and an exaggerated inflammatory response leading to progressive lung damage. CF is caused by bi-allelic pathogenic variants of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a chloride channel. CFTR is expressed in endothelial cells (ECs) and EC dysfunction has been reported in CF patients, but a role for this ion channel in ECs regarding CF disease progression is poorly described.We used an unbiased RNA sequencing approach in complementary models of CFTR silencing and blockade (by the CFTR inhibitor CFTRinh-172) in human ECs to characterise the changes upon CFTR impairment. Key findings were further validated in vitro and in vivo in CFTR-knockout mice and ex vivo in CF patient-derived ECs.Both models of CFTR impairment revealed that EC proliferation, migration and autophagy were downregulated. Remarkably though, defective CFTR function led to EC activation and a persisting pro-inflammatory state of the endothelium with increased leukocyte adhesion. Further validation in CFTR-knockout mice revealed enhanced leukocyte extravasation in lung and liver parenchyma associated with increased levels of EC activation markers. In addition, CF patient-derived ECs displayed increased EC activation markers and leukocyte adhesion, which was partially rescued by the CFTR modulators VX-770 and VX-809.Our integrated analysis thus suggests that ECs are no innocent bystanders in CF pathology, but rather may contribute to the exaggerated inflammatory phenotype, raising the question of whether normalisation of vascular inflammation might be a novel therapeutic strategy to ameliorate the disease severity of CF.

Association of circulating C-reactive protein and high-sensitivity C-reactive protein with components of sarcopenia: A systematic review and meta-analysis of observational studies

BACKGROUND

Sarcopenia, a multi-faceted skeletal muscle disorder in the older population, has poor health outcomes. Some previous observational studies investigated the association between circulating inflammatory markers and sarcopenia components to evaluate chronic inflammation as a risk factor for sarcopenia in the elderly population. Nevertheless, the association between circulating C-reactive protein (CRP) and hs-CRP, as the recognized markers of systemic inflammation and components of sarcopenia, is unclear. This meta-analysis aimed to investigate the association of muscle strength, muscle mass, and muscle function with two serum inflammatory markers, circulating C-reactive protein (CRP) and high-sensitive CRP (hs-CRP).

METHODS

We assessed all observational studies across different electronic databases including PubMed, Scopus, and Google Scholar using keywords such as "muscle strength", "muscle mass", "muscle function", CRP and hs-CRP from inception until the 30th of July 2019. Only studies that investigated the association between components of sarcopenia and CRP or hs-CRP levels were included. Participants' country, age, sex, BMI, and screening tool for sarcopenia were retrieved. The correlations between muscle strength, muscle mass, and muscle function with CRP, and hs-CRP were expressed as the correlation coefficient (r) with 95% confidence intervals (CIs). Begg's test and Egger's test were conducted to evaluate risk of publication bias in this study.

RESULTS

Initially, we found fifty-nine studies for the qualitative synthesis. Ultimately, nineteen adult cross-sectional studies comprising 14,650 subjects were included in the meta-analysis. Of them, fourteen studies measured the correlation between CRP or hs-CRP and muscle strength. There were significant inverse correlation between CRP and hs-CRP concentrations with muscle strength (ES (z) = -0.22; 95% CI = -0.34 to -0.09; P < 0.001), (ES (z) = -0.22; 95% CI = -0.34 to -0.09; P < 0.001), respectively. No publication bias was found between muscle strength and CRP (P = 0.53) or hs-CRP (P = 0.62) respectively.

CONCLUSION

Among diagnostic components of sarcopenia, impairment of muscle strength was independently associated with both inflammatory biomarkers. However, future cohort studies are essential to clarify the causal correlation.

Limb muscle size and contractile function in adults with cystic fibrosis: A systematic review and meta-analysis

BACKGROUND

There is conflicting evidence regarding the presence of limb muscle impairments in adults with cystic fibrosis (CF), and the factors associated with these muscle impairments. The objectives of this study were to compare limb muscle size and function between adults with CF and healthy controls; and to examine their associations with demographic and clinical variables in adults with CF.

METHODS

The systematic review was performed using PRISMA guidelines. Studies were included if they measured any aspect of limb muscle size or function in adults with CF. Meta-analyses were performed to compare muscle variables between CF and healthy controls; and to examine their associations with demographic and clinical variables.

RESULTS

Twenty-eight studies were included, with 747 adults with CF. The meta-analyses showed that adults with CF have smaller thigh muscles [standardized mean difference (SMD) = 0.57, p<.0011, I²=0%], and lower handgrip strength (SMD = 0.89, p=.0034, I²=74.03%), which was weakly correlated with forced expiratory volume in one second (FEV₁) (r=0.24, p=.035, I²=0%) and lower in females with CF (SMD = 2.05, p<.0001, I²=0%). There is no significant difference between adults with CF and controls in knee extensor strength (SMD = 0.25, p=.095, I²=42.79%).

CONCLUSIONS

Leg muscle atrophy and lower handgrip strength were noted. There may be a subgroup of adults with CF with knee extensor (quadriceps) weakness. Future studies are needed to better understand muscle impairments in people with CF; to explore the factors that can predict these muscle impairments; and to investigate their clinical significance in people with CF.

Diaphragmatic ultrasound: a review of its methodological aspects and clinical uses

The diaphragm is the main muscle of respiration, acting continuously and uninterruptedly to sustain the task of breathing. Diaphragmatic dysfunction can occur secondary to numerous pathological conditions and is usually underdiagnosed in clinical practice because of its nonspecific presentation. Although several techniques have been used in evaluating diaphragmatic function, the diagnosis of diaphragmatic dysfunction is still problematic. Diaphragmatic ultrasound has gained importance because of its many advantages, including the fact that it is noninvasive, does not expose patients to radiation, is widely available, provides immediate results, is highly accurate, and is repeatable at the bedside. Various authors have described ultrasound techniques to assess diaphragmatic excursion and diaphragm thickening in the zone of apposition. Recent studies have proposed standardization of the methods. This article reviews the usefulness of ultrasound for the evaluation of diaphragmatic function, addressing the details of the technique, the main findings, and the clinical applications.

Influence of sex gap on muscle strength and functional mobility in patients with cystic fibrosis

The objectives of this study were to determine whether there were differences in handgrip strength and functional mobility between patients with cystic fibrosis (CF) and healthy controls with regard to sex and to ascertain whether these differences were related to lung function. Thirty-eight patients with CF (21 women) and 38 healthy controls aged 18–65 years were included. Muscle weakness and functional mobility were assessed through handgrip strength; walking speed; and time, velocity, and power derived from a single sit-to-stand (STS) test. Patients with CF showed differences for STS variables and walking speed but not for handgrip strength, compared with healthy controls. Considering sex differences, female patients showed differences for all variables analyzed while males with CF only exhibited differences for STS variables, compared with healthy controls. Females with CF showed moderate relationship between muscle weakness, functional mobility, and lung function (|r| = 0.45–0.49; p ≤ 0.05) whereas no relationships were observed for males with CF. The influence of chronic infection with Pseudomonas aeruginosa and pancreatic insufficiency on muscle weakness and functional mobility was similar in both sexes. Differences in muscle strength and functional mobility were predominantly observed in females with CF. These results suggest an important effect of sex gap on muscle weakness and functional mobility in patients with CF.

Novelty The influence of sex gap on muscle weakness in CF has been shown. Muscle weakness was predominantly observed in females with CF.

Diaphragmatic ultrasound findings correlate with dyspnea, exercise tolerance, health-related quality of life and lung function in patients with fibrotic interstitial lung disease

BACKGROUND

Fibrotic interstitial lung disease (FILD) patients are typically dyspneic and exercise-intolerant with consequent impairment of health-related quality of life (HRQoL). Respiratory muscle dysfunction is among the underlying mechanisms of dyspnea and exercise intolerance in FILD but may be difficult to diagnose. Using ultrasound, we compared diaphragmatic mobility and thickening in FILD cases and healthy controls and correlated these findings with dyspnea, exercise tolerance, HRQoL and lung function.

METHODS

We measured diaphragmatic mobility and thickness during quiet (QB) and deep breathing (DB) and calculated thickening fraction (TF) in 30 FILD cases and 30 healthy controls. We correlated FILD cases' diaphragmatic findings with dyspnea, exercise tolerance (six-minute walk test), lung function and HRQoL (St. George's Respiratory Questionnaire).

RESULTS

Diaphragmatic mobility was similar between groups during QB but was lower in FILD cases during DB when compared to healthy controls (3.99 cm vs 7.02 cm; p <  0.01). FILD cases showed higher diaphragm thickness during QB but TF was lower in FILD when compared to healthy controls (70% vs 188%, p <  0.01). During DB, diaphragmatic mobility and thickness correlated with lung function, exercise tolerance and HRQoL, but inversely correlated with dyspnea. Most FILD cases (70%) presented reduced TF, and these patients had higher dyspnea and exercise desaturation, lower HRQoL and lung function.

CONCLUSION

Compared to healthy controls, FILD cases present with lower diaphragmatic mobility and thickening during DB that correlate to increased dyspnea, decreased exercise tolerance, worse HRQoL and worse lung function. FILD cases with reduced diaphragmatic thickening are more dyspneic and exercise-intolerant, have lower HRQoL and lung function.

ERS statement on respiratory muscle testing at rest and during exercise

Assessing respiratory mechanics and muscle function is critical for both clinical practice and research purposes. Several methodological developments over the past two decades have enhanced our understanding of respiratory muscle function and responses to interventions across the spectrum of health and disease. They are especially useful in diagnosing, phenotyping and assessing treatment efficacy in patients with respiratory symptoms and neuromuscular diseases. Considerable research has been undertaken over the past 17 years, since the publication of the previous American Thoracic Society (ATS)/European Respiratory Society (ERS) statement on respiratory muscle testing in 2002. Key advances have been made in the field of mechanics of breathing, respiratory muscle neurophysiology (electromyography, electroencephalography and transcranial magnetic stimulation) and on respiratory muscle imaging (ultrasound, optoelectronic plethysmography and structured light plethysmography). Accordingly, this ERS task force reviewed the field of respiratory muscle testing in health and disease, with particular reference to data obtained since the previous ATS/ERS statement. It summarises the most recent scientific and methodological developments regarding respiratory mechanics and respiratory muscle assessment by addressing the validity, precision, reproducibility, prognostic value and responsiveness to interventions of various methods. A particular emphasis is placed on assessment during exercise, which is a useful condition to stress the respiratory system.

Physical activity for children with chronic disease; a narrative review and practical applications

BACKGROUND

Physical activity (PA) is associated with a diverse range of health benefits. International guidelines suggest that children should be participating in a minimum of 60 min of moderate to vigorous intensity PA per day to achieve these benefits. However, current guidelines are intended for healthy children, and thus may not be applicable to children with a chronic disease. Specifically, the dose of PA and disease specific exercise considerations are not included in these guidelines, leaving such children with few, if any, evidence-based informed suggestions pertaining to PA. Thus, the purpose of this narrative review was to consider current literature in the area of exercise as medicine and provide practical applications for exercise in five prevalent pediatric chronic diseases: respiratory, congenital heart, metabolic, systemic inflammatory/autoimmune, and cancer.

METHODS

For each disease, we present the pathophysiology of exercise intolerance, summarize the pediatric exercise intervention research, and provide PA suggestions.

RESULTS

Overall, exercise intolerance is prevalent in pediatric chronic disease. PA is important and safe for most children with a chronic disease, however exercise prescription should involve the entire health care team to create an individualized program.

CONCLUSIONS

Future research, including a systematic review to create evidence-based guidelines, is needed to better understand the safety and efficacy of exercise among children with chronic disease.

Exercise capacity and muscle fatiguability alterations following a progressive maximal exercise of lower extremities in children with cystic fibrosis

Background

Impairment of peripheral skeletal muscle function is a common phenomenon in patients with cystic fibrosis (CF) in addition to great clinical connotations, such as lack of exercise tolerance and decrease of health-related quality of life. There is very limited data on the effects of maximal exercise on muscle fatiguability and exercise capacity in children with cystic fibrosis.

Objectives

The aim of this study was to evaluate the effect of progressive maximal exercise training of the lower extremities on exercise capacity and muscle fatiguability in children with cystic fibrosis.

Study design

Between June and September 2017, eighteen children aged 8–12 years were recruited in this study. This study had two groups of children; the CF group consisted of nine children (6 males and 3 females) with cystic fibrosis and the control group consisted of nine healthy age matched children (6 males and 3 females). The children underwent a progressive maximal cardiopulmonary exercise cycling test (CPET), muscle fatigue test, and magnetic resonance imaging (MRI) to measure a muscle cross-section area (CSA). Also, pulmonary functions were assessed.

Results

The findings of this study showed that the CF children had less pulmonary functions, had a less exercise capacity, and had a higher breathing reserve index and oxygen desaturation when compared with healthy children (p<0.05). On the other hand, there was a non-significant difference in muscle fatiguability, muscle cross-section area, and maximal voluntary contraction between the CF and healthy children (p>0.05).

Conclusion

This study indicates that progressive maximal exercise doesn't affect muscle fatiguability, muscle cross-section area, and maximal voluntary contraction in CF children with moderate respiratory diseases but includes lower exercise capacity. CF children and healthy age matched children have similar responses to maximal exercise in muscle fatiguability, muscle cross-section area, and maximal voluntary contractions but lower exercise capacity in the CF group.

Fatty acid profile in erythrocytes associated with serum cytokines in pediatric cystic fibrosis patients

ABSTRACT Objective To analyze erythrocyte fatty acid composition and its association with serum cytokine levels in pediatric cystic fibrosis patients. Methods A cross-sectional study was performed at a reference center in Rio de Janeiro, Brazil. We have included all pediatric patients aged 5-19 years with confirmed cystic fibrosis diagnosis. Erythrocyte fatty acid composition and serum cytokine (TNF-α, IL-1β, IL-6 and IL-8) and C-reactive protein levels were measured. The cut-off point to determine essential fatty acids deficiency was the linoleic acid concentration of <21%. Results Twenty-six children (<10 years old) and thirty-one adolescents were studied. Most patients were female and heterozygous for DF508 mutation and suffered from exocrine pancreatic insufficiency. Both children and adolescents had lower linoleic acid concentration (<21%). TNF-α was the only pro-inflammatory marker whose levels were increased; the increase was greater in children. An association between fatty acid composition in erythrocytes and cytokines IL-1β and IL-6 was observed (p<0.05). Conclusion The pediatric cystic fibrosis patients studied presented a deficiency of essential fatty acids, and an association between fatty acid profile in erythrocytes and serum pro-inflammatory cytokines was observed. These findings highlight the importance of this type of assessment that may open new possibilities for studying pathophysiology and treating cystic fibrosis patients, such as the dietary supplementation with n-3 fatty acids (eicosapentaenoic and docosahexaenoic acids). However, further longitudinal studies are needed for better clarification of the imbalance in lipid metabolism and inflammation in cystic fibrosis

Identifying decreased diaphragmatic mobility and diaphragm thickening in interstitial lung disease: the utility of ultrasound imaging

Objective:

To investigate the applicability of ultrasound imaging of the diaphragm in interstitial lung disease (ILD).

Methods:

Using ultrasound, we compared ILD patients and healthy volunteers (controls) in terms of diaphragmatic mobility during quiet and deep breathing; diaphragm thickness at functional residual capacity (FRC) and at total lung capacity (TLC); and the thickening fraction (TF, proportional diaphragm thickening from FRC to TLC). We also evaluated correlations between diaphragmatic dysfunction and lung function variables.

Results:

Between the ILD patients (n = 40) and the controls (n = 16), mean diaphragmatic mobility was comparable during quiet breathing, although it was significantly lower in the patients during deep breathing (4.5 ± 1.7 cm vs. 7.6 ± 1.4 cm; p < 0.01). The patients showed greater diaphragm thickness at FRC (p = 0.05), although, due to lower diaphragm thickness at TLC, they also showed a lower TF (p < 0.01). The FVC as a percentage of the predicted value (FVC%) correlated with diaphragmatic mobility (r = 0.73; p < 0.01), and an FVC% cut-off value of < 60% presented high sensitivity (92%) and specificity (81%) for indentifying decreased diaphragmatic mobility.

Conclusions:

Using ultrasound, we were able to show that diaphragmatic mobility and the TF were lower in ILD patients than in healthy controls, despite the greater diaphragm thickness at FRC in the former. Diaphragmatic mobility correlated with ILD functional severity, and an FVC% cut-off value of < 60% was found to be highly accurate for indentifying diaphragmatic dysfunction on ultrasound.

Inspiratory muscle function in asthmatic and healthy subjects: influence of age, nutrition and physical activity

OBJECTIVE

To compare inspiratory muscle function (strength and endurance) between asthmatics and healthy controls, and the influence of age, nutritional status and physical activity on them.

METHODS

This is a cross-sectional study. Asthmatic and healthy subjects, aged 6 to 18 years old, recruited from two public schools in Southern Brazil were included in the study. Asthmatic subjects were selected using the criteria presented by the International Study on Asthma and Allergies in Children and control subjects based on the absence of respiratory symptoms. Anthropometric data was measured, body mass index calculated and subjects classified as normal weight, overweight or obese. Physical activity levels, maximum inspiratory pressure (MIP) and inspiratory muscle endurance (IME) were also evaluated.

RESULTS

A total of 314 participants were included, separated into control group (181) and asthmatics (133), with a total mean age of 11 years. When both groups were compared, there were no significant differences in both MIP and IME. However, when groups were analyzed subdivided in children and adolescents, IME was significantly reduced (p = 0.003) in asthmatic adolescents. Indeed, when groups were also stratified considering the nutritional status, IME showed a reduction in asthmatic adolescents with overweight (p = 0.042) and obesity (p = 0.041) when compared to healthy controls. No effects of physical activity levels between groups were found.

CONCLUSIONS

Results demonstrate a reduction in the IME in asthmatic adolescents with overweight and obesity, indicating an association between asthma, nutritional status and respiratory muscle function.

Normal spectrum of pulmonary parametric response map to differentiate lung collapsibility: distribution of densitometric classifications in healthy adult volunteers

OBJECTIVES

Pulmonary parametric response map (PRM) was proposed for quantitative densitometric phenotypization of chronic obstructive pulmonary disease. However, little is known about this technique in healthy subjects. The purpose of this study was to describe the normal spectrum of densitometric classification of pulmonary PRM in a group of healthy adults.

METHODS

15 healthy volunteers underwent spirometrically monitored chest CT at total lung capacity (TLC) and functional residual capacity (FRC). The paired CT scans were analyzed by PRM for voxel-by-voxel characterization of lung parenchyma according to 4 densitometric classifications: normal lung (TLC ≥ -950 HU, FRC ≥ -856 HU); expiratory low attenuation area (LAA) (TLC ≥ -950 HU, FRC < -856 HU); dual LAA (TLC<-950 HU, FRC < -856 HU); uncharacterized (TLC < -950 HU, FRC ≥ -856 HU).

RESULTS

PRM spectrum was 78 % ± 10 % normal lung, 20 % ± 8 % expiratory LAA, and 1 % ± 1 % dual LAA. PRM was similar between genders, there was moderate correlation between dual LAA and spirometrically assessed TLC (R = 0.531; p = 0.042), and between expiratory LAA and VolExp/Insp ratio (R = -0.572; p = 0.026).

CONCLUSIONS

PRM reflects the predominance of normal lung parenchyma in a group of healthy volunteers. However, PRM also confirms the presence of physiological expiratory LAA seemingly related to air trapping and a minimal amount of dual LAA likely reflecting emphysema.

KEY POINTS

• Co-registration of inspiratory and expiratory computed tomography allows dual-phase densitometry. • Dual-phase co-registered densitometry reflects heterogeneous regional changes in lung function. • Quantification of lung in healthy subjects is needed to set reference values. • Expiratory low attenuation areas <30 % could be considered within normal range.

Cardiorespiratory and sensory responses to exercise in adults with mild cystic fibrosis

The purpose of this study was to evaluate cardiorespiratory fitness and reasons for exercise curtailment in a contemporary adult cystic fibrosis (CF) cohort with mild lung disease. Adults with mild CF (n = 19, forced expiratory volume in 1 s = 95 ± 17% predicted) were age-, sex-, ethnicity-, and body mass index-matched to healthy controls (n = 19) and underwent a detailed cardiopulmonary cycle exercise test. While CF subjects had a reduced peak oxygen uptake compared with controls, the values were normal when expressed as %predicted in 14/19 (74%) of subjects. Both groups demonstrated a normal cardiovascular limitation to exercise and stopped exercise primarily because of leg fatigue. Despite not being exercise-limited by respiratory factors, there was some evidence of ventilatory abnormalities as patients with mild CF had increased end-inspiratory lung volumes and reached an inflection/plateau in tidal volume relative to minute ventilation at lower exercise intensities compared with controls. Subjects with CF were not more likely to demonstrate expiratory flow limitation compared with controls and did not have evidence of dynamic hyperinflation during exercise. Despite increased end-inspiratory lung volumes and an earlier tidal volume inflection/plateau, CF subjects did not experience higher levels of dyspnea. In an exploratory analysis, a significant inverse correlation was observed between sweat chloride and peak work rate. Adult CF subjects with relatively well preserved spirometry have normal exercise performance relative to reference values and are primarily limited by nonrespiratory factors. However, ventilatory abnormalities were detected even in this mild CF cohort and should be evaluated in future therapeutic trials focused on disease-modifying therapies in mild CF.

Skeletal muscle contractility and fatigability in adults with cystic fibrosis

BACKGROUND

Recent discovery of cystic fibrosis transmembrane conductance regulator expression in human skeletal muscle suggests that CF patients may have intrinsic skeletal muscle abnormalities potentially leading to functional impairments. The aim of the present study was to determine whether CF patients with mild to moderate lung disease have altered skeletal muscle contractility and greater muscle fatigability compared to healthy controls.

METHODS

Thirty adults (15 CF and 15 controls) performed a quadriceps neuromuscular evaluation using single and paired femoral nerve magnetic stimulations. Electromyographic and mechanical parameters during voluntary and magnetically-evoked contractions were recorded at rest, during and after a fatiguing isometric task. Quadriceps cross-sectional area was determined by magnetic resonance imaging.

RESULTS

Some indexes of muscle contractility tended to be reduced at rest in CF compared to controls (e.g., mechanical response to doublets stimulation at 100 Hz: 74±30 Nm vs. 97±28 Nm, P=0.06) but all tendencies disappeared when expressed relative to quadriceps cross-sectional area (P>0.5 for all parameters). CF and controls had similar alterations in muscle contractility with fatigue, similar endurance and post exercise recovery.

CONCLUSIONS

We found similar skeletal muscle endurance and fatigability in CF adults and controls and only trends for reduced muscle strength in CF which disappeared when normalized to muscle cross-sectional area. These results indicate small quantitative (reduced muscle mass) rather than qualitative (intrinsic skeletal muscle abnormalities) muscle alterations in CF with mild to moderate lung disease.

Inflammation, oxidative stress, and cardiovascular disease risk factors in adults with cystic fibrosis

Cystic fibrosis (CF) represents one of a number of localized lung and non-lung diseases with an intense chronic inflammatory component associated with evidence of systemic oxidative stress. Many of these chronic inflammatory diseases are accompanied by an array of atherosclerotic processes and cardiovascular disease (CVD), another condition strongly related to inflammation and oxidative stress. As a consequence of a dramatic increase in long-lived patients with CF in recent decades, the specter of CVD must be considered in these patients who are now reaching middle age and beyond. Buttressed by recent data documenting that CF patients exhibit evidence of endothelial dysfunction, a recognized precursor of atherosclerosis and CVD, the spectrum of risk factors for CVD in CF is reviewed here. Epidemiological data further characterizing the presence and extent of atherogenic processes in CF patients would seem important to obtain. Such studies should further inform and offer mechanistic insights into how other chronic inflammatory diseases potentiate the processes leading to CVDs.

Alterations in respiratory and limb muscle strength and size in patients with sepsis who are mechanically ventilated

BACKGROUND

Skeletal muscle wasting and weakness are common in patients with sepsis in the intensive care unit, although less is known about deficits in diaphragm and limb muscles when mechanical ventilation also is required.

OBJECTIVE

The objective of this study was to concurrently investigate relative differences in both thickness and strength of respiratory and peripheral muscles during routine care.

DESIGN

A prospective, cross-sectional study of 16 alert patients with sepsis and 16 people who were healthy (control group) was used.

METHODS

Assessment was made of the diaphragm, upper arm, forearm, and thigh muscle thicknesses with the use of ultrasound; respiratory muscle strength by means of maximal inspiratory pressure; and isometric handgrip, elbow flexion, and knee extension forces with the use of portable dynamometry. To describe relative changes, data also were normalized to fat-free body mass (FFM) measured by bioelectrical impedance spectroscopy.

RESULTS

Patients (9 men, 7 women; mean age=62 years, SD=17) were assessed after a median of 16 days (interquartile range=11-29) of intensive care unit admission. Patients' diaphragm thickness did not differ from that of the control group, even for a given FFM. When normalized to FFM, only the difference in patients' mid-thigh muscle size significantly deviated from that of the control group. Within the patient sample, all peripheral muscle groups were thinner compared with the diaphragm. Patients were significantly weaker than were the control group participants in all muscle groups, including for a given FFM. Within the critically ill group, limb weakness was greater than the already-significant respiratory muscle weakness.

LIMITATIONS

Volitional strength tests were applied such that successive measurements from earlier in the course of illness could not be reliably obtained.

CONCLUSIONS

When measured at bedside, survivors of sepsis and a period of mechanical ventilation may have respiratory muscle weakness without remarkable diaphragm wasting. Furthermore, deficits in peripheral muscle strength and size may exceed those in the diaphragm.

Respiratory diseases and muscle dysfunction

Many respiratory diseases lead to impaired function of skeletal muscles, influencing quality of life and patient survival. Dysfunction of both respiratory and limb muscles in chronic obstructive pulmonary disease has been studied in depth, and seems to be caused by the complex interaction of general (inflammation, impaired gas exchange, malnutrition, comorbidity, drugs) and local factors (changes in respiratory mechanics and muscle activity, and molecular events). Some of these factors are also present in cystic fibrosis and asthma. In obstructive sleep apnea syndrome, repeated exposure to hypoxia and the absence of reparative rest are believed to be the main causes of muscle dysfunction. Deconditioning appears to be crucial for the functional impairment observed in scoliosis. Finally, cachexia seems to be the main mechanism of muscle dysfunction in advanced lung cancer. A multidimensional therapeutic approach is recommended, including pulmonary rehabilitation, an adequate level of physical activity, ventilatory support and nutritional interventions.

Diaphragm and peripheral muscle thickness on ultrasound: intra-rater reliability and variability of a methodology using non-standard recumbent positions

BACKGROUND AND OBJECTIVE

Reliable measurement of diaphragm and peripheral muscle thickness, using diagnostic ultrasound, has only been validated in the erect posture. However, in many clinical populations, including critically ill patients, the erect posture presents logistic difficulties. This study aimed to validate ultrasound measurement of diaphragm and peripheral muscle thickness in the recumbent position.

METHODS

An observational methodology of repeated but blind ultrasound and anthropometric measurements was applied, to assess inta-rater reliability. Thirteen healthy volunteers (aged 20-73years) participated. A pneumotachograph was used to target lung volume, as diaphragm thickness was measured from ultrasound at end-expiration, and both 25% and 50% of inspiratory capacity, while semi-recumbent. The thicknesses of the mid-upper arm, mid-forearm and mid-thigh musculature were also measured bilaterally while supine.

RESULTS

Diaphragm thickness could be reliably measured at end-expiration (intra-class correlation coefficient (ICC)=0.990, 95% confidence interval: 0.918-0.998), 25% of inspiratory capacity (ICC=0.959 (0.870-0.988)) and 50% of inspiratory capacity (ICC=0.994 (0.980-0.998)). Peripheral muscle thickness measurements were also reliable (ICC=0.998-1.0). Supine anthropometric measurements of limb segment lengths and girths were highly reproducible.

CONCLUSIONS

This ultrasound technique has good reliability in recumbent positions, making it useful for application to clinical populations when the erect posture is not practical.

Effect of acute exacerbations on skeletal muscle strength and physical activity in cystic fibrosis

BACKGROUND

Skeletal muscle weakness is an important complication of chronic respiratory disease. The effect of acute exacerbations on strength in patients with cystic fibrosis is not known.

METHODS

Quadriceps (QMVC) and respiratory muscle strength were measured in patients at the time of acute admission, at discharge and one month later. Patients wore an activity monitor during admission and at one month. Convalescent values were compared to the stable clinic population.

RESULTS

Data were available for 13 acute admissions and 25 stable CF outpatients. Strength and other parameters including daily step count did not differ significantly between the stable and one month post-admission groups. At admission, QMVC was 16.7 (8.3)% lower than at convalescence, whereas inspiratory muscle strength did not change significantly. Reduction in QMVC did not correlate with activity levels or with markers of systemic inflammation.

CONCLUSION

Further research is needed to identify the mechanisms responsible for the reduction in QMVC.

Raised interleukin-17 is immunolocalised to neutrophils in cystic fibrosis lung disease

Interleukin (IL)-17 is pivotal in orchestrating the activity of neutrophils. Neutrophilic inflammation is the dominant pathology in cystic fibrosis (CF) lung disease. We investigated IL-17 protein expression in the lower airway in CF, its cellular immunolocalisation and the effects of IL-17 on CF primary bronchial epithelial cells. Immunohistochemistry was performed on explanted CF lungs and compared with the non-suppurative condition pulmonary hypertension (PH). Airway lavages and epithelial cultures were generated from explanted CF lungs. Immunoreactivity for IL-17 was significantly increased in the lower airway epithelium in CF (median 14.1%) compared with PH (2.95%, p=0.0001). The number of cells staining positive for IL-17 in the lower airway mucosa was also increased (64 cells·mm(-1) compared with 9 cells·mm(-1) basement membrane, p=0.0005) and included both neutrophils in addition to mononuclear cells. IL-17 was detectable in airway lavages from explanted CF lungs. Treatment of epithelial cultures with IL-17 increased production of IL-8, IL-6 and granulocyte macrophage colony-stimulating factor. In conclusion, immunoreactive IL-17 is raised in the lower airway of people with CF and localises to both neutrophils and mononuclear cells. IL-17 increases production of pro-neutrophilic mediators by CF epithelial cells, suggesting potential for a positive feedback element in airway inflammation.