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.

Glucocorticoid-induced myopathy in people with asthma: a systematic review.

OBJECTIVES: To review the current literature on the evidence and the underlying characteristics of glucocorticoids (type, dosage, and duration) associated with myopathy in asthma. DATA SOURCES: Four electronic databases were searched to October 19, 2020. STUDY SELECTION: Inclusion criteria: adults or adolescents with asthma, taking systemic glucocorticoids, and measures of muscle impairments. RESULTS: Nine studies met the eligibility criteria. The methodologic quality of most studies was fair or good. Two studies reported significantly lower inspiratory muscle function in outpatients taking daily oral glucocorticoids (≥10 mg), but one study reported no such difference. No differences was found in limb muscle strength in one study. Only 11-36% patients with acute exacerbation taking glucocorticoids intravenously suffered from limb muscle weakness during/after critical care admissions. Two studies reported significant associations between dosage of oral glucocorticoid use and inspiratory and limb muscle function, whereas seven studies did not find any significant correlations among the characteristics of systemic glucocorticoids and myopathy. Two studies comparing people with non-glucocorticoid dependent asthma taking inhaled glucocorticoid and healthy people did not find any significant differences in their inspiratory muscle strength and endurance. CONCLUSIONS: There were limited studies and inconsistent results on glucocorticoid-induced myopathy in people with asthma, and its association with the characteristics of glucocorticoids use. We recommended future studies should use a commonly accepted operational definition of myopathy, utilize a cohort study design, measure the cumulative dosage of glucocorticoids, and integrate possible confounding factors in the analysis.

Functional Tests of Leg Muscle Strength and Power in Adults With Cystic Fibrosis.

BACKGROUND: Muscle weakness is an important systemic consequence in adults with cystic fibrosis, but it can be challenging to evaluate clinically. This study examined the validity of lower-extremity functional tests to assess quadriceps muscle strength and muscle power. METHODS: The subjects underwent 4 functional tests: 30-s sit-to-stand test, stair-climb power test, vertical jump height, and triple hop distance. Quadriceps muscle strength and power were tested by using a dynamometer (the accepted standard). Quadriceps strength was measured from 5 maximum voluntary isometric contractions to obtain peak torque. Quadriceps power was evaluated from the peak power and peak velocity attained during isotonic contractions of the quadriceps at a preset load of 20% of the peak torque. Pearson correlations were used to determine associations between functional tests and accepted measures of quadriceps strength and power. RESULTS: Fifteen adults with cystic fibrosis (9 males; mean ± SD age, 32 ± 13 y; mean ± SD FEV1% predicted, 73 ± 19) completed the study. The stair-climb power test had the strongest correlations with peak torque (r = 0.84, P < .001) and power (r = 0.65, P = .009). Vertical jump height was moderately correlated with quadriceps strength (r = 0.62, P = .014) and quadriceps peak power (r = 0.51, P = .048). Similarly, triple hop distance had moderate correlations with quadriceps strength (r = 0.78, P = .001) and peak power (r = 0.57, P = .026). The sit-to-stand test was only associated with quadriceps strength (r = 0.55, P = .034). CONCLUSIONS: Functional tests can be applied clinically to measure leg muscle strength and power, with the stair-climb power test having the strongest associations with the standard measures. The utility of using functional tests to evaluate longitudinal changes in muscle function and its association with clinical outcomes should be examined in cystic fibrosis.

Frailty assessment and impact of frailty on outcomes after transcatheter aortic valve replacement.

INTRODUCTION: Certain frail patients fail to achieve adequate functional or mortality benefit despite successful transcatheter aortic valve replacement (TAVR). Therefore, frailty assessment methods are becoming an important tool to identify and intervene on this high-risk patient subset for improving clinical outcomes. Areas covered: The authors provide an overview of frailty and frailty assessment tools being used in clinical practice and discuss the impact of frailty on the cardiac patients, particularly among the TAVR population. Expert commentary: Available evidence suggests that frailty assessment is critical for identifying patients at high risk of morbidity and mortality after TAVR procedures. However, there is lack of consensus for the best methodology to determine frailty and its optimal management in TAVR populations. Although, physical exercise is a commonly employed intervention to reduce frailty, a greater attention towards improving nutrition may convey more benefit than either intervention alone. Ongoing studies are investigating the benefits of a multicomponent approach to improve clinical outcomes in frail patients undergoing TAVR.