Força muscular como determinante da eficiência do consumo de oxigênio e da máxima resposta metabólica ao exercício em pacientes com DPOC leve/moderada

Tidal volume expandability and ventilatory efficiency as predictors of mortality in Taiwanese male patients with chronic obstructive pulmonary disease: A 10-year follow-up study - Is V̇O2peak or FEV1% the gold standard?

Despite our knowledge of the risk factors for mortality associated with chronic obstructive pulmonary disease (COPD), the mortality rate for this condition continues to increase. This study aimed to investigate the predictive power of physiological variables on all-cause mortality in COPD patients compared to peak oxygen uptake (V ˙ O2peak) and forced expired volume in one second (FEV1). We conducted a retrospective study of 182 COPD patients with complete lung function tests, cardiopulmonary exercise testing (CPET), and survival data. Cox regression analysis was used to estimate the hazard ratios for all-cause mortality. The median follow-up period was 6.8 (IQR 3.9-9.2) years. Out of the 182 patients in our study, sixty-two (34.1%) succumbed to various causes. Of these, 27.4% (n = 17) experienced acute exacerbations, 24.2% (n = 15) had advanced cancer, and 12.9% (n = 8) had cardiovascular disease as the primary cause of death. Another 25.8% (n = 16) passed away due to other underlying conditions, while 6.5% (n = 4) had an unknown cause of death. One patient's demise was attributed to a benign tumor, and another's to a connective tissue disease. The ratio of tidal volume to total lung capacity (VTpeak/TLC) and the ratio of minute ventilation and V ˙ O2 at nadir (V ˙ E/V ˙ O2nadir) (AUR 0.83, 95% CI 0.76-0.91) were superior predictors of all-cause mortality compared to V ˙ O2peak and FEV1%. A mortality prediction formula was derived using these variables. This study highlights the potential of VTpeak/TLC and V ˙ E/V ˙ O2nadir as predictive markers for COPD all-cause mortality in COPD. CPET is an effective tool for evaluating COPD mortality; however, the predictive equation requires further validation.

Effect of muscle distribution on lung function in young adults

BACKGROUND

At present, available research on the relationship between muscle distribution and respiratory function in healthy people is limited.

OBJECTIVE

To study the relationship between muscle distribution and lung function in healthy young adults.

METHODS

A total of 612 male and 1561 Female Chinese college students were recruited. visceral fat tissue (VAT), subcutaneous fat tissue (SAT), total body muscle mass (TMM), trunk muscle mass (TKMM), upper limb muscle mass (ULMM) and lower limb muscle mass (LLMM) was measured by body composition. Vital capacity (VC) was measured by spirometry instrument. Obesity classification was defined by muscle mass ratio (MMR), body mass index (BMI), body fat percentage (BFP), waist-to-hip ratio (WHR).

RESULTS

Among these positive correlation parameters, male VC had a high positive correlation with TMM and LLMM, while female VC had a high positive correlation with TMM and TKMM. After the population was divided into MMR, BMI, BFP, and WHR, further analysis showed that VC was positively correlated with TMM for males with MMR-low muscle (r = 0.483; p < 0.05), BMI-underweight (r = 0.265; p < 0.05), BMI-overweight + obesity (r = 0.272; p < 0.05), BFP-low fat (r = 0.306; p < 0.05), and WHR-normal subgroups (r = 0.316; p < 0.05), while LLMM was positively correlated with VC in the MMR-normal muscle (r = 0.285; p < 0.05), BMI-normal (r = 0.305; p < 0.05), BFP-normal fat (r = 0.304; p < 0.05), and WHR obesity subgroups (r = 0.266; p < 0.05). VC was positively correlated with TMM for females with MMR-low muscle (r = 0.169; p < 0.05), MMR-normal muscle (r = 0.241; p < 0.05), BMI-underweight (r = 0.241; p < 0.05), BMI-normal (r = 0.288; p < 0.05), WHR normal (r = 0.275; p < 0.05), and BFP-low fat subgroups (r = 0.255; p < 0.05), while TKMM was positively correlated with VC in the BMI-overweight + obesity (r = 0.342; p < 0.05), WHR-obesity (r = 0.227; p < 0.05), and BFP-normal subgroups (r = 0.256; p < 0.05).

CONCLUSIONS

Muscle distribution in young adults is highly correlated with VC, and this relationship is affected by gender and body types. In general, for thin, VC is more positively correlated with TMM, and for normal weight or obese, VC is more positively correlated with LLMM for males but with TKMM for females, respectively, in comparison with other tested indices. Further studies will be required to evaluate the relationship between muscle distribution and vital capacity in young adults.

Evaluation of isokinetic muscle strength of upper limb and the relationship with pulmonary function and respiratory muscle strength in stable COPD patients

Background

Upper limb muscle strength plays an important role in respiratory and pulmonary function, and limited research focuses on the role of strength and endurance of the elbow extensor and flexor. This study was conducted to accurately assess upper limb muscle function and quantified associations with pulmonary function and respiratory muscle strength in patients with stable chronic obstructive pulmonary disease (COPD).

Methods

In this cross-sectional study, patients with stable COPD treated in Yue-Yang Integrative Medicine Hospital from March 2014 to March 2016 were recruited. All participants underwent a pulmonary function test (forced expiratory volume in first second/forced vital capacity, FEV1/FVC; percentage value of predicted FEV1, FEV1%pred), a respiratory muscle strength test (maximal inspiratory pressure, MIP; maximal expiratory pressure, MEP), and an isokinetic test of dominant upper limb after a 24-hr interval (peak torque, PT; PT/body weight, PT/BW; total work, TW; endurance ratio, ER).

Results

A total of 88 patients with stable COPD (age: 65.5±8.7 years) were recruited, of which 73% (64 patients) were male. In the multiple stepwise regression analysis, sex remained as significant impactors in the final model for FEV1%pred (adjusted R²=0.243, P<0.001). Elbow flexor PT/BW and ER, sex, and BMI remained as significant impactors in the final model for FEV1/FVC (adjusted R²=0.255, P<0.01). Elbow flexor TW remained as significant impactors for MIP (adjusted R²=0.112, P=0.001), while elbow extensor PT and PT/BW and sex remained as significant impactors for MEP (adjusted R =0.385, P<0.01).

Conclusion

In stable COPD, pulmonary function and respiratory muscle strength are associated with upper limb muscle strength. In particular, elbow flexor endurance is likely an important impactor for pulmonary function and inspiratory muscle strength, while elbow extensor strength is of importance for expiratory muscle strength.

Muscle Dysfunction in Smokers and Patients With Mild COPD: A SYSTEMATIC REVIEW

PURPOSE

To describe and discuss the available evidence in the literature concerning muscle function and the association between smoking and muscle dysfunction in smokers and patients with mild chronic obstructive pulmonary disease (COPD).

METHODS

The literature search involved the following databases: PubMed, Pedro, CINAHL, Cochrane Library, Lilacs, and EMBASE. Studies were included if they investigated muscle strength and/or endurance and/or cross-sectional area (CSA) in smokers and/or patients with COPD classified as Global Initiative for Obstructive Lung Disease (GOLD) I and without lung cancer. Two authors screened and identified the studies for inclusion.

RESULTS

Eighteen studies were identified. Some studies found lower values in a variety of muscle strength variables in smokers compared with nonsmoking controls, whereas others found similar values between these groups. When comparing patients with COPD classified as GOLD I with smokers, COPD patients showed lower muscle strength. Two studies found no differences in muscle CSA between smokers compared with nonsmoking controls. Some preliminary evidence also shows that patients with COPD classified as GOLD I had lower CSA in comparison with smokers.

CONCLUSION

Results concerning muscle dysfunction in smokers are divergent, since some studies have shown worse results in a variety of muscle strength variables in smokers compared with nonsmoking controls, whereas other studies have not. Moreover, there is rather preliminary evidence indicating worse muscle dysfunction and lower CSA in patients with mild COPD in comparison with healthy (or non-COPD) smokers.

Is Inspiratory Muscle Weakness a Determinant of Endurance Exercise Tolerance During NIV-Supported Exercise in Patients With COPD?

PURPOSE

Previous research has reported that inspiratory muscle weakness is critical to decreased exercise tolerance and exercise tolerance improves with 10 cmH2O pressure support ventilation in patients with chronic obstructive pulmonary disease (COPD). The purpose of this study was to evaluate the effects of proportional assist ventilation (PAV) and continuous positive airway pressure (CPAP) compared with sham on exercise tolerance in patients with and without inspiratory muscle weakness.

METHODS

In a prospective design, 12 of 54 patients were eligible after clinical and comprehensive lung function evaluation, including maximum inspiratory pressure (MIP) measurement. Using baseline measures, participants were divided into 2 age-matched groups that differed in regard to MIP (Group 1, MIP <60 cmH2O, and Group 2, MIP ≥60 cmH2O). Each participant performed 3 constant work rate tests with noninvasive support (PAV, CPAP, sham) in random order on different days at 80% of maximal incremental power.

RESULTS

During the endurance tests, heart rate, peripheral oxygen saturation (SpO2), dyspnea perception scale, and exercise tolerance were measured. There were no significant differences between groups for heart rate, SpO2, dyspnea perception, or exercise tolerance during PAV, CPAP, or sham-supported exercise (P > .05 for all).

CONCLUSIONS

In this small representative group of patients with COPD, inspiratory muscle weakness was not a determining factor of performance during CPAP or PAV-supported aerobic exercise.

CPAP and EPAP elicit similar lung deflation in a non-equivalent mode in GOLD 3-4 COPD patients

INTRODUCTION

Lung hyperinflation is associated with inspiratory muscle strength reduction, nocturnal desaturation, dyspnea, altered cardiac function and poor exercise capacity in advanced COPD.

OBJECTIVES

We investigated the responses of inspiratory capacity (IC) and inspiratory muscle strength (PImax), comparing continuous positive airway pressure (CPAP) and expiratory positive airway pressure (EPAP) with the main hypothesis that there would be similar effects on lung deflation.

METHODS

Eligible patients were submitted to 10 cmH₂ O CPAP and EPAP on different days, under careful ECG (HR) and peripheral oxygen saturation (SpO₂ ) monitoring.

RESULTS

Twenty-one eligible COPD patients were studied (13 male/8 female, FEV₁ % predicted of 36.5 ± 9.8). Both CPAP and EPAP demonstrated significant post-pre (Δ) changes for IC and PImax, with mean ΔIC for CPAP and EPAP of 200 ± 100 mL and 170 ± 105 mL (P = .001 for both) in 13 and 12 patients (responders) respectively. There were similar changes in % predicted IC and PImax (∼7%, P = .001 for both) for responders and poor responder/non-responder agreement depending on CPAP/EPAP mode (Kappa = .113, P = .604). There were no differences in CPAP and EPAP regarding intensity of lung deflation (P =.254) and no difference was measured regarding HR (P = .235) or SpO₂ (P = .111)_. CONCLUSIONS: Both CPAP and EPAP presented a similar effect on lung deflation, without guaranteeing that the response to one modality would be predictive of the response to the other.

Relationship between aerobic capacity and pelvic floor muscles function: a cross-sectional study

The objective of this study was to evaluate the relationship between aerobic capacity and pelvic floor muscles (PFM) function in adult women. Women aged 18 or over and without urinary dysfunction or other chronic diseases were eligible to participate. They completed the habitual physical activity (HPA) questionnaire, underwent a PFM functional evaluation by palpation and perineometry, and performed a submaximal (between 75 and 85% of maximum heart rate) cardiopulmonary exercise (CPX) test to determine the ventilatory anaerobic threshold (VAT). Forty-one women were included (35±16 years, 75% physically active, 17% very active, and 8% sedentary and 17% presented grade 1 PFM contraction, 31.8% grade 2, 26.8% grade 3, and 24.4% grade 4, according to the modified Oxford Scale). The average PFM contraction pressure obtained by perineometer was 53±26 cmH2O and the average oxygen consumption at VAT (VO2VAT) obtained from CPX was 14±2 mL·kg-1·min-1. Significant correlations were found between PFM contraction pressure and VO2VAT (r=0.55; P<0.001); between PFM contraction pressure and HPA score (r=0.38; P=0.02); between age and VO2VAT (r=-0.25; P=0.049); and between VO2VAT and HPA score (r=0.36; P=0.02). An age-adjusted multiple linear regression equation (R2=0.32) was derived to estimate VO2VAT from the contraction value obtained by perineometer, so that the PFM contraction pressure was able to predict VO2VAT. The equation was validated using data from another group of 20 healthy women (33±12 years; PFM contraction: 49±23 cmH2O) and no significant difference was found between actual VO2VAT and predicted VO2VAT (13.1±1.9 vs 13.8±2.0 mL·kg-1·min-1). In conclusion, PFM function is associated with aerobic capacity in healthy women and PFM contraction pressure may be used to estimate VO2VAT in this population.