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      Positive end-expiratory pressure attenuates hemodynamic effects induced by an overload of inspiratory muscles in patients with COPD

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          Inspiratory muscle training (IMT) using a Threshold ® device is commonly used to improve the strength and endurance of inspiratory muscles. However, the effect of IMT, alone or with positive end-expiratory pressure (PEEP), on hemodynamic parameters in patients with chronic obstructive pulmonary disease (COPD) remains unknown.


          To assess the effects of an overload of inspiratory muscles using IMT fixed at 30% of the maximal inspiratory pressure (MIP), and IMT associated with 5 cmH 2O of PEEP (IMT + PEEP), on the echocardiographic parameters in healthy subjects and patients with COPD.


          Twenty patients with COPD (forced expiratory volume in 1 second 53.19±24.71 pred%) and 15 age-matched healthy volunteers were evaluated using spirometry, MIP, the COPD assessment test (CAT), and the modified Medical Research Council (mMRC) dyspnea scale. The E- (fast-filling phase) and A- (atrial contraction phase) waves were evaluated at the tricuspid and mitral valves during inspiration and expiration in the following sequence: at basal conditions, using IMT, and using IMT + PEEP.


          Patients with COPD had reduced MIPs versus the control group. Ten patients had CAT scores <10 and 12 patients had mMRC scores <2. E-wave values at the mitral valve were significantly decreased with IMT during the inspiratory phase in both groups. These effects were normalized with IMT + PEEP. During the expiratory phase, use of IMT + PEEP normalized the reduction in E-wave values in the COPD group. During inspiration at the tricuspid valve, reduction in E-wave values during IMT was normalized by IMT + PEEP in COPD group. During the expiratory phase, the value of the E-waves was significantly reduced with overload of the inspiratory muscles in both groups, and these effects were normalized with IMT + PEEP. A-waves did not change under any conditions.


          Acute hemodynamic effects induced by overloading of the inspiratory muscles were attenuated and/or reversed by the addition of PEEP in COPD patients.

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          Most cited references 42

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          New reference values for forced spirometry in white adults in Brazil.

          To describe spirometric reference equations for healthy Brazilian adults who have never smoked and to compare the predicted values with those derived in 1992. Reference equations for spirometry were derived in 270 men and 373 women living in eight cities in Brazil. Ages ranged from 20 to 85 years in women and from 26 to 86 years in men. Spirometry examinations followed the recommendations of the Brazilian Thoracic Society. Lower limits were derived by the analysis of the fifth percentiles of the residuals. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC and FEV1/forced expiratory volume in six seconds (FEV6) were best fitted by linear regression. Flows were best fitted using log equations. For both genders, greater height resulted in lower values for FEV1/FVC, FEV1/FEV6 and flow/FVC ratios. The reference values for FEV1 and FVC in the present study were higher than those derived for Brazilian adults in 1992. New predicted values for forced spirometry were obtained in a sample of white Brazilians. The values are greater than those obtained in 1992, probably due to technical factors.
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            Impact of inspiratory muscle training in patients with COPD: what is the evidence?

            A meta-analysis including 32 randomised controlled trials on the effects of inspiratory muscle training (IMT) in chronic obstructive pulmonary disease (COPD) patients was performed. Overall and subgroup analyses with respect to training modality (strength or endurance training, added to general exercise training) and patient characteristics were performed. Significant improvements were found in maximal inspiratory muscle strength (P(I,max); +13 cmH₂O), endurance time (+261 s), 6- or 12-min walking distance (+32 and +85 m respectively) and quality of life (+3.8 units). Dyspnoea was significantly reduced (Borg score -0.9 point; Transitional Dyspnoea Index +2.8 units). Endurance exercise capacity tended to improve, while no effects on maximal exercise capacity were found. Respiratory muscle endurance training revealed no significant effect on P(I,max), functional exercise capacity and dyspnoea. IMT added to a general exercise programme improved P(I,max) significantly, while functional exercise capacity tended to increase in patients with inspiratory muscle weakness (P(I,max) <60 cmH₂O). IMT improves inspiratory muscle strength and endurance, functional exercise capacity, dyspnoea and quality of life. Inspiratory muscle endurance training was shown to be less effective than respiratory muscle strength training. In patients with inspiratory muscle weakness, the addition of IMT to a general exercise training program improved P(I,max) and tended to improve exercise performance.
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              Decreasing cardiac chamber sizes and associated heart dysfunction in COPD: role of hyperinflation.

              Little is known about the role of abnormal lung function in heart size and heart dysfunction in patients with COPD. We studied the relationship of lung function with heart size and heart dysfunction and associated consequences for 6-min walk distance (6MWD) in patients with COPD of different severitites. In 138 patients with COPD (Global Initiative for Obstructive Lung Disease [GOLD] I-IV), we measured the size of all cardiac chambers, left ventricular diastolic dysfunction (relaxation and filling), and global right ventricular dysfunction (Tei-index) by echocardiography. We also measured lung function (spirometry, body plethysmography, and diffusion capacity) and 6MWD. The size of all cardiac chambers decreased with increasing GOLD stage. Overall, moderate relationships existed between variables of lung function and cardiac chamber sizes. Static hyperinflation (inspiratory-to-total lung capacity ratio [IC/TLC], functional residual capacity, and residual volume) showed stronger associations with cardiac chamber sizes than airway obstruction or diffusion capacity. IC/TLC correlated best with cardiac chamber sizes and was an independent predictor of cardiac chamber sizes after adjustment for body surface area. Patients with an IC/TLC 0.25. An impaired left ventricular diastolic filling pattern was independently associated with a reduced 6MWD. An increasing rate of COPD severity is associated with a decreasing heart size. Hyperinflation could play an important role regarding heart size and heart dysfunction in patients with COPD.

                Author and article information

                Int J Chron Obstruct Pulmon Dis
                Int J Chron Obstruct Pulmon Dis
                International Journal of COPD
                International Journal of Chronic Obstructive Pulmonary Disease
                Dove Medical Press
                06 October 2017
                : 12
                : 2943-2954
                [1 ]Medical Sciences Faculty of Minas Gerais, Post-Graduation Program in Health Sciences, Belo Horizonte, Brazil
                [2 ]Department of Cardiology, Clinics Hospital, Federal University of Minas Gerais, Belo Horizonte, Brazil
                Author notes
                Correspondence: Maria Glória Rodrigues-Machado, Faculdade Ciências Médicas-Minas Gerais, Pós-Graduação em Ciências da Saúde, 30130-110 Alameda Ezequiel Dias 275-Centro, Belo Horizonte, Minas Gerais, Brazil, Tel +55 31 3248 7229, Fax +55 31 3248 7221, Email maria.machado@
                © 2017 Schaper-Magalhães et al. This work is published and licensed by Dove Medical Press Limited

                The full terms of this license are available at and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

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