ORIGINAL ARTICLE

Expiratory muscle endurance in chronic obstructive pulmonary disease

A Ramírez-Sarmiento¹, M Orozco-Levi^1,2, E Barreiro¹, R Méndez¹, A Ferrer¹, J Broquetas^1,3, J Gea^1,2

¹ Servei de Pneumologia and Unitat de Recerca Respiratòria I Ambiental, Hospital del Mar-IMIM, Barcelona, Spain
² CEXS, Universitat Pompeu Fabra, Barcelona, Spain
³ Departamente Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain

Correspondence to:
Correspondence to:
Dr J Gea, Grup de Recerca de Pneumologia, IMIM, Avda Doctor Aiguader 80, 08003 Barcelona, Spain;
jgea{at}imim.es

Background: A reduction in expiratory muscle (ExM) endurance in patients with chronic obstructive pulmonary disease (COPD) may have clinically relevant implications. This study was carried out to evaluate ExM endurance in patients with COPD.

Methods: Twenty three patients with COPD (FEV₁ 35 (14)% predicted) and 14 matched controls were studied. ExM endurance was assessed using a method based on the use of an expiratory threshold valve which includes two steps. In step 1 the load is progressively increased (50 g every 2 minutes) until task failure is reached, and the pressure generated against the highest tolerated load is defined as the maximal expiratory sustainable pressure (Pthmax). In step 2 subjects breathe against a submaximal constant load (80% of Pthmax) and the time elapsed until task failure is termed the expiratory endurance time (Tth₈₀). In addition, the strength of peripheral muscles (handgrip, HGS) and respiratory muscles (maximal inspiratory and expiratory pressures, PImax and PEmax, respectively) was evaluated.

Results: Patients with COPD had lower ExM strength and endurance than controls: PEmax 64 (19)% predicted v 84 (14)% predicted (mean difference 20%; 95% confidence intervals (CI) 14 to 39); Pthmax 52 (27) v 151 (46) cm H₂O (mean difference 99, 95% CI 74 to 123); and Tth₈₀ 9.4 (6.3) v 14.2 (7.4) min (mean difference 4.8, 95% CI 1.0 to 10.4; p<0.01 for all). Interestingly, ExM endurance directly correlated with both the severity of airways obstruction (Pthmax with FEV₁, r=0.794, p<0.01) and the reduction in strength observed in different muscle groups (Pthmax with HG, PImax or PEmax, r=0.550, p<0.05; r=0.583, p<0.001; and r=0.584, p<0.001, respectively).

Conclusions: ExM endurance is decreased in patients with COPD. This impairment is proportional to the severity of the disease and is associated with lower strength in different muscle groups. This suggests that systemic effects are implicated in the impairment observed in ExM function.

Keywords: expiratory muscles; endurance; chronic obstructive pulmonary disease; threshold loading

Abbreviations: PImaxRV, maximal inspiratory pressure; PEmaxTLC, maximal expiratory pressure; Pthmax, maximal expiratory sustainable pressure; Tth₈₀, expiratory endurance time; HGS, hand grip dynamometry

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

• McKenzie, D. K., Butler, J. E., Gandevia, S. C. (2009). Respiratory muscle function and activation in chronic obstructive pulmonary disease. J. Appl. Physiol. 107: 621-629 [Abstract] [Full Text]  
• Man, W D-C, Hopkinson, N S, Harraf, F, Nikoletou, D, Polkey, M I, Moxham, J (2005). Abdominal muscle and quadriceps strength in chronic obstructive pulmonary disease. Thorax 60: 718-722 [Abstract] [Full Text]  
• Sharafkhaneh, A, Goodnight-White, S, Officer, T M, Rodarte, J R, Boriek, A M (2005). Altered thoracic gas compression contributes to improvement in spirometry with lung volume reduction surgery. Thorax 60: 288-292 [Abstract] [Full Text]  
• Polla, B, D'Antona, G, Bottinelli, R, Reggiani, C (2004). Respiratory muscle fibres: specialisation and plasticity. Thorax 59: 808-817 [Abstract] [Full Text]  
• Orozco-Levi, M. (2003). Structure and function of the respiratory muscles in patients with COPD: impairment or adaptation?. Eur Respir J 22: 41s-51s [Abstract] [Full Text]  
• Weiner, P., Magadle, R., Beckerman, M., Weiner, M., Berar-Yanay, N. (2003). Comparison of Specific Expiratory, Inspiratory, and Combined Muscle Training Programs in COPD. Chest 124: 1357-1364 [Abstract] [Full Text]  
• Weiner, P., Magadle, R., Beckerman, M., Weiner, M., Berar-Yanay, N. (2003). Specific Expiratory Muscle Training in COPD. Chest 124: 468-473 [Abstract] [Full Text]  
• Heijdra, Y. F., Pinto-Plata, V., Frants, R., Rassulo, J., Kenney, L., Celli, B. R. (2003). Muscle Strength and Exercise Kinetics in COPD Patients With a Normal Fat-Free Mass Index Are Comparable to Control Subjects. Chest 124: 75-82 [Abstract] [Full Text]