Abstract
Background: Chronic obstructive pulmonary disease (COPD) affect the action of the diaphragm, placing the muscle at a mechanical disadvantage and requiring the recruitment of accessory muscles of inspiration.
Objective: To evaluate the electromyographic activity (EA) of sternocleidomastoid (SCM) and of scalene muscles during and after the use of EPAP (expiratory positive airway pressure) in COPD patients.
Methods: A clinical single-blind trial involving 13 (57.1±7.1 years; 7M,6F) subjects with normal spirometry (controls) and 12 (57.2±8.3 years; 4M,8F) COPD patients (FEV1 44.0±20.0%predicted; FEV1/CFV 66.8±17.4). At baseline, we determined EA during spontaneous respiration, lung function parameters, and respiratory muscle strength. Subsequently, 15 cmH2O EPAP was applied by face mask for 25 min, during which the EA of the SCM and scalene muscles was recorded every 5 min. A final record was obtained 10 min after the mask removal.
Results: We found that the behavior of the EA of SCM and scalene muscles was comparable between the controls and COPD patients (p= 0.716 and p =0.789, respectively). However, during the use of EPAP, both muscles showed a trend toward an increase in the EA. In addition, there was a significant decrease in the EA of the SCM between the baseline and final measurements (p=0.034).
Conclusions: EPAP promotes a transient increase in EA and scalene muscle SCM, suggesting that use of this modality pressure increases the activity of these muscles. However, after removal of the EA muscle SCM reduces the levels below that obtained at baseline.
- © 2011 ERS
