Haddad G G, Jeng H J, Bazzy A R, Lai T L
J Appl Physiol (1985). 1986 Oct;61(4):1316-21. doi: 10.1152/jappl.1986.61.4.1316.
To investigate the changes in diaphragm electromyogram (EMG) during the course of severe loaded breathing, we subjected five conscious adult sheep to inspiratory flow resistive breathing (resistance greater than 150 cmH2O X l-1 X s) for up to 2-3 h and studied the total EMG power per breath (iEMG) and the EMG power per unit time after dividing the duration of EMG activity within each breath into three equal parts (iEMG1, iEMG2, and iEMG3). Both total breath iEMG and transdiaphragmatic pressure (Pdi) increased, remained at a high level for a certain period of time, and then started to fall. A change in the pattern of iEMG within a breath was observed during loaded breathing. The increase in total-breath iEMG was associated mostly with an increase in iEMG3, or the last part of the EMG power within each inspiration. Similarly, the decrease in total breath iEMG was primarily due to a decrease in iEMG3. We conclude that, in sheep subjected to severe IFR loads for prolonged periods the marked increase in total-breath iEMG at the beginning of loaded breathing and the marked decrease in this iEMG at the time of decrease in Pdi are largely due to changes in iEMG that occur during the latter third of each breath. We speculate that during loaded breathing the recruitment pattern of diaphragmatic muscle fibers changes during the course of an inspiratory effort.
为了研究重度负荷呼吸过程中膈肌肌电图（EMG）的变化，我们让5只清醒的成年绵羊进行吸气气流阻力呼吸（阻力大于150 cmH₂O·L⁻¹·s），持续2 - 3小时，并研究了每次呼吸的总EMG功率（iEMG）以及将每次呼吸中EMG活动持续时间等分为三个部分后的单位时间EMG功率（iEMG1、iEMG2和iEMG3）。每次呼吸的总iEMG和跨膈压（Pdi）均升高，在一段时间内保持在较高水平，然后开始下降。在负荷呼吸过程中观察到每次呼吸内iEMG模式的变化。每次呼吸总iEMG的增加主要与iEMG3的增加有关，即每次吸气内EMG功率的最后部分。同样，每次呼吸总iEMG的下降主要是由于iEMG3的下降。我们得出结论，在长时间承受重度吸气气流阻力负荷的绵羊中，负荷呼吸开始时每次呼吸总iEMG的显著增加以及Pdi下降时该iEMG的显著下降主要是由于每次呼吸后三分之一期间发生的iEMG变化。我们推测在负荷呼吸过程中，吸气努力过程中膈肌肌纤维的募集模式会发生变化。
