Brancatisano A, Engel L A, Loring S H
Thoracic Medicine Unit, Westmead Hospital, New South Wales, Australia.
J Appl Physiol (1985). 1993 Feb;74(2):688-94. doi: 10.1152/jappl.1993.74.2.688.
We related inspiratory muscle activity to inspiratory pressure generation (Pmus) at different lung volumes in five seated normal subjects. Integrated electromyograms were recorded from diaphragmatic crura (Edi), parasternals (PS), and lateral external intercostals (EI). At 20% increments in the vital capacity (VC) subjects relaxed and then made graded and maximal inspiratory efforts against an occluded airway. At any given level of pressure generation, Edi, PS, and EI increased with increasing lung volume. The Pmus generated at total lung capacity as a fraction of that at a low lung volume (between residual volume and 40% VC) was 0.39 +/- 0.15 (SD) for the diaphragm, 0.20 +/- 0.06 for PS, and 0.22 +/- 0.04 for the lateral EI muscles. Our results indicate a lesser volume dependence of the Pmus-EMG relationship for the diaphragm than for PS and EI muscles. This difference in muscle effectiveness with lung volume may reflect differences in length-tension and/or geometric mechanical advantage between the rib cage muscles and the diaphragm.
我们研究了5名坐位正常受试者在不同肺容量下吸气肌活动与吸气压力产生（Pmus）之间的关系。记录了膈肌脚（Edi）、胸骨旁肌（PS）和外侧肋间外肌（EI）的积分肌电图。在肺活量（VC）以20%的幅度增加时，受试者放松，然后对闭塞气道进行分级和最大吸气努力。在任何给定的压力产生水平下，Edi、PS和EI均随肺容量增加而增加。在总肺容量时产生的Pmus与低肺容量（残气量和40%VC之间）时产生的Pmus的比值，膈肌为0.39±0.15（标准差），PS为0.20±0.06，外侧EI肌为0.22±0.04。我们的结果表明，与PS和EI肌相比，膈肌的Pmus-肌电图关系对肺容量的依赖性较小。肌肉效能随肺容量的这种差异可能反映了胸廓肌肉和膈肌之间长度-张力和/或几何力学优势的差异。
