McKenzie D K, Allen G M, Gandevia S C
Prince of Wales Medical Research Institute, Randwick N.S.W., Sydney, Australia.
Respir Physiol. 1996 Aug;105(1-2):69-76. doi: 10.1016/0034-5687(96)00021-7.
Maximal inspiratory and transdiaphragmatic pressures vary with lung volume but the possibility that some of this variability reflects variable voluntary drive to the diaphragm has not been investigated systematically. We assessed the influence of lung volume on the ability to activate the diaphragm with voluntary effort during maximal Mueller manoeuvres. Voluntary activation of the diaphragm was assessed using twitch interpolation with bilateral phrenic nerve stimulation in 6 subjects. Each performed 10 maximal efforts at lung volumes around functional residual capacity (FRC) and additional efforts at volumes above and below FRC. Voluntary activation of the diaphragm was higher at lung volumes above FRC (> 60% TLC; activation 98.3 +/- 2.6%) than at lung volumes around FRC (45-60% TLC; activation 95.5 +/- 3.5%) and below FRC (< 45% TLC; activation 83.3 +/- 15.8%; p < 0.05). Submaximal diaphragm activation at low lung volumes may reflect differences in the length-tension relationships of the various inspiratory muscles and/or reflex inhibition of phrenic motoneurones at low lung volumes.
最大吸气压力和跨膈压随肺容积而变化，但这种变异性中部分是否反映了对膈肌的可变自主驱动，尚未进行系统研究。我们评估了在最大米勒动作期间，肺容积对通过自主努力激活膈肌能力的影响。在6名受试者中，使用双侧膈神经刺激的抽搐插值法评估膈肌的自主激活情况。每位受试者在功能残气量（FRC）附近的肺容积下进行10次最大努力，并在高于和低于FRC的容积下进行额外努力。肺容积高于FRC（>60%肺总量；激活率98.3±2.6%）时，膈肌的自主激活高于肺容积在FRC附近（45 - 60%肺总量；激活率95.5±3.5%）以及低于FRC（<45%肺总量；激活率83.3±15.8%；p<0.05）时。低肺容积下膈肌的次最大激活可能反映了各种吸气肌长度 - 张力关系的差异和/或低肺容积时膈运动神经元的反射性抑制。
