Decramer M
Respiratory Division, University Hospital, Leuven, Belgium.
Eur Respir J. 1997 Apr;10(4):934-41.
Hyperinflation clearly affects respiratory muscle interaction. It commonly increases the rib cage contribution to chest wall motion, whilst it reduces the abdominal contribution. This change is thought to result from the fact that hyperinflation severely reduces the mechanical advantage of the diaphragm, whilst it affects the mechanical advantage of the neck and rib cage muscles to a lesser extent. The mechanical disadvantage in the diaphragm induced by hyperinflation is presumably primarily the result of the length changes undergone by the diaphragm in acute hyperinflation. Changes in diaphragmatic geometry are generally considered to be less important in the reduction of the diaphragm's force-generating capacity. Further factors contributing to the mechanical disadvantage in the diaphragm include a reduction in the appositional component of diaphragmatic action (through reduction in the zone of apposition), and a reduction in the insertional component (through a shift in the alignment of the diaphragmatic fibres from axial to radial). In chronic hyperinflation, the diaphragm adapts to the chronically hyperinflated state. This adaptation to chronic foreshortening is similar to the adaptation occurring in the skeletal muscle. It is caused by a dropout of sarcomeres in series along the muscle fibres. It restores the force-generating capacity of the muscle, in part, but it reduces the capacity of the muscle to undergo length changes. The mechanical advantage of the parasternal intercostals and the scalenes is possibly less affected, because the length changes undergone by these muscles during hyperinflation are smaller. The factors determining the mechanical advantage of the parasternal intercostals are complex. Variables related to the mechanical advantage of the parasternal intercostals include: length changes; changes in angle between the parasternal intercostals and the sternum and between rib and sternum; and changes in mechanical arrangement among different parasternals. At present, it is difficult to develop an integrated view of these factors and of their change with hyperinflation. Finally, hyperinflation commonly results in recruitment of expiratory muscles. The functional significance of this expiratory muscle recruitment in patients is still debated.
过度充气明显影响呼吸肌的相互作用。它通常会增加胸廓对胸壁运动的贡献，同时减少腹部的贡献。这种变化被认为是由于过度充气严重降低了膈肌的机械优势，而对颈部和胸廓肌肉的机械优势影响较小。过度充气引起的膈肌机械劣势可能主要是急性过度充气时膈肌长度变化的结果。膈肌几何形状的变化通常被认为在降低膈肌产生力的能力方面不太重要。导致膈肌机械劣势的其他因素包括膈肌作用的贴附成分减少（通过贴附区的减少）和插入成分减少（通过膈肌纤维排列从轴向变为径向的改变）。在慢性过度充气时，膈肌会适应慢性过度充气状态。这种对慢性缩短的适应类似于骨骼肌中发生的适应。它是由沿肌纤维串联的肌节丢失引起的。它部分恢复了肌肉产生力的能力，但降低了肌肉进行长度变化的能力。胸骨旁肋间肌和斜角肌的机械优势可能受影响较小，因为这些肌肉在过度充气期间经历的长度变化较小。决定胸骨旁肋间肌机械优势的因素很复杂。与胸骨旁肋间肌机械优势相关的变量包括：长度变化；胸骨旁肋间肌与胸骨之间以及肋骨与胸骨之间角度的变化；以及不同胸骨旁肋间肌之间机械排列的变化。目前，很难对这些因素及其随过度充气的变化形成一个综合的观点。最后，过度充气通常会导致呼气肌的募集。这种呼气肌募集在患者中的功能意义仍存在争议。
