Gibson G J
Dept of Respiratory Medicine Freeman Hospital Newcastle upon Type, UK.
Eur Respir J. 1996 Dec;9(12):2640-9. doi: 10.1183/09031936.96.09122640.
Pulmonary hyperinflation is usually defined as an abnormal increase in functional residual capacity, i.e. lung volume at the end of tidal expiration. As such, it is virtually universal in patients with symptomatic diffuse airway obstruction. Hyperinflation inferred from a standard chest radiograph implies an increase in total lung capacity. The relaxation volume of the respiratory system (Vr) increases in patients with chronic airway disease as a result of changes in the elastic properties of the lungs and chest wall. In addition, a variable degree of dynamic hyperinflation may be present. This results from the onset of inspiration before lung volume has fallen to Vr. Dynamic hyperinflation is frequently present at rest in patients with moderate-to-severe airway obstruction, and it increases further on exercise, thereby increasing the mechanical load on the inspiratory muscles and at the same time reducing their mechanical advantage. Important clinical consequences and associations of hyperinflation include: distortions of chest wall motion; impaired inspiratory muscle function; increased oxygen cost of breathing; greater likelihood of hypercapnia; impaired exercise performance; and greater severity of breathlessness. The symptomatic improvement after treatment with a bronchodilator may be due, in part, to lessening of hyperinflation.
肺过度充气通常被定义为功能残气量异常增加，即潮气呼气末的肺容积。因此，它在有症状的弥漫性气道阻塞患者中几乎普遍存在。从标准胸部X线片推断出的过度充气意味着肺总量增加。由于肺和胸壁弹性特性的改变，慢性气道疾病患者的呼吸系统松弛容积（Vr）增加。此外，可能存在不同程度的动态过度充气。这是由于在肺容积降至Vr之前就开始吸气所致。动态过度充气在中重度气道阻塞患者静息时经常存在，运动时会进一步加重，从而增加吸气肌的机械负荷，同时降低其机械效率。过度充气的重要临床后果和关联包括：胸壁运动扭曲；吸气肌功能受损；呼吸氧耗增加；发生高碳酸血症的可能性更大；运动能力受损；以及呼吸急促更严重。使用支气管扩张剂治疗后症状改善可能部分归因于过度充气的减轻。
