O'Donnell D E, Hong H H, Webb K A
Respiratory Investigation Unit, Department of Medicine, Queen's University, Kingston, Ontario, Canada K7L 2V7.
J Appl Physiol (1985). 2000 May;88(5):1859-69. doi: 10.1152/jappl.2000.88.5.1859.
We mimicked important mechanical and ventilatory aspects of restrictive lung disorders by employing chest wall strapping (CWS) and dead space loading (DS) in normal subjects to gain mechanistic insights into dyspnea causation and exercise limitation. We hypothesized that thoracic restriction with increased ventilatory stimulation would evoke exertional dyspnea that was similar in nature to that experienced in such disorders. Twelve healthy young men [28 +/- 2 (SE) yr of age] completed pulmonary function tests and maximal cycle exercise tests under four conditions, in randomized order: 1) control, 2) CWS to 60% of vital capacity, 3) added DS of 600 ml, and 4) CWS + DS. Measurements during exercise included cardiorespiratory parameters, esophageal pressure, and Borg scale ratings of dyspnea. Compared with control, CWS significantly reduced the tidal volume response to exercise, increased dyspnea intensity at any given work rate or ventilation, and thus limited exercise performance. DS stimulated ventilation but had minimal effects on dyspnea and exercise performance. Adding DS to CWS further increased dyspnea by 1.7 +/- 0.6 standardized Borg units (P = 0.012) and decreased exercise performance (total work) by 21 +/- 6% (P = 0.003) over CWS alone. Across conditions, increased dyspnea intensity correlated best with decreased resting inspiratory reserve volume (r = -0.63, P < 0.0005). Dyspnea during CWS was described primarily as "inspiratory difficulty" and "unsatisfied inspiration," similar to restrictive disorders. In conclusion, severe dyspnea and exercise intolerance were provoked in healthy normal subjects when tidal volume responses were constrained in the face of increased ventilatory drive during exercise.
我们通过对正常受试者采用胸壁束缚（CWS）和死腔负荷（DS）来模拟限制性肺疾病的重要机械和通气方面，以深入了解呼吸困难的病因和运动受限的机制。我们假设，通气刺激增加的胸廓限制会引发与这些疾病中所经历的性质相似的运动性呼吸困难。12名健康年轻男性[年龄28±2（标准误）岁]在四种条件下按随机顺序完成了肺功能测试和最大周期运动测试：1）对照，2）将CWS设置为肺活量的60%，3）增加600 ml的DS，4）CWS + DS。运动期间的测量包括心肺参数、食管压力和呼吸困难的Borg量表评分。与对照相比，CWS显著降低了运动时的潮气量反应，在任何给定的工作率或通气量下增加了呼吸困难强度，从而限制了运动表现。DS刺激了通气，但对呼吸困难和运动表现影响最小。与单独的CWS相比，在CWS基础上增加DS使呼吸困难进一步增加1.7±0.6个标准化Borg单位（P = 0.012），运动表现（总功）降低21±6%（P = 0.003）。在所有条件下，呼吸困难强度增加与静息吸气储备量减少的相关性最佳（r = -0.63，P < 0.0005）。CWS期间的呼吸困难主要描述为“吸气困难”和“吸气不满足”，类似于限制性疾病。总之，当运动期间通气驱动增加而潮气量反应受到限制时，健康正常受试者会出现严重的呼吸困难和运动不耐受。
