Iandelli Iacopo, Aliverti Andrea, Kayser Bengt, Dellacà Raffaele, Cala Stephen J, Duranti Roberto, Kelly Susan, Scano Giorgio, Sliwinski Pawel, Yan Sheng, Macklem Peter T, Pedotti Antonio
Fondazione Don Gnocchi, I-50020 Pozzolatico, Italy.
J Appl Physiol (1985). 2002 May;92(5):1943-52. doi: 10.1152/japplphysiol.00393.2000.
To understand how externally applied expiratory flow limitation (EFL) leads to impaired exercise performance and dyspnea, we studied six healthy males during control incremental exercise to exhaustion (C) and with EFL at approximately 1. We measured volume at the mouth (Vm), esophageal, gastric and transdiaphragmatic (Pdi) pressures, maximal exercise power (W(max)) and the difference (Delta) in Borg scale ratings of breathlessness between C and EFL exercise. Optoelectronic plethysmography measured chest wall and lung volume (VL). From Campbell diagrams, we measured alveolar (PA) and expiratory muscle (Pmus) pressures, and from Pdi and abdominal motion, an index of diaphragmatic power (W(di)). Four subjects hyperinflated and two did not. EFL limited performance equally to 65% W(max) with Borg = 9-10 in both. At EFL W(max), inspiratory time (TI) was 0.66s +/- 0.08, expiratory time (TE) 2.12 +/- 0.26 s, Pmus approximately 40 cmH2O and DeltaVL-DeltaVm = 488.7 +/- 74.1 ml. From PA and VL, we calculated compressed gas volume (VC) = 163.0 +/- 4.6 ml. The difference, DeltaVL-DeltaVm-VC (estimated blood volume shift) was 326 ml +/- 66 or 7.2 ml/cmH2O PA. The high Pmus and long TE mimicked a Valsalva maneuver from which the short TI did not allow recovery. Multiple stepwise linear regression revealed that the difference between C and EFL Pmus accounted for 70.3% of the variance in DeltaBorg. DeltaW(di) added 12.5%. We conclude that high expiratory pressures cause severe dyspnea and the possibility of adverse circulatory events, both of which would impair exercise performance.
为了解外部施加的呼气流量限制（EFL）如何导致运动能力受损和呼吸困难，我们对6名健康男性进行了研究，分别在对照递增运动至疲劳（C）期间以及施加约为1的EFL时进行观察。我们测量了口腔容积（Vm）、食管、胃和跨膈压（Pdi）、最大运动功率（W(max)）以及C和EFL运动期间Borg呼吸困难量表评分的差值（Delta）。通过光电体积描记法测量胸壁和肺容积（VL）。根据坎贝尔图，我们测量了肺泡压（PA）和呼气肌压（Pmus），并根据Pdi和腹部运动测量了膈肌功率指数（W(di)）。4名受试者出现肺过度充气，2名未出现。EFL使运动能力同样受限至65%W(max)，两者的Borg评分均为9 - 10。在EFL时的W(max)下，吸气时间（TI）为0.66秒±0.08，呼气时间（TE）为2.12±0.26秒，Pmus约为40 cmH₂O，DeltaVL - DeltaVm = 488.7±74.1毫升。根据PA和VL，我们计算出压缩气体容积（VC）= 163.0±4.6毫升。差值DeltaVL - DeltaVm - VC（估计的血容量转移）为326毫升±66或7.2毫升/cmH₂O PA。高Pmus和长TE模拟了瓦尔萨尔瓦动作，而短TI不允许恢复。多元逐步线性回归显示，C和EFL的Pmus差值占DeltaBorg方差的70.3%。DeltaW(di)增加了12.5%。我们得出结论，高呼气压力会导致严重的呼吸困难以及发生不良循环事件的可能性，这两者都会损害运动能力。
