Grippo Antonello, Carrai Riccardo, Chiti Linda, Bruni Giulia Innocenti, Scano Giorgio, Duranti Roberto
Dept. of Internal Medicine, Section of Clinical Immunology and Respiratory Diseases, Univ. of Florence, Viale G.B. Morgagni, 85, 50134 Florence, Italy.
J Appl Physiol (1985). 2010 Aug;109(2):367-76. doi: 10.1152/japplphysiol.00608.2009. Epub 2010 May 20.
The role of nonrespiratory peripheral afferents in dyspnea perception has not been fully elucidated yet. Our hypothesis is that fatigue-induced activation of limb muscle metaboreceptors served by group IV fine afferent fibers may impact on respiratory effort perception. We studied 12 healthy subjects breathing against progressive inspiratory resistive loads (10, 18, 30, 40, and 90 cmH(2)O x l(-1) x s) before and after inducing low-frequency fatigue of quadriceps muscle by repeating sustained contractions at > or = 80% of maximal voluntary contraction. Subjects also underwent a sham protocol while performing two loaded breathing runs without muscle fatigue in between. During the loaded breathing, while subjects mimicked the quiet breathing pattern using a visual feedback, ventilation, tidal volume, respiratory frequency, pleural pressure swings, arterial oxygen saturation, end-tidal partial pressure of CO(2), and dyspnea by a Borg scale were recorded. Compared with prefatigue, limb muscle fatigue resulted in a higher increase in respiratory effort perception for any given ventilation, tidal volume, respiratory frequency, pleural pressure swings, end-tidal partial pressure of CO(2), and arterial oxygen saturation. No difference between the two runs was observed with the sham protocol. The present data support the hypothesis that fatigue of limb muscles increases respiratory effort perception associated with loaded breathing, likely by the activation of limb muscle metaboreceptors.
非呼吸性外周传入神经在呼吸困难感知中的作用尚未完全阐明。我们的假设是，由IV组细传入纤维支配的肢体肌肉代谢感受器的疲劳诱导激活可能会影响呼吸努力感知。我们研究了12名健康受试者，在通过以最大自主收缩的≥80%重复持续收缩诱导股四头肌低频疲劳之前和之后，让他们对抗渐进性吸气阻力负荷（10、18、30、40和90 cmH₂O·l⁻¹·s）进行呼吸。受试者还接受了假手术方案，即在两次有负荷呼吸试验之间进行两次无肌肉疲劳的试验。在有负荷呼吸期间，当受试者使用视觉反馈模仿安静呼吸模式时，记录通气量、潮气量、呼吸频率、胸膜压力波动、动脉血氧饱和度、呼气末二氧化碳分压以及用Borg量表评估的呼吸困难程度。与疲劳前相比，对于任何给定的通气量、潮气量、呼吸频率、胸膜压力波动、呼气末二氧化碳分压和动脉血氧饱和度，肢体肌肉疲劳导致呼吸努力感知的增加更高。假手术方案的两次试验之间未观察到差异。目前的数据支持这样的假设，即肢体肌肉疲劳会增加与有负荷呼吸相关的呼吸努力感知，可能是通过激活肢体肌肉代谢感受器实现的。
