Leduc D, Brunko E, De Troyer A
Laboratory of Cardiorespiratory Physiology, Brussels School of Medicine, and Chest Service, Erasme University Hospital, Brussels, Belgium.
Am J Respir Crit Care Med. 2001 Jan;163(1):49-54. doi: 10.1164/ajrccm.163.1.2004166.
Although high-frequency mechanical vibration of the rib cage reduces dyspnea, its effects on the respiratory muscles are largely unknown. We have previously shown that in anesthetized dogs, vibrating the rib cage during inspiration elicits a marked increase in the inspiratory electromyographic (EMG) activity recorded from the external intercostal muscles but does not affect tidal volume (VT). In the present studies, we have tested the hypothesis that the maintenance of VT results from the concomitant contraction of the internal interosseous (expiratory) intercostals. When the rib cage was vibrated (40 Hz) during hyperventilation-induced apnea, a prominent activity was recorded from the external intercostals but no activity was recorded from the internal intercostals, including when the muscles were lengthened by passive inflation. The internal intercostals remained also silent when vibration was applied during spontaneous inspiration, and the phasic expiratory EMG activity recorded from them was unaltered when vibration was applied during expiration. Thus, the internal interosseous intercostals in dogs are much less sensitive to vibration than the external intercostals, and they do not interfere with the action of these latter during rib cage vibration. This lack of sensitivity might be the result of a reflex inhibition of the muscle spindle afferents by afferents from external intercostal muscle spindles.
尽管胸廓的高频机械振动可减轻呼吸困难，但其对呼吸肌的影响在很大程度上尚不清楚。我们之前已经表明，在麻醉的犬中，吸气时振动胸廓会使肋间外肌记录到的吸气肌电图（EMG）活动显著增加，但不影响潮气量（VT）。在本研究中，我们检验了以下假设：潮气量的维持是由于骨间（呼气）肋间肌的协同收缩。在过度通气诱发的呼吸暂停期间振动胸廓（40Hz）时，肋间外肌记录到明显的活动，但肋间内肌未记录到活动，包括在被动充气使肌肉拉长时。在自主吸气期间施加振动时，肋间内肌也保持沉默，并且在呼气期间施加振动时，从肋间内肌记录到的阶段性呼气EMG活动未改变。因此，犬的骨间肋间肌对振动的敏感性远低于肋间外肌，并且在胸廓振动期间它们不会干扰肋间外肌的作用。这种敏感性的缺乏可能是肋间外肌肌梭传入纤维对肌梭传入纤维反射性抑制的结果。
