Niro Frank, Dubuc Benjamin, Sodeifi Kaveh Gaynor, Jensen Dennis
Department of Kinesiology and Physical Education, McGill University, Montréal, Quebec, Canada.
Translational Research in Respiratory Diseases Program, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada.
J Appl Physiol (1985). 2021 Dec 1;131(6):1679-1690. doi: 10.1152/japplphysiol.01118.2020. Epub 2021 Nov 4.
This study examined the effect of changes in end-inspiratory lung volume (EILV) and breathing pattern on neural activation of the crural diaphragm (EMG) and of the sternocleidomastoid (EMG), scalene (EMG), and external intercostal muscles (EMG) at constant ventilation (V̇). Twelve healthy adults performed a series of 30-s breathing trials at a constant V̇ corresponding to 15% of their maximum voluntary ventilation while ) altering EILV at a constant breathing pattern and ) altering breathing pattern at a constant EILV. Using a real-time visual display of each participant's spirogram, EILV was voluntarily targeted at 65% (EILV), 75% (EILV), 85% (EILV), and 95% (EILV) of each participant's inspired vital capacity, whereas breathing frequency () was targeted at 15, 35, and 50 breaths/min using a metronome. The tidal volume needed for a participant to maintain V̇ constant across trials was achieved via changes in end-expiratory lung volume. A multipair esophageal electrode catheter was used to record EMG, whereas surface electrodes were used to record EMG, EMG, and EMG. On average, EMG, EMG, EMG, and EMG increased as a function of increasing EILV at constant V̇, independent of changes in breathing pattern. The magnitudes of these increases were particularly notable in the transition from EILV to EILV, especially for EMG and EMG In healthy adults, as EILV increases toward total lung capacity, progressive compensatory increases in neural activation of the diaphragm and extra-diaphragmatic inspiratory muscles are needed to support V̇, independent of changes in breathing pattern. We examined the effect of changes in end-inspiratory lung volume (EILV) and breathing pattern on neural activation of the inspiratory muscles in healthy adults. We found that, at a constant ventilation, neural activation of the crural diaphragm and of the extra-diaphragmatic inspiratory muscles (sternocleidomastoid, scalene, and seventh external intercostals) increased as a function of increasing EILV, independent of changes in breathing pattern. Our results point to a critical mechanistic role of EILV in determining the level of central inspiratory neural drive needed to support ventilation.
本研究在恒定通气量（V̇）条件下，考察了吸气末肺容积（EILV）变化和呼吸模式对膈脚（肌电图，EMG）、胸锁乳突肌（EMG）、斜角肌（EMG）和肋间外肌（EMG）神经激活的影响。12名健康成年人在对应其最大自主通气量15%的恒定V̇下进行了一系列30秒的呼吸试验，其中：）在恒定呼吸模式下改变EILV，以及）在恒定EILV下改变呼吸模式。通过实时显示每位参与者的肺量图，将EILV自主设定为每位参与者吸气肺活量的65%（EILV）、75%（EILV）、85%（EILV）和95%（EILV），而呼吸频率（）使用节拍器设定为15、35和50次/分钟。通过呼气末肺容积的变化来实现参与者在各试验中维持V̇恒定所需的潮气量。使用多对食管电极导管记录EMG，而使用表面电极记录EMG、EMG和EMG。平均而言，在恒定V̇下，EMG、EMG、EMG和EMG随EILV增加而增加，与呼吸模式的变化无关。这些增加的幅度在从EILV到EILV的转变中尤为显著，尤其是对于EMG和EMG。在健康成年人中，随着EILV向肺总量增加，需要膈神经和膈外吸气肌神经激活的逐渐代偿性增加来支持V̇，与呼吸模式的变化无关。我们考察了吸气末肺容积（EILV）变化和呼吸模式对健康成年人吸气肌神经激活的影响。我们发现，在恒定通气量下，膈脚和膈外吸气肌（胸锁乳突肌、斜角肌和第七肋间外肌）的神经激活随EILV增加而增加，与呼吸模式的变化无关。我们的结果表明EILV在决定支持通气所需的中枢吸气神经驱动水平方面具有关键的机制作用。
