Wanke T, Lahrmann H, Formanek D, Zwick H
Pulmonary Department, Lainz Hospital, Vienna, Austria.
Eur J Appl Physiol Occup Physiol. 1992;64(3):266-71. doi: 10.1007/BF00626290.
The aim of our study was to examine the effect of posture on inspiratory muscle activity response to hypercapnia. Recent research has revealed that in normal subjects the activation of the rib cage muscles and of the diaphragm is actually greater in the upright than in the supine position during resting tidal breathing. In this study we examined whether the upright position necessarily entails a greater activation of the inspiratory muscles also under conditions of ventilatory stress. For this purpose we compared the responses to CO2-rebreathing in the supine and sitting positions in five volunteers, by simultaneously recording the electromyogram of the diaphragm (EMGdi) and the intercostal muscles (EMGint). The electromyogram was recorded by means of surface electrodes to measure the EMG amplitude. While the slopes of ventilatory (VE) response to increasing arterial CO2 tension (PaCO2) were similar in the two positions, both the EMGdi-VE and EMGint-VE relationship showed steeper slopes in the supine than in the sitting position. In each CO2 run the increases in EMGdi were linearly related to those in EMGint. This relationship was not affected by the body position. These results suggested that, in spite of similar ventilatory responses to CO2-rebreathing in the lying and sitting positions, the supine position, in humans, required a higher activation of the inspiratory muscles.
我们研究的目的是探讨姿势对高碳酸血症时吸气肌活动反应的影响。最近的研究表明，在静息潮气呼吸时，正常受试者直立位时胸廓肌肉和膈肌的激活程度实际上高于仰卧位。在本研究中，我们检验了在通气应激条件下，直立位是否必然也会导致吸气肌更大程度的激活。为此，我们通过同时记录膈肌（EMGdi）和肋间肌（EMGint）的肌电图，比较了5名志愿者在仰卧位和坐位时对二氧化碳再呼吸的反应。通过表面电极记录肌电图以测量肌电图幅度。虽然在两个体位下，通气（VE）对动脉血二氧化碳分压（PaCO2）升高的反应斜率相似，但EMGdi-VE和EMGint-VE关系在仰卧位时均比坐位时更陡。在每次二氧化碳试验中，EMGdi的增加与EMGint的增加呈线性相关。这种关系不受体位的影响。这些结果表明，尽管仰卧位和坐位对二氧化碳再呼吸的通气反应相似，但在人类中，仰卧位需要更高程度的吸气肌激活。
