Segizbaeva M O, Pogodin M A, Lavrova I N, Balykin M V, Aleksandrova N P
Fiziol Cheloveka. 2011 Mar-Apr;37(2):52-9.
The effect of head-down tilt on respiration and diaphragmal and parasternal muscles activity was investigated in 11 healthy subjects. The short-time (30 min) head-down tilt posture (-30 degrees relatively horizont) increased the inspiratory time (P < 0.05), decreased breathing frequency (P < 0.05), inspiratory and expiratory flow rate (P < 0.05) and increased the airway resistance (P < 0.05) compared with values in vertical posture. There were no significant changes in tidal volume and minute ventilation. Constant values of tidal volume and minute ventilation during head-down tilt were provided by increasing in EMG activity of parasternal muscles more then twice. It was established that the contribution of chest wall inspiratory muscles increased while the diaphragm's contribution decreased during head-down spontaneous breathing. Maximal inspiratory effort (Muller's maneuver) during head-down tilt evoked the opposite EMG-activity pattern: the contribution of inspiratory thoracic muscles was decreased and diaphragm's EMG-activity was increased compared with vertical posture. These results suggest that coordinate modulations in inspiratory muscles activity allows to preserve the functional possibility of human inspiratory muscles during short-time head-down tilt.
在11名健康受试者中研究了头低位倾斜对呼吸以及膈肌和胸骨旁肌活动的影响。与直立姿势相比，短时间（30分钟）头低位倾斜姿势（相对于水平方向-30度）增加了吸气时间（P<0.05），降低了呼吸频率（P<0.05）、吸气和呼气流量（P<0.05），并增加了气道阻力（P<0.05）。潮气量和分钟通气量无显著变化。胸骨旁肌肌电图活动增加两倍以上，从而在头低位倾斜期间提供了恒定的潮气量和分钟通气量。已确定在头低位自主呼吸期间胸壁吸气肌的贡献增加，而膈肌的贡献减少。头低位倾斜期间的最大吸气努力（米勒动作）引发了相反的肌电图活动模式：与直立姿势相比，吸气性胸廓肌的贡献减少，膈肌的肌电图活动增加。这些结果表明，吸气肌活动的协调性调节有助于维持人体吸气肌在短时间头低位倾斜期间的功能可能性。
