Gayan-Ramirez Ghislaine, Testelmans Dries, Maes Karen, Rácz Gábor Z, Cadot Pascal, Zádor Ernö, Wuytack Frank, Decramer Marc
Respiratory Muscle Research Unit, Laboratory of Pneumology and Respiratory Division, Katholieke Universiteit Leuven, Leuven Belgium.
Crit Care Med. 2005 Dec;33(12):2804-9. doi: 10.1097/01.ccm.0000191250.32988.a3.
Short-term mechanical ventilation has been proven to reduce diaphragm force and fiber dimensions. We hypothesized that intermittent spontaneous breathing during the course of mechanical ventilation would minimize the effects of mechanical ventilation on diaphragm force and expression levels of transcription factors (MyoD and myogenin).
Randomized, controlled experiment.
Animal basic science laboratory.
Male Wistar rats, weighing 350-500 g.
Anesthetized and tracheotomized rats were submitted to either 24 hrs of spontaneous breathing (SB, n = 5), 24 hrs of continuous controlled mechanical ventilation (CMV, n = 7), or controlled mechanical ventilation with intermittent spontaneous breathing: 60 mins every 5 hrs of mechanical ventilation repeated four times (ISB60, n = 8) or 5 mins every 5 hrs 55 mins of mechanical ventilation repeated four times (SB5, n = 9). They were compared with control animals free from intervention (C, n = 5).
The profile of the diaphragm force-frequency curve of the controls and SB group was significantly different from that of the ISB and CMV groups; especially, the mean asymptotic force was less in the ISB and CMV compared with controls and SB. CMV resulted in a significant decrease in the diaphragm type I (-26%, p < .05 vs. C) and type IIx/b (-39%, p < .005 vs. C and SB) cross-sectional area, whereas this was not observed in the ISB groups. Diaphragm MyoD protein expression was significantly decreased after ISB60 (-35%, p < .0001 vs. C and SB) and even more after CMV (-73%, p < .0001 vs. others). The same pattern was observed with myogenin protein levels. Positive relationships between diaphragm MyoD and myogenin protein levels and diaphragm force were observed.
The data demonstrated that intermittent spontaneous breathing during the course of mechanical ventilation may minimize the deleterious effect of controlled mechanical ventilation on diaphragm force, fiber dimensions, and expression of transcription factors.
短期机械通气已被证明会降低膈肌力量和纤维尺寸。我们假设在机械通气过程中间歇性自主呼吸可将机械通气对膈肌力量及转录因子（肌分化抗原（MyoD）和肌细胞生成素）表达水平的影响降至最低。
随机对照实验。
动物基础科学实验室。
体重350 - 500克的雄性Wistar大鼠。
对麻醉并进行气管切开的大鼠，分别给予24小时自主呼吸（SB，n = 5）、24小时持续控制机械通气（CMV，n = 7），或间歇自主呼吸的控制机械通气：每5小时机械通气60分钟，重复4次（ISB60，n = 8）或每5小时机械通气55分钟，每5小时中有5分钟自主呼吸，重复4次（SB5，n = 9）。将它们与未接受干预的对照动物（C，n = 5）进行比较。
对照组和SB组的膈肌力量 - 频率曲线轮廓与ISB组和CMV组显著不同；特别是，与对照组和SB组相比，ISB组和CMV组的平均渐近力较小。CMV导致膈肌I型（-26%，与C组相比p < 0.05）和IIx/b型（-39%，与C组和SB组相比p < 0.005）横截面积显著减小，而ISB组未观察到这种情况。ISB60后膈肌MyoD蛋白表达显著降低（-35%，与C组和SB组相比p < 0.0001），CMV后降低更明显（-73%，与其他组相比p < 0.0001）。肌细胞生成素蛋白水平也呈现相同模式。观察到膈肌MyoD和肌细胞生成素蛋白水平与膈肌力量之间存在正相关关系。
数据表明，机械通气过程中间歇性自主呼吸可将控制机械通气对膈肌力量、纤维尺寸和转录因子表达的有害影响降至最低。
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