BACKGROUND The electrical activity of the crural diaphragm (Eadi), a surrogate of respiratory drive, can now be measured at the bedside in mechanically ventilated patients with a specific catheter. The expected range of Eadi values under stressed or assisted spontaneous breathing is unknown. This study explored Eadi values in healthy subjects during unstressed (baseline), stressed (with a resistance) and assisted spontaneous breathing. The relation between Eadi and inspiratory effort was analyzed. METHODS Thirteen healthy male volunteers were included in this randomized crossover study. Eadi and esophageal pressure (Peso) were recorded during unstressed and stressed spontaneous breathing and under assisted ventilation delivered in pressure support (PS) at low and high assist levels and in neurally adjusted ventilatory assist (NAVA). Overall eight different situations were assessed in each participant (randomized order). Peak, mean and integral of Eadi, breathing pattern, esophageal pressure-time product (PTPeso) and work of breathing (WOB) were calculated offline. RESULTS Median [interquartile range] peak Eadi at baseline was 17 [13-22] μV and was above 10 μV in 92% of the cases. Eadimax defined as Eadi measured at maximal inspiratory capacity reached 90 [63 to 99] μV. Median peak Eadi/Eadimax ratio was 16.8 [15.6-27.9]%. Compared to baseline, respiratory rate and minute ventilation were decreased during stressed non-assisted breathing, whereas peak Eadi and PTPeso were increased. During unstressed assisted breathing, peak Eadi decreased during high-level PS compared to unstressed non-assisted breathing and to NAVA (p = 0.047). During stressed breathing, peak Eadi was lower during all assisted ventilation modalities compared to stressed non-assisted breathing. During assisted ventilation, across the different conditions, peak Eadi changed significantly, whereas PTPeso and WOB/min were not significantly modified. Finally, Eadi signal was still present even when Peso signal was suppressed due to high assist levels. CONCLUSION Eadi analysis provides complementary information compared to respiratory pattern and to Peso monitoring, particularly in the presence of high assist levels. Trial registration The study was registered as NCT01818219 in clinicaltrial.gov. Registered 28 February 2013.

中文翻译：

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在无压力，有压力和辅助的自发呼吸过程中通过电diaphragm肌活动传达的信息：一项生理研究。

背景技术现在可以在具有特定导管的机械通气患者中在床旁测量关键膜片（Eadi）的电活动，这是呼吸驱动的替代物。在压力或辅助自发呼吸下，Eadi值的预期范围是未知的。这项研究探讨了健康受试者在无压力（基线），压力（有阻力）和辅助自发呼吸期间的Eadi值。分析了Eadi与吸气量之间的关系。方法这项随机交叉研究包括13名健康男性志愿者。在无压力和有压力的自发呼吸过程中，在低和高辅助水平的压力支持（PS）以及神经调节的通气辅助（NAVA）中，在辅助通气情况下记录Eadi和食管压力（Peso）。每个参与者评估了总共八种不同的情况（随机顺序）。离线计算Eadi的峰值，平均值和积分，呼吸方式，食道压力时间乘积（PTPeso）和呼吸功（WOB）。结果在92％的病例中，基线时的[四分位数间距]峰值Eadi为17 [13-22] V，高于10V。Eadimax定义为在最大吸气量达到90 [63至99]μV时测得的Eadi。Eadi / Eadimax峰值中位数比为16.8 [15.6-27.9]％。与基线相比，紧张的无助呼吸过程中呼吸频率和分钟通气量减少，而峰值Eadi和PTPeso升高。在无压力辅助呼吸期间，与无压力无辅助呼吸和NAVA相比，高水平PS期间的峰值Eadi降低（p = 0.047）。在紧张的呼吸中 与有压力的无辅助呼吸相比，在所有辅助通气模式下的峰值Eadi都较低。在辅助通气过程中，在不同条件下，峰值Eadi发生了显着变化，而PTPeso和WOB / min并未发生明显变化。最后，即使由于辅助电平高而抑制了比索信号，Eadi信号仍然存在。结论与呼吸模式和比索监测相比，Eadi分析可提供补充信息，尤其是在辅助水平较高的情况下。试验注册该研究已在Clinicaltrial.gov中注册为NCT01818219。2013年2月28日注册。而PTPeso和WOB / min并未明显改变。最后，即使由于辅助电平高而抑制了比索信号，Eadi信号仍然存在。结论与呼吸模式和比索监测相比，Eadi分析可提供补充信息，尤其是在辅助水平较高的情况下。试验注册该研究已在Clinicaltrial.gov中注册为NCT01818219。2013年2月28日注册。而PTPeso和WOB / min并未明显改变。最后，即使由于辅助电平高而抑制了比索信号，Eadi信号仍然存在。结论与呼吸模式和比索监测相比，Eadi分析可提供补充信息，尤其是在辅助水平较高的情况下。试验注册该研究已在Clinicaltrial.gov中注册为NCT01818219。2013年2月28日注册。