Imanaka H, Kacmarek R M, Ritz R, Hess D
Respiratory Care Department, Massachusetts General Hospital, Boston, 02114, USA.
Am J Respir Crit Care Med. 1996 Mar;153(3):1019-24. doi: 10.1164/ajrccm.153.3.8630540.
Tracheal gas insufflation (TGI) has been recommended as an adjunct to mechanical ventilation in the presence of elevated Pa CO2. Based on our initial clinical experience with continuous flow TGI and pressure control ventilation (PCV), we were concerned about elevation in peak airway pressure as TGI was applied. In a lung model, we evaluated the effects of continuous flow TGI during both PCV and volume control ventilation (VCV). A single compartment lung model was configured with an artificial trachea into which an 8-mm endotracheal tube was positioned. TGI was established with a 16-G catheter positioned 2 cm beyond the tip of the endotracheal tube. Ventilation was provided by a Puritan-Bennett 7200ae ventilator with PCV 20 cm H2O or VCV with a tidal volume (VTt) similar to that with PCV. A rate of 15 breaths/min and PEEP of 10 cm H2O were used throughout. Inspiratory times (TI) of 1.0, 1.5, 2.0, and 2.5 s were used with TGI of 0, 4, 8, and 12 L/min. Lung model compliance (ml/cm H2O) and resistance (cm H2O/L/s) combinations of 20/20, 20/5, and 50/20 were used. Auto-PEEP, VT, and peak alveolar and airway opening pressures increased as TGI and Ti increased, regardless of lung mechanics settings (p<0.01). All increases were greater with VCV than PCV (p<0.05). Continuous flow TGI with both PCV and VT-uncorrected VCV may result in marked increases in Vt and system pressures, especially at long TI.
在动脉血二氧化碳分压（Pa CO2）升高时，气管内气体注入（TGI）已被推荐作为机械通气的辅助手段。基于我们对持续气流TGI和压力控制通气（PCV）的初步临床经验，我们担心应用TGI时气道峰压会升高。在一个肺模型中，我们评估了持续气流TGI在PCV和容量控制通气（VCV）期间的效果。构建了一个单腔肺模型，配备一根人工气管，将一根8毫米的气管内导管置于其中。通过将一根16G导管置于气管内导管尖端以远2厘米处来建立TGI。使用Puritan-Bennett 7200ae呼吸机进行通气，设置为PCV 20 cm H2O或VCV，潮气量（VTt）与PCV时相似。全程使用的呼吸频率为15次/分钟，呼气末正压（PEEP）为10 cm H2O。吸气时间（TI）分别为1.0、1.5、2.0和2.5秒，TGI流量分别为0、4、8和12升/分钟。肺模型顺应性（毫升/厘米H2O）和阻力（厘米H2O/升/秒）的组合分别为20/20、20/5和50/20。无论肺力学设置如何，随着TGI和TI增加，内源性呼气末正压（Auto-PEEP）、潮气量（VT）以及肺泡峰压和气道开口压均升高（p<0.01）。所有升高在VCV时均比PCV时更显著（p<0.05）。PCV和未校正VT的VCV联合持续气流TGI可能会导致潮气量和系统压力显著升高，尤其是在吸气时间较长时。
