Fauroux B, Pigeot J, Polkey M I, Isabey D, Clément A, Lofaso F
Pediatric Pulmonary Department, Armand Trousseau Hospital (BF, AC), Assistance Publique, Hôpitaux de Paris, Paris, France.
Crit Care Med. 2001 Nov;29(11):2097-105. doi: 10.1097/00003246-200111000-00009.
Home noninvasive mechanical ventilation (NIMV) is used with increasing frequency for the treatment of patients with respiratory failure caused by cystic fibrosis, yet the optimal mode of ventilation in such children is unknown. We compared the physiologic short-term effects of two ventilators with different modes (one pressure support and the other assist control/volume-targeted [AC/VT]) commonly used for domiciliary ventilation.
Prospective, randomized, crossover comparison of two ventilators with different modes.
Tertiary pediatric university hospital.
Eight children with cystic fibrosis (age, 11-17 yrs) and chronic respiratory failure (pH 7.4 +/- 0.0; PaO2, 57.5 +/- 7.5 torr; PaCO2, 46.1 +/- 2.5 torr), naive to NIMV.
Two 20-min runs of pressure support and AC/VT ventilation were performed in random order, each run being preceded and followed by 20 mins of spontaneous breathing.
Flow and airway pressure and esophageal and gastric pressures were measured to calculate esophageal (PTPes) and diaphragmatic pressure-time product (PTPdi) and the work of breathing.
The two NIMV sessions significantly improved blood gas variables and increased tidal volume with no change in respiratory rate. Indexes of respiratory effort decreased significantly during the two modes of NIMV compared with spontaneous breathing, with PTPdi/min decreasing from 497.8 +/- 115.4 cm H2O x sec x min(-1) during spontaneous breathing to 127.8 +/- 98.3 cm H2O x sec x min(-1) and 184.3 +/- 79.8 cm H2O x sec x min(-1), during AC/VT and pressure support, respectively (p <.0001), and the work of breathing decreasing from 1.83 +/- 0.12 J.L-1 during spontaneous breathing to 0.48 +/- 0.32 J.L-1 and 0.75 +/- 0.30 J.L-1, during AC/VT and pressure support, respectively (p <.0001). In addition, the effect of AC/VT ventilation was significantly superior to pressure support judged by PTPes and the work of breathing, but this result was explained by three patients who adapted extremely well to the AC/VT ventilation, with the disappearance of ventilator triggering, in effect adopting a controlled mode. There was a correlation between the improvement in PTPdi/min or the work of breathing and patient's subjective impression of comfort during the AC/VT ventilation.
In awake, stable children with cystic fibrosis, both AC/VT and pressure support unloaded the respiratory muscles. The disappearance of ventilator triggering occurred in a subgroup of patients during AC/VT ventilation, and this explained the good tolerance and the superiority of this mode in the present study.
家庭无创机械通气（NIMV）越来越频繁地用于治疗囊性纤维化引起的呼吸衰竭患者，但此类儿童的最佳通气模式尚不清楚。我们比较了两种常用于家庭通气的不同模式（一种是压力支持，另一种是辅助控制/容量靶向[AC/VT]）通气机的短期生理效应。
对两种不同模式通气机进行前瞻性、随机、交叉比较。
三级儿科大学医院。
8名患有囊性纤维化（年龄11 - 17岁）和慢性呼吸衰竭（pH 7.4±0.0；动脉血氧分压[PaO₂]，57.5±7.5托；动脉血二氧化碳分压[PaCO₂]，46.1±2.5托）且未使用过NIMV的儿童。
以随机顺序进行两次20分钟的压力支持通气和AC/VT通气，每次通气前后各有20分钟的自主呼吸。
测量流量、气道压力、食管和胃内压力，以计算食管压力时间乘积（PTPes）和膈肌压力时间乘积（PTPdi）以及呼吸功。
两次NIMV通气均显著改善了血气变量并增加了潮气量，呼吸频率无变化。与自主呼吸相比，两种NIMV模式下的呼吸努力指标均显著降低，PTPdi/分钟从自主呼吸时的497.8±115.4厘米水柱×秒×分钟⁻¹分别降至AC/VT通气时的127.8±98.3厘米水柱×秒×分钟⁻¹和压力支持通气时的184.3±79.8厘米水柱×秒×分钟⁻¹（p<0.0001），呼吸功从自主呼吸时的1.83±0.12焦·升⁻¹分别降至AC/VT通气时的0.48±0.32焦·升⁻¹和压力支持通气时的0.75±0.30焦·升⁻¹（p<0.0001）。此外，根据PTPes和呼吸功判断，AC/VT通气的效果显著优于压力支持，但这一结果是由3名对AC/VT通气适应极佳的患者所解释，他们的呼吸机触发消失，实际上采用了控制模式。在AC/VT通气期间，PTPdi/分钟或呼吸功的改善与患者的主观舒适度印象之间存在相关性。
在清醒、病情稳定的囊性纤维化儿童中，AC/VT和压力支持均减轻了呼吸肌负担。在AC/VT通气期间，一部分患者出现了呼吸机触发消失的情况，这解释了本研究中该模式良好的耐受性和优越性。
