Sharshar Tarek, Desmarais Gilbert, Louis Bruno, Macadou Gilles, Porcher Raphael, Harf Alain, Raphaël Jean-Claude, Isabey Daniel, Lofaso Frédéric
Service d'Explorations Fonctionnelles, Hôpital Raymond Poincaré, Garches, France.
Am J Respir Crit Care Med. 2003 Oct 1;168(7):760-9. doi: 10.1164/rccm.200203-241OC. Epub 2003 May 28.
We designed a new servoventilator that proportionally adjusts airway pressure to transdiaphragmatic pressure (Pdi) generated by the subject during inspiration. Each cycle is triggered by either a preset Pdi increase or a preset inspiratory flow value (whichever is reached first), whereas cycling-off is flow-dependent. We evaluated the servoventilator in seven healthy subjects at normocapnia and three levels of hypercapnia (normocapnia + 3, + 6, and + 9 mm Hg) comparatively with spontaneous breathing. Triggering was by Pdi in six subjects and flow in one. At all end-tidal carbon dioxide pressure levels, time from onset of diaphragm electromyographic activity to inspiratory flow was similar with and without the servoventilator. Airway pressure increased proportionally to Pdi variation during servoventilator breathing. Flow, tidal volume, respiratory rate, intrinsic positive end-expiratory pressure, and esophageal and transdiaphragmatic pressure-time products increased significantly with hypercapnia with and without the servoventilator. Breathing pattern parameters were similar in the two breathing modes, and no differences were found for intrinsic positive end-expiratory pressure or gastric pressure variation during exhalation. Esophageal and transdiaphragmatic pressure-time products were lower with than without the servoventilator. The Pdi-driven servoventilator was well synchronized to the subjects effort, delivering a pressure proportional to Pdi and reducing respiratory effort at normocapnia and hypercapnia.
我们设计了一种新型伺服呼吸机，它能在吸气过程中根据受试者产生的跨膈压（Pdi）成比例地调节气道压力。每个周期由预设的Pdi升高或预设的吸气流量值触发（以先达到者为准），而停机则取决于流量。我们在7名健康受试者处于正常碳酸血症和三种高碳酸血症水平（正常碳酸血症 + 3、+ 6和 + 9 mmHg）时，与自主呼吸进行比较，对该伺服呼吸机进行了评估。6名受试者通过Pdi触发，1名受试者通过流量触发。在所有呼气末二氧化碳压力水平下，无论有无伺服呼吸机，从膈肌肌电活动开始到吸气流量的时间相似。在伺服呼吸机辅助呼吸期间，气道压力随Pdi变化成比例增加。无论有无伺服呼吸机，随着高碳酸血症的出现，流量、潮气量、呼吸频率、内源性呼气末正压以及食管和跨膈压 - 时间乘积均显著增加。两种呼吸模式下的呼吸模式参数相似，呼气期间内源性呼气末正压或胃内压变化未发现差异。与无伺服呼吸机相比，有伺服呼吸机时食管和跨膈压 - 时间乘积更低。由Pdi驱动的伺服呼吸机与受试者的努力同步良好，在正常碳酸血症和高碳酸血症时输送与Pdi成比例的压力并减少呼吸功。
