Bersten A D, Rutten A J, Vedig A E
Department of Anaesthesia and Intensive Care, Flinders Medical Centre, Adelaide, South Australia.
Anaesth Intensive Care. 1993 Feb;21(1):67-71. doi: 10.1177/0310057X9302100116.
Breathing through an endotracheal tube, connector, and ventilator demand valve imposes an added load on the respiratory muscles. As respiratory muscle fatigue is thought to be a frequent cause of ventilator dependence, we sought to examine the efficacy of five different ventilators in reducing this imposed work through the application of pressure support ventilation. Using a model of spontaneous breathing, we examined the apparatus work imposed by the Servo 900-C, Puritan Bennett 7200a, Engstrom Erica, Drager EV-A or Hamilton Veolar ventilators, a size 7.0 and 8.0 mm endotracheal tube, and inspiratory flow rates of 40 and 60 l/min. Pressure support of 0, 5, 10, 15, 20 and 30 cm H2O was tested at each experimental condition. Apparatus work was greater with increased inspiratory flow rate and decreased endotracheal tube size, and was lowest for the Servo 900-C and Puritan Bennett 7200a ventilators. Apparatus work fell in a curvilinear fashion when pressure support was applied, with no major difference noted between the five ventilators tested. At an inspiratory flow rate of 40 l/min, a pressure support of 5 and 8 cm H2O compensated for apparatus work through size 8.0 and 7.0 endotracheal tubes and the Servo 900-C and Puritan Bennett 7200a ventilators. However, the maximum negative pressure was greater for the Servo 900-C. The added work of breathing through endotracheal tubes and ventilator demand valves may be compensated for by the application of pressure support. The level of pressure support required depends on inspiratory flow rate, endotracheal tube size, and type of ventilator.
通过气管内导管、接头和呼吸机需求阀进行呼吸会给呼吸肌增加负荷。由于呼吸肌疲劳被认为是呼吸机依赖的常见原因，我们试图通过应用压力支持通气来检验五种不同呼吸机在减少这种额外负荷方面的效果。使用自主呼吸模型，我们检验了Servo 900-C、伟康7200a、恩斯特龙 Erica、德尔格 EV-A或汉密尔顿Veolar呼吸机、7.0和8.0毫米尺寸的气管内导管以及40和60升/分钟的吸气流量所施加的器械功。在每个实验条件下测试了0、5、10、15、20和30厘米水柱的压力支持。器械功随着吸气流量增加和气管内导管尺寸减小而增大，并且对于Servo 900-C和伟康7200a呼吸机来说最低。当应用压力支持时，器械功呈曲线下降，在所测试的五种呼吸机之间未观察到重大差异。在吸气流量为40升/分钟时，5和8厘米水柱的压力支持通过8.0和7.0尺寸的气管内导管以及Servo 900-C和伟康7200a呼吸机补偿了器械功。然而，Servo 900-C的最大负压更大。通过气管内导管和呼吸机需求阀进行呼吸所增加的功可以通过应用压力支持来补偿。所需的压力支持水平取决于吸气流量、气管内导管尺寸和呼吸机类型。
