Nathan N, Sperandio M, Erdmann W, Westerkamp B, Van Dijk G, Scherpereel P, Feiss P
Service d'anesthésie-réanimation, CHU, Limoges, France.
Ann Fr Anesth Reanim. 1997;16(5):534-40. doi: 10.1016/s0750-7658(97)83349-7.
Physi Flex is the first commercially available apparatus capable for quantitative, or self-regulating target controlled inhalational anaesthesia, with a totally closed circuit, in adults and children. The fresh gas supply to the circuit is intermittent, automatically regulated by continuous monitoring of the volume and composition of the gas mixture in the breathing circuit. The circle system includes, instead of the two conventional one way valves, a blower creating a continuous unidirectional flow at 70 L.min-1. In addition to the CO2-absorber it contains an absorber with carbon, absorbing the anaesthetic vapour when switched into the circuit. The ventilator consists of four ventilating chambers, each one with a membrane separating the patient and the motor compartments. The displacement of the membranes generates and measures the tidal volume. Automatic ventilation is achieved by electric valves and motor gas, and manual ventilation using a bag. Spontaneous ventilation is also possible. The machine is operated via a computer with selects the number of ventilating chambers (one, two or four), and the tidal volume between 50 and 2,000 mL, depending on age, gender and weight of the patient. The computer maintains the gas volume and the gas and vapour concentrations at their preset values. The O2-flow and consumption, the N2O flow and uptake, FICO2 and FETCO2, FI and FET of the volatile anaesthetic, all other important data are displayed in a numerical and graphical form on a color screen and registered for a delayed analysis. The end tidal concentration of the volatile anaesthetic drives a stepmotor with a syringe containing the selected volatile anaesthetic agent with is directly injected into the breathing circuit where it is vaporized. Therefore the concentration of the anaesthetic vapour can be instantaneously increased with this injector at induction and lowered at end of anaesthesia with the carbon absorber, and the fresh gas consumption is significantly decreased.
Physi Flex是首款可用于成人和儿童的、具备定量或自我调节靶控吸入麻醉功能的商用设备，采用全封闭回路。回路的新鲜气体供应是间歇性的，通过持续监测呼吸回路中气体混合物的体积和成分进行自动调节。该循环系统没有传统的两个单向阀，而是包括一个鼓风机，以70L.min-1的速度产生持续单向气流。除了二氧化碳吸收器外，它还包含一个含碳吸收器，在接入回路时可吸收麻醉蒸汽。呼吸机由四个通气腔组成，每个通气腔都有一个膜片将患者和电机隔室分开。膜片的位移产生并测量潮气量。自动通气通过电动阀和电动气体实现，手动通气使用气囊。也可进行自主通气。该机器通过计算机操作，计算机根据患者的年龄、性别和体重选择通气腔的数量（一个、两个或四个），以及50至2000mL之间的潮气量。计算机将气体体积以及气体和蒸汽浓度维持在预设值。氧气流量和消耗量、氧化亚氮流量和摄取量、FICO2和FETCO2、挥发性麻醉剂的FI和FET，所有其他重要数据都以数字和图形形式显示在彩色屏幕上，并进行记录以便后续分析。挥发性麻醉剂的呼气末浓度驱动一个装有选定挥发性麻醉剂的注射器的步进电机，该注射器直接注入呼吸回路并在其中汽化。因此，在诱导时可通过该注射器瞬间提高麻醉蒸汽浓度，在麻醉结束时通过碳吸收器降低浓度，同时显著减少新鲜气体消耗。
