A new negative pressure ventilator

描述（由申请人提供）：使用气管插管和正压通气的长期呼吸支持与非常高的感染率相关，呼吸机相关性肺炎（VAP）是当今医院中主要和更严重的医院感染形式之一。该项目的目标是开发一种新型负压呼吸机，该呼吸机消除了留置组件，并允许患者呼吸室内空气，以减少VAP的发生率。负压呼吸机的原型是“铁肺”，最初由Drinker于1929年开发。它基本上由一个金属罐组成，容纳病人的整个身体直到颈部。罐内的压力循环低于环境压力以诱导吸气，然后返回到环境压力以允许呼气。在20世纪50年代末脊髓灰质炎流行期间，这种设备被成功地用于支持许多患者，但它很大，极大地限制了对患者进行常规护理的机会，并且提供了非常有限的生活质量。我们建议建立和测试一个新的负压呼吸机的原型，是小，重量轻。其工作原理与铁肺相似，但它采用的不是水箱，而是两段式人工肋骨架组件，其弹性护套紧密围绕胸壁。人工肋骨架是机械驱动的，以模仿呼吸过程中胸壁的运动，在吸气过程中在胸部和上腹部周围产生负压。使用人体模型，我们已经证明，这种设计能够产生大于-20厘米水柱的负压，足以诱导成年人受试者吸入。因为它是机械驱动的，所以它也可以用于诱导或增强咳嗽以清除气道，这是一种独特的能力。在拟议的计划中，我们将设计和建造该设备的原型，并开发一个电子控制系统，将允许患者触发固定速率操作。然后，我们将使用猪模型通过一系列6项急性体内研究来表征其性能。新设备克服了现有负压或正压通气系统的许多局限性，并有可能显著降低VAP的发生率。公共卫生相关性：该提案的目的是开发一种新型负压呼吸机，该呼吸机将提供呼吸支持，而无需气管插管或使用传统的正压呼吸机。当使用超过30天时，后一种装置与高感染率（>60%）相关，并且呼吸机相关性肺炎是医院感染的主要类别之一，并导致显著的发病率。通过在气道中不引入留置组件并允许患者呼吸室内空气，可以显著降低与长时间呼吸支持相关的感染率。

DESCRIPTION (provided by applicant): Long-term respiratory support using endotracheal intubation and positive pressure ventilation is associated with very high rates of infection, and ventilator-associated pneumonia (VAP) is among the leading and more serious forms of nosocomial infection in hospitals today. The objective of this program is the development of a new negative pressure ventilator that eliminates indwelling components and allows the patient to breathe room air to reduce the incidence of VAP. The prototype negative pressure ventilator is the "iron lung" originally developed by Drinker in 1929. It essentially consisted of a metal tank containing the patient's entire body up to the neck. The pressure inside the tank was cycled below ambient pressure to induce inhalation, and then returned to ambient to allow exhalation. That device was used successfully to support many patients for extended periods during the polio epidemics in the late 1950s, but it was large, greatly limited access to the patient for routine nursing care, and provided a very limited quality of life. We are proposing to build and test prototypes of a new negative pressure ventilator that is small and light in weight. The principle of operation is the similar to the iron lung, but instead of a tank, it employs a two-segment artificial rib cage assembly with an elastomeric jacket closely surrounding the chest wall. The artificial rib cage is mechanically actuated to mimic the movement of the chest wall during respiration, creating a negative pressure around the chest and upper abdomen during inhalation. Using a manikin, we have demonstrated that this design is able to generate negative pressures greater than -20 cm of water, enough to induce inhalation in an adult human subject. Because it is mechanically actuated, it may also be used to induce or augment a cough to clear the airways, a unique capability. In the proposed program, we will design and build prototypes of the device and develop an electronic control system that will permit either patient triggered fixed rate operation. We will then characterize its performance with a series of 6 acute in vivo studies using a porcine model. The new device overcomes many of the limitations of existing negative or positive pressure ventilation systems and has the potential to significantly reduce the incidence of VAP. PUBLIC HEALTH RELEVANCE: The objective of this proposal is the development of a novel negative pressure ventilator that will provide respiratory support without endotracheal intubation or the use of a conventional positive pressure ventilator. The latter devices are associated with high rates of infection (>60%) when used for periods exceeding 30 days, and ventilator-associated pneumonia is one of the major classes of nosocomial infection and causes significant morbidity. By introducing no indwelling components into the airway and allowing the patient to breathe room air, the infection rate associated with prolonged respiratory support can be significantly reduced.