SPONTANEOUS AIRWAY PRESSURE RELEASE VENTILATION (S-APRV). NOSOCOMIAL PNEUMONIA.

我们已经阐明了在高空气/氧气流量下，通过微小的气管切开进入气管，而不是依靠机械通气的情况下，诱发自主呼吸道压力释放通气的机制。通过直接经气管纤维光学造影术，我们观察到声门开口的自发关闭，随后通过空气/氧气流入气管，肺被动充气。声门打开后立即呼气。这些观察结果得到了非侵入性超声成像的证实。重要的是呼吸的努力和呼吸功都减少了90%以上，S-APRV不需要气管插管，保留了发声，不干扰口腔喂养，患者的行动能力受到最小程度的损害。持续的研究探索了机械通气患者医院内肺炎的影响因素。所有研究均在麻醉、瘫痪、插管的绵羊上进行，并进行为期3天的机械通气。没有使用抗生素。对照组绵羊被插管，头部向上倾斜(与人类一样)，根据需要进行吸食。对于研究绵羊，头部和气管管保持水平，没有吸引物。对照组所有绵羊的气管、支气管树和肺部均有广泛的细菌定植，胸部X线片异常，尸检发现肺炎。捕水器大部分没有粘液。研究组的所有绵羊都保持健康，胸部X光片和尸检结果正常。粘液和气管、支气管分泌物在捕水器中自发堆积。我们得出结论：在该绵羊模型中，机械通气时气管(和头部)的定位可以避免口气或胃内容物的肺吸入(侵袭)，并导致气管和支气管分泌物的自发清除，而不需要定期的气管吸气。

We have elucidated the mechanism through which Spontaneous Airway Pressure Release Ventilation (S-APRV) is induced during high air/orygen flow through a small minitracheostomy tube into the trachea, without resorting to mechanical ventilation. By direct transtracheal fiberoptic visualization, we observed spontaneous closure of the glottic opening, followed by passive inflation of the lungs through flow of air/oxygen into the trachea. Expiration followed immediately upon opening of the glottis. Those observations have been confirmed by non-invasive ultrasonic imaging. It is important that both effort of breathing, and work of breathing are reduced by well over 90%, S-APRV does not require tracheal intubation, vocalization is preserved, oral feeding is not interfered with, and patient mobility is minimally impaired. Continuing studies explore factors that contribute to nosocomial pneumonia in patients on mechanical ventilation. All studies are conducted on anesthetized, paralyzed sheep, intubated, and on mechanical ventilation for 3 days. No antibiotics are used. Control sheep were intubated and the head held angled upward (as in the human), suctioned as needed. For study sheep, head and tracheal tube were maintained horizontal, and there was no suctioning. All sheep in the control group showed extensive bacterial colonization of the tracheo-bronchial tree and lungs, with abnormal chest X-rays, and autopsy findings of pneumonia. The water traps remained for the most part clear of mucus. All sheep in the study group remained healthy, with normal chest X-ray films, and autopsy findings. Mucus and tracheobronchial secretions accumulated spontaneously in the water trap. We conclude that orientation of tracheal tube (and head) during mechanical ventilation can avert pulmonary aspiration (invasion) of orotracheal or gastric contents, and lead to spontaneous clearance of tracheobronchial secretions, without need for periodic tracheal suctioning in this sheep model.