Ventilator-Associated Pneumonia. Mucus Slurper. Mucucili

1、？鼻涕虫？ 在用气管内导管（ETT）插管的患者中，常规进行抽吸以从ETT和气管内去除粘液。粘液Slurper是一种新型的气管插管，其尖端径向排列有内置抽吸口。在机械通气72小时的绵羊中，我们评价了Mucus Slurper与传统气管吸引相比的安全性和有效性，以防止分泌物在ETT和气管腔内积聚。 2：呼吸机相关肺炎（VAP）中气管粘液转运和呼吸机的作用 重症患者通常采用半卧位，床头抬高30-45度角，以防止胃食管反流和肺误吸。 我们研究了在自主呼吸（无呼吸机）或机械通气绵羊中气管插管后对气管粘液清除的影响，气管位于水平上方或下方。我们的目标也是确定气管粘液清除受损，结合气管方向高于水平（因为它是在半卧位的人）是否与肺部细菌定植的风险增加，肺炎的发作。 通过对不透射线的钽盘和吹入气管的钽粉进行放射学追踪，测量气管粘液流速。 我们发现，气管插管后，随着气管升高到水平线以上，气管粘液清除变得高度异常，粘液向后移向肺部，随后肺部细菌定植。 3、？ETT袖带防漏？ 引入市售的高容量低压袖带（HVLP）以防止压力相关的气管损伤。在这样做时，套囊直径被设计成大于气管的管腔。因此，随着气管套囊在气管内膨胀，总是形成褶皱。定植的声门下分泌物沿着褶皱渗漏可导致下呼吸道定植和呼吸机相关性肺炎（VAP）。 我们通过在标准HVLP套囊周围覆盖第二个高弹性套囊制造了ETT套囊原型，该套囊由低蛋白天然乳胶橡胶制成，壁厚为40-50微米。我们将少量的水性润滑剂引入两个袖带之间的空间，以均匀地分布扩张压力。 到目前为止，我们的研究仅限于体外研究;体内测试和评估将随后进行。 4：预防机械通气猪的VAP 基于之前在绵羊中进行的镇静、插管和机械通气动物研究，我们已经表明，当头部/颈部抬高至水平以上30-45度时（如处于半卧位的人类），在24小时内开始出现均匀、广泛的气管支气管和肺部细菌定植;随后出现气体交换受损和急性呼吸衰竭。 当插管绵羊，机械通气，定位，使气管和气管导管保持水平，或与轻微的倾斜向下，然后机械通气72小时，有没有气管，支气管，或肺实质细菌定植。 然而，由于反刍动物和杂食动物的解剖和生理条件不同（如每天产生的唾液总量、气管长度、口咽-瘤胃植物群等），将绵羊肺研究的病理生理学结果转移到人类病理学是困难的。 因此，我们还研究了机械通气的杂食动物（猪），在全身麻醉和肠道喂养72-168小时。 这项研究表明，我们在绵羊身上的发现也适用于猪。 5.与医学研究中心的合作： 在我们的实验室发现的支持下，在2种不同的动物模型中预防VAP，我们现在与3个医学研究中心合作（1。马萨诸塞州总医院-Zapol、Bigatello、贝拉医生; 2.米兰大学，意大利-佩森蒂博士; 3. NIH临床重症监护室-Masur博士）。我们希望开始一项多中心试验，以确定我们预防VAP的方法在危重患者中是否可行、安全和有效。

1: The ?Mucus Slurper? In patients intubated with endotracheal tubes (ETT), suctioning is routinely performed to remove mucus from within the ETT, and the trachea. The Mucus Slurper is a novel ETT, with built-in suction ports arranged radially at its tip. In sheep mechanically ventilated for 72 hours, we evaluated safety and efficacy of the Mucus Slurper, compared to conventional tracheal suction, to prevent accumulation of secretions within the lumen of the ETT and trachea. 2: Tracheal mucus transport and the role of the ventilator in Ventilator Associated Pneumonia (VAP) Critically ill patients are usually positioned in the semi-recumbent position with the head of the bed elevated at an angle of 30-45 degrees, to prevent gastro-esophageal reflux, and pulmonary aspiration. We investigated the effects on tracheal mucus clearance after tracheal intubation in spontaneously breathing (without ventilator), or mechanically ventilated sheep, positioned with the trachea oriented above, or below horizontal. Our goal was also to determine whether impaired tracheal mucus clearance, combined with tracheal orientation above horizontal (as it is in semi-recumbent position in the human) was associated with increased risk for bacterial colonization of the lungs, and onset of pneumonia. Tracheal mucus velocity was measured via radiographic tracking of radiopaque tantalum disks and tantalum powder insufflated into the trachea. We found that after tracheal intubation, with the trachea elevated above horizontal, tracheal mucus clearance becomes highly abnormal, with mucus moving backward towards the lungs, followed by bacterial colonization of the lungs. 3: The ?Leak proof ETT cuff? Commercially available high-volume low-pressure cuffs (HVLP) were introduced to prevent pressure-related tracheal injury. In so doing, the cuff diameter was designed larger than the lumen of the trachea. Hence, with the tracheal cuff inflated within the trachea, folds always form. Leakage of colonized subglottic secretions along the folds can lead to colonization of the lower airways, and ventilator associated pneumonia (VAP). We manufactured a prototype ETT cuff by draping around the standard HVLP cuff a second, highly elastic cuff made of low-protein natural latex rubber, with a wall thickness of 40-50 microns. We introduced a small amount of aqueous lubricant into the space between the two cuffs to homogeneously distribute the distending pressure. Our studies until now have been confined to in vitro studies; in vivo testing and evaluation is to follow. 4: Prevention of VAP in mechanically ventilated pigs Based on previous animal studies in sheep sedated, intubated and mechanically ventilated, we have shown that when the head/neck are elevated 30-45 degrees above horizontal (as in the human in the semi-recumbent position), there was uniform, widespread tracheobronchial and lung bacterial colonization, starting within 24 h; followed by impaired gas exchange, and acute respiratory failure. When intubated sheep, on mechanical ventilation, were positioned so that the trachea and the tracheal tube were maintained horizontal, or with a slight incline downwards, and then mechanically ventilated for 72 h, there was no tracheal, bronchial, or lung parenchymal bacterial colonization. However, the transfer of pathophysiologic findings of pulmonary research in sheep, to human pathology, is difficult due to the different anatomical and physiologic conditions in ruminants and omnivores (such as the total amount of saliva produced per day, length of the trachea, oropharyngeal-rumen flora, etc.). We hence also studied mechanically ventilated omnivores (pigs), under general anesthesia and enteral feeding for 72-168 hours. This study showed that our findings in sheep, also apply to pigs. 5: Collaboration with medical research centers: Supported, by our laboratory finding to prevent VAP in 2 different animal models, we are now collaborating with 3 medical research centers (1. Massachusetts General Hospital - Drs. Zapol, Bigatello, Berra; 2. The University of Milan, Italy - Dr. Pesenti; 3. NIH Clinical Intensive Care Unit - Dr. Masur). We wish to start a multricenter trial on whether our approach to prevent VAP is feasible, safe, and effective in the critically ill human patient.