Nosocomial Pneumonia. Bacteriacidal Tracheal Tubes

我们利用绵羊模型进一步阐明了预防气管插管患者院内肺炎的因素，以及对机械通气(MV)的影响。 1.临床上广泛应用的声门下分泌物连续抽吸术(CASS)没有任何益处，而且与严重的气管粘膜损伤有关。 2.在短短的24小时内，如现在的临床操作一样放置头部，然后拔管，在没有任何不良临床发现的情况下，在接下来的2天内，肺部细菌定植、菌血症暴发和医院内肺炎的高发生率是相关的。 3.绵羊气管插管涂布磺胺嘧啶和洗必泰，机械通气24小时后，机械通气机的气管导管、隔水器、吸气、呼气管路均未见细菌生长。这一初步发现是第一个关于机械通气24小时后呼吸机回路中没有细菌生长的报告。 4.结合我们早先的发现，当气管和气管管位于水平以下时，在气管和肺部没有细菌生长，我们的发现提出了机械通风过程中的预防措施，这对于确定呼吸机系统以及上呼吸道和下呼吸道是否有细菌定植是重要的。

We have further elucidated factors that prevent nosocomial pneumonia in patients intubated, and on mechanical ventilation (MV), using the sheep model. 1. CASS (continuous aspiration of subglottic secretions), now widely practiced clinically, was shown to be of no benefit, and was associated with significant tracheal mucosal injury. 2. A brief 24 h of MV, with head positioned as now clinically practiced, followed by extubation was associated (and in the absence of any adverse clinical findings) with high probability of significant bacterial colonization of the lungs, bursts of bacteremia, and high incidence of nosocomial pneumonia during the subsequent 2 days. 3. When sheep were intubated with tracheal tubes coated with silver sulfadiazine and chlorhexidine, and mechanically ventilated for 24 h, there was no bacterial growth in the tracheal tube, in the water trap, or in the inspiratory and expiratory lines of the mechanical ventilator. This preliminary finding is the first report of absence of bacterial growth in the ventilator circuit after 24 h of MV. 4. Combined with our earlier findings showing absence of bacterial growth in the trachea, and in the lungs, when the trachea and the tracheal tube were oriented below horizontal, our findings suggest preventive measures during mechanical ventilation that can be of importance in determining the presence/absence of bacterial colonization of the ventilator system, and of the upper and lower respiratory tracts.