Abstract
Microaspiration of subglottic secretions through channels formed by folds in high volume-low pressure poly-vinyl chloride cuffs of endotracheal tubes is considered a significant pathogenic mechanism of ventilator-associated pneumonia (VAP). Therefore a series of prevention measures target the avoidance of microaspiration. However, although some of these can minimize microaspiration, benefits in terms of VAP prevention are not always obvious. Polyurethane-cuffed endotracheal tubes successfully reduce microaspiration but high quality data demonstrating VAP rate reduction are lacking. An analogous conclusion can be made regarding taper-shaped cuffs compared with classic barrel-shaped cuffs. More clinical data regarding these endotracheal tube designs are needed to demonstrate clinical value in addition to in vitro-based evidence. The clinical usefulness of endotracheal tubes developed for subglottic secretions drainage is established in multiple studies and confirmed by meta-analysis. Any change in cuff design will fail to prevent microaspiration if the cuff is insufficiently inflated. At least one well-designed trial demonstrated that continuous cuff pressure monitoring and control decrease the risk of VAP. Gel lubrication of the cuff prior to intubation temporarily hampers microaspiration through sludging the channels formed by folds in high volume-low pressure cuffs. As the beneficial effect of gel lubrication is temporarily, its potential to reduce VAP risk is probably nonsignificant. A minimum positive end-expiratory pressure of at least 5 cmH2O can be recommended as it reduces the risk of microaspiration in vitro and in vivo. One randomized controlled study demonstrated a reduced risk of VAP in patients ventilated with PEEP (5–8 cmH2O). Regarding head-of-bed elevation, it can be recommended to avoid supine positioning. Whether a 45° head-of-bed elevation is to be preferred above 25-30° head-of-bed elevation remains unproven. Finally, the routine monitoring of gastric residual volumes in mechanically ventilated patients receiving enteral nutrition cannot be recommended.
Highlights
Ventilator-associated pneumonia (VAP) remains a feared complication in intensive care unit (ICU) and high-risk surgical postoperative patients [1]
The prevention of VAP is focused on reducing the exposure time, maintaining oral hygiene by antiseptic rinsing, and avoidance of microaspiration [20,21,22]
The objective of this paper is to briefly review measures to avoid microaspiration of subglottic secretions and to evaluate their effectiveness in doing so and in preventing VAP
Summary
Ventilator-associated pneumonia (VAP) remains a feared complication in intensive care unit (ICU) and high-risk surgical postoperative patients [1]. Accumulation of oropharyngeal secretions colonized with these pathogens occurs above the endotracheal tube (ETT) cuff. Microaspiration of these subglottic secretions might occur through an underinflated tracheal cuff or through longitudinal folds in high volume-low pressure cuffs. The prevention of VAP is focused on reducing the exposure time, maintaining oral hygiene by antiseptic rinsing, and avoidance of microaspiration [20,21,22]. Several preventive measures have been developed to decrease the risk of microaspiration Some of these successfully reduced microaspiration, their potential to reduce VAP is not always proven.
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