Our study demonstrated that there was a low incidence of VAP in patients intubated with the PneuX System, there were no complications associated elective exchange to the PneuX System and intermittent SSD and decontamination of the subglottic space, the larynx, the pharyngeal space and the oral cavity can be performed reliably and safely using the PneuX System.
Previously, the incidence of VAP has been estimated to be much higher in general intensive care patients . The low incidence of VAP in this study may be explained by the fact that the PneuX System minimises a patient's exposure to multiple risk factors for VAP . The relative contribution of each strategy has not been quantified. Therefore, we do not attribute the low incidence of VAP to one strategy in particular.
This is the first article to demonstrate that elective reintubation can be performed safety in the critically ill. However, it should be noted that reintubation per se has not been shown to increase the incidence of VAP. The link between reintubation and VAP has only been demonstrated following premature extubation, which may be an accidental extubation or an intentional planned extubation with the subsequent failure of ventilation . Premature extubation leaves the lungs unprotected against pulmonary aspiration. In this setting, premature extubation has been estimated to increase the relative risk of VAP by 5.3 times . Our results suggest that it may be safe to electively exchange a conventional ETT to the PneuX System. This may not be applicable to all other devices. The PneuX System is a flexible armoured tube and has an atraumatic boat-tip . These features have been shown to ease reintubation over an introducer and passage through the glottis when compared to a conventional ETT, which is more rigid and has a bevel tip .
Our study also demonstrated that intermittent SSD can be performed reliably and safely using the PneuX System. Other SSD compatible devices have a single subglottic drainage port have been shown to fail on 48% of occasions, most commonly because of blockage of the subglottic drainage port by suctioned tracheal mucosa . The PneuX System has three circumferential subglottic drainage ports, which allow drainage to proceed through the two unoccluded ports should one of them become obstructed by suctioned tracheal mucosa .
Other SSD compatible devices also have conventional high volume low pressure cuffs, which have been shown to allow subglottic secretions to leak around the cuff . Consequently, continuous aspiration has been used to prevent the accumulation of secretions above the cuff. However, this may produce ischaemic injury to suctioned tracheal mucosa and therefore intermittent drainage is commonly used [16, 17]. In contrast, the PneuX System has a unique LVLP cuff, which has been shown to completely prevent pulmonary aspiration [10, 15]. Consequently, it is safe to allow subglottic secretions to build up above the cuff and perform intermittent SSD.
The superior performance of the LVLP cuff also enables decontamination of the subglottic space, the larynx, the pharyngeal space and the oral cavity to be performed using supracuff irrigation with a large volume of normal saline. It was notable that once subglottic drainage had been performed to dryness, a residual offensive collection of upper airway fluid (estimated at 10-30 mL) remained in the laryngopharynx. This residual material was only cleared by irrigation with large volumes of normal saline (up to 300 mL).
An important limitation of this study was that the incidence of VAP before introducing the PneuX System was unknown. Therefore, the impact of introducing the PneuX System could not be quantified. The retrospective nature of our study and the small number of patients included in our analysis from a single institution also represent weaknesses of our study. However, these represented all of the available patients at the time. In light of this exciting pilot data, we now hope to confirm our findings in prospective, multicentre studies with larger patient groups and in independent centres.
In conclusion, our study demonstrates that a low incidence of VAP is possible using the PneuX System. Our study also demonstrates that elective exchange and intermittent subglottic secretion drainage can be performed reliably and safely using the PneuX System.