The tracheal tube: gateway to ventilator-associated pneumonia

Abstract

Ventilator-associated pneumonia (VAP) is a major healthcare-associated complication with considerable attributable morbidity, mortality and cost. Inherent design flaws in the standard high-volume low-pressure cuffed tracheal tubes form a major part of the pathogenic mechanism causing VAP. The formation of folds in the inflated cuff leads to microaspiration of pooled oropharyngeal secretions into the trachea, and biofilm formation on the inner surface of the tracheal tube helps to maintain bacterial colonization of the lower airways. Improved design of tracheal tubes with new cuff material and shape have reduced the size and number of these folds, which together with the addition of suction ports above the cuff to drain pooled subglottic secretions leads to reduced aspiration of oropharyngeal secretions. Furthermore, coating tracheal tubes with antibacterial agents reduces biofilm formation and the incidence of VAP. In this Viewpoint article we explore the published data supporting the new tracheal tubes and their potential contribution to VAP prevention strategies. We also propose that it may now be against good medical practice to continue to use a 'standard cuffed tube' given what is already known, and the weight of evidence supporting the use of newer tube designs.

Figure 1

Diagram summarizing the pathogenic processes leading to ventilator-associated pneumonia (VAP; in black) and the preventative measures to combat each step (in red). Tooth brushing and chlorhexidine 2% washes help reduce oropharyngeal bacterial colonization [70]. The new generation of tracheal tubes forms the frontline barrier to reducing microaspiration by providing a better seal with the tracheal mucosa, allowing drainage of subglottic secretions and reducing colonisation of the lower respiratory tract.

Figure 2

Photograph of various bench tested tracheal tubes of different designs showing the internal channels created and the leak of liquid material past the cuff. Tube cuffs A and B are made from polyvinyl chloride, and cuffs C and D with thin polyurethane (C has an elongated cylindrical shape and D is a tapered cuff design). Tube E is the LoTrach™ ET tube. (Photograph courtesy of Dr Peter Young, Kings Lynn, UK.)

Figure 3

Endotracheal tube with subglottic suction port placed posteriorly and above the cuff for drainage of pooled secretion in the semi-recumbent position. Intermittent suction is applied to avoid ischaemic injury to the tracheal mucosa.