New tracheal tubes to prevent ventilator-associated pneumonia: where is the evidence?

against good medical practice to continue to use a ‘standard cuff ed tube’ given the weight of evidence supporting the use of newer tube designs to prevent ventilator-associated pneumonia (VAP). Th ere is strong evidence supporting the use of subglottic aspiration to prevent VAP [2]. However, other new tracheal tubes, such as polyurethane cuff ed, silver-coated, or low-volume low-pressure tubes, could not be recommended to prevent VAP in routine practice. Although recent studies found polyurethane-cuff ed tracheal tubes to be associated with signifi cantly reduced VAP rate, major limitations of these studies preclude defi nitive conclusions; these limitations include the use of subglottic aspiration [3], before/after study design [4], and clinical criteria to defi ne pneumonia [4,5]. One large multicenter study found the use of silvercoated tracheal tubes to be associated with signifi cant reduction in VAP rate [6]. However, limitations of this study should be taken into account, such as the signifi cant diff erence in the proportion of patients with chronic obstructive pulmonary disease between the two groups, and the small rate of late-onset VAP. Low-volume, low-pressure tracheal tubes were found to be associated with signifi cantly reduced leakage of blue dye in a randomized controlled study performed in a single ICU [7]. Similarly, some in vitro studies suggested benefi cial eff ects of conical shaped and guayule latex double-layered cuff s [8]. However, to date no randomized controlled study has evaluated the eff ect of these tubes on VAP prevention [9]. Th erefore, further well designed studies are required before recommending the use of new tracheal tubes in every critically ill patient requiring mechanical venti lation for longer than 24 hours.