Preventing Ventilator-Associated Pneumonia - The Role of the Endotracheal Tube

The endotracheal tube, rather than the ventilator, is responsible for the vast majority of cases of ventilator-associated pneumonia (VAP). Tracheal intubation should be avoided, or early extubation performed, if at all possible. With current high-volume low-pressure (HVLP) cuffs, pulmonary aspiration of microorganisms from the upper aerodigestive tract normally occurs and is frequently silent, until there is a clinical respiratory deterioration. Aspiration occurs by 3 mechanisms; channels within the HVLP cuff, in folding of the cuff upon movement and intermittent deflation of the cuff. This aspiration is the pivotal step in the development of VAP. The diagnosis of VAP is notoriously inaccurate and stifles the progress of research into prevention strategies. When treating bacteria present in the lung, the various paradigms of VAP diagnosis remain the only (and best) tools that we have to decide when the benefits of antibiotics outweigh the disadvantages. It is surprising, considering the accepted high mortality and cost of VAP, that until recently, there has been a massive under investment from industry in preventative technologies. New technologies should address the multiple factors implicated in the pathogenesis of VAP, including aspiration elimination by improved cuff designs. However, surrogate outcomes, such as pulmonary aspiration and tracheal colonisation (a more rigorous standard to aspire to), should be considered when evaluating preventative strategies. Pulmonary aspiration and/or tracheal colonisation by pathogenic organisms are undesirable and should be unacceptable. This review appraises the role of the endotracheal tube in both the development and prevention of VAP.