Novel Preventive Strategies for Ventilator-associated Pneumonia

Abstract

Ventilator-associated pneumonia (VAP) is a complication of mechanical ventilation and is defi ned as the occurrence of pneumonia in patients undergoing mechanical ventilation for at least 48 hours. Clinical suspicion of VAP arises when new infi ltrates are present on chest x-ray, and at least one of the following is present: Fever, leukocytosis, or purulent tracheo-bronchial secretions.Th e incidence of VAP reported in the literature ranges from 15 to 20% [1]. However, the real incidence of VAP is diffi cult to assess, given the extreme variability of the diagnostic criteria for pneumonia, which often rely on broncho scopic procedures. Th e specifi c mortality attribu table to VAP is also debated. Th e reported VAPassociated mortality ranges from 20 to 70%. Patients with VAP are often critically ill, and survival may be aff ected both by underlying conditions and the new-onset VAP. A recent study demonstrated a relatively limited attributable intensive care unit (ICU)-mortality of VAP, about 1-1.5%, when adjusting for severity of co-existing diseases [2]. In the last few years, various strategies have been investigated in order to reduce the incidence of VAP. Reducing the duration of intubation, oral and endotracheal tube (ETT) care, positioning, and ETT modifi cations are aspects that may have a role in the prevention of VAP. Many of these strategies have been incorporated into 'VAP bundles' , a set of treatments implemented simultaneously to reduce VAP incidence. Recent studies suggest that the use of bundle treatments can result in substantial reductions in rates of VAP [3].In this chapter, we will present some novel VAP prevention strategies, explaining the possible mechanisms by which they may be clinically benefi cial in reducing the incidence of VAP. A summary of these novel strategies is given in Table 1. Reduce duration of intubationTh e risk of developing VAP increases with prolonged intu bation, and reintubation is a known risk factor [4]. Th is fact suggests that the presence of the ETT, although necessary for the survival of the patient, interferes with the normal physiological mechanisms that maintain the airways free of bacterial contamination. When the ETT is in place, the cough refl ex is impaired and normal mucociliary fl ow is blocked by the infl ated cuff . Th e ETT itself allows bacteria to drain into the trachea and distal airways leading to pneumonia. Intubated patients may be more prone to develop VAP as compared to tracheostomized patients because the ETT keeps the trachea and the oropharynx in communication, acting as a bridge for bacteria to move toward the dependent airways. Aspiration of pathogens from the oropharynx in patients with subglottic dysfunction may occur both during extubation and reintubation. Th e rate of reintubation can be reduced by a variety of measures, including avoiding accidental removal of the ETT, improving planned extubations with weaning protocols designed to improve extubation success, and use of non-invasive ventilation (NIV).On the basis of the observatio...

Anaesthesiology and intensive care Possibilities of modification of risk factors for ventilator-associated pneumonia (VAP) in cardiac surgery patients

“…It should be remembered, however, that the endotracheal tube establishes a direct connection between the oropharyngeal cavity (colonized by bacterial flora) and the lower respiratory tract. For this reason, some authors believe that performing early tracheostomy (6-8 days after intubation), in comparison to late tracheostomy (14 days after intubation), may reduce the risk of VAP; however, this has not yet been unequivocally confirmed by clinical studies [13][14][15][16]. The intubation tube should be prevented from being accidentally removed, as reintubation further increases the risk of pneumonia [4, 14 17].…”

“…silver ions), which prevents the formation of bacterial biofilm inside the tube [13,17,[20][21][22]. However, the recommendations included in the guidelines are not unequivocal in this respect [15].…”

“…The search for new methods or procedures for VAP prevention includes the evaluation of the potential significance of new technological solutions, such as endotracheal tubes with ultrathin or modified (low-volume/low-pressure) cuffs, as well as the maintenance of constant pressure in the tube cuff, the removal of biofilm from the tube lumen with mucus shavers and the routine administration of physiological saline before suctioning of secretions from the trachea [13,15,22,[24][25][26]. It may also be beneficial to employ tubes with cuffs made of polyurethane or other materials (elastane, silicone, latex) instead of PVC, as well as tubes with different cuff shapes, in order to ensure better leak tightness [27][28][29].…”

“…In order to reduce the risk of gastric aspiration, the patient should be maintained in a semirecumbent position, with the chest and head raised (30-45°); a flat dorsal position should be avoided [1,4,9,13,30]. According to the literature, VAP is 3 times more likely to occur in patients lying in a flat dorsal position than in those placed in a semirecumbent position [31].…”

“…Some recent reports suggest that placing the patient in a lateral position may be more effective in preventing the aspiration of secretion from the subglottic area and VAP development than placing them in a semirecumbent position [13,22,32]. Clinical studies are currently being conducted in order to explain this issue and, perhaps, modify the recommendations.…”