Discuss the etiology of ventilator-associated pneumonia (VAP).
Discuss the historical methods used to define VAP.
Discuss the implications of surveillance for ventilator-associated events.
Describe appropriate care of the airway and ventilator circuit to avoid the development of VAP.
Discuss role of oral hygiene in the mechanically ventilated patient.
Discuss the impact of noninvasive ventilation, spontaneous awakening trials, spontaneous breathing trials, and patient position on the development of VAP.
Discuss the role of the gastrointestinal tract to minimize the risk of VAP.
Although the term ventilator-associated pneumonia (VAP) implies that the ventilator is the cause of the nosocomial pneumonia, a more appropriate term is artificial airway-associated pneumonia. Although contamination of the ventilator circuit may cause VAP, the most common cause is aspiration of contaminated oral secretions (Figure 4-1). VAP has become an increasing concern because it is not only associated with increased cost, but also with increased time on the ventilator, morbidity, and possibly mortality. It has been estimated that VAP results in an additional cost of about $50,000 per case. Thus third-party payers are evaluating whether the hospital should assume the cost of this iatrogenic infection. Therefore, VAP has become a major concern for hospitals, physicians, respiratory therapists, and nurses caring for ventilated patients. There has been much investigation of risk factors for VAP and effective strategies to decrease VAP rate. In this chapter the definition of VAP, causes of VAP, and strategies to reduce VAP are discussed.
Computed tomography taken from above the cuff of the endotracheal tube. Note the accumulation of secretions above the cuff (arrow), which can potentially be aspirated into the trachea.
Ventilator Circuit Versus the Artificial Airway
VAP is the result of organisms introduced into the respiratory tract during mechanical ventilation. This can arise from the ventilator circuit or by aspiration of contaminated secretions from above the cuff of the artificial airway. If a clean circuit is used and the patient is never disconnected, the organisms that accumulate in the circuit arise from the patient. However, if the circuit is disconnected and care is not taken to avoid contamination, the circuit could potentially cause VAP. This, however, is less likely to occur than the aspiration of contaminated oropharyngeal secretions.
The primary source of VAP is the aspiration of contaminated oropharyngeal secretions around the airway cuff (Figure 4-2). This occurs because of longitudinal folds that develop in inflated cuffs. To minimize this leakage, it is important to avoid accumulation of secretions above the cuff and to ensure that gastric contents do not move into the pharynx.
(A) Diagram illustrating folding of an artificial airway cuff creating a channel allowing fluid to move past the cuff. (B) Simulated microaspiration using dye ...