VENTILATOR ASSOCIATED PNEUMONIA

Ventilator associated pneumonia (VAP) is a common and major complication during mechanical ventilation, leading to increasing morbidity, mortality and cost.Accurate clinical diagnosis remains problematic. Difficulties in diagnosis of VAP have led to the development of new diagnostic techniques such as bronchoalveolar lavage and the bronchoscopic protected specimen brush.The development of preventative strategies depends upon an understanding of the pathogcnesis of VAP. The pathogenesis begins with upper airway and gastrointestinal colonisation, laryngopharyngeal pooling of secretions, then aspiration past the tracheal tube cuff leading to the over­whelming of compromised lung defences. The recent development of tracheal tube cuff prototypes that prevent aspiration are promising and need further evaluation.Useful preventative strategies include: strict infection control procedures; improvements in upper airway hygiene: the avoidance of nasal intubation; the use of sucralfate, rather than gastric alkalinisation; infrequent ventilator circuit changes; and possibly heat and moisture exchange filters and kinetic beds.Appropriate antimicrobial treatment of an established VAP requires early empirical therapy based on a knowledge of the epidemiology of early- and late-onset pneumonia, local pathogen patterns, recent antibiotic treatment, under­lying lung disease and recent microbiological cultures, followed by the use of narrow-spectrum antibiotics after organism identification.All the practical difficulties of diagnosing and treating pneumonia in patients undergoing artificial ventilation have encouraged a more detailed investigation of the determinants of VAP in the hope of developing more successful preventive strategies in the near future.