- Hospital-acquired pneumonia (i.e. pneumonia that begins 48 h or more after admission) is the leading cause of hospital acquired infection leading to mortality.
- VAP occurs 48 h or more after endotracheal intubation.
- Mechanical ventilation increases the risk of pneumonia due to micro-aspiration of oropharyngeal microorganisms via leakage around the endotracheal tube cuff or directly through the tube.
- Risk factors for VAP include: age over 70 years, chronic lung disease, depressed consciousness, and aspiration. The key modifiable factors increasing risk for VAP are previous antibiotic exposure, use of paralytic agents, re-intubation or prolonged intubation, frequent ventilator circuit changes, presence of a nasogastric tube, or intra-cranial pressure monitor. Local epidemiology varies significantly, but data from a large US study showed the major pathogens to be MRSA (14.8%), Pseudomonas aeruginosa (14.3%), and other Staphylococcus species (8.8%). A combination of clinical, microbiological, and radiological criteria is required for diagnosis. The principles of treating VAP include early antimicrobial therapy after appropriate specimens are taken (guided by the local microbiology), then de-escalation according to culture and susceptibility results. In many units this will result in empiric combination therapy to cover multi-resistant organisms. A total duration of 5-7 days of effective therapy is adequate for most pathogens, though most physicians would treat longer for Pseudomonas or true staphylococcal pneumonia. Prevention strategies include reducing need for ventilation, reducing colonization, and reducing aspiration.
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