Ventilator-associated and hospital-acquired pneumonia
Ventilator-associated pneumonia (VAP) is pneumonia that develops 48 hours or longer after mechanical ventilation is given by means of an endotracheal tube or tracheostomy. Ventilator-associated pneumonia (VAP) results from the invasion of the lower respiratory tract and lung parenchyma by microorganisms. Intubation compromises the integrity of the oropharynx and trachea and allows oral and gastric secretions to enter the lower airways.
Ventilator-associated pneumonia (VAP) is a complication in as many as 28% of patients who receive mechanical ventilation. The incidence of VAP increases with the duration of mechanical ventilation. Estimated rates are 3% per day for the first 5 days, 2% per day for days 6-10, and 1% per day after day 10. Outcomes are also related to the timing of the onset of VAP. Early-onset pneumonia occurs within the first 4 days of hospitalization, whereas late-onset VAP develops 5 or more days after admission. Late-onset pneumonias are usually associated with multidrug-resistant (MDR) organisms. CLINICAL PRESENTATION OF VAP
The patient's medical history should include an assessment for risk factors related to multidrug-resistant (MDR) pathogens. Such risk factors include the following:
Current hospitalization admission of greater than 5 days
Hospital admission more than 2 days in the preceding 90 days Antibiotic use in the previous 90 days
Residence in a nursing home or extended-care facility
Home infusion therapy and wound care
Long-term dialysis within 30 days
This assessment is important so that appropriate empiric antibiotics can be initiated before bacterial culture results return. If appropriate empiric antibiotics are selected, the subsequent adjustment of antibiotics does not improve the patient's mortality risk.
The diagnostic triad for VAP consists of the following clinical criteria:
Pulmonary infection: Signs include fever, purulent secretions, and leukocytosis Bacteriologic evidence of pulmonary infection
Radiologic suggestion of pulmonary infection
When the combination of radiologic infiltrates and 2 clinical criteria are observed, the sensitivity of diagnosing VAP is 69% and the specificity is 75%
Intubation with mechanical ventilation increases the risk of hospital-acquired pneumonia (HAP) 3- to 21-fold[6, 7, 8, 9] and should be avoided if possible. Noninvasive positive-pressure ventilation is an option to consider, especially in the following groups:
Patients with exacerbations of chronic obstructive pulmonary disease Patients with acute hypoxic respiratory failure
Patients with immunosuppression and respiratory failure
Orotracheal and orogastric tubes are preferred over nasal devices to reduce the risk of ventilator-associated pneumonia (VAP), although direct causality has not been proven.
Continuous aspiration of subglottic secretions reduces the risk of early-onset VAP. Results of a randomized, controlled trial showed a significant reduction in VAP (relative risk reduction of 42%), including late-onset VAP, when subglottic secretion drainage was performed while patients were on mechanical ventilation. Cuff pressures should be maintained at greater than 20 cm of water to prevent aspiration around the endotracheal tube.
Passive humidifiers or heat moisture exchangers are preferred to reduce colonization of the ventilator circuit. Ventilatory-circuit condensation should be prevented from entering the endotracheal tubes and any inline nebulizer. Frequent changes of the ventilator circuit, however, have not been shown to reduce the risk of VAP and are currently not recommended.
Protocols for sedation and weaning should be applied in the ICU to reduce the duration of mechanical ventilation. Pathophysiology
Feeding, positioning and Aspiration
Placing patients in a...