VAP/HAP

Hospital-acquired (or nosocomial) pneumonia (HAP) is pneumonia that occurs 48 hours or more after admission and did not appear to be incubating at the time of admission.  Ventilator-associated pneumonia (VAP) is a type of HAP that develops more than 48 to 72 hours after endotracheal intubation and the initiation of mechanical ventilation. It is probably caused by digestive tract colonization, followed by aspiration of contaminated secretions into the lower airways.  

Many of the risk factors for VAP increase the risk of colonization and aspiration, while most of the interventions to prevent VAP reduce colonization and aspiration.

Healthcare-associated pneumonia (HCAP) is defined as pneumonia that occurs in a non-hospitalized patient with extensive healthcare contact, as defined by one or more of the following:   Intravenous therapy, wound care, or intravenous chemotherapy within the prior 30 days, residence in a nursing home or other long-term care facility, hospitalization in an acute care hospital for two or more days within the prior 90 days, or attendance at a hospital or hemodialysis clinic within the prior 30 days

The guidelines can be accessed through the ATS web site at www.thoracic.org.

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PREVENTING VAP

Nebulizers can be incorporated into the ventilator circuit and used to deliver medications. However, they frequently become contaminated and might contribute to the development of VAP.

Use of a metered-dose inhaler probably eliminates this risk. Like a nebulizer, a metered-dose inhaler delivers aerosolized medication directly into the ventilator circuit. However, metered-dose inhalers do not become contaminated because they are not part of the ventilator circuit. Metered-dose inhalers are also less expensive, easier to use, and deliver a dose more reliably than nebulizers.

Decontamination of the digestive tract has been shown to decrease the colonization of bacteria in the upper respiratory tract. The methods used include antiseptics in the oropharynx and nonabsorbable antibiotics taken orally with or without systemic antibiotics.

Decontamination of the oropharynx — Gingival and dental plaque rapidly becomes colonized with aerobic pathogens in ICU patients due to poor oral hygiene and lack of mechanical elimination. A number of trials have evaluated the efficacy of decontamination of the oropharynx.

·                  Subglottic drainage. 

·                 Elevation of head.

·                 Maintaining an endotracheal tube airway cuff pressure that is adequate to prevent aspiration of contaminated secretions.

·                 Use of silver coated endotracheal tubes.

·                 Minimizing transport out of the ICU — Patients who are transported out of the ICU have an incidence of VAP that is three to four times that of patients who are never transported out of the ICU.

·                 Avoiding the need for reintubation.

·                 Use of Noninvasive instead of invasive mechanical ventilation whenever possible. (Positive end-expiratory pressure (PEEP) — The application of PEEP may decrease the incidence of VAP. In a trial that randomly assigned 131 mechanically ventilated patients to receive no PEEP or 5 to 8 cm H2O of PEEP, the PEEP group had a lower incidence of VAP (25-37%).  Positive tracheal pressure may act to oppose aspiration of pharyngeal secretions around the cuff of the endotracheal tube.

·                 Weaning protocols — Weaning protocols are recommended by many organizations, in order to reduce the duration of ventilation. This was illustrated by an observational study that found that the rate of VAP decreased from 15 percent to 5 percent after a weaning protocol was instituted.

The most significant risk factor for HAP is mechanical ventilation! In fact, many authors use the terms HAP and VAP interchangeably. Intubation increases the risk of pneumonia 6- to 21- fold. Other risk factors, which have emerged from multivariate analyses, include:

·                 Age >70 years

·                 Chronic lung disease

·                 Depressed consciousness

·                 Aspiration

·                 Chest surgery

·                 The presence of an intracranial pressure monitor or nasogastric tube

·                 H2 blocker or antacid therapy

·                 Transport from the ICU for diagnostic or therapeutic procedures

·                 Previous antibiotic exposure, particularly to third generation cephalosporins

·                 Reintubation or prolonged intubation

·                 Hospitalization during the fall or winter season

·                 Mechanical ventilation for acute respiratory distress syndrome

·                 Frequent ventilator circuit changes

·                 Paralytic agents

·                 Underlying illness

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