As frontline caregivers, ICU nurses can help their ventilated patients avoid VAP. To do this, you need to know how VAP develops, which prevention strategies are recommended, and why it’s critical to follow the guidelines.
Mechanical ventilation is a core component of supportive therapy for critical care patients who cannot breathe adequately on their own. Yet while a ventilator is often a lifesaving measure, it can frequently cause complications, including the nosocomial infection known as ventilator associated pneumonia, or VAP – defined as an airway infection that develops more than 48 hours after the patient was intubated (which indicates that it wasn’t present or developing at the time of intubation).
VAP is one of the most commonly acquired infections in the ICU, second only to catheter associated urinary tract infections (CAUTIs). It is the most fatal of the hospital acquired infections, with higher mortality rates than either central line infections or sepsis. Ventilated patients who develop VAP have mortality rates of 45 percent, compared to 28 percent for ventilated patients who do not develop VAP.
Strikingly, VAP adds an estimated $40,000 to the hospital bill – putting this complication under the scrutiny of the Centers for Medicare and Medicaid Services (CMS), although the government agency has not yet declined to reimburse for VAP, because it’s not entirely clear that it can always be prevented.
VAP occurs when there is a bacterial invasion of the pulmonary system in a patient receiving mechanical ventilation. The primary risk factor is the endotracheal tube itself – it can provide a direct passageway for airborne pathogens into the lungs, or act as a reservoir for pathogens by providing a place for biofilm to form or secretions to pool. The endotracheal tube also cancels out many of the body’s protective mechanisms – for example, it prevents the patient from coughing, which is a natural defense for clearing secretions that may otherwise be aspirated.
Patients who are elderly or immune compromised are at increased risk of VAP, as are those with an existing pulmonary illness (COPD, asthma, emphysema). Other risk factors include prolonged duration of ventilation, feeding by nasogastric tube, maintaining patients in a supine position, and staff non-compliance with handwashing and other infection control protocols.
Prevention Strategies for Nurses
Core strategies for preventing VAP focus on interrupting the three most common mechanisms by which it develops: the aspiration of secretions, the colonization of the aerodigestive tract, and the use of contaminated equipment. (Core strategies are defined by the CDC as those that are backed by high levels of scientific evidence and have demonstrated feasibility.)
The CDC recommends using non-invasive, positive-pressure ventilation (delivered continuously via a face or nose mask) instead of intubation wherever possible and minimizing the duration of ventilation. Proactive surveillance of ventilated patients is needed, particularly by nursing and respiratory therapy staff.
Three of the core recommendations for VAP prevention are autonomous nursing interventions, which you can practice every day in the ICU.
- Practicing good hand hygiene is essential – clean your hands with soap and water or an alcohol-based rub before touching the patient or the ventilator.
- Maintaining the patient’s oral hygiene can help to prevent bacterial colonization of the endotracheal tube. Regular care with an antiseptic solution is recommended, although specific practices are not defined.
- Unless there are contraindications, maintain the patient in a semirecumbent position, with the head of the bed elevated at an angle of 30 to 45 degrees, to help prevent aspiration. An analysis of risk factors associated with VAP found up to a 67 percent reduction in its incidence in patients maintained this way during the first 24 hours of intubation. Another randomized study of 86 ventilated patients found that those maintained in the semirecumbent position had a VAP incidence of only five percent, compared to 23 percent for the supine patients. And many other observational or randomized studies have confirmed the impact of patient position – while indicating that the preferred, semirecumbent position is rarely maintained.
There are other VAP prevention strategies that will fall mainly to respiratory therapy staff, but that nurses should be aware of, as members of a multi-disciplinary care team:
- A key concern is that secretions accumulate above the cuff on the endotracheal tube – and since the tube prevents the glottis from closing, these secretions can be aspirated or can leak into the lungs. Suctioning them is difficult because they can’t be reached by typical oral suctioning methods, so the CDC recommends a device known as a CASS tube which provides constant suction of oral secretions. Research indicates the device greatly lowers the chance of VAP.
- CDC guidelines also recommend using orotracheal rather than nasotracheal intubation, unless contraindicated. Nasal tubes can cause sinus infections, which can result in pathogens reaching the lower respiratory tract.
- Some studies suggest that proton pump inhibitors (Prevacid, Prilosec), which are commonly prescribed to prevent stress ulcers and gastritis in ICU patients, may increase the risk of VAP, by changing the acidity of the aerodigestive tract and making it more susceptible to bacterial colonization. Joint recommendations issued by SHEA and IDSA suggest avoiding PPIs whenever possible, but indicate that the preferential use of sucralfate (brand name Carafate) instead of PPIs is considered by the CDC to be an unresolved issue.
- The joint SHEA/IDSA guidelines also recommend a protocol to lighten sedation at regular intervals, in order to assess for neurological readiness to wean the patient from ventilation. (For ICU nurses, this will require increased monitoring and vigilance, as lightly sedated patients may be at increased risk of pain, anxiety, or attempts to self-extubate.) A randomized trial of 128 ventilated patients demonstrated that daily interruption of sedation resulted in a significant reduction of time on ventilation – decreasing the duration from 7.3 days to 4.9 days.
The CDC’s latest recommendations can be found in Guidelines for Preventing Health-Care-Associated Pneumonia.
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