Vol. 12 •Issue 10 • Page 19
Unlocking an Effective Approach to Ventilator-associated Pneumonia
Although ventilator-associated pneumonia is common, controversies abound in regards to its prevention, diagnosis and treatment. No universal definition of VAP exists, neither does a definitive list of risk factors. There’s also disagreement as to the role that anaerobes play, and the choice and duration of antibiotics is open to debate.
Clinicians must learn to navigate these controversies because much is at stake. VAP is the most frequent infection in the intensive care unit and the leading cause of death from nosocomial infection.1,2 It’s associated with increased ICU and hospital length of stay and adds significantly to hospitalization costs.
When planning an approach to VAP in your facility, you’ll need to strategize. Think about definitions. Focus on protocols. Use antibiotics appropriately. And don’t forget the small things because many times they can make a world of difference.
To come up with a uniform plan for handling VAP, clinicians should first take into account their facility’s characteristics. It doesn’t matter whether you work at a large university academic center or a rural community hospital. Take stock of what personnel and capabilities are available to you because a single physician can’t start a VAP program on his or her own.
A collaborative effort involving physicians, nursing, respiratory therapy and pharmacy is essential. For a program to work, it helps to have a physician “champion” to drive the process, but you need buy-in from all involved parties.
Our group practices pulmonary medicine at two community hospitals. Each has family practice residency programs, but there isn’t internal medicine subspecialty training. They offer all tertiary care services, including neurosurgery, cardiothoracic and trauma, though organ transplantation requires referral to larger academic centers. The hospitals have a mixed medical-surgical ICU, cardiac care unit and cardiothoracic ICU. They operate with a semi-open admissions policy in that any physician may admit to the ICU if they meet certain criteria, but critical care consultation is mandatory under specific instances.
Each of these characteristics of a facility may influence how you formulate your team. For example, hospitals that perform organ transplantation must be concerned about the different types of organisms that can infect immunocompromised patients.
The ICU medical director participates on the infection control committee. He reviews trends in VAP rates among the various ICUs in our hospital and looks for changing patterns in the causative bacteria. The infection control nurse, along with respiratory therapy, tracks all patients on mechanical ventilation, documents the cases of VAP, and calculates the incidence.
Through all our efforts, the VAP rate in our ICU has been about 50 percent that of a comparative national database over the past two years.
Several disputed issues surround VAP, and a major one is its definition. In a ventilator patient, for instance, the typical findings of increased secretions and a new infiltrate on chest X-ray can be seen in entities other than pneumonia, such as congestive heart failure and atelectasis. Fever and leukocytosis also may be absent.
Some physicians define VAP based on different quantitative bronchoscopic culture techniques using protected specimen brushing or bronchoalveolar lavage. Others use qualitative sputum culture. The sensitivity and specificity of these methods depends on the patient population and whether the patient was already taking antibiotics.
Likewise, different studies quote different risk factors. Some of these risk factors include advanced age, poor nutritional status, chronic obstructive pulmonary disease, trauma and underlying severity of illness.3
We define VAP usually on clinical grounds, meaning any significant positive culture (sputum, bronchoscopic or blood) in a setting the clinician feels is compatible with VAP. While many might disagree with this definition, the point is we apply it consistently when determining our VAP case rate. We routinely review this data at committee meetings, looking for trends and comparing it to national averages.
Choice and duration of antibiotics is another area of debate, as there are no absolutely agreed upon one-size-fits-all regimens. Some would suggest the duration of treatment depends on the severity of the pneumonia, the time to clinical improvement and the organism involved. For example, 21 days of therapy may be needed for treatment of resistant gram-negative organisms.
Whether the pneumonia is early or late onset is a key factor. Patients who acquire their infection shortly after admission tend to get typical community-acquired organisms, such as Streptococcus pneumoniae and Haemophilus influenzae, whereas patients who become infected after approximately .five days tend to get more aggressive organisms, such as Pseudomonas aeruginosa, Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA).
For early onset VAP, monotherapy may suffice. This may include a second-generation cephalosporin, a nonpseudomonal third-generation cephalosporin, a beta-lactam antibiotic with a beta-lactamase inhibitor, or a fluoroquinolone, especially if the patient is penicillin-allergic.
For late onset VAP, we worry about more resistant organisms and use antibiotics such as piperacillin/tazobactam, third-generation cephalosporins with antipseudomonal coverage, or a carbapenam. Many clinicians advocate combination therapy in these instances. If your hospital has a high incidence of MRSA, or if the patient has certain risk factors, consider vancomicin.
Once cultures have returned, though, it’s worthwhile to consider narrowing your antibiotic therapy to those organisms specifically identified. This concept is known as de-escalation of therapy.4 Rotating antibiotic use or restricting use of certain antibiotics may lead to less antibiotic resistance, thought it’s uncertain if this results in improved long-term outcomes.
Our microbiology lab and infectious .disease (ID) physicians track organisms involved and the antibiotic susceptibility patterns. The ID physicians print summaries every six months and distribute them to staff.
A local epidemiologic surveillance program such as this is important so as to customize a facility’s treatment.4 When choosing antibiotics, you need to realize that susceptibilities vary widely not just across the country, but within hospitals in the same city, between the ICU and regular floor patients, and even between different ICUs in the same hospital.
To stop patients from getting VAP in the first place, clinicians can take a number of preventive measures. This includes elevating the head of the bed of intubated patients to prevent aspiration, which may lead to pneumonia. The use of a specialized endotracheal tube with continuous aspiration of subglottic secretions may lessen VAP frequency by preventing aspiration of pooled secretions. A specialized bed with lateral rotation may help to clear secretions and prevent VAP, too.
Clinicians should be aware that nasogastric tubes might lead to sinusitis and increase the risk for VAP. On the other hand, prescribing sucralfate rather than antacids or H2 blockers for stress gastric ulcer prophylaxis may result in lower VAP rates. This occurs because the latter two agents affect gastric pH more and alter the gastric flora.
Issues directly related to respiratory therapy include therapist-driven weaning protocols, which may hasten the time to extubation and thus decrease VAP. Our hospital uses a postoperative weaning protocol. In a stable patient, the bedside nurse may suggest the protocol to the physician. The respiratory therapist then follows an algorithm to extubation. If the patient fails the protocol, the physician is notified and decides whether or not to try again later or request formal pulmonary consultation.
Also, the ventilator tubing may be a source of bacterial contamination, so the therapist and bedside nurse must be careful not to spill condensate into the endotracheal tube when turning the patient or adjusting the bedrails.
Some have thought that placing bacterial filters in respiratory circuits will decrease the VAP rate. However, a recent article stated this didn’t decrease the incidence of respiratory infections associated with mechanical ventilation and wasn’t necessary.5
Keep in mind that heat-moisture exchangers may be associated with lower VAP than heated humidifiers, and that there’s no advantage to frequent ventilator circuit changes for VAP prevention.3 As a result, some hospitals have implemented a policy of no or infrequent changes, a move that will save money as well as improve outcomes.
Other preventative measures like selective decontamination of the digestive tract (using a combination of intranasal, topical oral and intravenous antibiotics to sterilize the upper aerodigestive tract) remain controversial and aren’t well accepted in the United States.
The simplest preventative measure, handwashing, is the one most consistently missed. Its importance can’t be stressed enough.
In conclusion, clinicians should pick a definition of VAP and apply it consistently. Involve others in your program and share data with your medical staff. Track cases because surveillance helps. And adjust your antibiotic prescribing patterns to fit local susceptibility patterns.
Lastly, recognize that some relatively simple measures can be implemented to prevent VAP. Consider incorporating many of these into standard order sets so that care is applied consistently.
Dr. Chinsky has been in private practice with Chest Diseases of Northwestern Pennsylvania since 1991. He’s also the medical director of the ICU at St. Vincent Health Center in Erie, Pa.
For a list of references, please call John Crawford at (610) 278-1400, ext. 1499, or visit www.Respiratory-care-sleep-medicine.advanceweb.com.