Seven strategies to prevent VAP: a look at the evidence Why some popular approaches, from handwashing to good oral hygiene, may not be as evidence-based as you think by Bonnie Darves
Published in the May 2005 issue of Today's Hospitalist
As hospitalists increasingly find themselves in the ICU, either to back up intensivists or to take over primary management of medical patients, they are confronting the vexing problem of how to prevent ventilator-associated pneumonia (VAP).
VAP has garnered so much attention because of its effects on morbidity, mortality and costs. Even when aggressively treated, for example, the condition adds an average of four to nine days to ICU stays.
"We need to focus on the intervention that we know do work, not on what might work."
Peter Dodek, MD St. Paul's Hospital
amount of controversy, in part because there is so much debate over which clinical interventions work, and which don’t. There are significant differences in how VAP is prevented in North America and Europe, for example, that reflect not only differences in medical practice, but different interpretations of the medical literature.
To shed some light on the topic, Today’s Hospitalist talked to specialists in both critical care and pulmonary medicine, as well as internists and hospitalists with VAP expertise. We asked them to weigh in on tried-and-true VAP prevention strategies, as well as promising—and controversial—interventions to prevent the condition.
Some strategies like good hand hygiene are considered to be effective but widely underused. Despite the fact that there have been no randomized trials that have directly proven the effectiveness of handwashing to prevent VAP, most experts say that complying with the CDC’s hand-hygiene guidelines is an excellent starting point.
When appropriate, using noninvasive mask ventilation is still one of the best ways to prevent VAP, particularly when treating patients with COPD. But for a variety of reasons, experts say, physicians often don’t take full advantage of this strategy.
These approaches, however, are just the tip of the iceberg when it comes to preventing VAP. The short list of interventions in this article examines practices that address three key areas in VAP prevention: avoiding upper-airway colonization, shortening the duration of mechanical ventilation, and limiting antimicrobial resistance.
We start by examining strategies that are best supported by evidence and move on to strategies that may be effective, but are either controversial or poorly supported by the literature.
1. Semirecumbent positioning. While the literature strongly supports the benefits of elevating the heads of ICU patients’ beds between 30 and 45 degrees, the strategy remains underutilized. In part, that may be because of debate about just how much elevation is needed.
With the exception of certain fracture and post-neurosurgery patients and those with severe hypotension, however, experts say that elevating the head of the bed for these patients is safe and effective. That’s why they urge physicians to use the strategy, even if they’re not sure exactly what degree of elevation to use.
“Even 30 degrees is better than zero,” explains Dr. Saint. “We don’t want the perfect to become the enemy of the good.” “This is so simple, it has biological plausibility, and it doesn’t cost anything,” Dr. Wenzel says. “It’s mind-boggling that it doesn’t get done in many ICUs. And it won’t happen until clinicians say it’s a measure the ICU will be graded on.”
The good news is that simple strategies can drastically improve compliance. Dr. Boiteau, for example, says that the Canadian ICU Patient Safety Collaborative made elevating the heads of these patients’ beds a priority in “bundles” '74hat focused on VAP prevention.
“After we included bed head elevation in our VAP-prevention bundle of interventions,” Dr. Boiteau explains, “adherence went up dramatically. Some of our teams are consistently successful 90 percent of the time now.”
The trick is to constantly jog the memories of providers—and that includes both physicians and nurses—to make sure the heads of these patients’ beds are elevated.
“You need a persistent reminder—head of the bed elevation is included on our ventilator/critical care order set—to make this happen,” says Dr. Dressler. “My whole perspective as a hospitalist is that interventions will be consistently underused unless you create a mechanism for processes, as either a forced function or at least a forced thought.”
(Dr. Dressler points out that Emory’s VAP-prevention protocol also includes oral care procedures, aspiration precautions, hand hygiene, and spontaneous breathing trial, when appropriate.)
2. Sedation vacation and weaning assessment. It is wellestablished that the sooner patients are extubated, the lower their risk of developing VAP. One of the most effective ways to make sure that patients are extubated as soon as possible is to time sedation vacations—a six- to eight-hour daily period when sedating drugs are withheld, as appropriate—with daily spontaneous breathing trials and extubation-readiness assessment.
In some Canadian ICUs, Dr. Boiteau notes, that assessment occurs twice a day. Instead of relying on physicians to remember the assessment, the trick is to make sure that the assessment is part of a process. “You have to set up a process that guarantees that this assessment will occur every day,” Dr. Boiteau says.
“The sedation vacation is probably underutilized because it takes some work,” notes Dr. Sessler. “You need a tightly designed weaning protocol and a team approach among physicians, nurses and respiratory therapists to make it happen in a safe fashion.”
Experts note, however, that patients who are experiencing alcohol withdrawal or those with status asthmaticus may not be good candidates for early sedation vacations.
3. Continuous subglottic secretion removal. Several trials support the benefits of using tubes that continuously drain these secretions. That includes relatively new tubes that are fitted with separate dorsal lumens above the cuff and allow for easier suctioning.
Experts acknowledge, however, that this strategy presents several challenges. Correct placement and management, for example, requires a skilled provider team, because pressure of the tube cuff must be adequate to prevent secretion leakage into the lower airway.
In addition, some early-generation tubes have been associated with malfunction problems. And the tubes—the newest ones are silver-coated—are also more expensive than standard suction tubes.
Despite the tubes’ higher cost, there is a solid business case for using them. “These tubes cost a little more,” Dr. Dodek says, “but five level-II trials support their effectiveness. If you can prevent one case of VAP and save 4.3 ICU days, which is a conservative estimate, it’s clearly worth the extra expense.”
Another issue? These tubes are recommended primarily for patients who are likely to remain on ventilators for three days or longer, and they need to be inserted early on.
“These look very effective, but one challenge is that the tubes really need to be inserted from the beginning of intubation,” says Dr. Sessler. “They can be changed, but that carries some risk.”
Dr. Saint says that these barriers may make it challenging to convince your hospital to embrace them, but they still hold much potential. “We would prefer to see a definitive long-term multicenter trial evaluating these tubes,” he notes. “Until then, they’re still a reasonable idea.”
If you can overcome those barriers, however, experts say, you can expect generally good results. “We’re using these tubes system- wide now,” Dr. Boiteau says, “with good success.” (He notes, however, that the tubes are not yet being used in the OR.)
4. Oral vs. nasal feeding tubes.A growing body of evidence suggests that oral tubes may be better than nasal tubes in preventing VAP, Dr. Boiteau notes, but the evidence is largely inferential. The theory, which has been supported by published studies, says that oral tubes reduce sinusitis, a condition that is associated with the development of VAP in a number of patients.
“It’s best to avoid using nasal tubes whenever possible,” Dr. Sessler says, “because of the risk of sinus infection. Nasal tubes prevent normal drainage of the sinuses.”
Some experts acknowledge that the evidence may be a little unclear, but they urge physicians to consider the strategy anyway. “Even though the evidence for this [tube choice] is weaker,” Dr. Boiteau says, “we’ve included this intervention in our VAP bundle. Extrapolations from other studies have shown higher rates of VAP in patients with nasal tubes.”
5. Targeted oral hygiene with use of oral chlorhexidine gluconate washes. While experts acknowledge that there is little evidence directly tying enhanced oral hygiene practices to reduced VAP—strategies like stimulation of the gums, toothbrushing and use of oral washes—they say the practices are so benign and inexpensive that they are worth trying.
These strategies, for example, have proven effective in reducing pneumonia in nursing home patients. And while chlorhexidine washes are a relatively new area of study, the fact that these agents have reduced VAP in cardiac-surgery patients may have ramifications for ICU patients in general, even if there is not yet any direct evidence that it produces the same results in typical ICU patients.
“There is some evidence that the use of rinses and washes reduce infection,” Dr. Dressler says, “so we added that [intervention] the last time we modified our ventilator order set.”
Dr. Wenzel adds that not only is the strategy easy to implement, but it’s inexpensive. “It has biological plausibility and it’s been effective in reducing pneumonia in nursing homes,” he says. “That should translate well to the ICU.”
“We have an aggressive regimen for oral hygiene because we know that the bacterial flora replicate,” Dr. Boiteau says, “and there’s always a chance of micro-aspiration.”
(Dr. Sessler does note that in rare cases, patients have had hypersensitivity reactions to the washes.)
6. Stress ulcer prophylaxis. This intervention recently received a nod from the Institute for Healthcare Improvement, in part because the use of sucralfate has been shown to reduce gastric bleeding and VAP.
Other agents such as H2 blockers, antacids and proton-pump inhibitors may offer similar effects, but experts say that studies looking at these strategies have been underpowered. In general, the role of gastric pH in development of VAP remains poorly understood, and the practice could increase infection risks in some patients.
“Using agents to prevent stress gastritis should occur only in patients at high risk,” Dr. Saint explains. “These medications change the flora of the stomach, making it more basic and therefore a more viable venue for bacteria.”
Dr. Saint says that many physicians were more positive about sucralfate to prevent VAP until more recent research questioned their effectiveness.
7. Selective digestive tract decontamination. While this practice is widely used to prevent VAP in Europe, experts say that it doesn’t translate well to North America. The problem has to do with well-known antibiotic-resistance issues in ICUs.
“There is some new literature on this,” Dr. Dodek says, “so it’s something we will revisit. We’re not sure this is ready for prime time.”
For hospitalists who are trying to choose VAP-prevention interventions and promote their routine use—especially where a targeted protocol is lacking—Dr. Dodek urges a stepwise approach. Even starting with the evidence-based basics—semirecumbent positioning, orotracheal rather than nasal intubation and subglottic secretion drainage—can make a big difference in the short term.
“We need to focus on the interventions that we know do work, not on what might work,” says Dr. Dodek, who was lead author of the VAP-prevention clinical practice guideline published in the Aug. 17, 2004, Annals of Internal Medicine.
Bonnie Darves is a freelance writer specializing in health care. She is based in Lake Oswego, Ore.
Two strategies are better than one: “bundling” VAP prevention strategies
If there’s strength in numbers, there may also be benefits in “bundling” strategies to prevent ventilator-associated pneumonia (VAP). That’s the experience of the national Canadian ICU Patient Safety Collaborative, which several years ago began promoting bundles of interventions instead of giving a stamp of approval to individual strategies.
“Choose four or five interventions and bundle them,” suggests Paul Boiteau, MD, head of critical care for the Calgary Health Region and faculty advisor on VAP prevention to the collaborative. “It’s easier to do, easier to remember, and easier to garner people around a theme. It’s also easier to get the hospital CEO’s approval for funding interventions if you’re using a bundle approach that’s well-supported by evidence.”
The Canadian collaborative’s bundle includes the following strategies:
• Semirecumbent positioning.
• Sedation vacation and daily assessments of readiness for extubation.
• New-generation endotracheal tubes and continuous subglottic-secretion drainage.
• Oral, not nasal, gastric tubes.
• Aggressive oral hygiene.
The approach has helped reduce rates of VAP, with one center seeing up to a seven-fold decrease in the condition and others making impressive progress toward reducing VAP incidence.
As part of its “100,000 Lives” campaign, which promotes collaborative participation in hospital-based and ICU quality-improvement initiatives, the Institute for Healthcare Improvement (IHI) has tackled VAP as one of six areas that hospitals can address to reduce inpatient morbidity and mortality.
The Boston-based group has “bundled” four interventions that, combined, could improve outcomes for mechanically ventilated patients. Hospitalists can use the bundle to propel efforts to bolster VAPprevention protocols in their facilities.
The IHI VAP-prevention bundle includes the following strategies:
• Semirecumbent patient positioning, to at least 30 degrees.
• Ventilator weaning, via periodic sedation vacations and daily assessment of extubation readiness.
• Peptic ulcer disease (PUD) prophylaxis.
• Deep-vein thrombosis (DVT) prophylaxis.
“The bundle was developed in an effort to pick things that are relatively easy to do that will have a significant impact [on mechanically ventilated patients],” says David Calkins, MD, MPP, a fellow at IHI and a general internist at Massachusetts General Hospital.
He notes that the four-item focus is “not intended to rule out interventions that might have benefit,” but rather to promote reliability—ensuring that all elements are done for every patient for whom they’re appropriate.
When the IHI first announced its VAP bundle, some experts questioned what they viewed as obvious omissions. The CDC and others, for example, have recommended strategies including orotracheal intubation, closed endotracheal suction systems that allow for continuous subglottic secretion drainage, use of oral rather than nasal endotracheal tubes, and targeted oral hygiene practices, possibly including use of chlorhexedine gluconate washes.
Some experts also have wondered why some of the recommended interventions, such as PUD and DVT prophylaxis, are included, given that they’re a bit far afield from VAP.
“The IHI bundle is conceptually attractive, but I’m not aware of any literature that says DVT and PUD prophylaxis, though they’re good strategies for other purposes, help prevent VAP,” says Peter Dodek, MD, lead author of the VAP-prevention guidelines published in the Aug. 17, 2004, Annals of Internal Medicine.
Dr. Dodek says that the inclusion of the sedation vacation, despite the lack of a strong direct link to VAP reduction, is probably a good move. He says that any practice that supports earliest possible ventilator weaning could reduce VAP rates.
Dr. Calkins acknowledges that the bundle includes some elements that aren’t directly related to VAP, such as the PUD and DVT prophylaxis. “The bundle was originally developed with a broader focus, to reduce complications among all patients in ICU settings,” he says. “The components are all things that, individually, have been shown to reduce adverse outcomes.”
Dr. Calkins also notes that the Society of Critical Care Medicine and the Joint Commission on Accreditation of Healthcare Organizations have endorsed the VAP bundle.