September 2, 2008
Updates on VAP Prevention
Ventilator-associated pneumonia (VAP) remains a serious cause of morbidity, mortality and cost in our ICU’s. VAP occurs in 25-30% of mechanically ventilated patients and has mortality rates of 20-70%, though mortality may be primarily due to underlying conditions. Mortality attributable to VAP itself has been estimated as 7.3% and the attributable extra hospital stay 10 days, with an extra cost of $15, 986 per episode of VAP (Hugonnet et al 2004). Other cost estimates attributable to VAP have ranged from just under $12, 000 (Warren 2003) to over $40,000 (Rello 2002)
Several new articles relevant to prevention of ventilator-associated pneumonia (VAP) have appeared in recent weeks.
NICE just released an evidenced based guidance on technical patient safety solutions for prevention of ventilator-associated pneumonia. This had two primary evidence-based conclusions:
· Mechanically ventilated patients who are intubated should be positioned with their upper body elevated (in a semi-recumbent or seated position) for as much of the time as possible. For some patients this will not be appropriate (for example, those with spinal injuries).
· Oral antiseptics (for example, chlorhexidine) should be included as part of the oral hygiene regimen for all patients who are intubated and receiving mechanical ventilation.
The also noted that evidence suggests that selective decontamination of the digestive tract (SDD) using topical antibiotics may reduce the incidence of VAP also reduce mortality. However, concerns about the risk of infection with Clostridium difficile and the induction and/or selection of resistant, including multiresistant, microorganisms as a result of SDD kept them from recommending this. They also noted that a lack of robust evidence prevented any recommendations for the use of kinetic beds. They did note that although the evidence supported the use of elements of care bundles, there was insufficient evidence to recommend a care bundle of any specific design.
Our own comment on bundles is that they are an excellent way to get a group involved to change behavior and reach a desired outcome. The literature is replete with examples of how adopting a multicomponent intervention may achieved desired outcomes, even though one may not know which individual components of that intervention are most successful. Many hospitals are already using IHI’s VAP Bundle. The key components of that bundle are:
Note that the PUD prophylaxis remains controversial since the evidence of its effect on the incidence and severity of VAP remains conflicting. Also, the DVT prophylaxis is a general intervention for most ICU patients rather than being specifically a VAP-prevention measure.
Even a focused educational intervention can significantly reduce the incidence of VAP (Zack 2002).
The second major recent VAP prevention item was an article on use of silver-coated endotracheal tubes to prevent VAP that appeared in the August 20, 2008 issue of JAMA (Kollef et al 2008). That article showed the silver-coated endotracheal tubes led to a relative risk reduction for VAP of 36% in patients who were intubated for at least 24 hurs. Certainly sounds impressive! However, closer scrutiny of the article raises numerous questions. The rationale for using silver-coated endotracheal tubes makes good sense from a biological standpoint. The diagnosis of VAP was based on quantitative culture of bronchoalveolar fluid if VAP was suspected on the basis of radiographic findings or other clinical signs including fever or hypothermia, leukocytosis or leukopenia, or purulent tracheal aspirate. However, when one looks at the data, the absolute risk reduction for VAP was only 2.7% and the NNT (number needed to treat) to prevent one case of VAP was 37. More importantly, the silver-coated endotracheal tube group showed no improvement in mortality, duration of intubation, or ICU or total LOS. Data on antibiotic use or costs was not provided.
Other issues with the study were lack of standardization of other interventions (in both the control and silver arms), single blinding (the investigators were not blinded), relatively low rates of VAP in both the silver and control groups, a disproportionate percentage of patients with COPD in the control group, a low percentage of patients able to provide informed consent, and industry funding for the study. Note also that the “supplemental” information referred to in the article (having to do with criteria for diagnosis of VAP) is not downloadable from the website address provided in the article.
So we are left with an intervention that requires a large NNT and fails to improve any of the really important clinical outcomes. Call us skeptics! Before you run out and purchase these new silver-coated endotracheal tubes, we suggest you await further RCT’s that demonstrate improvement in the clinically relevant outcomes, not just reduction of bacteriologic outcomes. We think JAMA dropped the ball on this one, though the accompanying editorial takes a much more guarded and conservative view of the results.
We are very surprised at the conclusions of this paper. The authors of this paper are well respected and have published numerous excellent articles on both the pathophysiology and prevention of ICU infections. This is not one of them. We’re going to start using this article when we teach our students and residents how to read journal articles and differentiate true evidence-based medicine from “industry spin”. Had this been sponsored by a neutral organization, such as NIH, the title of this one would have read “Silver-Coated Endotracheal Tubes Fail to Reduce Mortality, Ventilator Time, ICU or Hospital LOS, or Resource Utilization”. And the first half of the comment section would not have been spent touting the benefits of the device tested. And it would not flout that preventing cases of VAP could save many lives and up to $40,000 per case when, in fact, the device tested saved no resources and was associated with more deaths (though not statistically significant).
While silver-coated endotracheal tubes may someday be shown in good randomized controlled double-blinded studies to impact on clinically relevant outcomes, we’ll wait for those studies before jumping on board.
Hugonnet S, Eggimann P, Borst F, Maricot P, Chevrolet J-C, Pittet D. Impact of Ventilator-Associated Pneumonia on Resource Utilization and Patient Outcome.
Infection Control and Hospital Epidemiology 2004; 25(12): 1090–1096, Dec 2004 http://www.journals.uchicago.edu/doi/pdf/10.1086/502349
Warren DK, Shukla SJ, Olsen MA, et al. Outcome and attributable cost of ventilator-associated pneumonia among intensive care unit patients in a suburban medical center. Crit Care Med. 2003;31:1312-1317 http://www.ccmjournal.com/pt/re/ccm/abstract.00003246-200305000-00003.htm;jsessionid=L66RdxRLr4JQcQ1nKtQRC95nT60Nlhf3rD0vbmyy0JdQtSK1VjP9!-1705959712!181195629!8091!-1
Rello J, Ollendorf DA, Oster G, Vera-Llonch M, Bellm L,
Redman R, Kollef MH.
Epidemiology and Outcomes of Ventilator-Associated Pneumonia in a Large US Database. Chest, Dec 2002; 122: 2115 - 2121. http://www.chestjournal.org/cgi/reprint/122/6/2115?maxtoshow=&HITS=25&hits=25&RESULTFORMAT=1&author1=rello&andorexacttitle=and&andorexacttitleabs=and&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT
Rello J, Lorente C, Diaz E, et al. Incidence, etiology, and outcome of nosocomial pneumonia in ICU patients requiring percutaneous tracheotomy for mechanical ventilation. Chest. 2003;124:2239-2243 http://www.chestjournal.org/cgi/reprint/124/6/2239?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=1&author1=rello+j&andorexacttitle=and&andorexacttitleabs=and&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT
Zack JE, Garrison T, Trovillion E, et al. Effect of an education program aimed at reducing the occurrence of ventilator-associated pneumonia. Crit Care Med. 2002;30:2407-2412 http://www.ccmjournal.com/pt/re/ccm/abstract.00003246-200211000-00001.htm;jsessionid=L8xVLZYC3pPJWVnLhXkW1l6RzkG9gKnYWvkQL1nNyM90h2Q1vhyF!-711215224!181195629!8091!-1?index=1&database=ppvovft&results=1&count=10&searchid=1&nav=search
NICE. PSG002 Technical patient safety solutions for prevention of ventilator-associated pneumonia in adults: guidance. 27 August 2008 http://www.nice.org.uk/nicemedia/pdf/PSG002Guidance.pdf
Kollef MH. Afessa B. Anzueto A. Veremakis C. Kerr KM. Margolis BD. Craven DE. Roberts PR. Arroliga AC. Hubmayr RD. Restrepo MI. Auger WR. Schinner R. NASCENT Investigation Group. Silver-coated endotracheal tubes and incidence of ventilator-associated pneumonia: the NASCENT randomized trial. JAMA 2008; 300(7):805-13 http://jama.ama-assn.org/cgi/content/abstract/300/7/805
Chastre, Jean MD Preventing Ventilator-Associated Pneumonia: Could Silver-Coated Endotracheal Tubes Be the Answer?. JAMA 2008; 300(7):842-844 http://jama.ama-assn.org/cgi/content/extract/300/7/842
Update: See our November 11, 2008 Patient Safety Tip of the Week “Probiotics and VAP Prevention”, January 2009 What’s New in the Patient Safety World “Preventing Infections in the ICU” and our February 16, 2010 Patient Safety Tip of the Week “Spin/Hype…Knowing It When You See It”.