Pneumonia Risk Lowered By Using Silver-Coated Tubes

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Main Category: Respiratory / Asthma
Also Included In: Ear, Nose and Throat
Article Date: 20 Aug 2008 - 0:00 PDT

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Patients in intensive care units who require mechanical ventilation are more likely to develop ventilator-associated pneumonia if they stay in hospitals longer. A new study published in the August 20 issue of JAMA reports that the use of a silver-coated endotracheal tube led to a reduction in the incidence of this type of pneumonia.

Ventilator-associated pneumonia tends to afflict patients with longer hospital stays, and the disease increases health care costs and makes patients more susceptible to infection from antibiotic-resistant pathogens. The development of this type of pneumonia occurs when pathogenic bacteria grow in the aerodigestive tract or when patients exhale contaminated secretions. "Prevention strategies often focus on modifiable risk factors for colonization and aspiration and can successfully reduce ventilator-associated pneumonia rates, but no single strategy completely eliminates ventilator-associated pneumonia," explain the authors. "Adherence to prevention guidelines is variable due to costs and lack of education, resources and leadership."

Since silver has blocked formation of harmful pathogens on ventilator tubes in animal studies and has displayed antimicrobial activity in the laboratory, Marin H. Kollef, M.D. (Washington University School of Medicine) and colleagues in the NASCENT Investigation Group conducted a trial to test its efficacy on humans. The randomized controlled trial consisted of 2,003 patients at 54 centers who were expected to require mechanical ventilation for at least 24 hours. Researchers randomly assigned the patients to undergo intubation with either a silver-coated tube or a non-coated tube with other similar characteristics. The study took place between 2002 and 2006.

The researchers based some conclusions on the 1,509 patients who were intubated for 24 hours or longer. They found that 4.8% of patients with silver-coated tubes and 7.5% of patients with uncoated tubes developed ventilator-associated pneumonia. This translates to a 35.9% relative reduction in risk for those using the silver-coated tube. When analyzing the 1,932 patients who were on ventilators for any length of time, 3.8% of patients using the silver-coated tubes and 5.8% of those using the uncoated tubes developed pneumonia - still a 34.2% relative reduction.

Further, patients with silver-coated tubes tended to develop ventilator-associated pneumonia later than patients with uncoated tubes. However, there were no significant difference between the two groups when measuring the median (midpoint) duration of intubation, length of stay in the intensive care unit (ICU) or in the hospital, death rates, or frequency and severity of adverse events.

"The results of this large, randomized, multicenter study demonstrated that the silver-coated endotracheal tube significantly reduced the incidence of microbiologically confirmed ventilator-associated pneumonia and had its greatest benefit during the peak time of ventilator-associated pneumonia occurrence, without any notable adverse events," conclude the authors. "The silver-coated endotracheal tube appears to offer a unique approach because it is the first intervention that becomes user-dependent after intubation, requiring no further action by the clinician."

An accompanying editorial written by Jean Chastre, M.D. (Groupe Hospitalier Pitie-Salpetriere, Paris) asked: "Based on the results of this trial, should clinicians reconsider guidelines for ventilator-associated pneumonia prevention and use a silver-coated endotracheal tube in all patients requiring intubation and mechanical ventilation in the ICU?"

Chastre opines that, "The answer is probably yes for the subset of patients at very high risk of developing early-onset ventilator-associated pneumonia, such as neurologically impaired patients or trauma patients, because the greatest effect of the intervention appeared to occur during the first 10 days of mechanical ventilation and was clinically relevant, with minimal effect on clinician workload."

"Important uncertainties exist regarding the exact benefit of silver-coated endotracheal tubes," concludes the researcher. "Consequently, silver-coated tubes should not be viewed as the definitive answer for ventilator-associated pneumonia prevention, and, until additional data confirm the clinical effectiveness and cost benefit of these devices, their issue should be restricted to high-risk patients treated in ICUs with benchmark value-based infection rates that remain above institutional goals despite implementation of a comprehensive strategy of usual preventive measures to prevent ventilator-associated pneumonia."

Silver-Coated Endotracheal Tubes and Incidence of Ventilator-Associated Pneumonia: The NASCENT Randomized Trial
Marin H. Kollef; Bekele Afessa; Antonio Anzueto; Christopher Veremakis; Kim M. Kerr; Benjamin D. Margolis; Donald E. Craven; Pamela R. Roberts; Alejandro C. Arroliga; Rolf D. Hubmayr; Marcos I. Restrepo; William R. Auger; Regina Schinner; for the NASCENT Investigation Group
JAMA(2008). 300[7]: pp. 805-813.
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Written by: Peter M Crosta
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