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Managing Suspected Ventilator-Associated Pneumonia
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What is the problem and what is known about it so far?
Patients connected to mechanical ventilators (“breathing machines”) sometimes develop lung infection. This is known as ventilator-associated pneumonia. Ventilator-associated pneumonia is hard to diagnose because patients on ventilators can develop the usual clinical findings of pneumonia (x-ray changes, fever, bronchial secretions, and bacteria in the respiratory tract) for many reasons other than pneumonia. Treating patients with antibiotics when they do not really have ventilator-associated pneumonia subjects them to the potential side effects and expense of the drugs. Some experts have recommended using invasive tests to diagnose ventilator-associated pneumonia rather than relying on clinical findings. The invasive tests involve inserting an instrument called a bronchoscope into the patient's respiratory tract to obtain samples of lung fluid and tissue. This potentially risky and expensive procedure has never been proven to improve patient outcomes.
Why did the researchers do this particular study?
To find out whether a strategy that involves invasive tests to diagnose ventilator-associated pneumonia is better than a strategy that relies on clinical findings.
Who was studied?
From 31 intensive care units in France, the researchers studied 413 patients suspected of having ventilator-associated pneumonia.
How was the study done?
The researchers randomly assigned patients to the use of either invasive diagnostic tests or clinical findings to guide the diagnosis and treatment of suspected ventilator-associated pneumonia. They then followed these patients to see who died or developed complications involving the heart, kidneys, lungs, nervous system, liver, or blood clotting. They also measured antibiotic use at 14 and 28 days.
What did the researchers find?
After accounting for baseline differences in the groups, patients who underwent the invasive tests were less likely than those in the clinical findings group to have died or suffered organ failure at 14 days. The advantage of using the invasive approach was less clear at 28 days, but the patients who had invasive tests still did better. The invasive strategy patients also had more antibiotic-free days than the clinical findings group.
What were the limitations of the study?
In this study, the doctors were aware of which group the patients were in, which could have influenced the way they prescribed antibiotics. In addition, the tests used to look for bacteria in lung fluids (cultures) in this study may differ from the ones used at other hospitals.
What are the implications of the study?
This study suggests that patients who undergo invasive tests to diagnose and manage suspected ventilator-associated pneumonia do better and spend fewer days taking antibiotics than patients in whom diagnosis and management is guided only by clinical findings.
Article and Author Information
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The summary below is from the full report titled “ Invasive and Noninvasive Strategies for Management of Suspected Ventilator-Associated Pneumonia. A Randomized Trial”. It is in the 18 April 2000 issue of Annals of Internal Medicine (volume 132, pages 621-630). The authors are.-Y. Fagon, J. Chastre, M. Wolff, C. Gervais, S. Parer-Aubas, F. Stéphan, T. Similowski, A. Mercat, J.-L. Diehl, J.-P. Sollet, and A. Tenaillon, for the VAP Trial Group.
- Copyright ©2004 by the American College of Physicians
