Systemic Review: Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is difficult to diagnose, and the precise role of invasive testing is controversial. Confronted with a changing clinical or radiographic setting demanding specific therapy, clinicians increasingly use invasive testing to supplement their clinical judgment. Invasive techniques include the protected-specimen brush (PSB) technique and BAL.

The PSB technique was developed in 1987 by Wimberly et al¹ and has since been improved. Because it was found that samples may become contaminated by organisms of the upper airway, methods have been advanced to protect the sampling fluid. In addition, quantitative culture methods have been developed to permit distinguishing infection from colonization. However, because of concerns about diagnostic accuracy, reproducibility of results, diagnostic thresholds, nonstandardized methodology, and lack of data on clinical outcome, few definitive recommendations have been reached.^2,3

The Health and Science Policy Committee of the American College of Chest Physicians assembled a panel of scientific experts to develop diagnostic recommendations based on a rigorous review of the literature. The panel included experienced methodologists to ensure that the review process was justifiable and unbiased. Recommendations were developed through group discussion and were based on direct evidence, when it was available, and expert consensus opinion, when direct evidence was not available.

To implement the evidence-based assessment, the panel adopted the following grading system for most recommendations:

Grade A: Recommendation based on direct scientific evidence;
Grade B: Recommendation based on scientific evidence, supplemented by expert opinion;
Grade C: Recommendation based on expert opinion alone; and
Grade D: There is no definitive evidence or consensus opinion.

This manuscript covers the following topic areas:

Panel methodology;
Epidemiology of VAP;
Radiologic diagnosis of VAP;
Clinical criteria in the diagnosis of VAP;
Endotracheal aspiration sampling;
BAL sampling;
The PSB technique;
Blinded, invasive diagnostic procedures; and
Invasive procedures in nonresolving pneumonia.

This executive summary reports the panelists’ major conclusions and final recommendations. The reader may assess the thoroughness of the evaluation process and the validity of the conclusions by reviewing each section.

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