Ventilator-associated pneumonia (VAP) continues to complicate the course of 8 to 28% of patients receiving mechanical ventilation (MV). In contrast to infections of more frequently involved organs (e.g., urinary tract and skin), for which mortality is low, ranging from 1 to 4%, the mortality rate for VAP ranges from 24 to 50% and can reach 76% in some specific settings or when lung infection is caused by high-risk pathogens. The predominant organisms responsible for infection are Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacteriaceae, but etiologic agents widely differ according to the population of patients in an intensive care unit, duration of hospital stay, and prior antimicrobial therapy. Because appropriate antimicrobial treatment of patients with VAP significantly improves outcome, more rapid identification of infected patients and accurate selection of antimicrobial agents represent important clinical goals. Our personal bias is that using bronchoscopic techniques to obtain protected brush and bronchoalveolar lavage specimens from the affected area in the lung permits physicians to devise a therapeutic strategy that is superior to one based only on clinical evaluation. When fiberoptic bronchoscopy is not available to physicians treating patients clinically suspected of having VAP, we recommend using either a simplified nonbronchoscopic diagnostic procedure or following a strategy in which decisions regarding antibiotic therapy are based on a clinical score constructed from seven variables. Selection of the initial antimicrobial therapy should be based on predominant flora responsible for VAP at each institution, clinical setting, information provided by direct examination of pulmonary secretions, and intrinsic antibacterial activities of antimicrobial agents and their pharmacokinetic characteristics. Further trials will be needed to clarify the optimal duration of treatment and the circumstances in which monotherapy can be safely used.

Ventilator-associated pneumonia.

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

/pdf/management-of-adults-with-hospital-acquired-and-ventilator-3akbwaj5yj.pdf

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

This Task Force was supported and endorsed by the following Societies: European Respiratory Society, European Society of Intensive Care Medicine, European Society of Clinical Microbiology and Infectious Diseases and European Society of Anaesthesiology.

⇓In the last decade, considerable investigational efforts have been made in the field of the management of ventilator-associated pneumonia (VAP). Several studies have provided important insights into the relationship of histology and bacteriology of VAP, which remain fundamental for all future research. Moreover, epidemiological research has allowed establishment of concepts for empiric initial antimicrobial treatment that are expected to improve clinical outcomes. Important contributions have also been made regarding prevention of VAP.



Fig. 1.— 

However, despite these advances, the majority of issues related to the management of VAP remain unresolved and are subject to controversy. This is particularly true for the diagnostic evaluation of the patient with suspected VAP. The lack of consensus regarding the best way to diagnose VAP explains in part why incidence rates vary widely from one study to another, from 5 to >50% of mechanically ventilated intensive care unit (ICU) patients.

In this review, a panel of experts in the field of VAP from four European societies has tried to provide an overview of the most important aspects under debate. In order to stimulate further research and discussion, presentation of the main topics was focussed on the breaking current knowledge. The issue of attributable mortality, which is also a matter of controversy, will not be addressed in this review. Each section of the review has been written in an attempt to answer three main questions: 1) what is not controversial, 2) what is still controversial and 3) what should be investigated? The following topics were reviewed: clinical diagnosis, bacteriological and histological aspects, aetiology, diagnostic techniques, antimicrobial treatment and prevention.

#### What is not controversial?

Clinical criteria for the diagnosis …

https://erj.ersjournals.com/content/erj/17/5/1034.full.pdf

Ventilator-associated pneumonia

Background The diagnosis and treatment of bacterial pneumonia in patients who are receiving mechanical ventilation remain a difficult challenge. The triggering receptor expressed on myeloid cells (TREM-1) is a member of the immunoglobulin superfamily, and its expression on phagocytes is specifically up-regulated by microbial products. The presence of soluble TREM-1 (sTREM-1) in bronchoalveolar-lavage fluid from patients receiving mechanical ventilation may be an indicator of pneumonia. Methods We conducted a prospective study of 148 patients receiving mechanical ventilation in whom infectious pneumonia was suspected. A rapid immunoblot technique was used to measure sTREM-1 in bronchoalveolar-lavage fluid. Two independent intensivists who were unaware of the results of the sTREM-1 assay determined whether community-acquired pneumonia and ventilator-associated pneumonia were present or absent. Results The final diagnosis was community-acquired pneumonia in 38 patients, ventilator-associated pneumonia in 46 ...

https://www.nejm.org/doi/pdf/10.1056/NEJMoa031544

Soluble triggering receptor expressed on myeloid cells and the diagnosis of pneumonia

The Influence of Mini-BAL Cultures on Patient Outcomes : Implications for the Antibiotic Management of Ventilator-Associated Pneumonia

The purpose of this prospective postmortem study was to assess the diagnostic accuracy of bronchoscopic techniques (bronchoalveolar lavage [BAL] and protected specimen brush [PSB]) and nonbronchoscopic techniques (blind bronchial sampling [BBS] and mini-BAL) in the diagnosis of ventilator-associated pneumonia (VAP). The results of each technique were compared with histology and culture of lung tissue specimens obtained by surgical pneumonectomies in 38 patients who died after at least 72 h of mechanical ventilation. Histology was positive for VAP in 18 patients and negative in 20 patients. There were 12 definite VAP (positive histology and positive lung cultures) and 6 histologic VAP (positive histology and negative cultures). Clinical pulmonary infection score (CPIS) at a threshold of 6 achieved a sensitivity of 72% and a specificity of 85%. When the CPIS was combined with the logarithmic concentration of the predominant microorganism obtained from the BBS sample culture, specificity was increased to 95%, for a threshold of 10. Using 10(3) cfu/ml as the threshold of positivity for cultures obtained with PSB and mini-BAL samples and 10(4) cfu/ml for cultures obtained with BBS and BAL, the respective sensitivities of these techniques for definite VAP were 42, 67, 83, and 58%. The sensitivity of BBS was significantly higher than that of PSB (p < 0.05). The area under the receiver operator characteristic curve was significantly greater for BBS than PSB (p < 0.05). Given that it is more sensitive and noninvasive, BBS is preferable to PSB for the diagnosis of VAP.

Bronchoscopic or blind sampling techniques for the diagnosis of ventilator-associated pneumonia.

This is a prospective, postmortem study to determine the accuracy of various bronchoscopic and non-bronchoscopic techniques in the diagnosis of ventilator-associated pneumonia. The authors prospectively studied patients who died in their intensive care unit. Within 15 minutes of death, patients underwent first blind bronchial sampling (BBS), then mini-bronchoalveolar lavage, protected specimen brush (PBS), and bronchoalveolar lavage. The specimens obtained from each study were cultured in a similar way. Within 30 minutes of death, a pneumonectomy was performed at the bedside under sterile conditions while maintaining mechanical ventilation. Either the right or left lung was removed, depending on the area of infiltrate on chest film. Six to 10 specimens were obtained aseptically and cultured. Histologic examination was performed on the lung to look for histologic evidence of bronchopneumonia. Ventilator-associated pneumonia was considered definite if histology exhibited signs of bronchopneumonia and lung tissue culture was positive. Ventilator-associated pneumonia was considered histologic if the histology was positive but the lung culture was negative. During the 2-year period of the study, a total of 146 patients died in the intensive care unit, but only 38 were included in the study. The other 118 patients were excluded for a variety of reasons, including autopsy not available within 30 minutes of death, sampling techniques not performed within 15 minutes of death, and immunocompromised hosts. Of the 38 patients in the study, 21 were receiving antibiotics at the time of death. Four had been on antibiotics that had been discontinued for 72 hours or more before death, and 13 were on no antibiotics during the hospitalization or on no antibiotics during the 7 days preceding death. On histology, 18 of the 38 patients had evidence of bronchopneumonia. Half of these 18 patients had moderate pneumonia, and half had evidence of severe pneumonia. Twenty patients had no evidence of bronchopneumonia. Twelve of the 18 patients with evidence of bronchopneumonia had positive cultures from the lung tissue. None of the lung tissue from the 20 patients without histologic evidence of bronchopneumonia yielded bacteria. In comparing the results of the various sampling techniques with diagnoses of definite ventilator-associated pneumonia, BBS had the greatest sensitivity and acceptable specificity at ≥104 organisms per milliliter. PBS had a sensitivity of only 42% at the ≥103 level but a 95% specificity. When the sampling techniques were compared in the 18 patients with definite or histologic evidence of ventilator-associated pneumonia and the 20 patients without ventilator-associated pneumonia, BBS maintained very good sensitivity and specificity at ≥104 organisms. PBS had a sensitivity of only 33% at ≥103 organisms but a 95% specificity. Another interesting result of the study was that clinical characteristics of the patients, including post-surgical status, previous trauma, simplified acute physiologic score, APACHE II score, McCabe score, body temperature, white blood cell count, Po2, Pco2, and radiologic score were not able to distinguish patients with pneumonia from those without pneumonia. Interestingly, the duration of mechanical ventilation did appear to differ significantly; patients with pneumonia were ventilated for 12.7 ± 9 days versus those without pneumonia, who were actually ventilated longer, at 33.1 ± 34.6 days. The only clinical measure which appeared to be discriminatory was the clinical pulmonary infection score (CPIS). Patients with pneumonia had a CPIS significantly higher than did those without pneumonia. At a CPIS of 6, the overall accuracy of the measure for the diagnosis of pneumonia was 79%. The sensitivity of a CPIS ≥6 was 72%, and its specificity was 85%. When the sum of the CPIS and logarithmic concentration of the organisms obtained in culture from BBS samples was >10, the specificity was 95%, and the sensitivity was 67%.

I. Guignon

Papers

Bronchoscopic or blind sampling techniques for the diagnosis of ventilator-associated pneumonia.

Bronchoscopic or Blind Sampling Techniques for Diagnosis of Ventilator-Associated Pneumonia

Diagnostic des bronchopneumopathies nosocomiales histologiquement prouvées: Comparaison de différentes techniques de prélèvement

Infections pulmonaires, opportunistes multiples compliquant l'évolution d'une histiocytose X