Clinical Criteria in the Diagnosis of Ventilator-Associated Pneumonia

Recent ventilator-associated pneumonia (VAP) guidelines recommend considering abbreviated therapy in patients with non−Pseudomonas aeruginosa VAP if clinical signs resolve. However, using an arbitrary day cutoff or clinical signs can be suboptimal for some, especially multiply injured patients, resulting in relapse and/or antibiotic resistance. Previously, we showed that repeat bronchoalveolar lavage (BAL) could guide antimicrobial duration for community-acquired VAP in trauma patients. The purpose of this study was to determine the appropriate duration of antimicrobial therapy for VAP in trauma patients secondary to hospital-acquired pathogens.

Patients with VAP secondary to MRSA, Pseudomonas aeruginosa (PA), Acinetobacter baumannii (AB), Stenotrophomonas maltophilia (SM), or Enterobacteriaceae (ENB) during 6 years were evaluated. All received empiric antimicrobial therapy based on duration of ICU stay. Therapy was tailored based on culture data. Repeat BAL was performed on day 4 of appropriate therapy. Microbiological resolution was defined as ≤10³ colony-forming units/mL. Recurrence was defined as ≥10⁵ colony-forming units/mL on subsequent BAL performed within 2 weeks after completion of appropriate therapy.

Six hundred and fifty-nine patients were identified. Seventy-seven percent of patients underwent repeat BAL: 96 with MRSA, 100 with AB, 139 with PA, 50 with SM, and 120 with ENB. The majority of patients with MRSA or PA achieved microbiological resolution after 14 days. Nearly 60% of patients with AB, SM, or ENB achieved microbiological resolution after 10 days. Overall recurrence was 2%.

Repeat BAL provides objective evidence for VAP resolution in the face of potentially confounding clinical factors. Hospital-acquired VAP can be managed effectively by a defined course of therapy with a low recurrence. Duration of antimicrobial therapy for VAP in trauma patients should be dictated by the causative pathogen.

Although there is a wealth of guidance concerning the management of patients with ventilator-associated pneumonia (VAP), compliance with recommendations concerning optimal treatment practices is highly variable.

This document presents a comprehensive care bundle package addressing all aspects of VAP diagnosis and treatment in an attempt to promote guideline-compliant practices. Uniquely, the development of these care bundles used a formalized method to assess the supporting data, based on multicriteria decision analysis.

This system allowed the numerous VAP management parameters identified from recent European guidelines to be ranked according to defined criteria. The resulting VAP care bundles are (a) diagnosis: early chest x-rays within 1 hour, immediate reporting of respiratory secretions Gram staining, and (b) therapy: immediate treatment, empiric therapy based on local pathogens and risk factors, de-escalation, assessment of response within 72 hours, and short therapy duration if feasible.

Adoption of these care bundles should rationalize VAP management practices and facilitate the development of consistent and guideline-compliant care processes.

Ventilator-associated pneumonia (VAP) is the most frequent intensive-care-unit (ICU)-acquired infection, with an incidence ranging from 6 to 52% [1,2,3,4]. Several studies have shown that critically ill patients are at high risk for getting such nosocomial infections [3], [4]. VAP continues to be a major cause of morbidity, mortality and increased financial burden in ICUs [5,6,7,8]. Over the years there has been a significant advance in our understanding of ventilator associated pneumonia. This article reviews the various aspects of VAP such as definition, risk factors, etiological agents, diagnosis, treatment and prevention with emphasis on the recent advances.

Fever and leukocytosis (FAL) in critically ill patients often triggers a “workup” that includes a respiratory secretion culture (RCx). We evaluated our respiratory culture practice associated with FAL. We hypothesized that FAL would be associated with a RCx, but would not be associated with a positive culture or treating a respiratory infection in critically injured patients during their first 14 intensive care unit (ICU) days.

An 18-month retrospective analysis was performed on consecutive ICU trauma patients admitted for 2 days or more to a level I trauma center. Data collected included demographics, injuries, RCxs (bronchoalveolar lavage or tracheal aspirate), maximum daily temperature, and a daily leukocyte count during the first 14 ICU days.

A total of 510 patients with a mean age of 49 and injury severity score of 19 were evaluated for a total of 3839 patient-days. Two hundred eleven patients had 489 RCxs obtained (2.4 RCxs/patient); 94 (19%) were obtained on consecutive days. Obtaining a RCx was associated with fever (relative risk, 4.8; 95% confidence interval, 4.1-5.8) and the combination of FAL (relative risk, 2.6; 95% confidence interval, 2.2-3.1), but not leukocytosis alone. Fever, leukocytosis, or FAL did not predict a positive RCx. One hundred twenty-eight patients were treated for a respiratory infection. Treatment of respiratory infections was contrary to the RCx results 24% of the time. The sensitivity and specificity of a positive RCx being associated with respiratory infection were 97% and 46%, respectively.

Fever and leukocytosis were associated with the decision to obtain RCxs but were not associated with positive RCxs in our ICU practice. Respiratory secretion culture results had a low specificity and did not consistently impact treatment decisions. Factors other than fever and leukocytosis alone should influence the decision to obtain RCxs during the first 14 days in the ICU after trauma.