Utility of bilateral bronchoalveolar lavage for the diagnosis of ventilator-associated pneumonia in critically ill surgical patients

Systematic review of studies investigating ventilator associated pneumonia diagnostics in intensive care

Background

Ventilator-associated pneumonia (VAP) is an important diagnosis in critical care. VAP research is complicated by the lack of agreed diagnostic criteria and reference standard test criteria. Our aim was to review which reference standard tests are used to evaluate novel index tests for suspected VAP.

Methods

We conducted a comprehensive search using electronic databases and hand reference checks. The Cochrane Library, MEDLINE, CINHAL, EMBASE, and web of science were searched from 2008 until November 2018. All terms related to VAP diagnostics in the intensive treatment unit were used to conduct the search. We adopted a checklist from the critical appraisal skills programme checklist for diagnostic studies to assess the quality of the included studies.

Results

We identified 2441 records, of which 178 were selected for full-text review. Following methodological examination and quality assessment, 44 studies were included in narrative data synthesis. Thirty-two (72.7%) studies utilised a sole microbiological reference standard; the remaining 12 studies utilised a composite reference standard, nine of which included a mandatory microbiological criterion. Histopathological criteria were optional in four studies but mandatory in none.

Conclusions

Nearly all reference standards for VAP used in diagnostic test research required some microbiological confirmation of infection, with BAL culture being the most common reference standard used.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01560-0.

Common respiratory viral infections: Bilateral versus unilateral bronchoalveolar lavage versus endotracheal aspiration

Data about the diagnostic efficiency of bilateral bronchoalveolar lavage (BAL) samples and endotracheal aspirates (EA) testing for common viral respiratory infections are scarce. We analyzed data from 167 cases, where bilateral BAL samples were tested, and from 101 cases, where BAL samples and EA were tested. Multiplex polymerase chain reaction (PCR) was performed with the fast track diagnostics viral respiratory panel, producing data on the adenovirus, coronavirus, enterovirus, human metapneumovirus, bocavirus, influenza virus, parainfluenza virus, rhinovirus, and respiratory syncytial virus status of patients with respiratory disease symptoms. In the bilateral BAL cohort, 46 (27.5%) cases were positive for at least one of the viruses mentioned above in both samples. Discrepant results (virus not detected on one side) were seen in six (3.6%) cases. In the BAL versus EA cohort, 12 (11.9%) cases were positive in both materials, discrepant results (only one material being positive) were observed in 11 (10.9%) cases, with seven (63.6%) BAL samples, and four (36.4%) EA being positive. Bilateral sampling does not significantly improve the diagnostic efficiency of BAL for the detection of common respiratory viral pathogens via PCR. The diagnostic quality of EA and BAL samples for the detection of common viral respiratory pathogens is comparable.

Clinical impact of pulmonary sampling site in the diagnosis of ventilator-associated pneumonia: A prospective study using bronchoscopic bronchoalveolar lavage

PURPOSE

It is unclear whether ventilator-associated pneumonia (VAP) is actually a bilateral and multifocal process. In addition, the diagnostic role of chest x-ray is under debate. Assuming a low microbiologic concordance between the left and right lungs, the reliability of a single pulmonary sampling becomes questionable. The purpose of this study was to determine whether the choice of the pulmonary sampling area is clinically relevant in the management of VAP.

METHODS

In 79 patients admitted to a university general intensive care unit with clinically suspected VAP, right- and left-lung bronchoalveolar lavage (BAL) samples were taken with separate bronchoscopes and quantitatively cultured. Primary end-point variable was microbiologic concordance rate between right- and left-lung BAL cultures. Secondary outcomes included predictors of microbiologic concordance, rates of appropriate antibiotic treatment, and diagnostic accuracy of chest x-ray.

RESULTS

BAL cultures were bilaterally negative in 21 (27%) of 79 patients, bilaterally positive in 36 (46%), and unilaterally positive (right in 12, left in 10) in 22 (28%). Intra-patient concordance was observed in 47 (59.5%) of 79 cases and independently associated with purulent secretions and bilateral infiltrates on chest x-ray. In simulated prescribing experiments, treatments chosen based on right or left cultures alone were as appropriate as those based on bilateral data in >90% of cases. The presence of a radiographic infiltrate in the sampling area predicted BAL culture positivity with a positive predictive value of only 61%.

CONCLUSIONS

In patients with clinically suspected VAP (especially those without purulent secretions or without radiographically documented bilateral infiltrates), quantitative culture of a single BAL sample may provide an incomplete assessment of lung microbiology, without having a relevant impact on the appropriateness of antimicrobial treatment. These findings suggest that single sampling of respiratory secretions, regardless radiographic opacity, seems to be a reliable diagnostic method in the management of VAP.

Bilateral versus unilateral bronchoalveolar lavage for the diagnosis of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) complicates the clinical course of critically injured intubated patients. Bronchoscopic bronchoalveolar lavage (BAL) represents an invasive and accurate means of VAP diagnosis. Unilateral and blinded techniques offer less invasive alternatives to bronchoscopic BAL. This study evaluated clinical criteria as well as unilateral directed versus bilateral BAL for VAP diagnosis.

METHODS

A retrospective chart review of 113 consecutive intubated trauma patients with clinically suspected VAP undergoing unilateral versus bilateral BAL was performed with comparison of positive culture results (>10(4) colony-forming units [CFU]/mL). Culture results were compared with chest radiograph (CXR) infiltrates and white blood cell (WBC) count elevation.

RESULTS

Bilateral BAL was more likely to be positive than unilateral BAL (50.4% vs. 25.5%). In 37.1% of bilateral BALs, there was discordance between the sides of positivity or the bacteria isolated. A CXR infiltrate and WBC count elevation did not predict positive BAL.

CONCLUSIONS

Clinical indicators of VAP are inaccurate, and bilateral bronchoscopic BAL is more likely than unilateral BAL to provide a positive sample in intubated trauma patients. Techniques that do not sample both lungs reliably should be avoided for diagnosis in this patient population.

Trauma-associated pneumonia in adult ventilated patients

BACKGROUND

The clinical pulmonary infection score (CPIS) and bronchoalveolar lavage (BAL) are 2 tools that have been validated to diagnose pneumonia in critically ill patients. However, the role of the CPIS in diagnosing trauma-associated pneumonia (TAP) remains in question.

METHODS

This prospective observational study included all trauma patients who were ventilated for longer than 48 hours from September 2008 to September 2009. The CPIS and quantitative culture results from the BAL were collected and used to define pneumonia.

RESULTS

A total of 162 patients were identified. In all, 58 (35.8%) and 104 (64.2%) had a CPIS greater than 5 and a CPIS of 5 or less, respectively. There were 95 (58.6%) patients who had a BAL completed regardless of CPIS. There were 65 patients who met the bacteriologic definition of pneumonia (≥10(4) colonies/mL), for an overall TAP incidence of 40.1%.

CONCLUSIONS

The CPIS is unreliable as a clinical tool to predict a positive BAL at 10(4) or 10(5) or higher threshold. Therefore, BAL should be used for the diagnosis of TAP based on clinical rationale and not the CPIS.

Efficacy of bilateral bronchoalveolar lavage for diagnosis of ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is a common nosocomial infection causing significant morbidity and mortality. The goal of this study was to determine the efficacy of bilateral versus unilateral bronchoalveolar lavage (BAL) for the detection of the causative bacterial agents of VAP. We retrospectively studied the quantitative bacterial cultures of 399 BAL sample pairs collected from 287 mechanically ventilated patients over a 5-year period at a U.S. tertiary-care teaching hospital. Trauma was the underlying illness in 69% of patients. No evidence of bacterial infection was found in 226 BAL pairs (56.6%). Among 173 positive BAL sample pairs, significant bacterial counts were detected exclusively in 6.4% of left-lung and 12.1% of right-lung samples. In contrast, 81.5% of positive sample pairs had significant bacterial counts in both lungs. All bacteria recovered at significant concentrations from bilateral samples would have been detected in a unilateral right-lung sample in 89% of positive sample pairs. Unilateral sampling would have failed to recover one or more significant isolates in 11% of positive pairs had only the right lung been sampled and in 16.7% had only the left lung been sampled. Our study shows that preferential sampling of the right lung improves the diagnostic efficacy of unilateral BAL for the detection of the etiologic agents of VAP. If bilateral sampling is performed, our results also indicate that pooling left- and right-lung samples for a single quantitative culture is comparable to processing samples individually.