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OBJECTIVES: Evaluate associations between volatile organic compounds (VOCs) in heat and moisture exchange (HME) filters and the presence of ventilator-associated pneumonia (VAP). SUMMARY BACKGROUND DATA: Clinical diagnostic criteria for VAP have poor inter-observer reliability, and cultures are slow to result. Exhaled breath contains VOCs related to Gram-negative bacterial proliferation, the most identified organisms in VAP. We hypothesized that exhaled VOCs on HME filters can predict nascent VAP in mechanically ventilated ICU patients. METHODS: Gas chromatography-mass spectrometry (GC-MS) was used to analyze 111 heat and moisture exchange (HME) filters from 12 intubated patients who developed VAP. Identities and relative amounts of VOCs were associated with dates of clinical suspicion and culture confirmation of VAP. Matched pairs t-tests were performed to compare VOC abundances in HME filters collected within three days pre- and post-clinical suspicion of VAP (pneumonia days), versus outside of these days (non-pneumonia days). A ROC curve was generated to determine the diagnostic potential of VOCs. RESULTS: Carbon disulfide, associated with the proliferation of certain Gram-negative bacteria, was found in samples collected during pneumonia days for 11 of 12 patients. Carbon disulfide levels were significantly greater (P=0.0163) for filters on pneumonia days. The AUROC for carbon disulfide was 0.649 (95%CI 0.419-0.88). CONCLUSIONS: Carbon disulfide associated with Gram-negative VAP can be identified on HME filters up to three days prior to the initial clinical suspicion, and approximately a week prior to culture confirmation. This suggests VOC sensors may have potential as an adjunctive method for early detection of VAP.
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BACKGROUND: Exposures to polyaromatic hydrocarbons (PAHs) contribute to cancer in the fire service. Fire investigators are involved in evaluations of post-fire scenes. In the US, it is estimated that there are up to 9000 fire investigators, compared to approximately 1.1 million total firefighting personnel. This exploratory study contributes initial evidence of PAH exposures sustained by this understudied group using worn silicone passive samplers. OBJECTIVES: Evaluate PAH exposures sustained by fire investigators at post-fire scenes using worn silicone passive samplers. Assess explanatory factors and health risks of PAH exposure at post-fire scenes. METHODS: As part of a cross-sectional study design, silicone wristbands were distributed to 16 North Carolina fire investigators, including eight public, seven private, and one public and private. Wristbands were worn during 46 post-fire scene investigations. Fire investigators completed pre- and post-surveys providing sociodemographic, occupational, and post-fire scene characteristics. Solvent extracts from wristbands were analyzed via gas chromatography-mass spectrometry (GC-MS). Results were used to estimate vapor-phase PAH concentration in the air at post-fire scenes. RESULTS: Fire investigations lasted an average of 148â¯minutes, standard deviation ± 93â¯minutes. A significant positive correlation (r=0.455, p<.001) was found between investigation duration and PAH concentrations on wristbands. Significantly greater time-normalized PAH exposures (p=0.039) were observed for investigations of newer post-fire scenes compared to older post-fire scenes. Regulatory airborne PAH exposure limits were exceeded in six investigations, based on exposure to estimated vapor-phase PAH concentrations in the air at post-fire scenes. DISCUSSION: Higher levels of off-gassing and suspended particulates at younger post-fire scenes may explain greater PAH exposure. Weaker correlations are found between wristband PAH concentration and investigation duration at older post-fire scenes, suggesting reduction of off-gassing PAHs over time. Exceedances of regulatory PAH limits indicate a need for protection against vapor-phase contaminants, especially at more recent post-fire scenes.