Diagnosis of pneumonia with an electronic nose: correlation of vapor signature with chest computed tomography scan findings

Laryngoscope. 2004 Oct;114(10):1701-5. doi: 10.1097/00005537-200410000-00005.

Abstract

Objectives/hypothesis: The electronic nose is a sensor of volatile molecules that is useful in the analysis of expired gases. The device is well suited to testing the breath of patients receiving mechanical ventilation and is a potential diagnostic adjunct that can aid in the detection of patients with ventilator-associated pneumonia.

Study design: A prospective study.

Methods: We performed a prospective study of patients receiving mechanical ventilation in a surgical intensive care unit who underwent chest computed tomography (CT) scanning. A single attending radiologist reviewed the chest CT scans, and imaging features were recorded on a standardized form. Within 48 hours of chest CT scan, five sets of exhaled gas were sampled from the expiratory limb of the ventilator circuit. The gases were assayed with a commercially available electronic nose. Both linear and nonlinear analyses were performed to identify correlations between imaging features and the assayed gas signatures.

Results: Twenty-five patients were identified, 13 of whom were diagnosed with pneumonia by CT scan. Support vector machine analysis was performed in two separate analyses. In the first analysis, in which a training set was identical to a prediction set, the accuracy of prediction results was greater than 91.6%. In the second analysis, in which the training set and the prediction set were different, the accuracy of prediction results was at least 80%, with higher accuracy depending on the specific parameters and models being used.

Conclusion: The electronic nose is a new technology that continues to show promise as a potential diagnostic adjunct in the diagnosis of pneumonia and other infectious diseases.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Breath Tests / instrumentation*
  • Critical Care
  • Electronics, Medical / instrumentation
  • Female
  • Humans
  • Male
  • Middle Aged
  • Pneumonia / diagnosis*
  • Pneumonia / etiology
  • Predictive Value of Tests
  • Prospective Studies
  • Respiration, Artificial / adverse effects*
  • Thorax
  • Tomography, X-Ray Computed