Near Infrared Diffuse Reflectance Spectroscopy to Measure Pulmonary Edema

  • Larry Leonardi (Institute for Biodiagnositics-National Research Center, Winnipeg, Manitoba, Canada) ;
  • David H.Burns (Department of Chemistry, McGill University, Montreal, Canada) ;
  • Luis Openheimer (Department of Surgery, Health Sciences Centre, Winnipeg, Canada) ;
  • Rene P.Michel (Department of Pathology, McGill University, Montreal, Canada)
  • Published : 2001.06.01


A non-invasive spectroscopic method is presented for the measurement of pulmonary edema. Both early diagnosis and quantitative edema estimates were investigated. The spectroscopic determination of pulmonary edema involved the acquisition of diffuse reflectance spectra in the near-infrared (NIR) region with change in water concentration - water is the main constituent of edema fluid. Pulmonary edema was induced into the excised perfused lungs of seven animals by elevating the hydrostatic pressure. Estimates of edema were ascertained from a partial least squares regression of the measured spectral response. Actual edema was determined from the change (increase) in total lung weight. Estimates in relative lung weight increases due to in vitro edema were made with the near infrared spectra. The results revealed that fluid accumulation produced spectral changes in the O-H and C-H absorptions as well as scattering changes in the spectra. Histology of the lung was used to verify the presence or absence of interstitial and alveolar edema. Results demonstrated that near infrared spectroscopy might provide a new tool for clinical assessment of pulmonary edema.