Am. J. Respir. Crit. Care Med.,
Volume 156, Number 5, November 1997, 1656-1661
Near-infrared Spectroscopic Method for Assessing
the Tissue Oxygenation State of Living Lung
TOSHIO
NORIYUKI,
HIDEKI
OHDAN,
SHINKICHIRO
YOSHIOKA,
YOSHIHIRO
MIYATA,
TOSHIMASA
ASAHARA,
and
KIYOHIKO
DOHI
Second Department of Surgery, Hiroshima University School of Medicine, 1-2-3 Kasumi, Minami-ku, Hiroshima, Japan
To quantify changes in tissue oxygenation of pathologic lungs, we applied a novel method using
near-infrared spectroscopy (NIRs). In in vitro experiments, we assayed the effect of photon scattering
on the absorption spectra of an in vitro system simulating structures of lung, which consists of test
tube containing air in hematocrit tubes and red blood cell suspension with various predetermined
hemoglobin concentrations. It was determined that photon scattering of the tissue containing air did
not affect the absorption in the NIR region. In in vivo experiments, we tested the applicability of the
NIRs technique in rat lungs under the following conditions: (1) hypoxic loading; (2) administration of
an inhibitor (NaCN) of the mitochondrial respiratory chain; (3) hemorrhagic shock. We found that:
(1) Changes in hemoglobin oxygenation state in the lung measured by NIRs depended on inspired oxygen concentrations; (2) NaCN-induced reduction of cytochrome oxidase a,a3 in the lung was observed; and (3) Total hemoglobin levels in the lung decreased after bleeding. Changes in the hemoglobin oxygenation state and cytochrome oxidase redox state in the lung were determined using the
least-square-curve fitting for NIR absorption spectra. Our NIRs technique was capable of assessing
the hemoglobin oxygenation and cytochrome oxidase redox state in the lung.
