Gas monitoring in XXXX sinuses using tunable diode laser spectroscopy.

@entity1 @entity26 @entity1568
We demonstrate a novel nonintrusive technique based on tunable diode laser absorption spectroscopy to investigate @entity1 sinuses in vivo. The technique relies on the fact that free gases have spectral imprints that are about 10.000 times sharper than spectral structures of the surrounding tissue. Two gases are detected; molecular @entity26 at 760 nm and water vapor at 935 nm. Light is launched fiber optically into the tissue in close proximity to the particular maxillary sinus under study. When investigating the frontal sinuses, the fiber is positioned onto the caudal part of the frontal bone. Multiply scattered light in both cases is detected externally by a handheld probe. Molecular @entity26 is detected in the maxillary sinuses on 11 volunteers, of which one had constantly recurring sinus problems. Significant @entity26 absorption imprint differences can be observed between different volunteers and also left-right asymmetries. Water vapor can also be detected, and by normalizing the @entity26 signal on the water vapor signal, the sinus @entity26 concentration can be assessed. Gas exchange between the sinuses and the nasal cavity is also successfully demonstrated by flushing @entity1568 through the nostril. Advantages over current ventilation assessment methods using ionizing radiation are pointed out.
