Gas monitoring in human sinuses using tunable diode laser spectroscopy

Abstract

Gas monitoring in human sinuses using tunable diode laser spectroscopyPersson, Linda; Andersson, Mats; Lewander, Märta; Svanberg, Katarina; Svanberg, Sune General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract. We demonstrate a novel nonintrusive technique based on tunable diode laser absorption spectroscopy to investigate human 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 oxygen 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 oxygen is detected in the maxillary sinuses on 11 volunteers, of which one had constantly recurring sinus problems. Significant oxygen absorption imprint differences can be observed between different volunteers and also left-right asymmetries. Water vapor can also be detected, and by normalizing the oxygen signal on the water vapor signal, the sinus oxygen concentration can be assessed. Gas exchange between the sinuses and the nasal cavity is also successfully demonstrated by flushing nitrogen through the nostril. Advantages over current ventilation assessment methods using ionizing radiation are pointed out. Gas monitoring in human sinuses

Laser spectroscopy of gas confined in nanoporous materials

“…Drying processes of wood have been studied [4]. A number of medical applications have been developed, for example measurements on the concentration of oxygen in the sinuses for diagnostic purposes [5]. There have also been feasibility studies to find out if it is possible to monitor the oxygen concentration in the lungs of premature neonates, with positive outcome [6].…”

Clinical system for non-invasive in situ monitoring of gases in the human paranasal sinuses

“…To emphasize these unusual and aggravating experimental conditions, the technique is often separately termed gas in scattering media absorption spectroscopy (GASMAS). The technique has been used to characterize various porous materials, such as polystyrene foam [4], wood [6], pharmaceutical tablets [7], and human sinus cavities [8]. Reviews of GASMAS are available in Refs.…”

“…the LabVIEW lock-in toolkit) [14] or by means of Fourier analysis [13,7]. Diagnostics of the human sinuses is a particularly interesting application of the GASMAS technique [8]. The maxillary and frontal sinuses are located behind the cheek bones and the frontal bone, respectively.…”

“…Current diagnostic methods of the paranasal sinuses include case history and, in selected cases, computed tomography (CT) [16]. The diagnostic potential of the GASMAS technique has been demonstrated on volunteers with a laboratory system for oxygen spectroscopy [17,8]. As discussed in Ref.…”

High sensitivity gas spectroscopy of porous, highly scattering solids

“…Since 2001, TDLAS and WMS have also been used for the sensing of gases dispersed within highly scattering media [5]. This approach, often referred to as gas in scattering media absorption spectroscopy (GASMAS), has since then been successfully used for the characterization of various materials, such as polystyrene foam [5,6], wood [7], fruit [8], biological tissue [9], and pharmaceutical solids [10]. However, GASMAS experiments suffer from a much lower sensitivity than the traditional use of TDLAS.…”