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Reflection Spectroscopy of Analgesized Skin
Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-6385-6760
Linköping University, Department of Biomedical Engineering.
Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
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2001 (English)In: Microvascular Research, ISSN 0026-2862, Vol. 62, no 3, 392-400 p.Article in journal (Refereed) Published
Abstract [en]

Analgesized skin, when subjected to heat stimuli, responds by increasing skin perfusion. This response does not originate from increased perfusion in superficial capillaries, but rather in the deeper lying vessels. The aim of this study was to assess changes in blood chromophore content, measured by reflection spectroscopy, in relation to the perfusion increase, especially regarding the chromophores oxyhemoglobin and deoxyhemoglobin. Eleven normal subjects were treated with analgesic cream (EMLA) and placebo for 20, 40, 60, 120, and 180 min. Individual reactions to local heating were classified as responses if the change in reflection data or the change in perfusion, as measured by laser Doppler blood flowmetry, exceeded 2 standard deviations of normal variation. The increase in blood perfusion or in blood content gave rise to an increased absorption, interpreted as an increase due mainly to the chromophore oxyhemoglobin. The number of responses increased with increased treatment time for EMLA-treated areas. In general, there was a good agreement between both methods; 44 of 55 classifications coincided for the two methods used. In conclusion, analgesized forearm skin, which had been exposed to local heating, responded with an elevated perfusion consisting of oxygenated blood. This strengthens the hypothesis that the flow increase occurs through dilatation of larger deeper lying skin vessels and not in the capillaries.

Place, publisher, year, edition, pages
ScienceDirect , 2001. Vol. 62, no 3, 392-400 p.
Keyword [en]
spectroscopy; laser Doppler flowmetry; EMLA; hemoglobin; analgesia; heat stimuli; skin microcirculation
National Category
Biomedical Laboratory Science/Technology
URN: urn:nbn:se:liu:diva-15184DOI: 10.1006/mvre.2001.2358OAI: diva2:113597
Available from: 2008-10-22 Created: 2008-10-22 Last updated: 2016-08-31Bibliographically approved
In thesis
1. In Vivo Diffuse Reflectance Spectroscopy of Human Tissue: From Point Measurements to Imaging
Open this publication in new window or tab >>In Vivo Diffuse Reflectance Spectroscopy of Human Tissue: From Point Measurements to Imaging
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents the non-invasive use of diffuse reflectance spectroscopy (DRS) to provide information about the biochemical composition of living tissue. During DRS measurements, the incident, visible light is partially absorbed by chromophores but also scattered in the tissue before being remitted.

Human skin and heart, the main tissue objects in this thesis, are dependent on a sufficient inflow of oxygenized blood, and outflow of metabolic byproducts. This process could be monitored by DRS using the spectral fingerprints of the most important tissue chromophores, oxyhemoglobin and deoxyhemoglobin.

The Beer-Lambert law was used to produce models for the DRS and has thus been a foundation for the analyses throughout this work. Decomposition into the different chromophores was performed using least square fitting and tabulated data for chromophore absorptivity.

These techniques were used to study skin tissue erythema induced by a provocation of an applied heat load on EMLA-treated skin. The absorbance differences, attributed to changes in the hemoglobin concentrations, were examined and found to be related to, foremost, an increase in oxyhemoglobin.

To estimate UV-induced border zones between provoked and nonprovoked tissue a modified Beer-Lambert model, approximating the scattering effects, was used. An increase of chromophore content of more than two standard deviations above mean indicated responsive tissue. The analysis revealed an edge with a rather diffuse border, contradictory to the irradiation pattern.

Measuring in the operating theater, on the heart, it was necessary to calculate absolute chromophore values in order to assess the state of the myocardium. Therefore, a light transport model accounting for the optical properties, and a calibrated probe, was adopted and used. The absolute values and fractions of the chromophores could then be compared between sites and individuals, despite any difference of the optical properties in the tissue.

A hyperspectral imaging system was developed to visualize the spatial distribution of chromophores related to UV-provocations. A modified Beer-Lambert approximation was used including the chromophores and a baseline as an approximate scattering effect. The increase in chromophore content was estimated and evaluated over 336 hours.

In conclusion, advancing from a restricted Beer-Lambert model, into a model estimating the tissue optical properties, chromophore estimation algorithms have been refined progressively. This has allowed advancement from relative chromophore analysis to absolute values, enabling precise comparisons and good prediction of physiological conditions.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2008. 88 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1210
National Category
Medical Laboratory and Measurements Technologies
urn:nbn:se:liu:diva-15191 (URN)978-91-7393-809-9 (ISBN)
Public defence
2008-10-31, Elsa Brändströmsalen, Södra entrén, Campus US, Universitetssjukhuset, Linköpings universitet, Linköping, 09:00 (English)
Available from: 2008-10-22 Created: 2008-10-22 Last updated: 2009-04-30Bibliographically approved

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Häggblad, Erik Larsson, MarcusStrömberg, TomasSalerud, Göran
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