liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Photon propagation in tissue and in biological fluids: applied for vascular imaging and haemodialysis monitoring
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on the photon propagation in tissue and in biological fluids in two main areas: (1) optical vessel imaging and (2) monitoring solutes removed in haemodialysis.

The aim of the optical vessel imaging study was to design and assess a new optical scanning technique for vessel imaging using NIR radiation. The results indicated that veins could be determined at three vascular levels (superficial, intermediate and deep) down to 3 mm. Moreover, experimental results demonstrated that the vessel imaging facility depends upon source-detector separation, relative position, and vessel depth and does not depend essentially on the radiant power from the light source. After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed (e.g. local blood flow, oxygen saturation).

The theoretical model, based on the diffusion approximation, was developed to explain theoretically the origin of experimental results. An analytical solution was obtained describing photon propagation under certain conditions during vessel identification. The modelled results confirmed previously obtained experimental results.

A new optical method for monitoring solutes in a spent dialysate using absorption of UV-radiation was developed. The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single haemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicated that the UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.

Furthermore, a clinical study suggested that the delivered dialysis dose in terms of the traditional urea Kt/V could be estimated by on-line measurement of the UV-absorption in the spent dialysate. This means that the UV-method may add a new methodology for improvement of the quality and adequacy of the dialysis.

An investigation of the wavelength dependence of the UV-absorbance when monitoring different compounds in the dialysate showed that the UV-absorbance correlates well to several small molecular weight solutes ( < 200 D), around 290-310 nm. The highest contribution to the total absorbance from the observed compounds was confirmed in this wavelength region. The results indicated, that it might be possible to measure the elimination of several substances that are retained in the uraemic patients and with potential clinical significance. From thisviewpoint, the UV-absorbance monitoring technique may become a more universal method to ensure the quality and adequacy of the dialysis.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2003. , 164 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 818
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-24500Local ID: 6624ISBN: 91-737-3638-4 (print)OAI: oai:DiVA.org:liu-24500DiVA: diva2:244821
Public defence
2003-05-06, Berzeliussalen, Universitetssjukhuset, Linköping, 09:00 (Swedish)
Opponent
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-01-29
List of papers
1. Optical non-invasive technique for vessel imaging: I. Experimental results
Open this publication in new window or tab >>Optical non-invasive technique for vessel imaging: I. Experimental results
2000 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, no 12, 3765-3778 p.Article in journal (Refereed) Published
Abstract [en]

This paper investigates some prerequisites for vessel imaging based on diffuse reflectance measurements in order to develop an optical non-invasive method for the imaging and monitoring of vessels.

The method utilizes near-infrared (NIR) radiation (890 nm) from a light emitting diode. The light is guided into the tissue via an optical fibre (diameter 1.0 mm). The backscattered light is collected by an optical fibre of the same type and detected by an optical power meter. The fibres are moved over the skin in two directions with the aid of two motors operated by a microcomputer. Spatially resolved reflectance at the skin surface could be presented as a vessel-map in a colour-coded form on a computer screen.

Experimental results indicate that the vessel imaging facility depends upon source-detector separation, relative position and vessel depth, and does not depend essentially on the radiant power from the light source. It is shown that, by a proper choice of probe parameters, one can improve the vessel identification ability.

After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed or to distinguish between injured and healthy tissue by monitoring local blood flow, oxygen saturation and the recirculation, pre- and post-operatively.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-54930 (URN)10.1088/0031-9155/45/12/318 (DOI)
Available from: 2010-04-22 Created: 2010-04-22 Last updated: 2017-12-12
2. Optical non-invasive technique for vessel imaging: II. A simplified photon diffusion analysis
Open this publication in new window or tab >>Optical non-invasive technique for vessel imaging: II. A simplified photon diffusion analysis
2000 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, no 12, 3779-3792 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this paper is to explain theoretically the origin of previously presented experimental results by an optical non-invasive method using NIR for imaging blood vessels based on a specific combination of several physical parameters. The theoretical model is based on the diffusion approximation derived from the transport theory deep in a bulk tissue. An analytical solution was obtained describing photon behaviour under certain conditions during vessel identification. The modelled results indicate that the vessel identification facility depends upon source-detector separation and vessel depth, and does not depend essentially on the radiant power from the light source. The solution offers a relatively simple theoretical explanation of the experimental results and can be applied to several other clinical applications using similar technical solutions.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-32636 (URN)10.1088/0031-9155/45/12/319 (DOI)18553 (Local ID)18553 (Archive number)18553 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
3. On-line monitoring of solutes in dialysate using adsorption of ultraviolet radiation: technical description
Open this publication in new window or tab >>On-line monitoring of solutes in dialysate using adsorption of ultraviolet radiation: technical description
2002 (English)In: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 25, no 8, 748-761 p.Article in journal (Refereed) Published
Abstract [en]

PURPOSE:

The aim of this work was to describe a new optical method for monitoring solutes in a spent dialysate using absorption of UV radiation.

METHOD:

The method utilises UV-absorbance determined in the spent dialysate using a spectrophotometrical set-up. Measurements were performed both on collected dialysate samples and on-line. During on-line monitoring, a spectrophotometer was connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through a specially-designed cuvette for optical single-wavelength measurements. The concentrations of several substances of various molecular sizes, electrical charge, transport mechanism, etc. were determined in the dialysate and in the blood using standard laboratory techniques. The correlation coefficient between UV-absorbance of the spent dialysate and concentration of the substances in the spent dialysate and in the blood was calculated from data based on the collected samples.

RESULTS:

The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single hemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicate a very good correlation between UV-absorbance and several small waste solutes removed such as urea, creatinine and uric acid in the spent dialysate and in the blood for every individual treatment at a fixed wavelength of 285 nm. Moreover, a good correlation between the UV-absorbance and substances like potassium, phosphate and beta2-microglobulin was obtained. The lowest correlation was achieved for sodium, calcium, glucose, vitamin B12 and albumin.

CONCLUSIONS:

A technique for on-line monitoring of solutes in the spent dialysate utilising the UV-absorbance was developed. On-line monitoring during a single hemodialysis session exploiting UV-absorbance represents a possibility to follow a single hemodialysis session continuously and monitor deviations in dialysis efficiency (e.g. changes in blood flow and clearance). The UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-54937 (URN)12296459 (PubMedID)
Available from: 2010-04-22 Created: 2010-04-22 Last updated: 2017-12-12
4. Estimation of delivered dialysis dose by on-line monitoring of the ultraviolet absorbance in the spent dialysate
Open this publication in new window or tab >>Estimation of delivered dialysis dose by on-line monitoring of the ultraviolet absorbance in the spent dialysate
2003 (English)In: American Journal of Kidney Diseases, ISSN 0272-6386, E-ISSN 1523-6838, Vol. 41, no 5, 1026-1036 p.Article in journal (Refereed) Published
Abstract [en]

Background:

Several methods are available to determine Kt/V, from predialysis and postdialysis blood samples to using on-line dialysate urea monitors or to ionic dialysance using a conductivity method. The aim of this study is to compare Kt/V calculated from the slope of the logarithmic on-line ultraviolet (UV) absorbance measurements, blood urea Kt/V, dialysate urea Kt/V, and Kt/V from the Urea Monitor 1000 (UM; Baxter Healthcare Corp, Deerfield, IL).

Methods:

Thirteen uremic patients on chronic thrice-weekly hemodialysis therapy were included in the study. The method uses absorption of UV radiation by means of a spectrophotometric set-up. Measurements were performed on-line with the spectrophotometer connected to the fluid outlet of the dialysis machine; all spent dialysate passed through a specially designed cuvette for optical single-wavelength measurements. UV absorbance measurements were compared with those calculated using blood urea and dialysate urea, and, in a subset of treatments, the UM.

Results:

Equilibrated Kt/V (eKt/V) obtained with UV absorbance (eKt/Va) was 1.19 ± 0.23; blood urea (eKt/Vb), 1.30 ± 0.20, and dialysate urea (eKt/Vd), 1.26 ± 0.21, and Kt/V in a subset measured by the UM (UM Kt/V) was 1.24 ± 0.18. The difference between eKt/Vb and eKt/Va was 0.10 ± 0.11, showing a variation similar to the difference between eKt/Vb and eKt/Vd (0.03 ± 0.10) and in a subset between eKt/Vb and UM Kt/V (−0.02 ± 0.11).

Conclusion:

The study suggests that urea Kt/V can be estimated by on-line measurement of UV absorption in the spent dialysate.

Keyword
Hemodialysis (HD), dialysis monitoring, dialysis dose, spectrophotometry, absorption, ultraviolet (UV), solute removal, spent dialysate, dialysis adequacy, dialysis efficiency, urea, Kt/V
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-14191 (URN)10.1016/S0272-6386(03)00200-2 (DOI)
Available from: 2007-01-04 Created: 2007-01-04 Last updated: 2017-12-13
5. On-line monitoring of solutes in dialysate using wavelength-dependent absorption of ultraviolet radiation
Open this publication in new window or tab >>On-line monitoring of solutes in dialysate using wavelength-dependent absorption of ultraviolet radiation
2003 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, no 3, 263-270 p.Article in journal (Refereed) Published
Abstract [en]

The aim of the study was to assess the wavelength dependence of the UV absorbance during monitoring of different compounds in the dialysate. UV absorbance was determined by using a double-beam spectrophotometer on dialysate samples taken at pre-determined times during dialysis, over a wavelength range of 180–380 nm. Concentrations of several removed substances, such as urea, creatinine, uric acid, phosphate and β 2-microglobulin, were determined in the blood and in the spent dialysate samples using standard laboratory techniques. Millimolar extinction coefficients, for urea, creatinine, monosodium phosphate and uric acid were determined during laboratory bench experiments. The correlation between UV absorbance and substances both in the dialysate and in the blood was calculated at all wavelengths. A time-dependent UV absorbance was determined on the collected dialysate samples from a single dialysis session over a wavelength range of 200–330 nm. The highest contribution from observed compounds relative to the mean value of the absorbance was found around 300 nm and was approximately 70%. The main contribution to the total absorbance from uric acid was confirmed at this wavelength. The highest correlation for uric acid, creatinine and urea was obtained at wavelengths from 280 nm to 320 nm, both in the spent dialysate and in the blood. The wavelength region with the highest correlation for phosphate and β 2-microglobulin, with a suitable UV-absorbance dynamic range, was from 300 to 330 nm. In the wavelength range of 220–270 nm the highest absorbance sensitivity for the observed substances was obtained. A suitable wavelength range for instrumental design seems tobe around 290–330 nm. The relatively high correlation between UV absorbance and the substances in the spent dialysate and in the blood indicates that the UV-absorbance technique can estimate the removal of several retained solutes known to accumulate in dialysis patients.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-24476 (URN)10.1007/BF02348430 (DOI)6592 (Local ID)6592 (Archive number)6592 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13

Open Access in DiVA

No full text

Authority records BETA

Fridolin, Ivo

Search in DiVA

By author/editor
Fridolin, Ivo
By organisation
Department of Biomedical EngineeringThe Institute of Technology
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 405 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf