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  • 1.
    Fors, Carina
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Karlsson, Daniel M G
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Ahn, Henrik Casimir
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Thoraxkirurgi. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Myocardial perfusion assessment using an ECG triggered laser doppler technique2005Ingår i: 13th Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005, Umeå: IFMBE , 2005, s. 83-84Konferensbidrag (Refereegranskat)
  • 2.
    Fors, Carina
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik.
    Karlsson, M G Daniel
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Ahn, Henrik Casimir
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Thoraxkirurgi. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    A system for on-line laser Doppler monitoring of ECG-traced myocardial perfusion2004Ingår i: IEEE EMBS,2004, Piscataway, NJ, USA: IEEE , 2004, s. 3796-Konferensbidrag (Refereegranskat)
  • 3.
    Karlsson, Daniel M G
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Ahn, Henrik Casimir
    Östergötlands Läns Landsting, Hjärtcentrum.
    Lönn, Urban
    Östergötlands Läns Landsting, Hjärtcentrum.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Analysis and processing of laser Doppler perfusion monitoring signals recorded from the beating heart2003Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, nr 3, s. 255-262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laser Doppler perfusion monitoring (LDPM) can be used for monitoring myocardial perfusion in the non-beating heart. However, the movement of the beating heart generates large artifacts. Therefore the aim of the study was to develop an LDPM system capable of correlating the laser Doppler signals to the cardiac cycle and to process the signals to reduce the movement artifacts. Measurements were performed on three calves, both on the normal beating heart and during occlusion of the left anterior descending coronary artery (LAD). The recorded LDPM signals were digitally processed and correlated to the sampled ECG. Large variations in the output (perfusion) and DC signals during the cardiac cycle were found, with average coefficients of variation of 0.36 and 0.14 (n-14), respectively. However, sections with a relatively low, stable output signal were found in late diastole, where the movement of the heart is at a minimum. Occlusion of the LAD showed the importance of recording the laser Doppler signals at an appropriate point in the cardiac cycle, in this case late systole, to minimise movement artifacts. It is possible to further reduce movement artifacts by increasing the lower cutoff frequency when calculating the output signal.

  • 4.
    Karlsson, Daniel M G
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Ahn, Henrik Casimir
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Thoraxkirurgi. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    Lönn, Urban
    Thoraxklin US .
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Analysis of laser Doppler flowmetry signals during the cardiac cyclle of the beating calf heart2000Ingår i: Abstracts 21st European Conference on Microcirculation, S. Karger, 2000, Vol. 37, s. 1-85, artikel-id Suppl. 1Konferensbidrag (Refereegranskat)
  • 5.
    Karlsson, Daniel M. G.
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Fors, Carina
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Casimir-Ahn, Henrik
    Östergötlands Läns Landsting, Hjärtcentrum.
    Myocardial perfusion monitoring during coronary artery bypass using an electrocardiogram-triggered laser Doppler technique2005Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, nr 5, s. 582-588Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrocardiogram (ECG)—triggered laser Doppler perfusion monitoring (LDPM) was used to assess myocardial perfusion, with minimum myocardial tissue motion influence, during coronary artery bypass grafting (CABG). Thirteen subjects were investigated at six phases: pre- and post-CABG; post aorta cross-clamping; pre and post left internal mammary artery (LIMA) graft declamping; and post aorta declamping. The perfusion signal was calculated in late systole and late diastole, with expected minimum tissue motion, and compared with arrested heart measurements. Patient conditions or artifacts caused by surgical activity made it impossible to perform and analyse data in all six phases for some patients. No significant (n=5) difference between perfusion signals pre- and post-CABG was found. Diastolic perfusion signal levels were significantly (p<0.02) lower compared with systolic levels. After aorta cross-clamping, the signal level was almost zero. A distinct perfusion signal increase after LIMA and aorta declamping, compared with pre-LIMA declamping, was found in ten cases out of 13. A significantly (p<0.04) lower perfusion signal in the arrested heart compared with in the beating heart was registered. Influence from mechanical ventilation was observed in 14 measurements out of 17. In conclusion, ECG-triggered LDPM can be used to assess myocardial perfusion during CABG. Perfusion signals were lower in the arrested heart compared with in the beating heart and in late diastole compared with late systole. No significant difference between pre- and post-CABG was found.

  • 6.
    Karlsson, Daniel M G
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Larsson, Marcus
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Strömberg, Tomas
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Influence of tissue movement on laser Doppler perfusion imaging2002Ingår i: Proc. SPIE 4624, Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring II, 106 (May 24, 2002), Vol. 4624 / [ed] Alexander V. Priezzhev and Gerard L. Cote, SPIE , 2002, s. 106-114Konferensbidrag (Refereegranskat)
    Abstract [en]

    The microvascular perfusion can be measured using laser Doppler blood flowmetry (LDF), a technique sensitive to the concentration of moving blood cells and their velocity. However, movements of the tissue itself can cause artifacts in the perfusion readings. In a clinical situation, these movement induced artifacts may arise from patient movements or from movements of internal organs e.g. the intestines or the beating heart. Therefore, we have studied how a well-controlled tissue movement affects the LDF signals during different flow conditions and for different surface structures. Tissue perfusion was recorded non-touch in one point using a laser Doppler perfusion imager. During the measurements the object was placed on a shaker that generated the movement (both horizontal and vertical). Measurements were carried out both on DELRIN® (polyacetal plastic) and the fingertip, for a wide range of velocities (0-3 cm/s). The influence of the microvascular perfusion was evaluated by occluding the brachial artery as well as blood emptying the finger and by using a flow model. The LDF signals were correlated to the movement. In vivo measurements showed that velocities above 0.8 cm/s gave a significant contribution to the perfusion signal. Corresponding velocities for the DELRIN® piece were higher (1.4 – 2.6 cm/s), and dependent on the surface structures and reflecting properties. By reducing the amount of specular reflection the movement influence was substantially lowered.

  • 7.
    Karlsson, Daniel M G
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Larsson, Marcus
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Strömberg, Tomas
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Influence of tissue movements on laser Doppler perfusion imaging2002Ingår i: Proceedings of SPIE Volume 4624: Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring II / [ed] Alexander V. Priezzhev; Gerard L. Cote, SPIE - International Society for Optical Engineering, 2002, Vol. 4624, s. 106-114Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The microvascular perfusion can be measured using laser Doppler blood flowmetry (LDF), a technique sensitive to the concentration of moving blood cells and their velocity. However, movements of the tissue itself can cause artifacts in the perfusion readings. In a clinical situation, these movement induced artifacts may arise from patient movements or from movements of internal organs e.g. the intestines or the beating heart. Therefore, we have studied how a well-controlled tissue movement affects the LDF signals during different flow conditions and for different surface structures. Tissue perfusion was recorded non-touch in one point using a laser Doppler perfusion imager. During the measurements the object was placed on a shaker that generated the movement (both horizontal and vertical). Measurements were carried out both on DELRIN« (polyacetal plastic) and the fingertip, for a wide range of velocities (0-3 cm/s). The influence of the microvascular perfusion was evaluated by occluding the brachial artery as well as blood emptying the finger and by using a flow model. The LDF signals were correlated to the movement. In vivo measurements showed that velocities above 0.8 cm/s gave a significant contribution to the perfusion signal. Corresponding velocities for the DELRIN« piece were higher (1.4 - 2.6 cm/s), and dependent on the surface structures and reflecting properties. By reducing the amount of specular reflection the movement influence was substantially lowered.

  • 8.
    Karlsson, Daniel M G
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Polarized laser Doppler perfusion imaging—reduction of movement-induced artifacts2005Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, nr 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laser Doppler perfusion imaging (LDPI) enables superficial tissue perfusion assessment, but is sensitive to tissue motion not related to blood cells. The aim was to investigate if a polarization technique could reduce movement-induced artifacts. A linearly polarized laser and a cross-polarized filter, placed in front of the detectors, were used to block specular reflection. Measurements were performed with, and without, the polarization filter, at a single site during horizontal and vertical movement of skin tissue (index finger, twelve subjects, n=112) and of a flow model (n=432), with varying surface structures. Measurements were repeated during different flow conditions and at increased skin specular reflection. Statistical analysis was performed using ANOVA models. The perfusion signal was lower (p<0.001, skin and p<0.05, flow model) using the polarization filter, due to movement artifact reduction. No significant influence from surface structure was found when using the polarization filter. Movement artifacts were lower (p<0.05) in the vertical movement direction, however, depending on flow conditions for skin measurements. Increased skin specular reflection gave rise to large movement artifacts without the polarization filter. In conclusion, the polarized LDPI technique reduces movement artifacts and is particularly appropriate when assessing, e.g., ulcers and burns, where specular reflection is high.

  • 9.
    Karlsson, M G Daniel
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Hübbert, Laila
    Östergötlands Läns Landsting, Hjärtcentrum.
    Lönn, Urban
    Östergötlands Läns Landsting, Hjärtcentrum.
    Janerot-Sjöberg, Birgitta
    Östergötlands Läns Landsting, Hjärtcentrum.
    Ahn, Henrik Casimir
    Östergötlands Läns Landsting, Hjärtcentrum.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Myocardial tissue motion influence on laser Doppler perfusion monitoring using tissue Doppler imaging2004Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 42, nr 6, s. 770-776Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tissue motion of the beating heart generates large movement artifacts in the laser Doppler perfusion monitoring (LDPM) signal. The aim of the study was to use tissue Doppler imaging (TDI) to localise intervals during the cardiac cycle where the influence of movement artifacts on the LDPM signal is minimum. TDI velocities and LDPM signals were investigated on three calves, for normal heartbeat and during occlusion of the left anterior descending coronary artery. Intervals of low tissue velocity (TDIint<1 cm s−1) during the cardiac cycle were identified. During occlusion, these intervals were compared with low LDPM signal intervals (LDPMint<50% compared with baseline). Low-velocity intervals were found in late systole (normal and occlusion) and late diastole (normal). Systolic intervals were longer and less sensitive to heart rate variation compared with diastolic ones. The overlap between LDPMint and TDIint in relation to TDIint length was 84±27% (n=14). The LDPM signal was significantly (p<0.001, n=14) lower during occlusion if calculated during minimum tissue motion inside TDIint), compared with averaging over the entire cardiac cycle without taking tissue motion into consideration. In conclusion, movement artifacts are reduced if the LDPM signal is correlated to the ECG and investigated during minimum wall motion. The optimum interval depends on the application; late systole and late diastole can be used.

  • 10.
    Karlsson, MG Daniel
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Movement artifact reduction in laser Doppler blood flowmetry: myocardial perfusion applications2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Laser Doppler perfusion monitoring (LDPM) and imaging (LDPI) enable assessment of tissue microvascular perfusion. The techniques are based on the Doppler broadening of the optical spectrum occurring when coherent laser light is scattered by moving red blood cells (RBC). However, if tissue motion not related to moving RBCs is present, artifacts arise in the derived perfusion estimate. The aim of this thesis was to develop and evaluate methods to reduce tissue motion influence on the perfusion estimate in general and for the specific purpose of enabling myocardial perfusion monitoring in the beating heart.

    An LDPM system, based on digital signal processing, was developed for myocardial perfusion assessment. To achieve an accurate estimate of the local microvascular perfusion, the varying myocardial tissue motion during the cardiac cycle is taken into account. By means of ECG-triggering, periods of minimum myocardial tissue motion can be pinpointed. The system and proposed methods were successfully evaluated both in an animal model (3 calves) and during coronary artery bypass grafting (CABG) on 13 humans. Animal studies showed the importance of processing during minimum tissue motion, at late diastole and/or late systole, to reduce movement artifacts. The human evaluation confirmed earlier animal findings and revealed low flow situations in the intraoperative phase. Influence of mechanical ventilation on the myocardial blood flow was found. The results justify investigation postoperative of CABG, where myocardial perfusion monitoring may give a rapid response to potential ischemia.

    The influence of tissue motion on LDPI was studied in model measurements and on the skin. A relatively large tissue velocity, compared to microvascular flow velocities, was needed to significantly influence the perfusion signal. Movement artifact magnitude depended on the movement direction and the surface structure. An LDPI system utilizing a polarization technique that blocks specularly reflected light is proposed. The method was evaluated in a flow model and on the skin of 12 subjects and was found to significantly reduce influence from tissue motion. Finally, a theoretical explanation of the origin of LDPI movement artifacts is proposed. Reduction of movement artifacts makes measurements more reliable and increases the potential of LDPI as a clinical tool.

    Delarbeten
    1. Analysis and processing of laser Doppler perfusion monitoring signals recorded from the beating heart
    Öppna denna publikation i ny flik eller fönster >>Analysis and processing of laser Doppler perfusion monitoring signals recorded from the beating heart
    2003 (Engelska)Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, nr 3, s. 255-262Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Laser Doppler perfusion monitoring (LDPM) can be used for monitoring myocardial perfusion in the non-beating heart. However, the movement of the beating heart generates large artifacts. Therefore the aim of the study was to develop an LDPM system capable of correlating the laser Doppler signals to the cardiac cycle and to process the signals to reduce the movement artifacts. Measurements were performed on three calves, both on the normal beating heart and during occlusion of the left anterior descending coronary artery (LAD). The recorded LDPM signals were digitally processed and correlated to the sampled ECG. Large variations in the output (perfusion) and DC signals during the cardiac cycle were found, with average coefficients of variation of 0.36 and 0.14 (n-14), respectively. However, sections with a relatively low, stable output signal were found in late diastole, where the movement of the heart is at a minimum. Occlusion of the LAD showed the importance of recording the laser Doppler signals at an appropriate point in the cardiac cycle, in this case late systole, to minimise movement artifacts. It is possible to further reduce movement artifacts by increasing the lower cutoff frequency when calculating the output signal.

    Ort, förlag, år, upplaga, sidor
    Springer, 2003
    Nationell ämneskategori
    Medicinsk laboratorie- och mätteknik
    Identifikatorer
    urn:nbn:se:liu:diva-24478 (URN)10.1007/BF02348429 (DOI)000183399600004 ()2-s2.0-0037842891 (Scopus ID)6594 (Lokalt ID)6594 (Arkivnummer)6594 (OAI)
    Tillgänglig från: 2009-10-07 Skapad: 2009-10-07 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
    2. Myocardial tissue motion influence on laser Doppler perfusion monitoring using tissue Doppler imaging
    Öppna denna publikation i ny flik eller fönster >>Myocardial tissue motion influence on laser Doppler perfusion monitoring using tissue Doppler imaging
    Visa övriga...
    2004 (Engelska)Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 42, nr 6, s. 770-776Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Tissue motion of the beating heart generates large movement artifacts in the laser Doppler perfusion monitoring (LDPM) signal. The aim of the study was to use tissue Doppler imaging (TDI) to localise intervals during the cardiac cycle where the influence of movement artifacts on the LDPM signal is minimum. TDI velocities and LDPM signals were investigated on three calves, for normal heartbeat and during occlusion of the left anterior descending coronary artery. Intervals of low tissue velocity (TDIint<1 cm s−1) during the cardiac cycle were identified. During occlusion, these intervals were compared with low LDPM signal intervals (LDPMint<50% compared with baseline). Low-velocity intervals were found in late systole (normal and occlusion) and late diastole (normal). Systolic intervals were longer and less sensitive to heart rate variation compared with diastolic ones. The overlap between LDPMint and TDIint in relation to TDIint length was 84±27% (n=14). The LDPM signal was significantly (p<0.001, n=14) lower during occlusion if calculated during minimum tissue motion inside TDIint), compared with averaging over the entire cardiac cycle without taking tissue motion into consideration. In conclusion, movement artifacts are reduced if the LDPM signal is correlated to the ECG and investigated during minimum wall motion. The optimum interval depends on the application; late systole and late diastole can be used.

    Ort, förlag, år, upplaga, sidor
    Springer, 2004
    Nationell ämneskategori
    Medicinsk laboratorie- och mätteknik
    Identifikatorer
    urn:nbn:se:liu:diva-22150 (URN)10.1007/BF02345210 (DOI)000225543500006 ()2-s2.0-10244245509 (Scopus ID)1260 (Lokalt ID)1260 (Arkivnummer)1260 (OAI)
    Tillgänglig från: 2009-10-07 Skapad: 2009-10-07 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
    3. Myocardial perfusion monitoring during coronary artery bypass using an electrocardiogram-triggered laser Doppler technique
    Öppna denna publikation i ny flik eller fönster >>Myocardial perfusion monitoring during coronary artery bypass using an electrocardiogram-triggered laser Doppler technique
    2005 (Engelska)Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, nr 5, s. 582-588Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Electrocardiogram (ECG)—triggered laser Doppler perfusion monitoring (LDPM) was used to assess myocardial perfusion, with minimum myocardial tissue motion influence, during coronary artery bypass grafting (CABG). Thirteen subjects were investigated at six phases: pre- and post-CABG; post aorta cross-clamping; pre and post left internal mammary artery (LIMA) graft declamping; and post aorta declamping. The perfusion signal was calculated in late systole and late diastole, with expected minimum tissue motion, and compared with arrested heart measurements. Patient conditions or artifacts caused by surgical activity made it impossible to perform and analyse data in all six phases for some patients. No significant (n=5) difference between perfusion signals pre- and post-CABG was found. Diastolic perfusion signal levels were significantly (p<0.02) lower compared with systolic levels. After aorta cross-clamping, the signal level was almost zero. A distinct perfusion signal increase after LIMA and aorta declamping, compared with pre-LIMA declamping, was found in ten cases out of 13. A significantly (p<0.04) lower perfusion signal in the arrested heart compared with in the beating heart was registered. Influence from mechanical ventilation was observed in 14 measurements out of 17. In conclusion, ECG-triggered LDPM can be used to assess myocardial perfusion during CABG. Perfusion signals were lower in the arrested heart compared with in the beating heart and in late diastole compared with late systole. No significant difference between pre- and post-CABG was found.

    Ort, förlag, år, upplaga, sidor
    Springer, 2005
    Nyckelord
    Laser Doppler perfusion monitoring, Coronary artery bypass grafting, Beating heart, Myocardial microcirculation, Movement artifacts, Electrocardiography
    Nationell ämneskategori
    Medicinsk laboratorie- och mätteknik
    Identifikatorer
    urn:nbn:se:liu:diva-14612 (URN)10.1007/BF02351031 (DOI)000234262300007 ()2-s2.0-29244438810 (Scopus ID)
    Tillgänglig från: 2007-08-27 Skapad: 2007-08-27 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
    4. Influence of tissue movement on laser Doppler perfusion imaging
    Öppna denna publikation i ny flik eller fönster >>Influence of tissue movement on laser Doppler perfusion imaging
    2002 (Engelska)Ingår i: Proc. SPIE 4624, Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring II, 106 (May 24, 2002), Vol. 4624 / [ed] Alexander V. Priezzhev and Gerard L. Cote, SPIE , 2002, s. 106-114Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    The microvascular perfusion can be measured using laser Doppler blood flowmetry (LDF), a technique sensitive to the concentration of moving blood cells and their velocity. However, movements of the tissue itself can cause artifacts in the perfusion readings. In a clinical situation, these movement induced artifacts may arise from patient movements or from movements of internal organs e.g. the intestines or the beating heart. Therefore, we have studied how a well-controlled tissue movement affects the LDF signals during different flow conditions and for different surface structures. Tissue perfusion was recorded non-touch in one point using a laser Doppler perfusion imager. During the measurements the object was placed on a shaker that generated the movement (both horizontal and vertical). Measurements were carried out both on DELRIN® (polyacetal plastic) and the fingertip, for a wide range of velocities (0-3 cm/s). The influence of the microvascular perfusion was evaluated by occluding the brachial artery as well as blood emptying the finger and by using a flow model. The LDF signals were correlated to the movement. In vivo measurements showed that velocities above 0.8 cm/s gave a significant contribution to the perfusion signal. Corresponding velocities for the DELRIN® piece were higher (1.4 – 2.6 cm/s), and dependent on the surface structures and reflecting properties. By reducing the amount of specular reflection the movement influence was substantially lowered.

    Ort, förlag, år, upplaga, sidor
    SPIE, 2002
    Nationell ämneskategori
    Medicin och hälsovetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-31098 (URN)10.1117/12.468313 (DOI)16829 (Lokalt ID)16829 (Arkivnummer)16829 (OAI)
    Konferens
    Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring II, San Jose, CA, USA, January 19, 2002
    Tillgänglig från: 2009-10-09 Skapad: 2009-10-09 Senast uppdaterad: 2016-08-31Bibliografiskt granskad
    5. Polarized laser Doppler perfusion imaging—reduction of movement-induced artifacts
    Öppna denna publikation i ny flik eller fönster >>Polarized laser Doppler perfusion imaging—reduction of movement-induced artifacts
    2005 (Engelska)Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, nr 6Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Laser Doppler perfusion imaging (LDPI) enables superficial tissue perfusion assessment, but is sensitive to tissue motion not related to blood cells. The aim was to investigate if a polarization technique could reduce movement-induced artifacts. A linearly polarized laser and a cross-polarized filter, placed in front of the detectors, were used to block specular reflection. Measurements were performed with, and without, the polarization filter, at a single site during horizontal and vertical movement of skin tissue (index finger, twelve subjects, n=112) and of a flow model (n=432), with varying surface structures. Measurements were repeated during different flow conditions and at increased skin specular reflection. Statistical analysis was performed using ANOVA models. The perfusion signal was lower (p<0.001, skin and p<0.05, flow model) using the polarization filter, due to movement artifact reduction. No significant influence from surface structure was found when using the polarization filter. Movement artifacts were lower (p<0.05) in the vertical movement direction, however, depending on flow conditions for skin measurements. Increased skin specular reflection gave rise to large movement artifacts without the polarization filter. In conclusion, the polarized LDPI technique reduces movement artifacts and is particularly appropriate when assessing, e.g., ulcers and burns, where specular reflection is high.

    Ort, förlag, år, upplaga, sidor
    SPIE - International Society for Optical Engineering, 2005
    Nationell ämneskategori
    Medicinsk laboratorie- och mätteknik
    Identifikatorer
    urn:nbn:se:liu:diva-30112 (URN)10.1117/1.2120467 (DOI)000234859400005 ()16409068 (PubMedID)2-s2.0-33645238951 (Scopus ID)15582 (Lokalt ID)15582 (Arkivnummer)15582 (OAI)
    Tillgänglig från: 2009-10-09 Skapad: 2009-10-09 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
  • 11.
    Lind, Leili
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Lyth, Johan
    Region Östergötland, Regionstyrelsen, Enheten för forskningsstöd Ledningsstaben.
    Karlsson, Daniel M. G.
    Linköpings universitet, Institutionen för medicinsk teknik.
    Wiréhn, Ann-Britt
    Region Östergötland, Regionstyrelsen, Enheten för forskningsstöd Ledningsstaben.
    Persson, Lennart
    Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Lungmedicinska kliniken US.
    COPD patients require more health care than heart failure patients2018Ingår i: ERS International Congress 2018, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Background: Populations of elderly patients with advanced stages of chronic obstructive pulmonary disease (COPD) or heart failure (HF) are growing, urging the need for specialized health care in the patients’ home. A 4 year (2013-2017) telehealth intervention single-centre clinical study has been completed. We hypothesized that the two groups of patients, advanced COPD or HF, would exhibit differences regarding exacerbations and the need of health care.

    Objective: To study exacerbations of COPD or HF, and patients’ need of health care.

    Methods: A telemonitoring system, the Health Diary, which is based on digital pen technology, was employed. Patients with at least 2 hospital admissions the previous year were included. Responsible nurses and physicians at a specialized home care unit at a university hospital checked all daily patient reports. Physicians identified exacerbations using information provided through the telemonitoring system and patient contacts. Consumed health care was assessed as the number of patient contacts (home visits or telephone consultations).

    Results: Totally, 94 patients with advanced disease were enrolled (36 COPD and 58 HF patients) of which 53 patients (19 COPD and 34 HF patients) completed the 1-yr study period. The major reason for not completing the study was death (13 COPD, 15 HF patients). Average numbers of exacerbations were 3.1 and 0.8 and patient contacts were 94 and 67 per COPD and HF patient, respectively.

    Conclusions: Compared to HF patients, COPD patients exhibit exacerbations more frequently and demand much more home health care. This difference of health care consumption is mainly due to disease characteristics.

  • 12.
    Lindbergh, Tobias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Häggblad, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Karlsson, Daniel M G
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Ahn, Henrik Casimir
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Thoraxkirurgi. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    Salerud, Göran
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Strömberg, Tomas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Hjärtmuskelns syresättning mätt med diffus reflektansspektroskopi under by-passkirurgi på människa2005Ingår i: Medicinteknikdagar MTF,2005, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 13.
    Lyth, Johan
    et al.
    Region Östergötland, Regionstyrelsen, Enheten för forskningsstöd Ledningsstaben.
    Lind, Leili
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Karlsson, Daniel
    The National Board of Health and Welfare, Department for Knowledge-Based Policy of Social Services, eHealth and Structured Information Unit, Stockholm, Sweden.
    Persson, Lennart Hans
    Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Lungmedicinska kliniken US.
    Wiréhn, Ann-Britt
    Region Östergötland, Regionstyrelsen, Enheten för forskningsstöd Ledningsstaben.
    Can a telemonitoring system lead to decreased hospital admissions in elderly patients?2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Background: Populations of elderly patients with chronic obstructive pulmonary disease (COPD) or heart failure (HF) are growing. To prevent exacerbations leading to inpatient care, a 4 year (2013-2017) telehealth intervention non-randomized single-centre clinical study was performed. We hypothesized that the patients, grouped by advanced COPD or HF, would exhibit decreased need of hospital admissions.

    Objective: To study hospital admissions in patients with COPD or HF using a telemonitoring system, the Health Diary.

    Methods: A telemonitoring system, the Health Diary, based on digital pen technology, was employed. Patients with COPD or HF treated at the University Hospital in Linköping were included if they had at least 2 hospital admissions the previous year. Data on hospital admissions was obtained from the administrative healthcare database. Expected number of hospital admissions for the study year was calculated using 5-year data for a group of patients with matching diagnosis and history of hospital admissions and was compared to the actual value in the intervention group using Poisson regression.

    Results: Together with the included patients, 159 HF and 136 COPD non-intervention patients was used to calculate the expected values for hospital admissions. For the 58 included HF patients, the average number of hospital admissions of 0.81 was 32.8 percent (p=0.04) lower than expected. For the 36 included COPD patients, the average number of hospital admissions of 1.44 was 37.0 percent (p=0.02) lower than expected.

    Conclusions: Use of the telemonitoring system, the Health Diary, decreases hospital admissions in elderly with COPD and HF.

  • 14.
    Wårdell, Karin
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Karlsson, Daniel M G
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Lönn, Urban
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Thoraxkirurgi. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    Träff, Stefan
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    Casimir-Ahn, Henrik Casimir
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Thoraxkirurgi. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    ECG-triggering of the Laser Doppler Signal - an Approach for perfusion Imagning on the Beating Calf Heart.2001Ingår i: Proceedings of SPIE jfr 1998-2000 SPIE proceedings ISSN 1017-2653, ISSN 1605-7422, Vol. 4254, s. 49-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

      

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