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  • 1.
    Andersson, Roger
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Fridolin, Ivo
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Magnusson, M.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Measurements of solutes in dialysate using UV-absorption: analysis of the factors influencing correlation between UV-absorption and solutes in the spent dialysate2002Other (Other (popular science, discussion, etc.))
  • 2.
    Andersson, Roger
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Fridolin, Ivo
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Magnusson, Martin
    Linköping University, Department of Medicine and Care, Nephrology. Linköping University, Faculty of Health Sciences.
    Ask, Per
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Analysis of the relationship between UV-absorbance of solute contents during a dialysis sessionManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, the influence from patient anamnesis and haemodialysis session specifications onto the relationship between obtained ultra violet (UV) absorbance and urea concentration in the spent dialysate were discussed. A characterisation of the relationship was done by an intercept value and a slope. Recently, a new a dialysate monitoring device, using UV- absorbance, been developed by our group which has found a relationship between the UV- absorbance and waste products in the dialysate but this relationship vary between patients. In the present investigation, 13 patients performing totally 84 sessions were characterised using 31 possible affecting parameters. Using a multi-regression analysis 11 parameters were found significant as affecting parameters. In a novel mathematical model approach the obtained UV- absorbance and incorporating possible affecting parameters we could predict urea concentration from the UV-absorption in the spent dialysate in the total material of patients and dialysis sessions. For all the 84 sessions R2 between 0.938 and 0.996 were obtained. A performed analysis of variance rejects the assumption of equal conditions for the relationship between diabetics and non-diabetics patients in the material (F=5.2 for intercept and F=14.4 for slope). The urea concentration could be estimated with an accuracy of 11% (one standard deviation) which is normally clinically sufficient. The non-invasive UV -absorption method therefore seems to have great potential for monitoring and control haemodialysis sessions.

  • 3.
    Andersson, Roger
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Guiterrez, Alberto
    Department of Renal Medicine, Huddinge University Hospital, Sweden.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Non-invasive monitoring of haemodynamic changes in haemodialysis patients using photoplethysmography (PPG)2002Manuscript (preprint) (Other academic)
    Abstract [en]

    Presently there is no simple non-invasive method to monitor haemodynamic changes during haemodialysis but such a method is highly needed. This study aims at investigating the possibility to monitor such changes during a single haemodialysis session using a photoplethysmography method (PPG). This non-invasive method illuminates a proportion of the patients skin and the received PPG-signal reflects local blood flow. The haemodialysis sessions were performed as in normal routine with more frequently performed blood pressure measurements by an oscillometric method or with continuous intra arterial blood pressure measurements. The obtained PPG-signals are linked to the blood pressure changes and are affected by the ultrafiltration rate and drugs administrated during the session. The relation between the blood pressure changes and the changes in the different PPG components seems however to be complex and need to be investigate further. The PPG-method shows promises, which is emphasised by the strong need of a non-invasive monitoring method.

  • 4.
    Bergstrand, Sara
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Källman, Ulrika
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Department of Dermatology, Södra Älvsborgs Sjukhus, Borås, Sweden.
    Ek, Anna-Christina
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Health Care in Linköping.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Sjöberg, Folke
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Anaesthesiology and Intensive Care in Linköping.
    Lindgren, Margareta
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Pressure-induced vasodilation and reactive hyperemia at different depths in sacral tissue under clinically relevant conditions2014In: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 21, no 8, p. 761-771Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To characterize pressure-induced vasodilatation and reactive hyperemia at different sacral tissue depths in different populations under clinically relevant pressure exposure.

    METHODS: Forty-two subjects (< 65 years), 38 subjects (≥ 65 years), and 35 patients (≥ 65 years) participated. Interface pressure, skin temperature, and blood flow at tissue depths of 1 mm, 2 mm, and 10 mm (using laser Doppler flowmetry and photoplethysmography) were measured in the sacral tissue before, during, and after load in a supine position.

    RESULTS: pressure-induced vasodilatation and reactive hyperemia were observed at three tissue depths. At 10 mm depth, the proportion of subjects with a lack of pressure-induced vasodilatation was higher compared to superficial depths. The patients had higher interface pressure during load than the healthy individuals, but there were no significant differences in blood flow. Twenty-nine subjects in all three study groups were identified with a lack of pressure-induced vasodilatation and reactive hyperemia.

    CONCLUSIONS: pressure-induced vasodilatation and reactive hyperemia can be measured at different tissue depths. A lack of these responses was found in healthy individuals as well as in patients indicating an innate susceptibility in some individuals, and are potential important factors to evaluate in order to better understand the etiology of pressure ulcers.

  • 5.
    Bergstrand, Sara
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Nursing Science.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Ek, Anna-Christina
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Nursing Science. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Internal Medicine.
    Lindgren, Margareta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Nursing Science.
    Blood flow at different depth in the tissue measured with PPG and laser Doppler technique2008In: Third Congress of the World Unionof Wound Healing Societies,2008, 2008, p. 31-31Conference paper (Other academic)
    Abstract [en]

       

  • 6.
    Bergstrand, Sara
    et al.
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Ek, Anna-Christina
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Internal Medicine.
    Lindén, Maria
    Mälardalen University, Västerås, Sweden.
    Lindgren, Margareta
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques2009In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 15, no 2, p. 139-147Article in journal (Refereed)
    Abstract [en]

    Background/purpose: This study has evaluated a multi-parametric system combining laser Doppler flowmetry and photoplethysmography in a single probe for the simultaneous measurement of blood flow at different depths in the tissue. This system will be used to facilitate the understanding of pressure ulcer formation and in the evaluation of pressure ulcer mattresses.

    Methods: The blood flow in the tissue over the sacrum was measured before, during and after loading with 37.5 mmHg, respectively, 50.0 mmHg. The evaluation of the system consisted of one clinical part, and the other part focusing on the technicalities of the probe prototype.

    Results: An increase in blood flow while loading was the most common response, but when the blood flow decreased during loading it was most affected at the skin surface and the blood flow responses may be different due to depths of measurement. Reactive hyperaemia may occur more frequently in the superficial layers of the tissue.

    Conclusion: The study showed that the new system is satisfactory for measuring tissue blood flow at different depths. The laser Doppler complements the photoplethysmography, and further development of the system into a thin flexible probe with the ability to measure a larger area is required.

  • 7.
    Bergstrand, Sara
    et al.
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Lindén, Maria
    n/a.
    Ek, Anna-Christina
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Länne, Toste
    Linköping University, Department of Medicine and Health Sciences. Linköping University, Faculty of Health Sciences.
    Lindgren, Margareta
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Tissue blood flow responses to external pressure in the sacral region using PPG and laser Doppler technique.2009In: European Pressure Ulcer Advisory Panels, Amsterdam., 2009Conference paper (Refereed)
  • 8.
    Edner, A.
    et al.
    University of Agriculture Science Uppsala, Sweden.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Brostrom, H.
    University of Agriculture Science Uppsala, Sweden.
    Bergh, A.
    University of Agriculture Science Uppsala, Sweden.
    Does a magnetic blanket induce changes in muscular blood flow, skin temperature and muscular tension in horses?2015In: Equine Veterinary Journal, ISSN 0425-1644, E-ISSN 2042-3306, Vol. 47, no 3, p. 302-307Article in journal (Refereed)
    Abstract [en]

    Reasons for performing studyStatic magnetic blankets are often claimed to induce increases in blood flow, reduce muscle tension and tenderness, and be beneficial in both prevention and treatment of musculoskeletal injuries in horses. However, there are no studies that confirm alleged beneficial effects of magnets on muscles of the back in healthy horses. ObjectivesTo investigate whether static magnets sewn into a blanket affect back muscle blood flow, skin temperature, mechanical nociceptive threshold (MNT) and behaviour in healthy horses. Study designProspective, randomised, blinded, placebo-controlled crossover study. MethodsThe following outcome measurements of the back of 10 healthy horses were performed; blood flow by photoplethysmography, skin temperature by use of thermistors in conjunction with digital infrared thermography, and MNTs by algometry. The horses behaviour was filmed during the procedure and scored on an ethogram. Measurements were performed repeatedly for a 30min baseline period. Thereafter a blanket with active, static magnets (900 gauss) or placebo magnets was placed on the horse and measurements were performed for a 60min treatment period and a 30min post treatment period. The study procedure was repeated on the consecutive day, when the horse received the alternative treatment. ResultsBlood flow in muscle, skin temperatures, MNTs and behavioural traits did not differ between active and placebo magnetic blankets. Skin temperature increased similarly during both active and placebo blanket treatment. ConclusionsIn healthy horses, magnetic blankets did not induce additional significant effects on muscle blood flow, skin temperature, MNTs and behaviour when compared with nonmagnetic blankets.

  • 9.
    Enlund, Gunnar
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Intensive Care UHL.
    Johansson, M
    Vegfors, Magnus
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Photoplethysmography (PPG) reflexts changes in blood flow at different vascular levels1997In: World Congress on Medical Physics and Biomedical Engineering,1997, 1997Conference paper (Refereed)
  • 10.
    Fridolin, I.
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Magnusson, M.Linköping University, Department of Biomedical Engineering, Physiological Measurements.Lindberg, L-G.Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Measurements of solutes in dialysate using UV absorption.: Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring, Vl 4263, SPIE - The International Society for Optical Engineering, San Jose, California, January 21-25, 2001 2001Conference proceedings (editor) (Other academic)
  • 11.
    Fridolin, Ivo
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Hansson, Kurt
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Optical non-invasive technique for vessel imaging: II. A simplified photon diffusion analysis2000In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, no 12, p. 3779-3792Article in journal (Refereed)
    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.

  • 12.
    Fridolin, Ivo
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    On-line monitoring of solutes in dialysate using wavelength-dependent absorption of ultraviolet radiation2003In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, no 3, p. 263-270Article in journal (Refereed)
    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.

  • 13.
    Fridolin, Ivo
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Optical non-invasive technique for vessel imaging: I. Experimental results2000In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, no 12, p. 3765-3778Article in journal (Refereed)
    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.

  • 14.
    Fridolin, Ivo
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Scanner for vessel identification and monitoring (SVIM)1998In: BIOs Conference,1998, 1998Conference paper (Other academic)
  • 15.
    Fridolin, Ivo
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Magnusson, M.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Measurement of solutes in dialysate using UV absorption2001In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4263, p. 40-47Conference paper (Other academic)
    Abstract [en]

    The aim of this work was to describe a new method for optical monitoring of solutes in a spent dialysate. The method utilizes UV light absorption employing a commercially available spectrophotometer. Measurements were performed both on collected dialysate samples and on-line. The concentration of several removed solutes and electrolytes in the serum and in the dialysate was determined simultaneously using standard laboratory techniques. During on-line monitoring the spectrophotometer was connected to the fluid outlet of the dialysis machine. On-line measurements during a single hemodialysis session demonstrated a possibility to monitor deviations in the dialysator performance (e.g. dialysator in bypass). The experimental results indicated a good correlation between UV absorption and several removed solutes (urea, creatinine) in the spent dialysate. The correlation coefficient for urea and creatinine concentrations in the dialysate was very high for every individual treatment. The UV absorbance correlates well to the concentrations of several solutes thought to be uremic toxins. The results indicate that the technique can be used as a continuous, on-line method for monitoring deviations in the dialysator performance and may estimate the removal of the overall toxins. In the future, the new method will be used to evaluate parameters describing delivery of the prescribed treatment dose such as KT/V and Urea Reduction Rate (URR).

  • 16.
    Fridolin, Ivo
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Magnusson, Martin
    Linköping University, Department of Medicine and Care, Nephrology. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    On-line monitoring of solutes in dialysate using adsorption of ultraviolet radiation: technical description2002In: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 25, no 8, p. 748-761Article in journal (Refereed)
    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.

  • 17.
    Glasin, Joakim
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Emergency Medicine.
    Henricson, Joakim
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Region Östergötland, Heart and Medicine Center, Department of Dermatology and Venerology. Linköping University, Faculty of Medicine and Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Björk Wilhelms, Daniel
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Emergency Medicine.
    Wireless vitals: Proof of concept for wireless patient monitoring in an emergency department setting2019In: Journal of Biophotonics, ISSN 1864-063X, E-ISSN 1864-0648, Vol. 12, no 4, article id e201800275Article in journal (Refereed)
    Abstract [en]

    Vital sign assessment is a common task in emergency medicine, but resources for continuous monitoring are restricted, data is often recorded manually, and entangled wires cause frustration. Therefore, we designed a small, wireless photoplethysmographic device capable of continuously assessing pulse, respiratory frequency and oxygen saturation on the sternum and tested the performance and feasibility in an emergency department setting. Fifty (56.3 20.2 years), consenting emergency patients (29 male) were recruited. Heart rate, respiratory rate and oxygen saturation were recorded simultaneously using the device and standard monitoring equipment. Data was compared using Bland-Altman plotting (heart rate, respiratory rate) and mean difference (oxygen saturation). The bias for heart- and respiratory rate was 0.4 (limits of agreements -11.3, 12.2 and -6.1, 7.0). Mean difference for oxygen saturation was -0.21 +/- 2.35%. This may be the first wireless device to use photoplethysmography on the sternum for vital sign assessment. We noted good agreement with standard monitors, but lack of standardization in data processing between monitoring systems may limit the generalizability of these findings. Although further improvements are needed, the feasibility of this approach provides proof of concept for a new paradigm of large scale, wireless patient monitoring.

  • 18.
    Hagblad, J.
    et al.
    Mälardalen University.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Kaisdotter Andersson, A.
    Mälardalen University.
    Bergstrand, Sara
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Lindgren, Margareta
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Ek, Anna-Christina
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Internal Medicine.
    Folke, M.
    Mälardalen University.
    Linden, M.
    Mälardalen University.
    A technique based on laser Doppler flowmetry and photoplethysmography for simultaneously monitoring blood flow at different tissue depths2010In: Medical and Biological Engineering and Computing, ISSN 0140-0118, Vol. 48, no 5, p. 415-422Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to validate a non-invasive optical probe for simultaneous blood flow measurement at different vascular depths combining three photoplethysmography (PPG) channels and laser Doppler flowmeter (LDF). Wavelengths of the PPG were near-infrared 810 nm with source-to-detector separation of 10 and 25 mm, and green 560 nm with source-to-detector separation of 4 mm. The probe is intended for clinical studies of pressure ulcer aetiology. The probe was placed over the trapezius muscle, and depths from the skin to the trapezius muscle were measured using ultrasound and varied between 3.8 and 23 mm in the 11 subjects included. A provocation procedure inducing a local enhancement of blood flow in the trapezius muscle was used. Blood flows at rest and post-exercise were compared. It can be concluded that this probe is useful as a tool for discriminating between blood flows at different vascular tissue depths. The vascular depths reached for the different channels in this study were at least 23 mm for the near-infrared PPG channel (source-to-detector separation 25 mm), 10-15 mm for the near-infrared PPG channel (separation 10 mm), and shallower than 4 mm for both the green PPG channel (separation 4 mm) and LDF.

  • 19.
    Hagblad, Jimmie
    et al.
    Malardalen University, Sweden .
    Folke, Mia
    Malardalen University, Sweden .
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Linden, Maria
    Malardalen University, Sweden .
    Technical issues related to the long-term monitoring of blood flow at different depths using LDF and PPG2012In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 33, no 6, p. 985-996Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate an integrated probe using LDF and multiple PPG, for the long-term aspects of skin temperature and blood flow variations at different tissue depths, and especially to investigate whether the presence of the probe affects the temperature. Measurements of temperature and blood flow were performed over 60 min on the lower back of ten subjects, lying on a mattress. The surface temperature of the skin was also measured before and after the 60 min period, and repeated with three probe configurations with the probe switched on, turned off and in the absence of a probe. A general increase in the blood flow was found to occur during the 60 min interval at all depths reached by this probe, but with variations over time. No difference was found in temperatures recorded for the different probe configurations. According to our measurements, the presence of the probe does not affect the skin surface temperature at 60 min. Our investigation shows that skin temperature can be expected to increase and approach the body core temperature by just lying in supine position on the mattress. The increase in temperature and blood flow that is known to occur, possibly attributable to pressure-induced vasodilatation, must be taken into consideration when performing these kinds of measurements.

  • 20.
    Hagblad, Jimmie
    et al.
    Mälardalen University.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Kaisdotter Andersson, Annika
    Mälardalen University.
    Bergstrand, Sara
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Lindgren, Margareta
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Ek, Anna-Christina
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Internal Medicine.
    Folke, Mia
    Mälardalen University.
    Lindén, Maria
    Mälardalen University.
    Simultan registrering av blodflöde på flera djup2009Conference paper (Refereed)
  • 21.
    Hallman, David M
    et al.
    University of Gavle.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Arnetz, Bengt B
    Wayne State University.
    Lyskov, Eugene
    University of Gavle.
    Effects of static contraction and cold stimulation on cardiovascular autonomic indices, trapezius blood flow and muscle activity in chronic neck-shoulder pain2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 8, p. 1725-1735Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to investigate reactions in trapezius muscle blood flow (MBF), muscle activity, heart rate variability (HRV) and systemic blood pressure (BP) to autonomic tests in subjects with chronic neck-shoulder pain and healthy controls. Changes in muscle activity and blood flow due to stress and unfavourable muscle loads are known underlying factors of work-related muscle pain. Aberration of the autonomic nervous system (ANS) is considered a possible mechanism. In the present study, participants (n = 23 Pain, n = 22 Control) performed autonomic tests which included a resting condition, static hand grip test (HGT) at 30% of maximal voluntary contraction, a cold pressor test (CPT) and a deep breathing test (DBT). HRV was analysed in time and frequency domains. MBF and muscle activity were recorded from the upper trapezius muscles using photoplethysmography and electromyography (EMG). The pain group showed reduced low frequency-HRV (LF) and SDNN during rest, as well as a blunted BP response and increased LF-HRV during HGT (a dagger systolic 22 mm Hg; a dagger LF(nu) 27%) compared with controls (a dagger systolic 27; a dagger LF(nu) 6%). Locally, the pain group had attenuated trapezius MBF in response to HGT (Pain 122% Control 140%) with elevated trapezius EMG following HGT and during CPT. In conclusion, only HGT showed differences between groups in systemic BP and HRV and alterations in local trapezius MBF and EMG in the pain group. Findings support the hypothesis of ANS involvement at systemic and local levels in chronic neck-shoulder pain.

  • 22.
    Jönsson, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Vascular surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Laurent, Claes
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Eneling, Martin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Skau, Tommy
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Cardiology.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Automatic ankle pressure measurements using PPG in ankle-brachial pressure index determination2005In: Scandinavian Cardiovascular Journal,2005, Sweden: Taylor & Francis , 2005, p. 13-Conference paper (Refereed)
  • 23.
    Jönsson, Björn
    et al.
    Linköping University, Department of Medicine and Care, Vascular surgery. Linköping University, Department of Medicine and Care, Anaesthesiology. Linköping University, Faculty of Health Sciences.
    Laurent, Claes
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Eneling, Martin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Skau, Tommy
    Linköping University, Department of Medicine and Care, Vascular surgery. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Automatic ankle pressure measurements using PPG in ankle-brachial pressure index determination2005In: European Journal of Vascular and Endovascular Surgery, ISSN 1078-5884, E-ISSN 1532-2165, Vol. 30, no 4, p. 395-401Article in journal (Refereed)
    Abstract [en]

    Objective

    To evaluate a new technique using a photoplethysmographic (PPG) probe for automatic ankle pressure measurements.

    Design

    Comparative study on two techniques for ankle pressure measurement.

    Setting

    University hospital.

    Material

    Thirty-five patients with leg arterial disease and eight healthy volunteers. Ankle-brachial indices (ABPI) were measured using conventional CW Doppler technique and PPG-based prototype equipment for the ankle pressure recordings.

    Chief outcome measures

    ABPIs calculated from CW Doppler and PPG ankle pressure measurements. The PPG signals were analysed both by visual judgement and by a software based, automatic algorithm.

    Main results

    The mean difference between ABPIs calculated from CW Doppler recordings and PPG (visual analysis) was −0.01 (limits of agreement (±two standard deviations) +0.16 to −0.19). The correlation coefficient was 0.93. When the algorithm was used, the mean difference (CW Doppler−PPG) was 0.05 (limits of agreement 0.28 to −0.18, r=0.89).

    Conclusions

    The PPG method is a promising technique with an inherent potential for automatisation of the ankle pressure measurements, thereby reducing the observer-dependency in ABPI recordings.

  • 24.
    Jönsson, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Vascular surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Laurent, Claes
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Eneling, Martin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Skau, Tommy
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Cardiology.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Automatisk ankeltryckmätning med PPG för bestämning av ankel-armindex (ABP)2005In: Svensk Kirurgi,2005, 2005, p. 23-Conference paper (Refereed)
  • 25.
    Jönsson, Björn
    et al.
    Linköping University, Department of Medicine and Care, Vascular surgery. Linköping University, Faculty of Health Sciences.
    Laurent, Claes
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Skau, Tommy
    Linköping University, Department of Medicine and Care, Vascular surgery. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    A new probe for ankle systolic pressure measurement using Photoplethysmography (PPG)2005In: Annals of Biomedical Engineering, ISSN 0090-6964, E-ISSN 1573-9686, Vol. 33, no 2, p. 232-239Article in journal (Refereed)
    Abstract [en]

    An automated method for ankle systolic pressure measurement, less operator dependent than the standard continuous wave (CW) Doppler technique, would imply an advantage both in patient measurements and in epidemiological studies. We present a new photoplethysmographic (PPG) probe that uses near-infrared light (880 nm) to detect pulsatory blood flow underneath the distal end of a standard pneumatic cuff. The probe is adapted to the anatomical conditions at the ankle, permitting recording of pressures in both ankle arteries separately. The validity of the equipment was tested with CW Doppler-derived systolic pressures and invasive blood pressure measurements for reference. In 20 healthy subjects, visual analysis of the PPG curves revealed a mean difference between CW Doppler and PPG measurements of –0.5 mmHg (SD 6.9). Corresponding results for the anterior and posterior tibial arteries separately were –1.8 mmHg (SD 6.2) and 0.9 mmHg (SD 7.3), respectively. A correct probe position was essential for the results. In direct recordings from the dorsalis pedis artery in 10 intensive care patients, PPG underestimated systolic pressure in the anterior tibial artery by 4.5 mmHg (SD 12.1). With further development, the PPG probe, integrated in the pneumatic cuff, may simplify measurements of ankle systolic pressures.

  • 26.
    Jönsson, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Vascular surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Laurent, Claes
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Skau, Tommy
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    A new probe for ankle systolic pressure measurements using photopethysmography2004In: International Angiology,2004, 2004, p. 186-186Conference paper (Other academic)
  • 27.
    Jönsson, Björn
    et al.
    Linköping University, Department of Medicine and Care, Vascular surgery. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Skau, Tommy
    Linköping University, Department of Medicine and Care, Vascular surgery. Linköping University, Faculty of Health Sciences.
    Thulesius, Olav
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences.
    Is oscillometric ankle pressure reliable in leg vascular disease?2001In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 21, no 2, p. 155-163Article in journal (Refereed)
    Abstract [en]

    The objective of the study was to evaluate the validity of oscillometric systolic ankle pressure in symptomatic leg arterial occlusive disease. Ankle pressure measurements using oscillometric curves obtained using a standard 12-cm cuff with a specially designed device for signal processing were validated against the continuous wave (CW) Doppler technique. Thirty-four subjects without signs or symptoms of peripheral vascular disease (68 legs) and 47 patients with leg ischaemia (85 legs) varying from moderate claudication to critical ischaemia were examined. The oscillometric curves were analysed using several algorithms reported in the literature, based on the assumption that maximum oscillations are recorded near mean arterial pressure. In normals, reasonable agreement between CW Doppler and oscillometric methods was seen. When an algorithm that determined the lowest cuff pressure at which maximum oscillations occurred, and a characteristic ratio for systolic pressure of 0·52 was used, the mean difference between CW Doppler and oscillometry was 1·7 mmHg [range −19 to +27, limits of agreement (2 SD) 21·1 mmHg]. In ischaemic legs, oscillometry overestimated systolic ankle pressure by a mean of 28·8 mmHg [range –126 to +65, limits of agreement 82·8 mmHg]. The difference was more pronounced among patients with critical ischaemia compared with claudicants, and also more evident among diabetics. The error of oscillometric pressure determination in subjects with leg arterial disease inversely increased with CW Doppler ankle pressure. In 39% of the recordings in legs with a CW Doppler systolic pressure below 100 mmHg, the oscillometric mean arterial pressure was higher than the recorded CW Doppler systolic pressure. In conclusion, the oscillometric method to determine systolic ankle pressure, based on the concept of maximum cuff oscillations occurring near mean arterial pressure, is not reliable in leg arterial disease, usually overestimating ankle pressure.

  • 28.
    Källman, Ulrika
    et al.
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Bergstrand, Sara
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Ek, Anna-Christina
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Health Care.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Lindgren, Margareta
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Different lying positions and their effects on tissue blood flow and skin temperature in older adult patients2013In: Journal of Advanced Nursing, ISSN 0309-2402, E-ISSN 1365-2648, Vol. 69, no 1, p. 133-144Article in journal (Refereed)
    Abstract [en]

    Aim. To report a study to compare the effects of different lying positions on tissue blood flow and skin temperature in older adult patients. This article reports the evaluation of study design and procedures. Background. To reduce risk of pressure ulcers, repositioning of immobile patients is a standard nursing practice; however, research into how different lying positions effect tissue microcirculation is limited. Design. Descriptive comparative design. Methods. From MarchOctober 2010, 20 inpatients, aged 65 years or older, were included in the study. Tissue blood flow and skin temperature were measured over bony prominences and in gluteus muscle in four supine and two lateral positions. Results. The blood flow over the bony prominence areas was most influenced in the superficial skin and especially in the 30 degrees lateral position, where the blood flow decreased significantly in comparison with the supine positions. There were significant individual differences in blood flow responses, but no common trend was identified among the patients considered at risk for pressure ulcer development. The study procedure worked well and was feasible to perform in an inpatient population. Conclusion. The lying positions seem to influence the tissue blood flow over the bony prominences in different ways in older adult inpatients, but further study is needed to confirm the results and to make recommendations to clinical practice. The study procedure worked well, although some minor adjustments with regard to heat accumulation will be made in future studies.

  • 29.
    Källman, Ulrika
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Södra Älvsborgs Sjukhus, Borås, Sweden .
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Bergstrand, Sara
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Ek, Anna-Cristina
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Health Care in Linköping.
    Fredrikson, Mats
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Lindgren, Margareta
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    The Effects of Different Lying Positions on Interface Pressure, Skin Temperature, and Tissue Blood Flow in Nursing Home Residents2015In: Biological Research for Nursing, ISSN 1099-8004, E-ISSN 1552-4175, Vol. 17, no 2, p. 142-151Article in journal (Refereed)
    Abstract [en]

    Background: Although repositioning is considered an important intervention to prevent pressure ulcers, tissue response during loading in different lying positions has not been adequately explored.

    Aim: To compare the effects of different lying positions on interface pressure, skin temperature, and tissue blood flow in nursing home residents.

    Method: From May 2011 to August 2012, interface pressure, skin temperature, and blood flow at three tissue depths were measured for 1 hr over the sacrum in 30 supine tilt and 0 supine positions and over the trochanter major in 30lateral and 90lateral positions in 25 residents aged 65 years or older. Measurement of interface pressure was accomplished using a pneumatic pressure transmitter connected to a digital manometer, skin temperature using a temperature sensor, and blood flow using photoplethysmography and laser Doppler flowmetry.

    Results: Interface pressure was significantly higher in the 0supine and 90lateral positions than in 30supine tilt and 30 lateral positions. The mean skin temperature increased from baseline in all positions. Blood flow was significantly higher in the 30 supine tilt position compared to the other positions. A hyperemic response in the post pressure period was seen at almost all tissue depths and positions.

    Conclusion: The 30supine tilt position generated less interface pressure and allowed greater tissue perfusion, suggesting that this position is the most beneficial.

  • 30.
    Laurent, Claes
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Jönsson, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Vascular surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Vegfors, Magnus
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Eneling, M
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Nonivasive monitoring of systolic blood pressuire on the arm utilizing photoplethysmpgraphy (PPG)2004In: Proceedings of SPIE jfr 1998-2000 SPIE proceedings ISSN 1017-2653, ISSN 1605-7422, p. 99-107Article in journal (Refereed)
  • 31.
    Laurent, Claes
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Jönsson, Björn
    Linköping University, Department of Medicine and Care, Vascular surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery. Linköping University, Faculty of Health Sciences.
    Vegfors, Magnus
    Linköping University, Department of Medicine and Care, Anaesthesiology. Linköping University, Faculty of Health Sciences.
    Eneling, Martin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Noninvasive monitoring of systolic blood pressure on the arm utilizing photoplethysmography (PPG): clinical report2004In: Proc. SPIE 5318, Advanced Biomedical and Clinical Diagnostic Systems II / [ed] Gerald E. Cohn; Warren S. Grundfest; David A. Benaron; Tuan Vo-Dinh, Bellingham WA, USA: SPIE , 2004, p. 99-Conference paper (Refereed)
    Abstract [en]

    A soft (silicone) probe, containing six light emitting diodes (880 nm) and three photo detectors, utilizes photoplethysmography (PPG) to monitor pulsations from the brachialis artery under an occluding cuff during deflation. When the arterial pulse returns, measured by PPG, the corresponding pressure in the cuff is determined. This pressure is assumed to equal the systolic pressure. An assessment trial was performed on 21 patients (9 women and 12 men, aged 27-69) at the Neuro-Intensive care unit. Since the patients were already provided with arterial needles, invasive blood pressure could be used as the reference. By choosing a threshold, for detecting pulses, as a fraction (4%) of the maximum amplitude, the systolic blood pressure was underestimated (-0.57 mmHg, SD 12.1). The range of systolic pressure for the patients was 95.5 - 199.0 mmHg, n=14. The method is promising, but improvements still have to be made in order to improve the technique.

  • 32.
    Laurent, Claes
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Jönsson, Björn
    Linköping University, Department of Medicine and Care, Vascular surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery. Linköping University, Faculty of Health Sciences.
    Vegfors, Magnus
    Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Non-invasive measurement of systolic blood pressure on the arm utilising photoplethysmography: development of the methodology2005In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, no 1, p. 131-135Article in journal (Refereed)
    Abstract [en]

    Photoplethysmography (PPG) can be used to measure systolic blood pressure at the brachial artery. With a specially designed probe, positioned in the most distal position beneath a pressure cuff on the upper arm, this is possible. The distance between the light source (880 nm) and the photodetector was 20 mm. A test was performed on neuro-intensive care patients by determining blood pressure from the PPG curves, and, when it was compared with systolic blood pressure obtained from inserted indwelling arterial catheters, a correlation factor of r=0.95 was achieved. The difference between blood pressure obtained using PPG and invasive blood pressure measurement was 3.9±9.1 mmHg (mean±SD), n=19. The depth to the brachial artery was 13.9±4.1 mm (mean±SD), n=18. A digital PPG system utilising pulsating light was also developed.

  • 33.
    Laurent, Claes
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Jönsson, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Vascular surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Vegfors, Magnus
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Non-invasive monitoring of systolic blood preassure on arm utilizing photoplethysmography (PPG)2000In: World Congress of Medical Physics and Biomedical Engineering,2000, Springer-Verlag , 2000, p. 131-135Conference paper (Refereed)
    Abstract [en]

    Photoplethysmography (PPG) can be used to measure systolic blood pressure at the brachial artery. With a specially designed probe, positioned in the most distal position beneath a pressure cuff on the upper arm, this is possible. The distance between the light source (880 nm) and the photodetector was 20 mm. A test was performed on neuro-intensive care patients by determining blood pressure from the PPG curves, and, when it was compared with systolic blood pressure obtained from inserted indwelling arterial catheters, a correlation factor of r=0.95 was achieved. The difference between blood pressure obtained using PPG and invasive blood pressure measurement was 3.9±9.1 mmHg (mean±SD), n=19. The depth to the brachial artery was 13.9±4.1 mm (mean±SD), n=18. A digital PPG system utilising pulsating light was also developed.

  • 34.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Photoplethysmography: methodological studies and applications1991Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Photoplethysmography (PPG), an optical non-invasive technique for measuring skin perfusion changes, was investigated and evaluated. The method was compared with laser Doppler flowmetry (LDF) when measuring perfusion changes in human fingers and forearms. The results showed that both PPG and LDF reflect changes in skin perfusion under certain conditions related to the sample volume of PPG. This volume is in turn related to the wavelength and the probe type used. In addition, an increased sensitivity to perfusion changes can, in some vascular beds, be obtained when using a shorter wavelength (560 nm). The DC-coupled PPG does not provide a consistent measure of skin perfusion changes induced by local temperature variations.

    Optical properties of blood in motion were studied in perfusion models. Light reflection and transmission was found to be dependant on several parameters such as blood volume, viscosity, red blood cell orientation and haematocrit. The results also indicate that a shorter wavelength can be used to extract information about blood volume changes, whereas a longer wavelength primarily reflects changes in red cell orientation.

    A fibre optic sensor for monitoring of respiratory- and heart rates from the same fibre optic probe has been developed. Blood perfusion changes, synchronous with the heart- and the respiration rates, were measured by analysing reflected light from the skin surface. The new sensor has the advantages of being totally non-invasive. It can be positioned anywhere on the skin surface and is also insensitive to electromagnetic disturbances.

    Pulse oximetry utilizes the PPG signal for monitoring of the arterial oxygen saturation. The pulse oximeter signal was studied under various blood flow conditions, simulated in an in vitro model. The results indicate that blood flow conditions may affect the accuracy of the instrument.

  • 35.
    Lindberg, Lars-Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Fridolin, Ivo
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Magnusson, M
    Non-invasive optical dialysate monitoring1999In: Congress of the European Renal Association, European Dialysis and Transplant Association,1999, 1999Conference paper (Refereed)
  • 36.
    Lindberg, Lars-Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Lennmarken, Claes
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Intensive Care UHL.
    Vegfors, Magnus
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Pulse oximetry-clinical implications and recent technical developments1995In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 39, p. 279-287Article in journal (Refereed)
  • 37.
    Lindberg, Lars-Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Vegfors, Magnus
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Lennmarken, Claes
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Intensive Care UHL.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Pulse oximeter signal at various blood flow conditions in an In vitro model1995In: Medical & Biological Engineering & Computing, ISSN 0140-0118, Vol. 33, p. 87-91Article in journal (Refereed)
  • 38.
    Naslund, J.
    et al.
    Näslund, J., Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden.
    Pettersson, Jonas
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering.
    Lundeberg, T.
    Rehabilitation Medicine University Clinic Stockholm, Danderyds Hospital, Stockholm, Sweden.
    Linnarsson, D.
    Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Non-invasive continuous estimation of blood flow changes in human patellar bone2006In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 44, no 6, p. 501-509Article in journal (Refereed)
    Abstract [en]

    A photoplethysmographic (PPG) technique to assess blood flow in bone tissue has been developed and tested. The signal detected by the PPG consists of a constant-level (DC) component - which is related to the relative vascularization of the tissue - and a pulsatile (AC) component - which is synchronous with the pumping action of the heart. The PPG probe was applied on the skin over the patella. The probe uses near-infrared (804 nm) and green (560 nm) light sources and the AC component of the PPG signals of the two wavelengths was used to monitor pulsatile blood flow in the patellar bone and the overlying skin, respectively. Twenty healthy subjects were studied and arterial occlusion resulted in elimination of PPG signals at both wavelengths, whereas occlusion of skin blood flow by local surface pressure eliminated only the PPG signal at 560 nm. In a parallel study on a physical model with a rigid tube we showed that the AC component of the PPG signal originates from pulsations of blood flow in a rigid structure and not necessarily from volume pulsations. We conclude that pulsatile blood flow in the patellar bone can be assessed with the present PPG technique. © International Federation for Medical and Biological Engineering 2006.

  • 39.
    Naslund, J.
    et al.
    Näslund, J., Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden, Nobels väg 8, Stockholm, SE-17177, Sweden.
    Walden, M.
    Department of Orthopaedics, Hässleholm Hospital, Hässleholm, Sweden.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Decreased pulsatile blood flow in the patella in patellofemoral pain syndrome2007In: American Journal of Sports Medicine, ISSN 0363-5465, E-ISSN 1552-3365, Vol. 35, no 10, p. 1668-1673Article in journal (Refereed)
    Abstract [en]

    Background: Anterior knee pain without clinical and radiologic abnormalities has primarily been explained from a purely structural view. A recently proposed biologic and homeostatic explanation questions the malalignment theory. No objective measurement of the pathophysiology responsible for changes in local homeostasis has been presented. Hypothesis: Flexing the knee joint interferes with the perfusion of the patellar bone in patellofemoral pain syndrome. Study Design: Case control study, Level of evidence, 4. Methods: Pulsatile blood flow in the patella was measured continuously and noninvasively using photoplethysmography. Measurements were made with the patient in a resting position with knee flexion of 20°and after passive knee flexion to 90°. In total, 22 patients with patellofemoral pain syndrome were examined bilaterally, and 33 subjects with healthy knees served as controls. Results: The pulsatile blood flow in the patient group decreased after passive knee flexion from 20°to 90°(systematic change in position, or relative position [RP] = -0.32, 95% confidence interval for RP, -0.48 to -0.17), while the response in the control group showed no distinct pattern (RP = 0.17, 95% confidence interval for RP, -0.05 to 0.31). The difference between the groups was significant (P =.0002). The median change in patients was -26% (interquartile range, 37). Conclusions: Pulsatile patellar blood flow in patellofemoral pain syndrome patients is markedly reduced when the knee is being flexed, which supports the previous notion of an ischemic mechanism involved in the pathogenesis of this pain syndrome. © 2007 American Orthopaedic Society for Sports Medicine.

  • 40.
    Nilsson, Lena
    et al.
    Linköping University, Department of Medicine and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Goscinski, T.
    Department of Anaesthesiology and Intensive Care, Linköping University Hospital, Linköping, Sweden.
    Kalman, S.
    Department of Anaesthesiology and Intensive Care, Karolinska University Hospital, Huddinge, Sweden.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Johansson, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Combined photoplethysmographic monitoring of respiration rate and pulse: A comparison between different measurement sites in spontaneously breathing subjects2007In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 51, no 9, p. 1250-1257Article in journal (Refereed)
    Abstract [en]

    Background: The non-invasive photoplethysmographic (PPG) signal reflects blood flow and volume in a tissue. The PPG signal shows variation synchronous with heartbeat (PPGc), as used in pulse oximetry, and variations synchronous with breathing (PPGr). PPGr has been used for non-invasive monitoring of respiration with promising results. Our aim was to investigate PPG signals recorded from different skin sites in order to find suitable locations for parallel monitoring of variations synchronous with heartbeat and breathing. Methods: PPG sensors were applied to the forearm, finger, forehead, wrist and shoulder on 48 awake healthy volunteers. From these sites, seven PPG signals were simultaneously recorded during normal spontaneous breathing over 10 min. Capnometry served as respiration and electrocardiogram (ECG) as pulse reference signals. PPG signals were compared with respect to power spectral content and squared coherence. Results: Forearm PPG measurement showed significantly higher power within the respiratory region of the power spectrum [median (quartile range) 42 (26)%], but significantly lower power within the cardiac region [9 (10)%] compared with the other skin sites. PPG finger measurement showed the opposite, in transmission mode, the power within the respiratory region was significantly lower [4 (10)%] and within the cardiac region significantly higher [45 (25)%] than the other sites. PPGc coherence values were generally high [>0.96 (0.08)], and PPGr coherence values lower [0.83 (0.35)-0.94 (0.17)]. Conclusion: Combined PPG respiration and pulse monitoring is possible, but there are significant differences between the respiratory and cardiac components of the PPG signal at different sites. © 2007 Acta Anaesthesiol Scand.

  • 41.
    Nilsson, Lena
    et al.
    Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
    Goscinski, Tomas
    Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
    Johansson, Anders
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Kalman, Sigga
    Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
    Age and gender do not influence the ability to detect respiration by photoplethysmography2006In: Journal of clinical monitoring and computing, ISSN 1387-1307, E-ISSN 1573-2614, Vol. 20, no 6, p. 431-436Article in journal (Refereed)
    Abstract [en]

    Objective  The non-invasive technique photopl- ethysmography (PPG) can detect changes in blood volume and perfusion in a tissue. Respiration causes variations in the peripheral circulation, making it possible to monitor breaths using an optical sensor attached to the skin. The respiratory-synchronous part of the PPG signal (PPGr) has been used to monitor respiration during anaesthesia, and in postoperative and neonatal care. Studies addressing possible differences in PPGr signal characteristics depending on gender or age are lacking.

    Methods  We studied three groups of 16 healthy subjects each during normal breathing; young males, old males and young females, and calculated the concordance between PPGr, derived from a reflection mode PPG sensor on the forearm, and a reference CO2 signal. The concordance was quantified by using a squared coherence analysis. Time delay between the two signals was calculated. In this process, we compared three different methods for calculating time delay.

    Results  Coherence values ≥0.92 were seen for all three groups without any significant differences depending on age or gender (p = 0.67). Comparison between the three different methods for calculating time delay showed a correlation r = 0.93.

    Conclusions  These results demonstrate clinically important information implying the possibility to register qualitative PPGr signals for respiration monitoring, regardless of age and gender.

  • 42.
    Nilsson, Lena
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Goscinski, Tomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology.
    Kalman, Sigga
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Johansson, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Detection of breaths by photoplethysmography is independent of age and sex2005In: Congress of the Scandinavian Society of Anaesthesiology and intensive care,2005, 2005, p. 19-Conference paper (Refereed)
  • 43.
    Nilsson, Lena
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Goscinski, Tomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology.
    Kalman, Sigga
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Johansson, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Photoplethysmography for central and obstructive apnea detection2005In: Congress of the Scandinavian Society of Anaesthesiology and intensive care,2005, 2005, p. 19-Conference paper (Refereed)
  • 44.
    Nilsson, Lena
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Goscinski, Tomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology.
    Kalman, Sigga
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Anaesthesiology. Östergötlands Läns Landsting, Anaesthesiology and Surgical Centre, Department of Anaesthesiology and Intensive Care VHN.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Johansson, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Time relation between respiratory signals can be analysed by automated algorithms2005In: Congress of the Scandinavian Society of Anaesthesiology and intensive care,2005, 2005, p. 19-Conference paper (Refereed)
  • 45. Palmerud, P.
    et al.
    Zhang, Q.
    Forsman, M.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Non-invasive photoplethysmography for muscle blood flow assessment in ergonomic applications2010In: European Journal of Applied Physiology, ISSN 1439-6319Article in journal (Refereed)
  • 46.
    Pilt, Kristjan
    et al.
    Tallinn University of Technology, Estonia .
    Ferenets, Rain
    Tallinn University of Technology, Estonia .
    Meigas, Kalju
    Tallinn University of Technology, Estonia .
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Temitski, Kristina
    Tallinn University of Technology, Estonia .
    Viigimaa, Margus
    Tallinn University of Technology, Estonia .
    New Photoplethysmographic Signal Analysis Algorithm for Arterial Stiffness Estimation2013In: Scientific World Journal, ISSN 1537-744X, E-ISSN 1537-744X, Vol. 2013Article in journal (Refereed)
    Abstract [en]

    The ability to identify premature arterial stiffening is of considerable value in the prevention of cardiovascular diseases. The "ageing index" (AGI), which is calculated from the second derivative photoplethysmographic (SDPPG) waveform, has been used as one method for arterial stiffness estimation and the evaluation of cardiovascular ageing. In this study, the new SDPPG analysis algorithm is proposed with optimal filtering and signal normalization in time. The filter parameters were optimized in order to achieve the minimal standard deviation of AGI, which gives more effective differentiation between the levels of arterial stiffness. As a result, the optimal low-pass filter edge frequency of 6 Hz and transitionband of 1 Hz were found, which facilitates AGI calculation with a standard deviation of 0.06. The study was carried out on 21 healthy subjects and 20 diabetes patients. The linear relationship (r = 0.91) between each subjects age and AGI was found, and a linear model with regression line was constructed. For diabetes patients, the mean AGI value difference from the proposed model y(AGI) was found to be 0.359. The difference was found between healthy and diabetes patients groups with significance level of P andlt; 0.0005.

  • 47. Sandberg, M
    et al.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Evaluation of muscle blood flow changes induced by needle stimulation using a new non-invasive technique2000In: EFIC Third Congress on the European Federation of IASP Chapters,2000, 2000Conference paper (Other academic)
  • 48. Sandberg, M.
    et al.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Non-invasive measurement of blood flow in trapezius muscle - a methodological study2010In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201XArticle in journal (Refereed)
  • 49.
    Sandberg, Margareta
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Larsson, Britt
    Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Different patterns of blood flow response in the trapezius muscle following needle stimulation (acupuncture) between healthy subjects and patients with fibromyalgia and work-related trapezius myalgia2005In: European Journal of Pain, ISSN 1090-3801, Vol. 9, no 5, p. 497-510Article in journal (Refereed)
    Abstract [en]

    Needle stimulation (acupuncture) has recently been shown to increase blood flow in the tibialis anterior muscle and overlying skin in healthy subjects (HS) and patients with fibromyalgia (FM). The aim of the present study was to examine the effect of needle stimulation on local blood flow in the trapezius muscle and overlying skin in HS and two groups of patients suffering from chronic pain in the trapezius muscle, i.e., FM and work-related trapezius myalgia (TM) patients. Two modes of needling, deep muscle stimulation (Deep) and subcutaneous needle insertion (SC), were performed at the upper part of the shoulder and blood flow was monitored for 60 min post-stimulation. Blood flow changes were measured non-invasively by using a new application of photoplethysmography. Increased blood flow in the trapezius muscle and overlying skin was found in all three groups following both Deep and SC. In HS, Deep was superior to SC in increasing skin and muscle blood flow, whereas in FM, SC was as effective as, or even more effective, than Deep. In the severely affected TM patients, no differences were found between the stimuli, and generally, a lesser blood flow response to the stimuli was found. At Deep, the muscle blood flow increase was significantly larger in HS, compared to the two patient groups. Positive correlations were found between muscle blood flow at Deep and pressure pain threshold in the trapezius muscle, neck movement and pain experienced at the stimulation, and negative correlations were found with spontaneous pain-related variables, symptom duration and age, pointing to less favorable results with worsening of symptoms, and to the importance of nociceptor activation in blood flow increase. It was hypothesized that the different patterns of muscle blood flow response to the needling may mirror a state of increased sympathetic activity and a generalized hypersensitivity in the patients. The intensity of stimulation should be taken into consideration when applying local needle stimulation (acupuncture) in order to increase the trapezius muscle blood flow in chronic pain conditions.

  • 50.
    Sandberg, Margareta
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Peripheral effects of needle stimulation (acupuncture) on skin and muscle blood flow in fibromyalgia2004In: European Journal of Pain, ISSN 1090-3801, Vol. 8, no 2, p. 163-171Article in journal (Refereed)
    Abstract [en]

    Acupuncture has become a widely used treatment modality in various musculoskeletal pain conditions. Acupuncture is also shown to enhance blood flow and recovery in surgical flaps. The mechanisms behind the effect on blood flow were suggested to rely on vasoactive substances, such as calcitonin gene-related peptide, released from nociceptors by the needle stimulation. In a previous study on healthy subjects, one needle stimulation into the anterior tibial muscle was shown to increase both skin and muscle blood flow. The aim of this study was to examine the effect of needle stimulation on local blood flow in the anterior tibial muscle and overlying skin in patients suffering from a widespread chronic pain condition. Fifteen patients with fibromyalgia (FM) participated in the study. Two modes of needling, deep muscle stimulation and subcutaneous needle insertion were performed at the upper anterior aspect of the tibia, i.e., in an area without focal pathology or ongoing pain in these patients. Blood flow changes were assessed non-invasively by photoplethysmography (PPG). The results of the present study were partly similar to those earlier found at a corresponding site in healthy female subjects, i.e., deep muscle stimulation resulted in larger increase in skin blood flow (mean (SE)): 62.4% (13.0) and muscle blood flow: 93.1% (18.6), compared to baseline, than did subcutaneous insertion (mean (SE) skin blood flow increase: 26.4% (6.2); muscle blood flow increase: 46.1% (10.2)). However, in FM patients subcutaneous needle insertion was followed by a significant increase in both skin and muscle blood flow, in contrast to findings in healthy subjects where no significant blood flow increase was found following the subcutaneous needling. The different results of subcutaneous needling between the groups (skin blood flow: p=0.008; muscle blood flow: p=0.027) may be related to a greater sensitivity to pain and other somatosensory input in FM.

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