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  • 251.
    Rudner, Mary
    et al.
    Linköping University, Department of Neuroscience and Locomotion. Linköping University, Faculty of Health Sciences.
    Cedefamn, Jonny
    Friman, Ola
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Lundberg, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Söderfeldt, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Are levels of language processing reflected in neural activation? - An fMRI study.2001In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 13, no 6Article in journal (Refereed)
  • 252. Rundquist, I
    et al.
    Smith, Q R
    Michel, M E
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Öberg, Åke
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Rapoport, S I
    Sciatic nerve blood flow measured by laser Doppler flowmetry and [14C]iodoantipyrine.1985In: American Journal of Physiology, ISSN 0002-9513, E-ISSN 2163-5773, Vol. 248, no 3 Pt 2, p. H311-317Article in journal (Refereed)
    Abstract [en]

    Blood flow was examined in sciatic nerves of pentobarbital-anesthetized rats by means of laser Doppler flowmetry (LDF) and intravenous [14C]iodoantipyrine infusion. Continuous LDF signals demonstrated slow oscillations and acute, pressure-related changes in flow. The steady-state LDF signal was related linearly to nerve blood flow, as measured with [14C]iodoantipyrine, in intact nerves and nerves stripped of the epineurium. In 14 intact nerves, nerve blood flow averaged 0.27 +/- 0.03 (SE) ml X min-1 X g-1, whereas it averaged 0.13 +/- 0.01 in 5 stripped nerves. Autoradiographs of [3H]-nicotine-infused nerves and intra-arterial injection of 57Co-labeled microspheres demonstrated that flow was not uniform throughout the nerve cross section. The results indicate that LDF can be used to examine nerve blood flow in vivo, demonstrate a linear relation between the LDF signal and flow, and establish absolute values for blood flow in intact and stripped nerves of the anesthetized rat.

  • 253.
    Salerud, Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Tenland, T.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Spontaneous oscillations in skin blood flow studied by Laser Doppler Flowmetry1981In: 5th Nordic Meeting on Medical and Biological Engineering,1981, 1981, p. 216-Conference paper (Refereed)
  • 254.
    Salerud, Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Tenland, T.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Rhythmical variations in human skin blood flow.1983In: International journal of microcirculation : clinical and experimental / sponsored by the European Society for Microcirculation, ISSN 0167-6865, Vol. 2, p. 91-102Article in journal (Refereed)
  • 255.
    Salerud, Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Local postischemic hyperemia in the gastrocnemius muscle studied by single fiber laser Doppler flowmetry1986In: XIV International Conference of European Society for Microcirculation,1986, 1986Conference paper (Other academic)
  • 256.
    Salerud, Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Simultaneous 3-channel laser Doppler flowmetry. An improvement of the single fibre technique.1987In: 7th Nordic Meeting on Medical and Biological Engineering,1987, 1987, p. 113-Conference paper (Refereed)
  • 257.
    Salerud, Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Single Fiber Laser Doppler Flowmetry: a method for assessing blood flow in tissue1986In: XIV International Conference of European Society for Microcirculation,1986, 1986Conference paper (Other academic)
  • 258.
    Salerud, Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Single-fibre laser Doppler flowmetry: A method for deep tissue perfusion studies1987In: Medical & Biological Engineering & Computing, ISSN 0140-0118, Vol. 25, p. 329-334Article in journal (Refereed)
  • 259.
    Salerud, Göran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Spelman, F.A.
    Single fiber laser Doppler flowmetry for tissue perfusion measurements1985In: XIV International Conference on Medical and Biological Engineering and VII International Conference on Medical Physics,1985, 1985, p. 1095-Conference paper (Refereed)
  • 260. 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)
  • 261. 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)
  • 262.
    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.

  • 263.
    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.

  • 264.
    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.
    Lundeberg, Thomas
    Division of Physiology II, Karolinska Institutet, Stockholm, 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. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Effects of acupuncture on skin and muscle blood flow in healthy subjects2003In: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 90, no 1-2, p. 114-119Article in journal (Refereed)
    Abstract [en]

    In 14 healthy female subjects, the effects of needle stimulation (acupuncture) on skin and muscle blood flow were investigated using a non-invasive custom-designed probe and photoplethysmography (PPG). In randomised order, 2–7 days apart, three modes of needle stimulation were performed on the anterior aspect of the tibia: superficial insertion (SF), insertion into the anterior tibial muscle (Mu), and insertion into the muscle including manipulation of the needle in order to elicit a distinct sensation of distension, heaviness or numbness (DeQi). Before intervention, the subjects rested for 30 min. After the intervention, the needle was left in situ for 20 min. Blood flow recordings were performed intermittently from 10 min prior to the intervention to the end of the trial. In a fourth session, serving as control, corresponding measurements were performed without any needle stimulation. Area under curve was calculated for 5-min periods prior to and after stimulation, respectively, and for the remaining 15-min period after stimulation. Compared to the control situation, muscle blood flow increased following both Mu and DeQi for 20 min, with the latter being more pronounced for the initial 5 min. Skin blood flow increased for 5 min following DeQi. However, no increase was found following SF. The DeQi stimulation was preceded by higher visual analogue scale ratings of anxiety prior to stimulation, which might have influenced skin blood flow to some extent. The results indicate that the intensity of the needling is of importance, the DeQi stimulation resulting in the most pronounced increase in both skin and muscle blood flow.

  • 265.
    Sandberg, Margareta
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Zhang, Qiuxia
    Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden.
    Styf, Jorma
    Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . 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 monitoring of muscle blood perfusion by photoplethysmography: Evaluation of a new application2005In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 183, no 4, p. 335-343Article in journal (Refereed)
    Abstract [en]

    Aim: To evaluate a specially developed photoplethysmographic (PPG) technique, using green and near-infrared light sources, for simultaneous non-invasive monitoring of skin and muscle perfusion.

    Methods: Evaluation was based on assessments of changes in blood perfusion to various provocations, such as post-exercise hyperaemia and hyperaemia following the application of liniment. The deep penetrating feature of PPG was investigated by measurement of optical radiation inside the muscle. Simultaneous measurements using ultrasound Doppler and the new PPG application were performed to elucidate differences between the two methods. Specific problems related to the influence of skin temperature on blood flow were highlightened, as well.

    Results: Following static and dynamic contractions an immediate increase in muscle perfusion was shown, without increase in skin perfusion. Liniment application to the skin induced a rapid increase in skin perfusion, but not in muscle. Both similarities and differences in blood flow measured by Ultrasound Doppler and PPG were demonstrated. The radiant power measured inside the muscle, by use of an optical fibre, showed that the near-infrared light penetrates down to the vascular depth inside the muscle.

    Conclusions: The results of this study indicate the potentiality of the method for non-invasive measurement of local muscle perfusion, although some considerations still have to be accounted for, such as influence of temperature on blood perfusion.

  • 266.
    Schiotz Thorud, Hanne-Mari
    et al.
    Buskerud University College.
    Helland, Magne
    Buskerud University College.
    Aaras, Arne
    Buskerud University College.
    Martin Kvikstad, Tor
    Buskerud University College.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Horgen, Gunnar
    Buskerud University College.
    Eye-Related Pain Induced by Visually Demanding Computer Work2012In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 89, no 4, p. E452-E464Article in journal (Refereed)
    Abstract [en]

    Purpose. Eye strain during visually demanding computer work may include glare and increased squinting. The latter may be related to elevated tension in the orbicularis oculi muscle and development of muscle pain. The aim of the study was to investigate the development of discomfort symptoms in relation to muscle activity and muscle blood flow in the orbicularis oculi muscle during computer work with visual strain. less thanbrgreater than less thanbrgreater thanMethods. A group of healthy young adults with normal vision was randomly selected. Eye-related symptoms were recorded during a 2-h working session on a laptop. The participants were exposed to visual stressors such as glare and small font. Muscle load and blood flow were measured by electromyography and photoplethysmography, respectively. less thanbrgreater than less thanbrgreater thanResults. During 2 h of visually demanding computer work, there was a significant increase in the following symptoms: eye-related pain and tiredness, blurred vision, itchiness, gritty eyes, photophobia, dry eyes, and tearing eyes. Muscle load in orbicularis oculi was significantly increased above baseline and stable at 1 to 1.5% maximal voluntary contraction during the working sessions. Orbicularis oculi muscle blood flow increased significantly during the first part of the working sessions before returning to baseline. There were significant positive correlations between eye-related tiredness and orbicularis oculi muscle load and eye-related pain and muscle blood flow. Subjects who developed eye-related pain showed elevated orbicularis oculi muscle blood flow during computer work, but no differences in muscle load, compared with subjects with minimal pain symptoms. less thanbrgreater than less thanbrgreater thanConclusions. Eyestrain during visually demanding computer work is related to the orbicularis oculi muscle. Muscle pain development during demanding, low-force exercise is associated with increased muscle blood flow, possible secondary to different muscle activity pattern, and/or increased mental stress level in subjects experiencing pain compared with subjects with minimal pain.

  • 267.
    Selskog, Pernilla
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Brandt, Einar
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Wigström, Lars
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Karlsson, Matts
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Quantification and Visualization of myocardial strain-rate tensors from time-resolved 3D cine phase contrast MRI.2001In: Proc. Intl. Soc. Mag. Reson. Med.,2001, 2001, p. 1870-1870Conference paper (Refereed)
  • 268.
    Sjöberg, Birgitta Janero
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wranne, Bengt
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Subaortic flow profiles in aortic valve disease: a two-dimensional color Doppler study.1994In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 7, no 3 Pt 1, p. 276-285Article in journal (Refereed)
    Abstract [en]

    With time-corrected color Doppler echocardiography, the aortic subvalvular spatial flow velocity profile was registered in two perpendicular planes in 10 patients with aortic valve disease and in 5 healthy control subjects. Patients with predominant aortic valve stenosis had a fairly flat profile, and the subvalvular diameter, obtained from left parasternal two-dimensional tissue imaging, provided a good estimate of the mean of the two transverse flow axes. This explains the accuracy in determination of stroke volume and aortic valve area that is reported in studies on patients with aortic valve stenosis when the continuity equation is used. However, the use of apical pulsed Doppler ultrasound registrations from the left ventricular outflow tract and parasternal two-dimensional echocardiography for flow area calculation may introduce large errors in calculated stroke volume in certain patients with aortic regurgitation and in normal subjects, because of a non-flat spatial velocity profile or an inaccurate estimate of flow area.

  • 269.
    Sjöberg, Birgitta Janero
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Eidenvall, L
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wranne, Bengt
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Vascular characteristics influence the aortic ultrasound Doppler signal: computer and hydraulic model simulations.1993In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 147, no 3, p. 271-279Article in journal (Refereed)
    Abstract [en]

    There is an increasing demand for non-invasive methods for the assessment of left ventricular function. Ultrasound Doppler methods are promising, and the early systolic flow velocity signal immediately distal to the aortic valve has been used clinically for this purpose. However, the signal is influenced not only by left ventricular ejection but also by systemic vascular characteristics. Their relative contribution to the time-velocity signal has not been analysed in depth previously. A theoretical analysis, based on a three-element Windkessel model, neglecting peripheral outflow in early systole and assuming linear pressure rise, was therefore tested in computer and hydraulic model simulations where peripheral outflow was included. Significant changes in early aortic flow velocity parameters were found when vascular characteristics were altered. As predicted by the theory, with a standardized aortic valve area and aortic pressure change, the simulations confirmed that maximal flow velocity is related to compliance of the aorta and the large arteries, and that maximal acceleration is inversely related to the characteristic impedance of the aorta. Therefore, maximal velocity and acceleration can be used for assessment of left ventricular function only in situations where vascular characteristics can be considered relatively constant or where they can be estimated.

  • 270. Språngberg, Anders
    et al.
    TERIO, Heikki
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    ENGBERG, Anders
    Griffiths, Derek
    PRESSURE-FLOW STUDIES PREOPERATIVELY AND POSTOPERATIVELY IN PATIENTS WITH BENIGN PROSTATIC HYPERTROPHY - ESTIMATION OF THE URETHRAL PRESSURE-FLOW RELATION AND URETHRAL ELASTICITY1991In: Neurourology and Urodynamics, ISSN 0733-2467, E-ISSN 1520-6777, Vol. 10, no 2, p. 139-167Article in journal (Refereed)
    Abstract [en]

    Pressure/flow studies were performed in 28 men with benign prostatic hypertrophy. Twenty-three of the men were also studied postoperatively. Urethral function during micturition was quantified by the urethral pressure/flow relation, P(det) = P(mo) + L(m) Q(m), where P(det) is detrusor pressure, P(mo) is minimal opening pressure, Q is flow rate, and m and L(m) are parameters. Using this method to quantify urethral function, three urodynamically different types of obstruction can be defined. In the first of these, P(mo) is elevated corresponding to Schafer’s compressive obstruction. The second is a constrictive type of obstruction in which m greater-than-or-equal-to 4/3 and L(m) is elevated and the third is a low-compliant type of obstruction in which m less-than-or-equal-to 1 and L(m) is elevated. The two latter types of obstruction may be combined with a compressive obstruction. The preoperative pressure/flow relations were mostly characterized by a very high P(mo), a moderately elevated L(m), and a low m. Thus the majority of patients had a combination of compressive and low-compliant obstruction. Postoperatively, micturitions were much improved and the pressure/flow relations often had an even lower P(mo) than normal, a normal L(m), and a high m. From the pressure/flow relations, the elasticity of the flow-controlling zone can be estimated and described by the urethral pressure/area relation, p(A) = P(mo) + K(n) A(n), where p(A) is the intrinsic urethral pressure, A is the cross-sectional area of the flow-controlling zone and K(n) and n are parameters describing the distensibility of the flow-controlling zone. Preoperatively, the flow-controlling zone had a low distensibility. The shape of the curve suggested that the urethra could have been distended further by higher pressure. Postoperatively, the urethra was distended to larger cross-sectional areas, but in many cases the shape of the curve suggested that distension was restricted by fibrosis. Median and range values for the model parameters as well as discriminating limits between the preoperative micturitions and micturitions in elderly men without voiding problems are presented. The exponent m is not perfectly reproducible but tends to be the same if a person performs several micturitions. The residual sum of squares is often increased more than 100% if an exponent m value other than the optimal one is used for curve fitting. Results when the micturitions were analysed with Schafer’s model and classified using the maximum flow/pressure at maximum flow diagram recommended by the International Continence Society are also shown.

  • 271. Spånberg, Anders
    et al.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    ENGBERG, Anders
    TERIO, Hikki
    URODYNAMIC ASSESSMENT OF OBSTRUCTION - SHOULD IT BE EVALUATED ACCORDING TO GRIFFITHS OR SCHAFER MODEL1987In: Scandinavian Journal of Urology and Nephrology, ISSN 0036-5599, E-ISSN 1651-2065, no 105Article in journal (Refereed)
  • 272. Spånberg, Anders
    et al.
    Terio, Hikki
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    PRESSURE-FLOW STUDIES IN ELDERLY MEN WITHOUT VOIDING PROBLEMS - ESTIMATION OF THE URETHRAL PRESSURE-FLOW RELATION AND URETHRAL ELASTICITY1990In: Neurourology and Urodynamics, ISSN 0733-2467, E-ISSN 1520-6777, Vol. 9, no 2, p. 123-138Article in journal (Refereed)
    Abstract [en]

    The flow in the urethra is controlled by an elastic constriction, the flow-controlling zone. The distensibility of this zone is described by the pressure/area relation, which gives the static pressure as a function of the cross-sectional area at the flow-controlling zone. The pressure/area relation can be calculated from the pressure/flow relation, which is estimated from the pressure/flow plot obtained at a urodynamic examination. In this study the urethral pressure/flow and pressure/area relations were estimated for 21 randomly selected men (62–75 years old) without voiding problems.

    Nineteen of 21 persons in this group had pressure/flow relations with a low slope. This corresponds to a low slope in the pressure/area relation indicating high distensibility of the flow-controlling zone, which for 18 persons was estimated to be distended to areas larger than 10 mm2 during micturition. Twenty persons had a minimal urethral opening pressure below 55 cm H2O. The estimated pressure/area relation was linear in 59% of the micturitions, indicating that the flow-controlling zone could have been distended to a larger cross-sectional area, if the bladder had achieved a higher pressure. The 10th–90th percentiles for maximum flow and detrusor pressure at maximum flow were 7.2–24.3 ml/s and 24–76 cm H2O, respectively. Four persons had low flow and low pressure, indicating diminished detrusor contractility with age. Twenty-four percent of the persons had unstable bladder contractions with a pressure rise < 15cm H2O and 19% with a pressure rise < 15cm H2O.

  • 273. Spånberg, Anders
    et al.
    Terio, Hikki
    Enberg, Anders
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    QUANTIFICATION OF URETHRAL FUNCTION BASED ON GRIFFITHS MODEL OF FLOW THROUGH ELASTIC TUBES1989In: Neurourology and Urodynamics, ISSN 0733-2467, E-ISSN 1520-6777, Vol. 8, no 1, p. 29-52Article in journal (Refereed)
    Abstract [en]

    Griffiths' model of flow-through elastic tubes makes it possible to relate the elastic properties of the flow-controlling zone to the pressure/flow relation of the urethra. In this work the pressure function p(A) = Pmo + Kn An, where A is cross-sectional area, Pmo the minimal opening pressure, and Kn and n parameters describing urethral distensibility, describes the elastic properties of the flow-controlling zone. By curve-fitting in the pressure/flow plot, the three parameters pmo, Kn, and n can be estimated analytically. Using this model it is possible to identify three different biomechanical changes that may cause obstruction. First, pmo may be elevated. Second, the urethra can be distended to a certain area only, corresponding to high values of Kn and n. Third, the urethra can be distended but a higher-than-normal pressure increase above Pmo is needed, Kn is high, and n is low. With this model it is possible to quantify urethral function for both scientific and clinical purposes.

  • 274.
    Spångberg, Anders
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Urology in Östergötland.
    Folkestad, Bengt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Urology in Östergötland.
    Kristjansson, B
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    New method to quantify the urodynamic improvement when treating bladder utlet obstruction - The efficacy of transurethral resectionin benign prostatic hypertrophy1995In: Neurology, ISSN 0028-3878, E-ISSN 1526-632X, Vol. 14, no 4, p. 325-335Article in journal (Refereed)
  • 275.
    Stenow, Erik
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Fiber-optic sensors for blood flow and respiration rate measurements1995Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Optical fibers and fiber-optic sensors have in the last century been subjects for a great interest especially in industry and communication but also in medicine. Optical fibers are used in endoscopes and as light guides for laser surgery. Biomedical sensors using fiberoptics has among other things been developed for analyzes of blood gases, temperature and blood pressure measurement. This thesis describes a method utilizing a fiber-optic sensor for limb blood flow measurement and a new fiber-optic sensor for respiratory rate monitoring.

    Venous occlusion plethysmography is a standard method for measuring blood flow in extremities. Today is a mercury strain gauge sensor the most common sensor for this measurement. The mercury strain gauge sensor is very flexible and easy to use, however, there are disadvantages such as temperature drift and long term instability. In addition free mercury from wasted or braken sensor is an environmental problem. We have developed and shown that a fiber-optic sensor that utilizes the microbending principle, can be used for venous occlusion plethysmography in the limb as an alternative to the mercury strain gauge sensor.

    The respiratory rate sensor uses an optical fiber that detects the evaporated humidity that departs from the mouth and/or nose at each exhalatfon. The condensed humidity on the fiber end surface substantially alters the coupling ratio of light from the fiber. A number of experiments and computer simulations are determined to evaluate and explain the function of the sensor.

  • 276. Storck, K
    et al.
    Karlsson, Matts
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Modelling and Simulation .
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Heat transfer simulation in the evaluation of the nasal thermistor technique1996In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 43, p. 1187-1191Article in journal (Refereed)
  • 277.
    Strindhall, Jan
    et al.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindgren, Per-Eric
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Löfgren, Sture
    Department of Microbiology, Hospital of Ryhov, Jönköping, Sweden.
    Kihlström, Erik
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Variations among clinical isolates of Staphylococcus aureus to induce expression of E-selectin and ICAM-1 in human endothelial cells2002In: FEMS Immunology and Medical Microbiology, ISSN 0928-8244, E-ISSN 1574-695X, Vol. 32, no 3, p. 227-235Article in journal (Refereed)
    Abstract [en]

    Eighteen clinical isolates of Staphylococcus aureus, nine methicillin-sensitive and nine methicillin-resistant, were investigated for their ability to induce expression of E-selectin and ICAM-1 in human endothelial cells. Upregulation of adhesion molecules varied between isolates; 17 isolates induced expression of E-selectin and 13 of ICAM-1. Some isolates induced a significant expression of E-selectin without stimulation of ICAM-1, whereas the opposite was not found. Bacterial viability was required for induction of the adhesion molecules. The kinetics of ICAM-1 expression in S. aureus-infected cells differed from those stimulated with interleukin-1β (IL-1β). On the other hand, expression of E-selectin was very similar in S. aureus-infected and IL-1β-stimulated cells. There was no correlation between ability of S. aureus to induce expression of cell adhesion molecules, methicillin susceptibility, pulse field gel electrophoresis patterns, biochemical characteristics, phage typing and toxin production.

  • 278. Sun, Y
    et al.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Eidenvall, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Wranne, Bengt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Estimation of pulsatile flow by surface integration of velocity vectors in Doppler ultrasound images from two arthogonal planes1995In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 8, p. 904-914Article in journal (Refereed)
  • 279. Sun, Y
    et al.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Sjöberg, Birgitta Janero
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Eidenvall, L
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wranne, Bengt
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Estimation of volume flow rate by surface integration of velocity vectors from color Doppler images.1995In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 8, no 6, p. 904-914Article in journal (Refereed)
    Abstract [en]

    A new Doppler echocardiographically based method has been developed to quantify volume flow rate by surface integration of velocity vectors (SIVV). Electrocardiographic-gated color Doppler images acquired in two orthogonal planes were used to estimate volume flow rate through a bowl-shaped surface at a given time and distance from the probe. To provide in vitro validation, the method was tested in a hydraulic model representing a pulsatile flow system with a restrictive orifice. Accurate estimates of stroke volume (+/- 10%) were obtained in a window between 1.2 and 1.6 cm proximal to the orifice, just before the region of prestenotic acceleration. By use of the Bernoulli's equation, the estimated flows were used to generate pressure gradient waveforms across the orifice, which agreed well with the measured flows. To demonstrate in vivo applicability, the SIVV method was applied retrospectively to the determination of stroke volume and subaortic flow from the apical three-chamber and five-chamber views in two patients. Stroke volume estimates along the left ventricular outflow tract showed a characteristic similar to that in the in vitro study and agreed well with those obtained by the Fick oxygen method. The region where accurate measurements can be obtained is affected by instrumental factors including Nyquist velocity limit, wall motion filter cutoff, and color flow sector angle. The SIVV principle should be useful for quantitative assessment of the severity of valvular abnormalities and noninvasive measurement of pulsatile volume flows in general.

  • 280. Sun, Y
    et al.
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Wranne, Bengt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Mathematical model that characterizes transmitral and pulmonary venous flow velocity patterns1995In: American journal of physiology, ISSN 0002-9513, Vol. 268, p. 476-489Article in journal (Refereed)
  • 281. Sun, Y
    et al.
    Sjöberg, Birgitta Janero
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wranne, Bengt
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Mathematical model that characterizes transmitral and pulmonary venous flow velocity patterns.1995In: American Journal of Physiology, ISSN 0002-9513, E-ISSN 2163-5773, Vol. 268, no 1 Pt 2, p. H476-89Article in journal (Refereed)
    Abstract [en]

    The transmitral and pulmonary venous flow velocity (TMFV and PVFV, respectively) patterns are related to the physiological state of the left heart by use of an electrical analog model. Filling of left ventricle (LV) through the mitral valve is characterized by a quadratic Bernoulli's resistance in series with an inertance. Filling of the left atrium (LA) through the pulmonary veins is represented by a lumped network of linear resistance, capacitance, and inertance. LV and LA are each represented by a time-varying elastance. A volume dependency is incorporated into the LV model to produce physiological pressure-volume loops and Starling curves. The state-space representation of the analog model consists of 10 simultaneous differential equations, which are solved by numerical integration. Model validity is supported by the following. First, the expected effects of aging and decreasing LV compliance on TMFV and PVFV are accurately represented by the model. Second, the model-generated TMFV and PVFV waveforms fit well to pulsed-Doppler recordings in normal and postinfarct patients. It is shown that the TMFV deceleration time is prolonged by the increase in LV compliance and, to a lesser extent, by the increase in LA compliance. A shift from diastolic dominance to systolic dominance in PVFV occurs when LA compliance or pulmonary perfusion pressure increases or when LV compliance or mitral valve area decreases. The present model should serve as a useful theoretical basis for echocardiographic evaluation of LV and LA functions.

  • 282. Sun, Ying
    et al.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Sjöberg, Birgitta Janero
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Eindvall, Lars
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wranne, Bengt
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Estimation of volume flow rate by surface integration of velocity vectors from color Doppler images1997In: Journal of the American College of Cardiology, ISSN 0735-1097, E-ISSN 1558-3597, Vol. 8, no 6, p. 904-914Article in journal (Refereed)
    Abstract [en]

    A new Doppler echocardiographically based method has been developed to quantify volume flow rate by surface integration of velocity vectors (SIVV). Electrocardiographic-gated color Doppler images acquired in two orthogonal planes were used to estimate volume flow rate through a bowl-shaped surface at a given time and distance from the probe. To provide in vitro validation, the method was tested in a hydraulic model representing a pulsatile flow system with a restrictive orifice. Accurate estimates of stroke volume (±10%) were obtained in a window between 1.2 and 1.6 cm proximal to the orifice, just before the region of prestenotic acceleration. By use of the Bernoulli's equation, the estimated flows were used to generate pressure gradient waveforms across the orifice, which agreed well with the measured flows. To demonstrate in vivo applicability, the SIVV method was applied retrospectively to the determination of stroke volume and subaortic flow from the apical three-chamber and five-chamber views in two patients. Stroke volume estimates along the left ventricular outflow tract showed a characteristic similar to that in the in vitro study and agreed well with those obtained by the Fick oxygen method. The region where accurate measurements can be obtained is affected by instrumental factors including Nyquist velocity limit, wall motion filter cutoff, and color flow sector angle. The SIVV principle should be useful for quantitative assessment of the severity of valvular abnormalities and noninvasive measurement of pulsatile volume flows in general.

  • 283.
    Sundberg, Mikael
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Johansson, Anders
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Öberg, Åke
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Fibre-optic array for curvature assessment: application in otitis diagnosis2004In: Medical & Biological Engineering & Computing, ISSN 0140-0118, Vol. 42, no 2, p. 245-252Article in journal (Refereed)
    Abstract [en]

    A contact-free sensor consisting of two parallel optical-fibre arrays was designed to assess surface shapes of diffusely scattering media. By sequentially illuminating objects using one fibre array and detecting the diffusely back-scattered photons by the other, a source-detector intensity matrix was formed, where the matrix element (i, j) was the intensity at detector j when light source i was excited. Experimental data from convex and concave polyacetal plastic surfaces were recorded. A mathematical model was used for simulating source-detector intensity matrices for the surfaces analysed in the experiments. Experimental results from the system were compared with the theoretically expected results provided by the mathematical model. The shape and relative amplitude showed similar behaviour in the experiments and simulations. A convex/concave discriminator index D, representing the detected intensity difference between two source-detector separations, was defined. The relative dynamic range of D, defined as the difference between the maximum and the minimum divided by the mean of the index, was 1.37 for convex surfaces and 0.68 for concave surfaces, at a measuring distance of 4.5mm. The index D was positive for convex surfaces and negative for concave surfaces, which showed that the system could distinguish between convex and concave surfaces, an important result for the diagnosis of otitis media.

  • 284.
    Sundberg, Mikael
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Peebo, Markus
    Linköping University, Department of Clinical and Experimental Medicine, Oto-Rhiono-Laryngology and Head & Neck Surgery . Linköping University, Faculty of Health Sciences.
    Öberg, Åke
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Lundquist, Per-Gotthard
    Linköping University, Department of Clinical and Experimental Medicine, Oto-Rhiono-Laryngology and Head & Neck Surgery . Linköping University, Faculty of Health Sciences.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diffuse reflectance spectroscopy of the human tympanic membrane in otitis media2004In: Physiological Measurement, ISSN 0967-3334, Vol. 25, no 6, p. 1473-1483Article in journal (Refereed)
    Abstract [en]

    We have investigated if features in the diffuse reflectance spectra from in vivo spectroscopic measurements of the tympanic membrane could aid the diagnosis of otitis media in children. Diffuse reflectance spectroscopy, in the visible wavelength range, was used in 15 ears from children with otitis media with effusion before and after myringotomy and in 15 healthy ears as a reference. Two previously published erythema detection algorithms yielded numerical quantities of haemoglobin content. With a combination of the algorithms, induced erythema (after myringotomy) was distinguished from healthy ears using Student's t-test (p < 0.01). Otitis media with mucous effusion was distinguished from (1) otitis media with serous effusion, (2) induced erythema and (3) healthy ears, (p < 0.05) using Student's t-test for independent groups and the paired t-test for dependent groups. Our results imply that reflectance spectroscopy is a promising technique to be used for the diagnosis of otitis media.

  • 285. Tamura, T.
    et al.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    A comparision between Laser Doppler Flowmetry and Micro Photoplethysmograhy1984In: 6th Nordic Meeting on Medical and Biological Engineering,1984, 1984Conference paper (Refereed)
  • 286. Tamura, T.
    et al.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Evaluation of fiber optic photoplethysmography1985In: XIV International Conference on Medical and Biological Engineering and VII International Conference on Medical Physics,1985, 1985, p. 1001-Conference paper (Refereed)
  • 287. Tamura, T.
    et al.
    Togawa, T.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Öberg, Åke
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Evaluation of single fiber laser Doppler flowmetry1987In: Microcirculation - an update, vol 1 / [ed] Masaharu Tsuchiya, Amsterdam: Excerpta medica , 1987, p. 362-363Chapter in book (Other academic)
    Abstract [en]

        

  • 288. Tamura, T.
    et al.
    Togawa, T.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Spelman, F.A.
    Evaluation of skeletal muscle blood flow by single fiber tissue Doppler flowmetry1985In: Japanese Conference in Angiology, J Jap Coll Angiol Vol 25,1985, 1985, p. 1137-1137Conference paper (Other academic)
  • 289. Tenland, T.
    et al.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Spatial and temporal variations in human skin blood flow1983In: International journal of microcirculation : clinical and experimental / sponsored by the European Society for Microcirculation, ISSN 0167-6865, Vol. 2, p. 81-90Article in journal (Refereed)
    Abstract [en]

      

  • 290. Teriö, H
    et al.
    Spångberg, A
    Engberg, A
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Estimation of elastic properties in the urethral flow controlling zone by signal analysis of urodynamic pressure/flow data.1989In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 27, no 3, p. 314-321Article in journal (Refereed)
    Abstract [en]

    When urethral flow is treated as a lossless flow through an elastic tube, the relationship between the detrusor pressure and the urinary flow can be related to the elasticity of the flow-controlling zone of the urethra. A recent analytical method of describing urethral elasticity is implemented on a computer. The function p(Q) = pmo + LmQm is fitted to the recorded pressure/flow data. p(Q) is the detrusor pressure, Q the flow and pmo, m and Lm parameters. The elastic properties are then obtained as p(A) = pmo + KnAn, where p(A) is the static pressure, A the cross-sectional area of the flow-controlling zone and n and Kn calculated parameters. The urodynamic methods used and the computer implementation of the analytical method are described. In obstructed and unobstructed men without neurological symptoms, the elastic properties could be estimated in 94 per cent of the micturitions. The method makes it possible to describe urethral flow properties with Griffiths' model in a standardised way and compare results obtained by different investigators. It is recommended for quantification of urethral obstruction in research and for assessment of borderline cases of obstruction in clinical practice.

  • 291.
    Thunberg, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Correction for displacement artifacts in phase contrast magnetic resonance imaging2001Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Magnetic resonance imaging (MRI) is an imaging modality which provides good conditions for studies of flow and motion in the cardiovascular system. A variety of different imaging pulse sequences enables both anatomical and functional studies. When using the phase contrast imaging technique it is possible to perform velocity measurements in moving tissues and in blood. Acquired velocity data can be used for quantitative flow measurements which is valuable information in the assessment of different cardiovascular dysfunctions. In regions where the flow is accelerating and/or moving obliquely relative to the gradient axis, velocity measurements become displaced in the reconstructed velocity image. These displacement artifacts hamper the accuracy of phase contrast imaging and restrict subsequent flow analysis in regions which are of great clinical interest.

    This thesis includes an introduction to phase contrast imaging and how displacement artifacts are manifested in the reconstructed velocity image. A theoretical framework is presented which shows how the measured phase shift can be written as a sum of different phase contributions induced by velocity and higher orders of motion. This framework was then used to find the instant during the acquisition of MR data which can be considered as the instant for velocity encoding. Correction methods were developed using the knowledge of the time points at which velocity and spatial encoding are performed in the pulse sequence. The implementation of these correction methods included modifications of a 3D phase contrast pulse sequence and development of post processing algorithms involving streamline calculations. In vitro and in vivo experiments were performed which demonstrated how the displacement artifacts severely distorted the accuracy of phase contrast imaging in regions of stenotic and oblique flow. After correction, significant improvements were achieved which were demonstrated using velocity profiles and streamline visualization.

    The results of this thesis shows that corrupted velocity measurements caused by displacement artifacts can be alleviated using the suggested correction methods. This may be of importance for subsequent flow analysis and visualization of stenotic and/or oblique flow.

    List of papers
    1. Correction for acceleration-induced displacement artifacts in phase contrast imaging
    Open this publication in new window or tab >>Correction for acceleration-induced displacement artifacts in phase contrast imaging
    Show others...
    2000 (English)In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 43, no 5, p. 734-738Article in journal (Refereed) Published
    Abstract [en]

    The acceleration-induced displacement artifact impairs the accuracy of MR velocity measurements. This study proposes a post processing method for correction of this artifact. Velocity measurements were performed in a flow phantom containing a constriction. Velocity curves were obtained from streamlines parallel to the frequency, phase, and slice directions, respectively. The acceleration-induced displacement artifact was most prominent when the frequency encoding direction was aligned with the flow direction. After correction, velocity assignment improved and a more accurate description of the flow was obtained. In vivo measurements were performed in the aorta in a patient with a repaired aortic coarctation. The correction method was applied to velocity data along a streamline parallel to the frequency encoding direction. The result after correction was a new location of the peak velocity and improved estimates of the velocity gradients.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-26712 (URN)10.1002/(SICI)1522-2594(200005)43:5<734::AID-MRM16>3.0.CO;2-A (DOI)11306 (Local ID)11306 (Archive number)11306 (OAI)
    Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13
    2. Correction for displacement artifacts in 3D phase contrast imaging
    Open this publication in new window or tab >>Correction for displacement artifacts in 3D phase contrast imaging
    2002 (English)In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 16, no 5, p. 591-597Article in journal (Refereed) Published
    Abstract [en]

    Purpose

    To correct for displacement artifacts in 3D phase contrast imaging.

    Materials and Methods

    A 3D phase contrast pulse sequence was modified so that displacements of velocity measurements were restricted to one direction. By applying a postprocessing method, displaced measurements could be traced back to their accurate positions. Flow studies were performed using a phantom that generated flow through a stenosis, directed oblique relative to the phase and frequency encoding directions. Velocity profiles and streamline visualization were used to compare displaced and corrected velocity data to a reference.

    Results

    Velocity profiles obtained from the original measurement showed skewed profiles due to the displacement artifact, both at close proximity to the orifice as well as further downstream. After correction, concordance with the reference improved considerably.

    Conclusion

    The displacement artifact, which restricts the accuracy of phase contrast measurements, can be corrected for using the proposed method. Correction of the phase contrast velocity data may improve the accuracy of subsequent flow analysis and visualization.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-26708 (URN)10.1002/jmri.10187 (DOI)11301 (Local ID)11301 (Archive number)11301 (OAI)
    Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13
  • 292.
    Thurin, Anders
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics.
    Goushegir, G
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Thulesius, O
    Venous flow in an in vitro model: effect of extravascular pressure1997In: Journal of Vascular Surgery, ISSN 0741-5214, E-ISSN 1097-6809, Vol. 3, p. 130-136Article in journal (Refereed)
  • 293. Tibbling, Lita
    et al.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Pope, C E
    Electromyography of human oesophageal smooth muscle.1986In: Scandinavian Journal of Gastroenterology, ISSN 0036-5521, E-ISSN 1502-7708, Vol. 21, no 5, p. 559-567Article in journal (Refereed)
    Abstract [en]

    The aim was to study whether electromyography (EMG) activity is synchronous with oesophageal motor activity as assessed by manometry from the same oesophageal site. Patients with different motor disorders of the oesophagus and control subjects were investigated. EMG recordings were made by means of a suction capsule with silver/silver chloride spike electrodes. Slow EMG waves synchronous with respiration were recorded from the lower oesophageal sphincter and intermittently from the body of the oesophagus. Edrophonium increased spike discharges; atropine diminished or abolished spike discharges after swallowing. Swallowing caused a burst of spiking activity which began immediately after deglutition. Continuous sips of water produced constant EMG activity but no peristaltic contractions as seen by manometry. In a patient with scleroderma and aperistalsis, swallowing elicited vigorous electrical activity. The different EMG findings without simultaneous contractions at manometry are interpreted as a response to a swallow by the longitudinal muscle of the oesophagus.

  • 294. Tibbling, Lita
    et al.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    POPE, CE
    ELECTROMYOGRAPHY OF THE HUMAN ESOPHAGUS1982In: Gastroenterology, ISSN 0016-5085, E-ISSN 1528-0012, Vol. 82, no 5Article in journal (Refereed)
  • 295.
    Tibbling, Lita
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Oto-Rhiono-Laryngology and Head & Neck Surgery . Linköping University, Faculty of Health Sciences.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Sökjer, H.
    Oesophagus fysiology mot bakgrund av nya medicintekniska landvinningar1977In: Svensk Oe NH Tidskrift, ISSN 1400-0121, Vol. 1, no 2, p. 1-1Article in journal (Other academic)
  • 296. Tibbling, Lita
    et al.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Öberg, Åke
    Linköping University, Department of Biomedical Engineering.
    ACCURACY AND VALIDITY OF ESOPHAGEAL MANOMETRY SYSTEMS1980In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 25, no 5Article in journal (Refereed)
  • 297.
    Ugnell, Håkan
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    The time-variable photoplethysmographic signal; dependence on the heart synchronous signal on wavelengt and sample volume1995In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 17, no 8, p. 571-578Article in journal (Refereed)
  • 298.
    Uhlin, Fredrik
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Nephrology.
    Fridolin, Ivo
    Tek.Univ Tallin.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Magnusson, Martin
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Nephrology.
    Clearance variation monitored by on-line UV-absorbance during haemodialysis2005In: Nordic Baltic Conference Biomedical Engineering and medical physics,2005, 2005Conference paper (Other academic)
  • 299.
    Uhlin, Fredrik
    et al.
    Linköping University, Department of Medicine and Health Sciences, Internal Medicine . Linköping University, Faculty of Health Sciences.
    Fridolin, Ivo
    Centre of Biomedical Engineering, Tallinn Technical University, Tallinn, Estonia.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Magnusson, Martin
    Linköping University, Department of Medicine and Health Sciences. Linköping University, Faculty of Health Sciences.
    Estimating total urea removal and protein catabolic rate by monitoring UV absorbance in spent dialysate2005In: Nephrology Dialysis Transplantation, ISSN 0931-0509, Vol. 20, no 11, p. 2458-2464Article in journal (Refereed)
    Abstract [en]

    Background. Dialysate-based, on-line measurements of Kt/V and protein catabolic rate (PCR) in dialysis patients have been considered more accurate compared with measurements on the blood side during dialysis. The primary aim of this study was to compare total removed urea (TRU) and PCR, normalized to body weight (nPCRw), obtained by three dialysate-based methods: (i) on-line ultraviolet (UV) absorbance of the spent dialysate; (ii) total dialysate collection (TDC), as reference method; and (iii) Urea Monitor 1000 (UM) from Baxter Healthcare Corp.

    Methods. We studied 10 uraemic patients on chronic, thrice-weekly haemodialysis. We made absorption measurements (UV radiation) on-line with a spectrophotometer connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through an optical cuvette for single-wavelength measurements. UV absorbance measurements were compared with TDC and the UM.

    Results. nPCRw obtained with UV absorbance was 0.82±0.17, that from TDC 0.81±0.18, and that measured by UM 0.87±0.18, which was significantly higher than the results of the other methods. The difference between nPCRw calculated by TDC and by UM was –0.05±0.06, showing a slightly lower SD than the difference between nPCRw by TDC and UV absorbance, –0.01±0.07.

    Conclusion. The study demonstrates that TRU, and consequently PCR, can be estimated by on-line measurement of the UV absorption in the spent dialysate.

  • 300.
    Uhlin, Fredrik
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Nephrology.
    Fridolin, Ivo
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Magnusson, Martin
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Nephrology.
    Icke-invasiv kontinuerlig övervakning av bloddialys UV absorption2004In: Njurmedicins regionmöte,2004, 2004Conference paper (Other academic)
34567 251 - 300 of 341
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