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Publications (10 of 65) Show all publications
Lindfors, M., Frenckner, B., Sartipy, U., Bjällmark, A. & Broomé, M. (2017). Venous Cannula Positioning in Arterial Deoxygenation During Veno-Arterial Extracorporeal Membrane Oxygenation-A Simulation Study and Case Report. Artificial Organs, 41(1), 75-81
Open this publication in new window or tab >>Venous Cannula Positioning in Arterial Deoxygenation During Veno-Arterial Extracorporeal Membrane Oxygenation-A Simulation Study and Case Report
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2017 (English)In: Artificial Organs, ISSN 0160-564X, E-ISSN 1525-1594, Vol. 41, no 1, p. 75-81Article in journal (Refereed) Published
Abstract [en]

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is indicated in reversible life-threatening circulatory failure with or without respiratory failure. Arterial desaturation in the upper body is frequently seen in patients with peripheral arterial cannulation and severe respiratory failure. The importance of venous cannula positioning was explored in a computer simulation model and a clinical case was described. A closed-loop real-time simulation model has been developed including vascular segments, the heart with valves and pericardium. ECMO was simulated with a fixed flow pump and a selection of clinically relevant venous cannulation sites. A clinical case with no tidal volumes due to pneumonia and an arterial saturation of below 60% in the right hand despite VA-ECMO flow of 4 L/min was described. The case was compared with simulation data. Changing the venous cannulation site from the inferior to the superior caval vein increased arterial saturation in the right arm from below 60% to above 80% in the patient and from 64 to 81% in the simulation model without changing ECMO flow. The patient survived, was extubated and showed no signs of hypoxic damage. We conclude that venous drainage from the superior caval vein improves upper body arterial saturation during veno-arterial ECMO as compared with drainage solely from the inferior caval vein in patients with respiratory failure. The results from the simulation model are in agreement with the clinical scenario.

Keywords
Cannulation, Differential hypoxia, Dual circulations, Extracorporeal membrane oxygenation, Harlequin syndrome, Modeling, Simulation, Venoarterial
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:hj:diva-37105 (URN)10.1111/aor.12700 (DOI)000393318500013 ()2-s2.0-84963626905 (Scopus ID)
Note

QC 20160613

Available from: 2016-06-13 Created: 2017-08-31 Last updated: 2017-08-31Bibliographically approved
Josefsson, L., Larsson, M. K., Bjällmark, A. & Emmer, Å. (2016). Analysis of polyvinyl alcohol microbubbles in human blood plasma using capillary electrophoresis. Journal of Separation Science, 39(8), 1551-1558
Open this publication in new window or tab >>Analysis of polyvinyl alcohol microbubbles in human blood plasma using capillary electrophoresis
2016 (English)In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 39, no 8, p. 1551-1558Article in journal (Refereed) Published
Abstract [en]

Recently, a new type of ultrasound contrast agent that consists of air-filled microbubbles stabilized with a shell of polyvinyl alcohol was developed. When superparamagnetic nanoparticles of iron oxide are incorporated in the polymer shell, a multimodal contrast agent can be obtained. The biodistribution and elimination pathways of the polyvinyl alcohol microbubbles are essential to investigate, which is limited with today's techniques. The aim of the present study was, therefore, to develop a method for qualitative and quantitative analysis of microbubbles in biological samples using capillary electrophoresis with ultraviolet detection. The analysis parameters were optimized to a wavelength at 260 nm and pH of the background electrolyte ranging between 11.9 and 12. Studies with high-intensity ultrasonication degraded microbubbles in water showed that degraded products and intact microbubbles could be distinguished, thus it was possible to quantify the intact microbubbles solely. Analysis of human blood plasma spiked with either plain microbubbles or microbubbles with nanoparticles demonstrated that it is possible to separate them from biological components like proteins in these kinds of samples.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2016
Keywords
Capillary electrophoresis, Contrast agents, Human blood plasma, Polyvinyl alcohol microbubbles
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:hj:diva-37078 (URN)10.1002/jssc.201501342 (DOI)000374773000018 ()2-s2.0-84963701455 (Scopus ID)
Available from: 2016-05-18 Created: 2017-08-30Bibliographically approved
Maksuti, E., Widman, E., Larsson, D., Urban, M. W., Larsson, M. & Bjällmark, A. (2016). Arterial stiffness estimation by shear wave elastography: Validation in phantoms with mechanical testing. Ultrasound in Medicine and Biology, 42(1), 308-321
Open this publication in new window or tab >>Arterial stiffness estimation by shear wave elastography: Validation in phantoms with mechanical testing
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2016 (English)In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 42, no 1, p. 308-321Article in journal (Refereed) Published
Abstract [en]

Arterial stiffness is an independent risk factor found to correlate with a wide range of cardiovascular diseases. It has been suggested that shear wave elastography (SWE) can be used to quantitatively measure local arterial shear modulus, but an accuracy assessment of the technique for arterial applications has not yet been performed. In this study, the influence of confined geometry on shear modulus estimation, by both group and phase velocity analysis, was assessed, and the accuracy of SWE in comparison with mechanical testing was measured in nine pressurized arterial phantoms. The results indicated that group velocity with an infinite medium assumption estimated shear modulus values incorrectly in comparison with mechanical testing in arterial phantoms (6.7 +/- 0.0 kPa from group velocity and 30.5 +/- 0.4 kPa from mechanical testing). To the contrary, SWE measurements based on phase velocity analysis (30.6 +/- 3.2 kPa) were in good agreement with mechanical testing, with a relative error between the two techniques of 8.8 +/- 6.0% in the shear modulus range evaluated (40-100 kPa). SWE by phase velocity analysis was validated to accurately measure stiffness in arterial phantoms.

Keywords
Accuracy, Arterial phantom, Arterial stiffness, Group velocity, Lamb waves, Mechanical testing, Phase velocity, Poly(vinyl alcohol), Shear modulus, Shear wave elastography
National Category
Medical Image Processing
Identifiers
urn:nbn:se:hj:diva-37089 (URN)10.1016/j.ultrasmedbio.2015.08.012 (DOI)000367733800032 ()26454623 (PubMedID)2-s2.0-84957007046 (Scopus ID)
Note

QC 20160203

Available from: 2016-02-03 Created: 2017-08-30Bibliographically approved
Larsson, M. K., Da Silva, C., Gunyeli, E., Bin Ilami, A. A., Szummer, K., Winter, R. & Bjällmark, A. (2016). The potential clinical value of contrast-enhanced echocardiography beyond current recommendations. Cardiovascular Ultrasound, 14, Article ID 2.
Open this publication in new window or tab >>The potential clinical value of contrast-enhanced echocardiography beyond current recommendations
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2016 (English)In: Cardiovascular Ultrasound, ISSN 1476-7120, E-ISSN 1476-7120, Vol. 14, article id 2Article in journal (Refereed) Published
Abstract [en]

Background: Contrast agents are used in resting echocardiography to opacify the left ventricular (LV) cavity and to improve LV endocardial border delineation in patients with suboptimal image quality. If a wider use of contrast-enhanced echocardiography would be adopted instead of the current selective approach, diagnoses such as myocardial ischemia and LV structural abnormalities could potentially be detected earlier. The aim was therefore to retrospectively investigate if contrast- enhanced echocardiography beyond the current recommendations for contrast agent usage affects assessment of wall motion abnormalities, ejection fraction (EF) and detection of LV structural abnormalities. A secondary aim was to evaluate the user dependency during image analysis. Methods: Experienced readers (n = 4) evaluated wall motion score index (WMSI) and measured EF on greyscale and contrast-enhanced images from 192 patients without indications for contrast-enhanced echocardiography. Additionally, screening for LV structural abnormalities was performed. Repeated measurements were performed in 20 patients by the experienced as well as by inexperienced (n = 2) readers. Results: Contrast analysis resulted in significantly higher WMSI compared to greyscale analysis (p < 0.003). Of the 83 patients, classified as healthy by greyscale analysis, 55 % were re-classified with motion abnormalities by contrast analysis. No significant difference in EF classification (>= 55 %, 45-54 %, 30-44 %, < 30 %) was observed. LV structural abnormalities, such as increased trabeculation (n = 21), apical aneurysm (n = 4), hypertrophy (n = 1) and thrombus (n = 1) were detected during contrast analysis. Intra- and interobserver variability for experienced readers as well as the variability between inexperienced and experienced readers decreased for WMSI and EF after contrast analysis. Conclusions: Contrast-enhanced echocardiography beyond current recommendations for contrast agent usage increased the number of detected wall motion and LV structural abnormalities. Moreover, contrast- enhanced echocardiography increased reproducibility for assessment of WMSI and EF.

Place, publisher, year, edition, pages
BioMed Central, 2016
Keywords
Contrast agent, Echocardiography, Wall motion score index, Ejection fraction
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:hj:diva-37082 (URN)10.1186/s12947-015-0045-0 (DOI)000367428000002 ()26729298 (PubMedID)2-s2.0-84959525597 (Scopus ID)
Available from: 2016-01-29 Created: 2017-08-30 Last updated: 2017-11-29Bibliographically approved
Maksuti, E., Larsson, D., Widman, E., Urban, M., Larsson, M. & Bjällmark, A. (2015). Accuracy of arterial shear wave elastography by phase velocity - validation with mechnical tesing in phantoms.. In: Proceedings of the Fourteenth International Tissue Elasticity Conference: . Paper presented at Fourteenth International Tissue Elasticity Conference, Bardolino, Lake Garda, Verona Italy, September 21-24, 2015.
Open this publication in new window or tab >>Accuracy of arterial shear wave elastography by phase velocity - validation with mechnical tesing in phantoms.
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2015 (English)In: Proceedings of the Fourteenth International Tissue Elasticity Conference, 2015Conference paper, Oral presentation with published abstract (Other academic)
National Category
Medical Equipment Engineering
Identifiers
urn:nbn:se:hj:diva-42105 (URN)
Conference
Fourteenth International Tissue Elasticity Conference, Bardolino, Lake Garda, Verona Italy, September 21-24, 2015
Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2018-11-26Bibliographically approved
Bassan, G., Larsson, D., Nordenfur, T., Bjällmark, A. & Larsson, M. (2015). Acquisition of multiple mode shear wave propagation in transversely isotropic medium using dualprobe setup. In: : . Paper presented at Medicinteknikdagarna, 13-14 oktober 2015.
Open this publication in new window or tab >>Acquisition of multiple mode shear wave propagation in transversely isotropic medium using dualprobe setup
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2015 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Medical Image Processing
Identifiers
urn:nbn:se:hj:diva-37059 (URN)
Conference
Medicinteknikdagarna, 13-14 oktober 2015
Available from: 2017-08-31 Created: 2017-08-31 Last updated: 2017-08-31Bibliographically approved
Maksuti, E., Larsson, D., Widman, E., Urban, M. W., Larsson, M. & Bjällmark, A. (2015). Influence of confined geometries in shear wave elastography: an experimental study. In: : . Paper presented at Medicinteknikdagarna, 13-14 oktober 2015, Uppsala.
Open this publication in new window or tab >>Influence of confined geometries in shear wave elastography: an experimental study
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2015 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Medical Engineering
Identifiers
urn:nbn:se:hj:diva-42175 (URN)
Conference
Medicinteknikdagarna, 13-14 oktober 2015, Uppsala
Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2018-11-30Bibliographically approved
Härmark, J., Larsson, M. K., Razuvajev, A., Koeck, P. J., Paradossi, G., Brodin, L.-Å., . . . Bjällmark, A. (2015). Investigation of the elimination process of a multimodal polymer-shelled contrast agent in rats using ultrasound and transmission electron microscopy. Biomedical Spectroscopy and Imaging, 4(1), 81-93
Open this publication in new window or tab >>Investigation of the elimination process of a multimodal polymer-shelled contrast agent in rats using ultrasound and transmission electron microscopy
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2015 (English)In: Biomedical Spectroscopy and Imaging, ISSN 2212-8794, Vol. 4, no 1, p. 81-93Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: A novel polymer-shelled contrast agent (CA) with multimodal imaging and target specific potential was developed recently and tested for its acoustical properties using different in-vitro setups.

OBJECTIVE: The aim of this study was to investigate the elimination of three types of the novel polymer-shelled CA, one unmodified and two shell modified versions, in rats.

METHODS: The blood elimination time was estimated by measuring the image intensity, from ultrasound images of the common carotid artery, over time after a bolus injection of the three types of the novel CA. The commercially available CA SonoVue was used as a reference. The subcellular localization of the three CAs was investigated using transmission electron microscopy.

RESULTS: The ultrasound measurements indicated a blood half-life of 17–85 s for the different types of the novel CA, which was significant longer than the blood half-life time for SonoVue. Additionally, CAs were exclusively found in the circulatory system, either taken up by, or found in the vicinity of macrophages.

CONCLUSIONS: Compared to the commercially available CA SonoVue, the blood circulation times for the three types of the novel polymer-shelled CA were prolonged. Moreover, macrophages were suggested to be responsible for the elimination of the CA.

Keywords
Contrast agent, polymer, subcellular localization, transmission electron microscope, ultrasound imaging
National Category
Medical Engineering
Research subject
Medical Technology
Identifiers
urn:nbn:se:hj:diva-37077 (URN)10.3233/BSI-140099 (DOI)000358507400006 ()
Funder
EU, FP7, Seventh Framework Programme, 245572]
Available from: 2015-03-03 Created: 2017-08-31 Last updated: 2018-04-11Bibliographically approved
Maksuti, E., Bjällmark, A. & Broomé, M. (2015). Modelling the heart with the atrioventricular plane as a piston unit. Medical Engineering and Physics, 37(1), 87-92
Open this publication in new window or tab >>Modelling the heart with the atrioventricular plane as a piston unit
2015 (English)In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 37, no 1, p. 87-92Article in journal (Refereed) Published
Abstract [en]

Medical imaging and clinical studies have proven that the heart pumps by means of minor outer volume changes and back-and-forth longitudinal movements in the atrioventricular (AV) region. The magnitude of AV-plane displacement has also shown to be a reliable index for diagnosis of heart failure. Despite this, AV-plane displacement is usually omitted from cardiovascular modelling. We present a lumped-parameter cardiac model in which the heart is described as a displacement pump with the AV plane functioning as a piston unit (AV piston). This unit is constructed of different upper and lower areas analogous with the difference in the atrial and ventricular cross-sections. The model output reproduces normal physiology, with a left ventricular pressure in the range of 8-130 mmHg, an atrial pressure of approximatly 9 mmHg, and an arterial pressure change between 75 mmHg and 130 mmHg. In addition, the model reproduces the direction of the main systolic and diastolic movements of the AV piston with realistic velocity magnitude (similar to 10 cm/s). Moreover, changes in the simulated systolic ventricular-contraction force influence diastolic filling, emphasizing the coupling between cardiac systolic and diastolic functions. The agreement between the simulation and normal physiology highlights the importance of myocardial longitudinal movements and of atrioventricular interactions in cardiac pumping.

Keywords
Atrioventricular interaction, Cardiac function, Cardiac pumping, Longitudinal function, Cardiac model, Bond graphs
National Category
Biomedical Laboratory Science/Technology
Identifiers
urn:nbn:se:hj:diva-37087 (URN)10.1016/j.medengphy.2014.11.002 (DOI)000349585100011 ()25466260 (PubMedID)2-s2.0-84920913473 (Scopus ID)
Available from: 2015-03-24 Created: 2017-08-30Bibliographically approved
Broomé, M., Frenckner, B., Broman, M. & Bjällmark, A. (2015). Recirculation during veno-venous extra-corporeal membrane oxygenation: A simulation study. International Journal of Artificial Organs, 38(1), 23-30
Open this publication in new window or tab >>Recirculation during veno-venous extra-corporeal membrane oxygenation: A simulation study
2015 (English)In: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 38, no 1, p. 23-30Article in journal (Refereed) Published
Abstract [en]

PURPOSE:

Veno-venous ECMO is indicated in reversible life-threatening respiratory failure without life-threatening circulatory failure. Recirculation of oxygenated blood in the ECMO circuit decreases efficiency of patient oxygen delivery but is difficult to measure. We seek to identify and quantify some of the factors responsible for recirculation in a simulation model and compare with clinical data.

METHODS:

A closed-loop real-time simulation model of the cardiovascular system has been developed. ECMO is simulated with a fixed flow pump 0 to 5 l/min with various cannulation sites - 1) right atrium to inferior vena cava, 2) inferior vena cava to right atrium, and 3) superior+inferior vena cava to right atrium. Simulations are compared to data from a retrospective cohort of 11 consecutive adult veno-venous ECMO patients in our department.

RESULTS:

Recirculation increases with increasing ECMO-flow, decreases with increasing cardiac output, and is highly dependent on choice of cannulation sites. A more peripheral drainage site decreases recirculation substantially.

CONCLUSIONS:

Simulations suggest that recirculation is a significant clinical problem in veno-venous ECMO in agreement with clinical data. Due to the difficulties in measuring recirculation and interpretation of the venous oxygen saturation in the ECMO drainage blood, flow settings and cannula positioning should rather be optimized with help of arterial oxygenation parameters. Simulation may be useful in quantification and understanding of recirculation in VV-ECMO.

National Category
Medical Image Processing Other Medical Engineering
Identifiers
urn:nbn:se:hj:diva-37067 (URN)10.5301/ijao.5000373 (DOI)000351285800005 ()25588762 (PubMedID)2-s2.0-84928177837 (Scopus ID)
Funder
Swedish Research Council, 2012-2800]
Available from: 2015-02-06 Created: 2017-08-31Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1188-8098

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