| 1. |
- Bergkvist, Max, 1976-, et al.
(author)
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Vascular Occlusion in a Porcine Flap Model : Effects on Blood Cell Concentration and Oxygenation.
- 2017
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In: Plastic and Reconstructive Surgery - Global Open. - : Wolters Kluwer. - 2169-7574. ; 5:11
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Journal article (peer-reviewed)abstract
- Background: Venous congestion in skin flaps is difficult to detect. This study evaluated the ability of tissue viability imaging (TiVi) to measure changes in the concentration of red blood cells (CRBC), oxygenation, and heterogeneity during vascular provocations in a porcine fasciocutaneous flap model.Methods: In 5 pigs, cranial gluteal artery perforator flaps were raised (8 flaps in 5 pigs). The arterial and venous blood flow was monitored with ultrasonic flow probes. CRBC, tissue oxygenation, and heterogeneity in the skin were monitored with TiVi during baseline, 50% and 100% venous occlusion, recovery, 100% arterial occlusion and final recovery, thereby simulating venous and arterial occlusion of a free fasciocutaneous flap. A laser Doppler probe was used as a reference for microvascular perfusion in the flap.Results: During partial and complete venous occlusion, increases in CRBC were seen in different regions of the flap. They were more pronounced in the distal part. During complete arterial occlusion, CRBC decreased in all but the most distal parts of the flap. There were also increases in tissue oxygenation and heterogeneity during venous occlusion.Conclusions: TiVi measures regional changes in CRBC in the skin of the flap during arterial and venous occlusion, as well as an increase in oxygenated hemoglobin during venous occlusion that may be the result of reduced metabolism and impaired delivery of oxygen to the tissue. TiVi may provide a promising method for measuring flap viability because it is hand-held, easy to-use, and provides spatial information on venous congestion.
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| 2. |
- Elawa, Sherif, et al.
(author)
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Skin perfusion and oxygen saturation after mastectomy and radiation therapy in breast cancer patients
- 2024
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In: Breast. - : Elsevier. - 0960-9776 .- 1532-3080. ; 75
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Journal article (peer-reviewed)abstract
- The pathophysiological mechanism behind complications associated with postmastectomy radiotherapy (PMRT) and subsequent implant-based breast reconstruction are not completely understood. The aim of this study was to examine if there is a relationship between PMRT and microvascular perfusion and saturation in the skin after mastectomy and assess if there is impaired responsiveness to a topically applied vasodilator (Methyl nicotinate - MN). Skin microvascular perfusion and oxygenation >2 years after PMRT were measured using white light diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) in the irradiated chest wall of 31 women with the contralateral breast as a control. In the non-irradiated breast, the perfusion after application of MN (median 0.84, 25th-75th centile 0.59-1.02 % RBC × mm/s) was higher compared to the irradiated chest wall (median 0.51, 25th-75th centile 0.21-0.68 % RBC × mm/s, p < 0.001). The same phenomenon was noted for saturation (median 91 %, 25th-75th centile 89-94 % compared to 89 % 25th-75th centile 77-93 %, p = 0.001). Eight of the women (26%) had a ≥10 % difference in skin oxygenation between the non-irradiated breast and the irradiated chest wall. These results indicate that late microvascular changes caused by radiotherapy of the chest wall significantly affect skin perfusion and oxygenation.
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| 3. |
- Kifle, Yonatan Habteslassie, et al.
(author)
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NFC Powered Implantable Temperature Sensor
- 2019
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In: 2019 41ST ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC). - : IEEE. - 9781538613115 - 9781538613122 ; , s. 4359-4362
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Conference paper (peer-reviewed)abstract
- Inductively powered 99% accurate implantable temperature sensor is designed, characterized and the findings are presented in this paper. The implantable sensors deliver a continuous temperature reading to external storage or readout devices via Near Field Communication interface. A 2.76 mu H rectangular inductive coil printed on a thin biocompatible plastic substrate is designed to establish the coupling link through NFC interface with external readout devices. A commercially available wide range temperature sensor chip is mounted along with the developed inductive coil on the same plastic substrate. For 50 samples, the received signal strength indicator, temperature accuracy and statistical distribution of measurement levels is investigated. Comparison of predetermined temperature in a controlled temperature and humidity chamber versus the temperature reading from the developed sensors proves a 99% accuracy.
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| 4. |
- Zötterman, Johan, 1975-, et al.
(author)
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Better Protection of Glass-Fronted Stoves Is Needed in Sweden Because of the Increase in the Number of Contact Burns Among Small Children
- 2018
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In: Journal of Burn Care & Research. - : Oxford University Press. - 1559-047X .- 1559-0488. ; 39:4, s. 618-622
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Journal article (peer-reviewed)abstract
- The impression among the attending physicians at their Burn Centre is that the number of contact burns caused by glass-fronted stoves is increasing, particularly in the youngest group of patients. It is an interesting subgroup, as these injuries are preventable. The authors’ aim of this study was to find out whether the incidence of burns after contact with glass-fronted stoves has increased.The authors included all patients aged between 0 and 3.9 years who presented to the National Burn Centre during the period 2008–2015 with contact burn injuries caused by glass-fronted stoves. The change in incidence over time was calculated from national records and analyzed with simple linear regression.Fifty-six patients were included, of whom 20 were treated during the past 2 years of the study. Thirty-seven of the 56 were boys (66%), median (10–90 percentiles) age was 1.1 (0.7–2.5) years, percentage total body surface area burned was 0.6% (0.1–2.0), 12 were admitted for overnight stay in hospital, and seven needed operations. The incidence was 0.34/100 000 children-years during the first 2 years, and it was three times as high during the past 2 years. The increase in incidence was 0.24/100 000 children-years by each 2-year period (P = .02).The authors’ results indicate that contact burns among children caused by glass-fronted stoves are increasing in Sweden. The authors propose that there should be a plan for their prevention put in place.
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| 5. |
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| 6. |
- Zötterman, Johan, 1975-, et al.
(author)
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Intraoperative Laser Speckle Contrast Imaging in DIEP Breast Reconstruction : A Prospective Case Series Study
- 2020
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In: Plastic and Reconstructive Surgery - Global Open. - : Wolters Kluwer. - 2169-7574. ; 8:1, s. e2529-e2529
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Journal article (peer-reviewed)abstract
- Laser speckle contrast imaging (LSCI) is a laser-based perfusion imaging technique that recently has been shown to predict ischemic necrosis in an experimental flap model and predicting healing time of scald burns. The aims were to investigate perfusion in relation to the selected perforator during deep inferior epigastric artery perforator (DIEP) flap surgery, and to evaluate LSCI in assisting of prediction of postoperative complications. METHODS: Twenty-three patients who underwent DIEP-procedures for breast reconstruction at 2 centers were included. Perfusion was measured in 4 zones at baseline, after raising, after anastomosis, and after shaping the flap. The perfusion in relation to the selected perforator and the accuracy of LSCI in predicting complications were analyzed. RESULTS: After raising the flap, zone I showed the highest perfusion (65 ± 10 perfusion units, PU), followed by zone II (58 ± 12 PU), zone III (53 ± 10 PU), and zone IV (45 ± 10 PU). The perfusion in zone I was higher than zone III (P = 0.002) and zone IV (P < 0.001). After anastomosis, zone IV had lower perfusion than zone I (P < 0.001), zone II (P = 0.01), and zone III (P = 0.02). Flaps with areas <30 PU after surgery had partial necrosis postoperatively (n = 4). CONCLUSIONS: Perfusion is highest in zone I. No perfusion difference was found between zones II and III. Perfusion <30 PU after surgery was correlated with partial necrosis. LSCI is a promising tool for measurement of flap perfusion and assessment of risk of postoperative ischemic complications.
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| 7. |
- Zötterman, Johan, 1975-
(author)
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Laser Speckle Contrast Imaging in Reconstructive Surgery
- 2020
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Doctoral thesis (other academic/artistic)abstract
- ObjectivesReconstructive surgery aims to restore function or normal appearance by reconstructing defective organs after trauma or disease. In patients undergoing reconstructive surgery, previous trauma, surgery or radiotherapy can result in compromised blood supply. This will affect the viability of the tissue and increases the risk for postoperative complications, such as ischemia and infection. It is therefore important to assess the tissue viability, both before, during and after the surgery. This can be done using different techniques that monitor the perfusion of the skin covering the affected area. In this thesis, LSCI have been evaluated for tissue monitoring in reconstructive surgery. The technique allows for a fast and noninvasive assessment of superficial tissue perfusion over a wide field. Based on previous work on the technology, we have seen clear advantages with LSCI compared to other methods, for example laser Doppler flowmetry (LDF). We have evaluated laser speckle contrast imaging (LSCI) as a tool for tissue monitoring in reconstructive surgery in four studies.MethodsIn study I we used a bench top model and healthy subjects to address methodological concerns subjected to the LSCI technology. We investigated the effect of motion distance and angle on the assessed perfusion value In study II we used a porcine model to compare LSCI and LDF as tools to detect partial and full venous outflow obstruction. We used both methods to assess a flap based on the cranial gluteal artery perforator with partial and complete occlusion of the vein and artery. In study III we used the same porcine model as in study II to investigate the possibility to use LSCI intraoperatively to identify flap areas with compromised circulation and thereby predict areas with a high risk of postoperative necrosis. In study IV we used LSCI for intraoperative evaluation of tissue viability during deep inferior epigastric perforator (DIEP) free flap surgery and to investigate the perfusion distribution according to the Hartrampf zones, as measured with LSCI, in relation to the selected perforator in the deep inferior epigastric perforator free flap.ResultsIn study I we saw that tissue perfusion as measured with LSCI increases with increasing tissue motion, independent of frame rate, number of images, and tissue perfusion. Measured perfusion will decrease when images are acquired at an angle larger than 45° but distances between 15 and 40 cm do not affect the measured perfusion. In study II we observed significant decreases in perfusion during both partial and complete venous occlusion with both LSCI and LDF. However, higher variability seen with LDF, measured as % coefficient of variation. In study III a decrease in perfusion during the first 30 min after raising the flap and a perfusion value below 25 PU after 30 min was a predictor for tissue morbidity 72h after surgery. In study IV the highest perfusion values were found in zone I and higher perfusion in zone II compared to zone III, directly after the flap was raised. No remaining significant difference between zone I, II and III could be seen after anastomosis of the vessels. All flaps with a minimum perfusion <30 PU, measured after the flap was shaped and inserted, later suffered from partial flap necrosis.ConclusionLSCI is a technology that has the potential to contribute to tissue monitoring in reconstructive surgery. It has many advantages over other techniques, such as the fast acquisition time, the spatial resolution and the fact that it is completely non-invasive. However, the current system is still too bulky to be easily introduced into a clinical setting and the technology is also subject to certain drawbacks which limit its usability. It is sensitive to motion artefacts; only superficial tissue is assessed and cannot offer absolute perfusion data. If these disadvantages could be addressed, LSCI could contribute to a more accurate survey of tissue perfusion and thus better outcome in reconstructive surgery.
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| 8. |
- Zötterman, Johan, 1975-, et al.
(author)
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The use of laser speckle contrast imaging to predict flap necrosis: An experimental study in a porcine flap model
- 2019
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In: Journal of Plastic, Reconstructive & Aesthetic Surgery. - : ELSEVIER SCI LTD. - 1748-6815 .- 1878-0539. ; 72:5, s. 771-777
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Journal article (peer-reviewed)abstract
- Background: We evaluated the use of laser speckle contrast imaging (LSCI) in the perioperative planning in reconstructive flap surgery. The aim of the study was to investigate whether LSCI can predict regions with a high risk of developing postoperative necrosis. Our hypothesis was that, perioperatively, such regions have perfusion values below a threshold value and show a negative perfusion trend. Methods: A porcine flap model based on the cranial gluteal artery perforator was used. Images were acquired before surgery, immediately after surgery (t = 0), after 30 min (t =30 min), and after 72h (t = 72 h). Regions of interest (ROIs) were chosen along the central axis of the flap. Clinical evaluation of the flap was made during each time point. Results: At t = 72 h, a demarcation line could be seen at a distance of 15.8 +/- 0.4 cm away from the proximal border of the flaps. At t =0, perfusion decreased gradually from the proximal to the distal ROI. At t =30 min, perfusion was significantly lower in the ROI distal to the final demarcation line than that at t = 0, and in all flaps, these ROIs had a perfusion amp;lt;25 PU. At t= 72 h, perfusion in the ROI proximal to this line returned to baseline levels, whereas perfusion in the distal ROI remained low. Conclusions: In our model, a decrease in perfusion during the first 30 min after surgery and a perfusion amp;lt;25 PU at t = 30 min was a predictor for tissue morbidity 72 h after surgery, which indicates that LSCI is a promising technique for perioperative monitoring in reconstructive flap surgery. (C) 2018 Published by Elsevier Ltd on behalf of British Association of Plastic, Reconstructive and Aesthetic Surgeons.
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