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Lennmyr, Fredrik
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Publications (10 of 39) Show all publications
Reinius, H., Batista Borges, J., Engström, J., Ahlgren, O., Lennmyr, F., Larsson, A. & Fredén, F. (2019). Optimal PEEP during one-lung ventilation with capnothorax: An experimental study. Acta Anaesthesiologica Scandinavica, 63(2), 222-231
Open this publication in new window or tab >>Optimal PEEP during one-lung ventilation with capnothorax: An experimental study
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2019 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 63, no 2, p. 222-231Article in journal (Refereed) Published
Abstract [en]

Background: One‐lung ventilation (OLV) with induced capnothorax carries the risk of severely impaired ventilation and circulation. Optimal PEEP may mitigate the physiological perturbations during these conditions.

Methods: Right‐sided OLV with capnothorax (16 cm H2O) on the left side was initiated in eight anesthetized, muscle‐relaxed piglets. A recruitment maneuver and a decremental PEEP titration from PEEP 20 cm H2O to zero end‐expiratory pressure (ZEEP) was performed. Regional ventilation and perfusion were studied with electrical impedance tomography and computer tomography of the chest was used. End‐expiratory lung volume and hemodynamics were recorded and.

Results: PaO2 peaked at PEEP 12 cm H2O (49 ± 14 kPa) and decreased to 11 ± 5 kPa at ZEEP (P < 0.001). PaCO2 was 9.5 ± 1.3 kPa at 20 cm H2O PEEP and did not change when PEEP step‐wise was reduced to 12 cm H2O PaCO2. At lower PEEP, PaCO2 increased markedly. The ventilatory driving pressure was lowest at PEEP 14 cm H2O (19.6 ± 5.8 cm H2O) and increased to 38.3 ± 6.1 cm H2O at ZEEP (P < 0.001). When reducing PEEP below 12‐14 cm H2O ventilation shifted from the dependent to the nondependent regions of the ventilated lung (P = 0.003), and perfusion shifted from the ventilated to the nonventilated lung (P = 0.02).

Conclusion: Optimal PEEP was 12‐18 cm H2O and probably relates to capnothorax insufflation pressure. With suboptimal PEEP, ventilation/perfusion mismatch in the ventilated lung and redistribution of blood flow to the nonventilated lung occurred.

Keywords
anesthesia, capnothorax, cardio-thoracic surgery, one lung ventilation, optimal PEEP, PEEP titration
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-268620 (URN)10.1111/aas.13247 (DOI)000454814700012 ()30132806 (PubMedID)
Funder
Swedish Heart Lung Foundation
Note

Title in thesis list of papers: Optimal PEEP during one lung ventilation with capnothorax. An experimental study

Available from: 2015-12-08 Created: 2015-12-08 Last updated: 2019-01-31Bibliographically approved
Sedigh, A., Nordling, S., Carlsson, F., Larsson, E., Norlin, B., Lubenow, N., . . . Lorant, T. (2019). Perfusion of Porcine Kidneys With Macromolecular Heparin Reduces Early Ischemia Reperfusion Injury. Transplantation, 103(2), 420-427
Open this publication in new window or tab >>Perfusion of Porcine Kidneys With Macromolecular Heparin Reduces Early Ischemia Reperfusion Injury
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2019 (English)In: Transplantation, ISSN 0041-1337, E-ISSN 1534-6080, Vol. 103, no 2, p. 420-427Article in journal (Refereed) Published
Abstract [en]

Background: Previously, we have been able to demonstrate the possibility of coating the inner surface of the renal arteries in porcine kidneys with a heparin conjugate during hypothermic machine perfusion (HMP). The purpose of this study was to assess the efficacy of this treatment in reducing early ischemia-reperfusion injury.

Method: Brain death was induced in male landrace pigs by stepwise volume expansion of an epidural balloon catheter until negative cerebral perfusion pressure (CPP) was obtained. Both kidneys (matched pairs; n = 6 + 6) were preserved for 20 hours byHMP during which 50mg heparin conjugate was added to one of the HMP systems (treated group). A customized ex vivo normothermic oxygenated perfusion (NP) system with added exogenous creatinine was used to evaluate early kidney function. Blood, urine and histological samples were collected during the subsequent 3 hours of NP.

Results: Kidney weight was lower at the end of NP (P = 0.017) in the treated group compared with control kidneys. The rate of decline in creatinine level was faster (P = 0.024), total urinary volume was higher (P = 0.031), and the level of urine neutrophil gelatinase-associated lipocalin (NGAL) was lower (P = 0.031) in the treated group. Histologically, less tubular changes were seen (P = 0.046). During NP intrarenal resistance remained lower (P < 0.0001) in the treated group.

Conclusions: Perfusion of porcine kidneys with heparin conjugate during HMP reduces preservation injury and improves organ function shortly after reperfusion. No increased risk of bleeding was seen in this setup. This protective strategy may potentially improve the quality of transplanted kidneys in the clinical setting.

Place, publisher, year, edition, pages
LIPPINCOTT WILLIAMS & WILKINS, 2019
National Category
Surgery
Identifiers
urn:nbn:se:uu:diva-377674 (URN)10.1097/TP.0000000000002469 (DOI)000457576600035 ()30299374 (PubMedID)
Funder
VINNOVA
Available from: 2019-02-25 Created: 2019-02-25 Last updated: 2019-02-25Bibliographically approved
Aakhus, M., Ågerfalk, P. & Lennmyr, F. (2018). Digital Innovation as Design of Digital Practice: Doctors as Designers in Healthcare. In: Proceedings of the 51st Hawaii International Conference on System Sciences, Association for Information Systems: . Paper presented at 51st Hawaii International Conference on System Sciences, Association for Information Systems (HICSS 2018), Waikoloa Village, Hawaii, USA, 2-6 January 2018 (pp. 4594-4601). Association for Information Systems
Open this publication in new window or tab >>Digital Innovation as Design of Digital Practice: Doctors as Designers in Healthcare
2018 (English)In: Proceedings of the 51st Hawaii International Conference on System Sciences, Association for Information Systems, Association for Information Systems, 2018, p. 4594-4601Conference paper, Published paper (Refereed)
Abstract [en]

Medical professionals are increasingly assuming the role of maker and creator. At the same time, digital innovations, as part of evolving information infrastructures, are becoming increasingly prevalent in healthcare. In this paper, we adopt a Schönian approach to understand how a medical professional, who is not an IS designer by trade, engages in the design of digital practice -” turning what may appear as a failed digital innovation effort into a successful design of digital practice. Our inquiry suggests three pragmatic principles that call for further investigation: (a) professionals can make a significant contribution to design work by inventing means for fact-based, reflective engagement with the situation; (b) the reorganization of work practice involves organizational design, information system design, and communication design; and (c) developing design as digital practice entails the development of fact-based design practice and must engage practical theories.

Place, publisher, year, edition, pages
Association for Information Systems, 2018
National Category
Information Systems, Social aspects
Research subject
Information Systems
Identifiers
urn:nbn:se:uu:diva-374767 (URN)10.24251/HICSS.2018.579 (DOI)978-0-9981331-1-9 (ISBN)
Conference
51st Hawaii International Conference on System Sciences, Association for Information Systems (HICSS 2018), Waikoloa Village, Hawaii, USA, 2-6 January 2018
Available from: 2019-01-23 Created: 2019-01-23 Last updated: 2019-09-12Bibliographically approved
Lindblom, R. P., Molnar, M., Israelsson, C., Röjsäter, B., Wiklund, L. & Lennmyr, F. (2018). Hyperglycemia Alters Expression of Cerebral Metabolic Genes after Cardiac Arrest. Journal of Stroke & Cerebrovascular Diseases, 27(5), 1200-1211
Open this publication in new window or tab >>Hyperglycemia Alters Expression of Cerebral Metabolic Genes after Cardiac Arrest
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2018 (English)In: Journal of Stroke & Cerebrovascular Diseases, ISSN 1052-3057, E-ISSN 1532-8511, Vol. 27, no 5, p. 1200-1211Article in journal (Refereed) Published
Abstract [en]

Background: Survivors of cardiac arrest often experience neurologic deficits. To date, treatment options are limited. Associated hyperglycemia is believed to further worsen the neurologic outcome. The aim with this study was to characterize expression pathways induced by hyperglycemia in conjunction with global brain ischemia.

Methods: Pigs were randomized to high or normal glucose levels, as regulated by glucose and insulin infusions with target levels of 8.5-10 mM and 4-5.5 mM, respectively. The animals were subjected to 5-minute cardiac arrest followed by 8 minutes of cardiopulmonary resuscitation and direct-current shock to restore spontaneous circulation. Global expression profiling of the cortex using microarrays was performed in both groups.

Results: A total of 102 genes differed in expression at P<.001 between the hyperglycemic and the normoglycemic pigs. Several of the most strongly differentially regulated genes were involved in transport and metabolism of glucose. Functional clustering using bioinformatics tools revealed enrichment of multiple biological processes, including membrane processes, ion transport, and glycoproteins.

Conclusions: Hyperglycemia during cardiac arrest leads to differential early gene expression compared with normoglycemia. The functional relevance of these expressional changes cannot be deduced from the current study; however, the identified candidates have been linked to neuroprotective mechanisms and constitute interesting targets for further studies.

Keywords
Cerebral, ischemia-reperfusion, gene expression, glucose, hyperglycemia, microarray, pigs
National Category
Neurosciences
Identifiers
urn:nbn:se:uu:diva-351620 (URN)10.1016/j.jstrokecerebrovasdis.2017.11.036 (DOI)000428778400016 ()29306595 (PubMedID)
Funder
Erik, Karin och Gösta Selanders Foundation
Available from: 2018-06-13 Created: 2018-06-13 Last updated: 2018-06-13Bibliographically approved
Tovedal, T., Lubberink, M., Morell, A., Estrada, S., Golla, S. S., Myrdal, G., . . . Lennmyr, F. (2017). Blood Flow Quantitation by Positron Emission Tomography During Selective Antegrade Cerebral Perfusion. Annals of Thoracic Surgery, 103(2), 610-616
Open this publication in new window or tab >>Blood Flow Quantitation by Positron Emission Tomography During Selective Antegrade Cerebral Perfusion
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2017 (English)In: Annals of Thoracic Surgery, ISSN 0003-4975, E-ISSN 1552-6259, Vol. 103, no 2, p. 610-616Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Perfusion strategies during aortic surgery usually comprise hypothermic circulatory arrest (HCA), often combined with selective antegrade cerebral perfusion (SACP) or retrograde cerebral perfusion. Cerebral blood flow (CBF) is a fundamental parameter for which the optimal level has not been clearly defined. We sought to determine the CBF at a pump flow level of 6 mL/kg/min, previously shown likely to provide adequate SACP at 20°C in pigs.

METHODS: Repeated positron emission tomography (PET) scans were used to quantify the CBF and glucose metabolism throughout HCA and SACP including cooling and rewarming. Eight pigs on cardiopulmonary bypass were assigned to either HCA alone (n = 4) or HCA+SACP (n = 4). The CBF was measured by repeated [(15)O]water PET scans from baseline to rewarming. The cerebral glucose metabolism was examined by [(18)F]fluorodeoxyglucose PET scans after rewarming to 37°C.

RESULTS: Cooling to 20°C decreased the cortical CBF from 0.31 ± 0.06 at baseline to 0.10 ± 0.02 mL/cm(3)/min (p = 0.008). The CBF was maintained stable by SACP of 6 mL/kg/min during 45 minutes. After rewarming to 37°C, the mean CBF increased to 0.24 ± 0.07 mL/cm(3)/min, without significant differences between the groups at any time-point exclusive of the HCA period. The net cortical uptake (Ki) of [(18)F]fluorodeoxyglucose after rewarming showed no significant difference between the groups.

CONCLUSIONS: Cooling autoregulated the CBF to 0.10 mL/cm(3)/min, and 45 minutes of SACP at 6 mL/kg/min maintained the CBF in the present model. Cerebral glucose metabolism after rewarming was similar in the study groups.

National Category
Surgery
Identifiers
urn:nbn:se:uu:diva-302609 (URN)10.1016/j.athoracsur.2016.06.029 (DOI)000397165400067 ()27592601 (PubMedID)
Available from: 2016-09-07 Created: 2016-09-07 Last updated: 2018-09-03Bibliographically approved
Tovedal, T., Thelin, S. & Lennmyr, F. (2016). Cerebral oxygen saturation during pulsatile and non-pulsatile cardiopulmonary bypass in patients with carotid stenosis.. Perfusion, 31(1), 72-77
Open this publication in new window or tab >>Cerebral oxygen saturation during pulsatile and non-pulsatile cardiopulmonary bypass in patients with carotid stenosis.
2016 (English)In: Perfusion, ISSN 0267-6591, E-ISSN 1477-111X, Vol. 31, no 1, p. 72-77Article in journal (Refereed) Published
Abstract [en]

Pulsatile and non-pulsatile cardiopulmonary bypass (CPB) flows may have different impact on cerebral oxygen saturation in patients with restricted cerebral arterial blood supply. Twenty patients, ten diagnosed with carotid stenosis (CS, n = 10) and ten without known carotid disease (Controls, n = 10), were subjected to one period of pulsatile and one period of non-pulsatile flow (6-8 min each) during CPB at 32°C. Cerebral oxygen saturation was registered by near-infrared light spectroscopy (NIRS). The mean arterial pressure (MAP) was significantly lowered by pulsatile CPB flow. The NIRS tissue oxygenation index (TOI) tended to decrease in the CS group and increase in the Controls during pulsatile flow compared with non-pulsatile; however, the changes were not statistically significant. No significant correlations were seen between the changes in MAP and TOI across the observation periods. In conclusion, pulsatile CPB flow caused slightly decreased mean arterial pressure while the effect on cerebral oxygenation was unclear. Pulsatile flow was not found superior to non-pulsatile flow in patients with or without carotid stenosis.

National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:uu:diva-266555 (URN)10.1177/0267659115586280 (DOI)000366585600012 ()25948696 (PubMedID)
Available from: 2015-11-10 Created: 2015-11-10 Last updated: 2017-12-01Bibliographically approved
Tovedal, T., Thelin, S. & Lennmyr, F. (2015). Cerebral oxygen saturation during pulsatile and non-pulsatile cardiopulmonary bypass in patients with carotid stenosis. Perfusion
Open this publication in new window or tab >>Cerebral oxygen saturation during pulsatile and non-pulsatile cardiopulmonary bypass in patients with carotid stenosis
2015 (English)In: Perfusion, ISSN 0267-6591, E-ISSN 1477-111XArticle in journal (Refereed) Published
Keywords
Cardiopulmonary bypass, carotid stenosis, pulsatile CPB flow, NIRS
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-248678 (URN)
Available from: 2015-04-07 Created: 2015-04-07 Last updated: 2017-12-04
Morell, A., Lennmyr, F., Jonsson, O., Tovedal, T., Pettersson, J., Bergquist, J., . . . Bjørnerud, A. (2015). Influence of blood/tissue differences in contrast agent relaxivity on tracer based MR perfusion measurements. Magnetic Resonance Materials in Physics, Biology and Medicine, 28(2), 135-147
Open this publication in new window or tab >>Influence of blood/tissue differences in contrast agent relaxivity on tracer based MR perfusion measurements
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2015 (English)In: Magnetic Resonance Materials in Physics, Biology and Medicine, ISSN 0968-5243, E-ISSN 1352-8661, Vol. 28, no 2, p. 135-147Article in journal (Refereed) Published
Abstract [en]

PURPOSE:

Perfusion assessment by monitoring the transport of a tracer bolus depends critically on conversion of signal intensity into tracer concentration. Two main assumptions are generally applied for this conversion; (1) contrast agent relaxivity is identical in blood and tissue, (2) change in signal intensity depends only on the primary relaxation effect. The purpose of the study was to assess the validity and influence of these assumptions.

MATERIALS AND METHODS:

Blood and cerebral tissue relaxivities r1, r2, and r2* for gadodiamide were measured in four pigs at 1.5 T. Gadolinium concentration was determined by inductively coupled plasma atomic emission spectroscopy. Influence of the relaxivities, secondary relaxation effects and choice of singular value decomposition (SVD) regularization threshold was studied by simulations.

RESULTS:

In vivo relaxivities relative to blood concentration [in s-1 mM-1 for blood, gray matter (GM), white matter (WM)] were for r1 (2.614 ± 1.061, 0.010 ± 0.001, 0.004 ± 0.002), r2 (5.088 ± 0.952, 0.091 ± 0.008, 0.059 ± 0.014), and r2* (13.292 ± 3.928, 1.696 ± 0.157, 0.910 ± 0.139). Although substantial, by a nonparametric test for paired samples, the differences were not statistically significant. The GM to WM blood volume ratio was estimated to 2.6 ± 0.9 by r1, 1.6 ± 0.3 by r2, and 1.9 ± 0.2 by r2*. Secondary relaxation was found to reduce the tissue blood flow, as did the SVD regularization threshold.

CONCLUSION:

Contrast agent relaxivity is not identical in blood and tissue leading to substantial errors. Further errors are introduced by secondary relaxation effects and the SVD regularization.

Keywords
MRI, relaxivity, contrast agent, perfusion
National Category
Radiology, Nuclear Medicine and Medical Imaging Analytical Chemistry
Research subject
Radiology; Medical Radiophysics
Identifiers
urn:nbn:se:uu:diva-170528 (URN)10.1007/s10334-014-0452-5 (DOI)000352149200004 ()
Available from: 2012-03-28 Created: 2012-03-12 Last updated: 2017-12-07Bibliographically approved
Zoerner, F., Lennmyr, F., Wiklund, L., Martijn, C. & Semenas, E. (2015). Milrinone and esmolol decrease cardiac damage after resuscitation from prolonged cardiac arrest. Acta Anaesthesiologica Scandinavica, 59(4), 465-474
Open this publication in new window or tab >>Milrinone and esmolol decrease cardiac damage after resuscitation from prolonged cardiac arrest
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2015 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 59, no 4, p. 465-474Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Long-term survival after cardiac arrest (CA) due to shock-refractory ventricular fibrillation (VF) is low. Clearly, there is a need for new pharmacological interventions in the setting of cardiopulmonary resuscitation (CPR) to improve outcome. Here, hemodynamic parameters and cardiac damage are compared between the treatment group (milrinone, esmolol and vasopressin) and controls (vasopressin only) during resuscitation from prolonged CA in piglets.

METHODS: A total of 26 immature male piglets were subjected to 12-min VF followed by 8-min CPR. The treatment group (n = 13) received i.v. (intravenous) boluses vasopressin 0.4 U/kg, esmolol 250 μg/kg and milrinone 25 μg/kg after 13 min, followed by i.v. boluses esmolol 375 μg/kg and milrinone 25 μg/kg after 18 min and continuous esmolol 15 μg/kg/h infusion during 180 min reperfusion, whereas controls (n = 13) received equal amounts of vasopressin and saline. A 200 J monophasic counter-shock was delivered to achieve resumption of spontaneous circulation (ROSC) after 8 min CPR. If ROSC was not achieved, another 200 J defibrillation and bolus vasopressin 0.4 U/kg would be administered in both groups. Direct current shocks at 360 J were applied as one shot per minute over maximally 5 min. Hemodynamic variables and troponin I as a marker of cardiac injury were recorded.

RESULTS: Troponin I levels after 180 min reperfusion were lower in the treatment group than in controls (P < 0.05). The treatment group received less norepinephrine (P < 0.01) and had greater diuresis (P < 0.01). There was no difference in survival between groups.

CONCLUSION: The combination of milrinone, esmolol and vasopressin decreased cardiac injury compared with vasopressin alone.

National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-251850 (URN)10.1111/aas.12480 (DOI)000351537900008 ()25790148 (PubMedID)
Available from: 2015-04-24 Created: 2015-04-24 Last updated: 2017-12-04Bibliographically approved
Sedigh, A., Nordling, S., Larsson, R., Larsson, E., Norlin, B., Lubenow, N., . . . Lorant, T. (2015). Perfusion Of Porcine Kidneys With Macromolecular Heparin Ameliorates Early Ischemia Reperfusion Injury. Transplant International, 28, 94-95
Open this publication in new window or tab >>Perfusion Of Porcine Kidneys With Macromolecular Heparin Ameliorates Early Ischemia Reperfusion Injury
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2015 (English)In: Transplant International, ISSN 0934-0874, E-ISSN 1432-2277, Vol. 28, p. 94-95Article in journal, Meeting abstract (Other academic) Published
National Category
Surgery
Identifiers
urn:nbn:se:uu:diva-281006 (URN)000367726700253 ()
Available from: 2016-04-01 Created: 2016-03-16 Last updated: 2018-05-18
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