| 1. |
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| 2. |
- Sedigh, Amir, et al.
(författare)
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Perfusion of Porcine Kidneys With Macromolecular Heparin Reduces Early Ischemia Reperfusion Injury
- 2019
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Ingår i: Transplantation. - : LIPPINCOTT WILLIAMS & WILKINS. - 0041-1337 .- 1534-6080. ; 103:2, s. 420-427
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Aakhus, Mark, et al.
(författare)
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Digital Innovation as Design of Digital Practice : Doctors as Designers in Healthcare
- 2018
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Ingår i: Proceedings of the 51st Hawaii International Conference on System Sciences (HICSS). - 9780998133119 ; , s. 4594-4601
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 4. |
- Arthursson, Henrik, et al.
(författare)
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Cerebral oxygenation and autoregulation during rewarming on cardiopulmonary bypass
- 2023
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Ingår i: Perfusion. - : Sage Publications. - 0267-6591 .- 1477-111X. ; 38:3, s. 523-529
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Tidskriftsartikel (refereegranskat)abstract
- Background Rewarming on cardiopulmonary bypass (CPB) is associated with increased metabolic demands; however, it remains unclear whether cerebral autoregulation is affected during this phase. This RCT aims to describe the effects of 20% supranormal, compared to normal CPB flow, on monitoring signs of inadequate perfusion, oxygenation, and disturbed cerebral autoregulation, during the rewarming phase of CPB. Method Thirty two patients scheduled for coronary artery bypass grafting were allocated to a Control group (n = 16) receiving a CPB pump flow corresponding to preoperatively measured cardiac output, and an Intervention group (n = 16) receiving the corresponding CPB pump flow increased by 20% during rewarming. Cerebral Oximetry Index (COx) was calculated with the aid of Near Infrared Spectroscopy. Results Twenty five patients were included in the data. Results show a median COx value of 0.0 (IQR -0.33-0.5) (Control) and 0.0 (IQR -0.15-0.25) (Intervention), respectively; p = .85 with individual variations within groups. The median cerebral perfusion pressure (CPP) was 55 (52-58) (Control) and 61 (54-66) mmHg (Intervention); p = .08. No significant difference in rSO2 values was observed between the groups (58.5% (50-61) versus 64% (58-68); p = .06). Conclusion The present study showed no difference between increased and normal CPB pump flow with respect to cerebral autoregulation during rewarming. Large variations in cerebral autoregulation were seen at individual level.
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| 5. |
- Biglarnia, Ali-Reza, 1973-, et al.
(författare)
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Efficacy and safety of continuous local infusion of ropivacaine after retroperitoneoscopic live donor nephrectomy
- 2011
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Ingår i: American Journal of Transplantation. - : Elsevier BV. - 1600-6135 .- 1600-6143. ; 11:1, s. 93-100
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Tidskriftsartikel (refereegranskat)abstract
- Morphine-based analgesia is effective but can compromise donor safety. We investigated whether continuous infusion of local anesthetics (CILA) can provide sufficient pain control and reduce morbidity related to opiate analgesics after hand-assisted retroperitoneoscopic (HARS) live donor nephrectomy. Forty consecutive live kidney donors underwent HARS and were treated with the ON-Q system providing CILA with 0.5% ropivacaine through two SilvaGard® catheters placed in the retroperitoneal cavity and the rectus sheath, respectively. The case control group consisted of 40 donors matched with regard to sex, age, BMI and surgical technique. All donors were maintained on standardized multimodal analgesia combining nurse-controlled oxycodone treatment and acetaminophen. CILA donors had lower median cumulative consumption of morphine equivalents (CCME) (7 mg [0-56] vs. 42 mg [15-127]; p < 0.0000001), lower incidence of nausea (18 [45%] vs. 35 [87.5%] donors; p < 0.001), shorter time in postoperative care unit (160 vs. 242.5 min; p < 0.001) and shorter hospital stay (4 [4-7] vs. 6 [4-11] days; p < 0.001). In 32.5% of CILA donors the CCME was 0 mg (0% in matched control group, p < 0.001). CILA with 0.5% ropivacaine provides effective postoperative pain relief, reduces the need for opioid treatment and promotes postoperative recovery. Continuous local infusion of ropivacaine provides sufficient analgesia and opioid-sparing effect as well as reduces the incidence of nausea and vomiting after hand-assisted retroperitoneoscopic live donor nephrectomy.
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| 6. |
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| 7. |
- Farrokhnia, Nasim, et al.
(författare)
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Differential early mitogen-activated protein kinase activation in hyperglycemic ischemic brain injury in the rat
- 2005
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Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 35:7, s. 457-463
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hyperglycemia aggravates brain injury induced by focal ischemia-reperfusion. The mitogen-activated protein kinase (MAPK) members extracellular-signal regulated kinase (Erk) and c-Jun N-terminal kinase (JNK) have been proposed as mediators of ischemic brain injury, and Erk is strongly activated by combined hyperglycemia and transient global ischemia. It is unclear whether similar MAPK activation appears in focal brain ischemia with concomitant hyperglycemia. DESIGN: Hyperglycemia was induced in rats by an intraperitoneal bolus of glucose (2 g kg(-1)). The rats were then subjected to 90 min of transient middle cerebral artery occlusion (MCAO). Erk and JNK activation were investigated with immunofluorescence and Western blot along with infarct size measurement based on tetrazolium staining and neurological score. RESULTS: The hyperglycemic rats showed increased tissue damage and impaired neurological performance after 1 day compared with controls. The hyperglycemia was generally moderate (< 15 mM). Erk activation was increased after 30 min of reperfusion in the ischemic cortex of the hyperglycemic rats, while JNK activation was present on the contralateral side. Phospho-Erk immunofluorescence revealed marked neuronal activation of Erk in the ischemic cortex of hyperglycemic rats compared with controls. CONCLUSION: Besides confirming the detrimental effects of hyperglycemia on focal ischemia-reperfusion, this study shows that hyperglycemia strongly activates the pathogenic mediator Erk in the ischemic brain in the early phase of reperfusion. JNK activation at this stage is present in the nonischemic hemisphere. The functional relevance of these findings needs further investigation.
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| 8. |
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| 9. |
- Farrokhnia, Nasim, et al.
(författare)
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Experimental treatment for focal hyperglycemic ischemic brain injury in the rat
- 2005
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Ingår i: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 167:2, s. 310-314
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Tidskriftsartikel (refereegranskat)abstract
- Hyperglycemia aggravates ischemic brain injury, possibly due to the activation of signaling pathways involving reactive oxygen species, Src and mitogen-activated protein kinases. The aim of this study was to investigate the effects of the spin trap agent alpha-phenyl-N-tert-butyl nitrone (PBN), the Src family kinase inhibitor PP2 and the MEK1-inhibitor U0126 on focal hyperglycemic ischemic brain injury. Temporary middle cerebral artery occlusion (90 min) was induced in four groups of rats (PBN, PP2, and U0126 vs. control). Neurological testing and tetrazolium red staining were performed after 1 day. PBN decreased the infarct volume by 70% compared with the control (P<0.05) and a tendency towards reduced infarcts was seen in the PP2 or U0126 groups. Furthermore, neurological testing was consistent with the volumetric analysis. In conclusion, PBN appears to be a potential neuroprotective agent in hyperglycemic, focal ischemic brain injury, while the efficacy of PP2 and U0126 could not be confirmed by the present data.
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| 10. |
- Farrokhnia, Nasim, 1972-
(författare)
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Hyperglycemia and Focal Brain Ischemia : Clinical and Experimental Studies
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diabetes is a major risk factor for ischemic stroke and is associated with increased mortality. Additionally, hyperglycemia, a common complication in acute stroke, is associated with poor outcome.In order to identify the correlation between blood glucose and early mortality, multiple logistic regression analyses were used and odds ratios calculated in a retrospective study of 447 stroke patients. Eighty-one patients (18%) had diabetes. The odds ratios for 30-day case-fatality and blood glucose were 1.9 and 1.6 in diabetic and non-diabetic patients respectively. Optimal blood glucose concentrations in respective group were 10.3 and 6.3 mmol/L, as determined by receiver operator characteristic (ROC) curves.Cerebral ischemia triggers different signaling pathways including mitogen-activated protein kinases (MAPK) which regulate fundamental cell functions. In an experimental rat model of combined hyperglycemia and transient middle cerebral artery occlusion (MCAO), the activation pattern of one such MAPK, extracellular signal-regulated kinase (ERK) was studied along with infarct volumes and neurological function. Hyperglycemia resulted in markedly increased ERK activation and approximately three-fold increase of infarcts compared with controls. Based on the increased ERK activation, further experiments were conducted to limit the hyperglycemic-ischemic damage by interfering with ERK and supposedly related mechanisms. Consequently, rats were given U0126 (inhibiting ERK activation), PBN (anti-oxidative), PP2 (inhibiting src-family kinases), or vehicle. PBN reduced infarcts and improved neurological function compared with controls while no statistically significant effects were observed for U0126 or PP2. However, when the dose was doubled, U0126 significantly reduced infarcts and improved neurological function after 1 day in hyperglycemic rats. Post-ischemic ERK activation was completely inhibited by U0126 as demonstrated with Western immunoblotting. The findings suggest that ERK is an important mediator of hyperglycemic-ischemic brain injury and possible target for future interventions.
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| 11. |
- Farrokhnia, Nasim, et al.
(författare)
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MEK-inhibitor U0126 in hyperglycaemic focal ischaemic brain injury in the rat
- 2008
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Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 38:9, s. 679-85
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hyperglycaemia aggravates ischaemic brain injury, possibly due to activation of signalling pathways involving mitogen-activated protein kinases (MAPK). In this study, the activation of MAPK/ERK was inhibited using the upstream inhibitor of MAPK-ERK-kinase (MEK) U0126, and the effects on focal brain ischaemia were evaluated during normo- and hyperglycaemia. MATERIALS AND METHODS: Temporary (90 min) middle cerebral artery occlusion (MCAO) was induced in five groups of rats. U0126 (400 microg kg(-1)) or vehicle was given as 60-min intravenous infusions starting either 30 min prior to MCAO or 30 min prior to reperfusion. The infarct size was determined by perfusion with tetrazolium red after 24 h of survival, and the neurology was tested with the 4-level scale of Bederson and performance on an inclined plane. The inhibitory effect on the targeted MEK enzyme was investigated by analysing the phosphorylation of the downstream target ERK with western immunoblotting. Two subgroups were investigated with magnetic resonance imaging (MRI), including diffusion-weighted (DWI) and perfusion-weighted imaging (PWI). RESULTS: U0126 effectively reduced the infarct size and improved neurology in hyperglycaemic rats both when given before and after ischemic onset. This effect was not accompanied by any detectable changes in cerebral blood flow on MRI. Normoglycaemic rats had generally milder injuries compared with the hyperglycaemic and there was a nonsignificant trend for U0126 to reduce damage also in the nonhyperglycaemic groups. CONCLUSIONS: In conclusion, U0126 appears to be neuroprotective in this model of hyperglycaemic ischaemic brain injury. The findings support the pathogenic importance of the MEK-ERK pathway in hyperglycaemic-ischaemic brain injury.
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| 12. |
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| 13. |
- Jonsson, Ove, 1966-
(författare)
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Cerebral Perfusion and Metabolism during Experimental Extracorporeal Circulation
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neurologic injuries are major causes of mortality and morbidity after cardiac surgery. This thesis aimed to investigate cerebral metabolism and perfusion abnormalities in pigs during hypothermic circulatory arrest, selective antegrade cerebral perfusion (SACP) and extracorporeal circulation following progressive venous stasis. Hypothermic circulatory arrest induced a metabolic pattern consistent with overt ischaemia, which was absent following SACP. In contrast, metabolism during SACP was influenced by the perfusate temperature, where a colder perfusate (20 °C) preserved cellular metabolism and membrane integrity better than a warmer perfusate (28 °C). The minimum SACP flow required to maintain metabolism during hypothermia at 20 °C was investigated with magnetic resonance imaging, protein S100β, near infrared spectroscopy and microdialysis. The findings suggested an ischaemic threshold close to 6 ml/kg/min in the present models. Furthermore, regional differences in perfusion with a hemispheric distribution were apparent at all flow levels and differed from earlier studies where the differences were uniform and followed a neuranatomical pattern. Venus stasis following superior vena cava congestion produced measurable signs of impaired cerebral perfusion and patterns of cerebral ischaemia were evident in individual animals. As venous pressure increased, the mean arterial pressure stayed more or less unchanged, generating reduced cerebral perfusion pressure and consequently an increased risk of ischaemia, which may impair cerebral perfusion, especially in cases of compromised arterial flow during extracorporeal circulation. In conclusion, cerebral metabolism and perfusion are influenced by temperature, SACP flow levels and venous congestion. In clinical practice, the regional differences in perfusion during SACP may be of pathogenic importance in focal cerebral ischaemia. Furthermore, the reduced superior vena cava cannula flow may pass undetected during bicaval cardiopulmonary bypass if the superior vena cava flow is not specifically monitored.
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| 14. |
- Jonsson, Ove, 1966-, et al.
(författare)
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Minimal Safe Arterial Blood Flow During Selective Antegrade Cerebral Perfusion at 20° Centigrade
- 2011
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Ingår i: Annals of Thoracic Surgery. - : Elsevier BV. - 0003-4975 .- 1552-6259. ; 91:4, s. 1198-1205
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundSelective antegrade cerebral perfusion (SACP) enables surgery on the aortic arch, where cerebral ischemia may cause neurologic sequels. This study aims to identify the minimum arterial flow level to maintain adequate cerebral perfusion during SACP in deep hypothermia in the pig.MethodsTwo groups of pigs were subjected to SACP at 20°C α-stat. In group 1 (n = 6), flow was stepwise adjusted from 8-6-4-2-8 mL · kg−1 · min−1 and in group 2 (n = 5), flow was kept constant at 6 mL · kg−1 · min−1. Magnetic resonance imaging and spectroscopy were performed at each flow level together with hemodynamic monitoring and blood gas analysis. The biochemical marker of cerebral damage protein S100β was measured in peripheral blood.ResultsDecreased mixed venous oxygen saturation and increased lactate in magnetic resonance spectroscopy was seen as a sign of anaerobic metabolism below 6 mL · kg−1 · min−1. No ischemic damage was seen on diffusion-weighted imaging, but the concentrations of S100β were significantly elevated in group 1 compared with group 2 at the end of the experiment (p < 0.05). Perfusion-weighted imaging showed coherence between flow setting and cerebral perfusion, increase of blood volume across time, and regional differences in perfusion during SACP.ConclusionsThe findings suggest an ischemic threshold close to 6 mL · kg−1 · min−1 in the present model. Regional differences in perfusion during SACP may be of pathogenic importance to focal cerebral ischemia.
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| 15. |
- Lennmyr, Fredrik, et al.
(författare)
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Activation of mitogen-activated protein kinases in experimental cerebral ischemia
- 2002
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 106:6, s. 333-40
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Mitogen-activated protein kinases (MAPK) regulate cell survival and differentiation. The aim of the present study is to investigate the activation pattern of different MAPKs [extracellular signal-regulated kinase (ERK), c-jun-N-terminal kinase (JNK) and p38] after cerebral ischemia. MATERIAL AND METHODS: Rats were subjected to cerebral ischemia using a model for transient (2 h) and permanent middle cerebral artery occlusion (MCAO). The rats were allowed 6 h to 1 week of survival before immunohistochemical evaluation with phospho-specific antibodies, recognizing activated MAPKs. RESULTS: ERK was activated in ipsilateral blood vessels, neurons and glia, but also in contralateral vessels. JNK activation was absent in neurons but appeared in arterial blood vessels and glia at the lesion side. Active p38 was observed in macrophages in maturing infarcts. CONCLUSIONS: ERK and JNK may participate in the angiogenic response to cerebral ischemia. ERK, but not JNK, was activated in neurons, possibly indicating a pathophysiologic role. Active p38 might be involved in the inflammatory reaction.
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| 16. |
- Lennmyr, Fredrik, et al.
(författare)
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Cerebral effects of hyperglycemia in experimental cardiac arrest
- 2010
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 38:8, s. 1726-1732
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate the effects of cardiac arrest on cerebral perfusion and oxidative stress during hyperglycemia and normoglycemia. Design: Experimental animal model. Setting: University laboratory. Subjects: Triple-breed pigs (weight, 22-27 kg). Interventions: Thirty-three pigs were randomized and clamped at blood glucose levels of 8.5-10 mM (high) or 4-5.5 mM (normal) and thereafter subjected to alternating current-induced 12-min cardiac arrest followed by 8 mins of cardiopulmonary resuscitation and direct-current shock to restore spontaneous circulation. Measurements and Main Results: Hemodynamics, regional near-infrared light spectroscopy, regional venous HbO(2), and biochemical markers (Protein S100 beta, troponin I, F-2-isoprostanes reflecting oxidative stress and inflammation) were monitored and/or sampled throughout an observation period of 4 hrs. No significant differences were seen in hemodynamics or biochemical profile. The cerebral oxygenation by means of regional near-infrared light spectroscopy was higher in the hyperglycemic (H) than in the normal (N) group after restoration of spontaneous circulation (p < .05). However, tendencies toward increased protein S100 beta and 15-keto-dihydro-prostaglandin F-2 alpha were observed in the H group but were not statistically significant. Conclusions: The responses to 12-min cardiac arrest and cardiopulmonary resuscitation share large similarities during hyperglycemia and normoglycemia. The higher cerebral tissue oxygenation observed in the hyperglycemia needs to be confirmed and the phenomenon needs to be addressed in future studies.
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| 17. |
- Lennmyr, Fredrik, et al.
(författare)
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Expression of vascular endothelial growth factor (VEGF) and its receptors (Flt-1 and Flk-1) following permanent and transient occlusion of the middle cerebral artery in the rat.
- 1998
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Ingår i: Journal of neuropathology and experimental neurology. - 0022-3069 .- 1554-6578. ; 57:9, s. 874-82
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Tidskriftsartikel (refereegranskat)abstract
- Vascular endothelial growth factor (VEGF) is a known endothelial mitogen and a potent enhancer of vascular permeability although its role in focal cerebral ischemia is still not completely understood. The present report describes the immunohistochemical distribution of VEGF and its 2 receptors, Flt-1 and Flk-1 at day 1 and 3 following permanent and transient middle cerebral artery occlusion (MCAO) in the rat. A bilateral increase in VEGF immunoreactivity, particularly in neurons and blood vessels, was seen in both the experimental designs by day 1. By day 3, the immunoreactivity was restricted chiefly to the lesion side, where reaction was most prominent in the border zones of the infarcts. Immunoreaction to VEGF was more pronounced in cases of permanent MCAO than in transient MCAO. Flt-1 reaction was increased in neurons, glial and endothelial cells after both transient and permanent MCAO. Immunoreactivity to Flk-1 was prominent in glial cells and was present to some extent in endothelial cells. These findings indicate an early upregulation of VEGF and its receptors after permanent as well as transient focal cerebral ischemia in the rat.
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| 18. |
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| 19. |
- Lennmyr, Fredrik, et al.
(författare)
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Increased brain injury and vascular leakage after pretreatment with p38-inhibitor SB203580 in transient ischemia
- 2003
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 108:5, s. 339-45
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Focal cerebral ischemia activates intracellular signaling pathways including the mitogen-activated protein kinase p38, which may be involved in the process of ischemic brain injury. In this study, the effect of pretreatment with the p38-inhibitor SB203580 on infarct size and blood-brain barrier (BBB) breakdown was investigated with magnetic resonance imaging (MRI). MATERIALS AND METHODS: Rats were given SB203580 (n = 6) or vehicle (n = 6) in the right lateral ventricle prior to transient (90 min) middle cerebral artery occlusion (MCAO) on the left side. The rats were examined with serial MRI during MCAO, at reperfusion and after 1 and 4 days. RESULTS: The mean infarct size on T2-weighted images after 1 day was significantly higher in the SB203580-treated group than in controls (300 +/- 95 mm3 vs 126 +/- 75 mm3; P < 0.01). Vascular gadolinium leakage, indicating BBB breakdown, was significantly larger in the SB203580-treated group than in controls after 1 day (median leakage score 18.5; range 15-21 vs 6.5; 4-17; P < 0.05) and 4 days (11; 6-15 vs 3.5; 1-9; P < 0.05), although no significant difference was seen initially. CONCLUSION: Pretreatment with SB203580 may aggravate ischemic brain injury and cerebral vascular leakage in the present model of transient ischemia.
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| 20. |
- Lennmyr, Fredrik, 1971-
(författare)
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Signal Transduction in Focal Cerebral Ischemia : Experimental Studies on VEGF, MAPK and Src family kinases
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cerebral ischemia elicits a wide range of events, including complex activation of various intracellular signaling pathways. This study aims to investigate the expression of vascular endothelial growth factor (VEGF) and the activation pattern of mitogen-activated protein kinases (MAPK) in reponse to focal cerebral ischemia. Furtermore, the functional roles of the p38 MAPK and the Src family kinases (SFKs) are investigated with specific signal transduction inhibitors in the rat in vivo.VEGF was found upregulated in several cell types including neurons, glia and vascular cells after both permanent and transient cerebral ischemia. VEGF-receptor 1 (VEGFR1) was expressed in a similar manner, while VEGFR2 expression was more restricted and confined to endothelial cells and glia.The main MAPK pathways, including extracellular-regulated kinase (ERK), c-jun N-terminal kinase (JNK) and p38, were differentially activated by cerebral ischemia. ERK activation was present in blood vessels, suggesting a potential role in neovascularization. JNK was also activated in blood vessels in the infarcted hemisphere, possibly reflecting an interaction with ERK, whereas p38 activity was absent in vessels. In neurons, ERK was activated in cortical cells up to days of survival, while no substantial JNK or p38 activation was seen in ischemic neurons. Invading macrophages showed distinct activation of p38 and to some extent also JNK but not ERK. Glia showed activation of all MAPK to a variable extent.Pretreatment with the p38-inhibitor SB203580 before transient cerebral ischemia (ischemia-reperfusion) was investigated with magnetic resonance imaging (MRI). The experiment group suffered worse infarcts and blood-brain barrier (BBB) damage than controls, which contrasts to previous studies. The results might be attributed to interference with protective effects of the vehicle or with preconditioning mechanisms. The SFK-inhibitor PP2 significantly reduced infarct size after cerebral ischemia-reperfusion, which is consistent with previously reported effects in permanent ischemia. Due to the multifunctional role of SFKs, it cannot be easily concluded in exactly what cellular context(s) SFKs are of importance to cerebral ischemia.In conclusion, the VEGF and MAPK systems of extra- and intracellular signaling are activated in focal cerebral ischemia. Manipulation of p38 as well as SFK in vivo can influence the course of transient cerebral ischemia, which may be of significance to the understanding of the pathology of cerebral ischemia and to the development of therapeutic strategies.
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| 21. |
- Lennmyr, Fredrik, et al.
(författare)
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Src family kinase-inhibitor PP2 reduces focal ischemic brain injury
- 2004
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 110:3, s. 175-9
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate the neuroprotective potential of the Src family kinase (SFK) inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo(3,4-d)pyrimidine (PP2) in transient focal cerebral ischemia in the rat. MATERIAL AND METHODS: Sprague-Dawley rats were exposed to transient (90 min) middle cerebral artery occlusion (MCAO) and evaluated after 1 day of survival. PP2 (1.5 mg/kg i.p.) or vehicle was given 30 min after MCAO. The lesions were examined with magnetic resonance imaging (MRI), tri-phenyl tetrazolium chloride (TTC) staining and the functional outcome was determined using neurological scoring according to Bederson et al. RESULTS: PP2-treated rats showed approximately 50% reduction of infarct size on T2-weighted MRI and in TTC staining compared with controls (P < 0.05). Moreover, the neurological score was better in the PP2 group than controls (P < 0.05). CONCLUSION: PP2 is a potential neuroprotective agent in cerebral ischemia-reperfusion. The interference of PP2 with SFKs and/or other pathways remains to be elucidated.
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| 22. |
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| 23. |
- Lindblom, Rickard P F, 1981-, et al.
(författare)
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Hyperglycemia Alters Expression of Cerebral Metabolic Genes after Cardiac Arrest
- 2018
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Ingår i: Journal of Stroke & Cerebrovascular Diseases. - : Elsevier BV. - 1052-3057 .- 1532-8511. ; 27:5, s. 1200-1211
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 24. |
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| 25. |
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| 26. |
- Molnar, Maria, et al.
(författare)
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Hyperglycaemia increases S100β after short experimental cardiac arrest
- 2014
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 58:1, s. 106-113
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Hyperglycaemia is associated with aggravated ischaemic brain injury. The main objective of this study was to investigate the effects on cerebral perfusion of 5 min of cardiac arrest during hyperglycaemia and normoglycaemia.METHODS:Twenty triple-breed pigs (weight: 22-29 kg) were randomised and clamped at blood glucose levels of 8.5-10 mM [high (H)] or 4-5.5 mM [normal (N)] and thereafter subjected to alternating current-induced 5 min-cardiac arrest followed by 8 min of cardiopulmonary resuscitation and direct current shock to restore spontaneous circulation.RESULTS:Haemodynamics, laser Doppler measurements and regional venous oxygen saturation (HbO2 ) were monitored, and biochemical markers in blood [S100β, interleukin (IL)-6 and tumour necrosis factor (TNF)] quantified throughout an observation period of 3 h. The haemodynamics and physiological measurements were similar in the two groups. S100β increased over the experiment in the H compared with the N group (P < 0.05). IL-6 and TNF levels increased across the experiment, but no differences were seen between the groups.CONCLUSIONS:The enhanced S100β response is compatible with increased cerebral injury by hyperglycaemic compared with normoglycaemic 5 min of cardiac arrest and resuscitation. The inflammatory cytokines were similar between groups.
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| 27. |
- Molnar, Maria
(författare)
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Hyperglycemia in Experimental Cerebral Ischemia
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cerebral ischemia is a life-threatening condition associated with a substantial morbidity and mortality. Hyperglycemia, a common coexisting phenomenon in both stroke and cardiac arrest (CA), may further aggravate ischemic brain injury. To date, the therapeutic possibilities are lim-ited and the search for new treatment modalities is warranted. One aspect of such a research could be to better understand the cerebral pathogenesis induced by hyperglycemic ischemia-reperfusion.We investigated the combination of ischemia and hyperglycemia in two experimental models of stroke and CA. The aims were to test the neuroprotective potential of the sulfonated nitrone 2-sulfophenyl-N-tert-butylnitrone (S-PBN) in focal hyperglycemic cerebral ischemia (1), to outline the short-terms effects of hyperglycemia in prolonged (2) and short CA (3) and to performed a global transcriptome analysis of brain from hyperglycemic and normoglycemic CA (4).In a stroke model rats were made hyperglycemic prior to transient middle cerebral artery oc-clusion and randomized to S-PBN or saline. We found that S-PBN may ameliorate hyperglyce-mic-ischemic brain damage by improving the neurological performance after 1 day of survival, but did not reduce the infarct size.To study the cerebral oxidative state and perfusion after CA, pigs were randomized and clamped at blood glucose levels of 8.5 ̶ 10.0 mmol/L (high) and 4.0 ̶ 5.5 mmol/L (normal), sub-jected to 12 ̶ min of CA, followed by 8 min of cardiopulmonary resuscitation (CPR), and ob-served for 180 min.Increased oxygenation was found at higher glucose levels measured by near-infrared light spec-troscopy after CA. Tendencies toward increased protein S100β and 15-keto-dihydro-prostaglandin F2α were observed in the hyperglycemic group.We hypothesized that in combination with a brief period of CA, the preischemic hyperglycemia would worsen the cerebral injury compared with normoglycemia. We used a glycemic protocol similar to that in Paper II, whereby pigs were subjected to 5 ̶ min of CA, followed by 8 min of CPR, and observed for 180 mins. An increased level of the cerebral marker S100β was found in hyperglycemic pigs compared with normoglycemic pigs after CA.Global transcriptome analysis using microarray analysis revealed a different early metabolic gene expression in hyperglycemic CA compared with normoglycemic CA.
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| 28. |
- Molnar, Maria, et al.
(författare)
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Neuroprotection by S-PBN in hyperglycemic ischemic brain injury
- 2011
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Ingår i: Coronary artery disease: 2011 update. - Bologna : Medimond. - 9788875876197 ; , s. 41-43
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Konferensbidrag (refereegranskat)abstract
- Background: Hyperglycemia exacerbates focal ischemic brain damage supposedly through various mechanisms. One such mechanism is oxidative stress involving reactive oxygen and nitrogen species (RONS) production. Nitrones attenuate oxidative stress in various models of brain injury. Sulphonated nitrones are hydrophilic and highly feasible to administer in experimental settings. Sodium 2-sulfophenyl-N-tert-butyl nitrone (S-PBN) has been shown neuroprotective in experimental brain trauma. Together with the theories on increased oxidative stress in focal brain ischemia with concomitant hyperglycemia, we hypothesised that S-PBN might be neuroprotective under those circumstances as well. Material and methods: The rats were made hyperglycemic by intraperitoneal bolus of glucose (2 g/kg) and then subjected to 90 min transient middle cerebral artery occlusion (MCAO). They were randomised to a therapeutic regime of S-PBN (47 mg/kg) or saline given intravenously. Neurological testing and tetrazolium red staining were performed after 1 day. Results: S-PBN improved the neurological performance at day 1 both in Bederson score (1,3 +/- 0,8 vs. 2,7 +/- 0,48)(figure 1) and on the inclined plane [74,5% +/- 4,6 (S-PBN) vs. 66% +/- 8,3 (control) P< 0.05] (figure 2); but did not reduce the infarct size (figure 3). Physiological data did not differ between groups (table1).
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| 29. |
- Molnar, Maria, et al.
(författare)
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Neuroprotection by S-PBN in hyperglycemic ischemic brain injury in rats
- 2010
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 115:3, s. 163-168
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hyperglycemia exacerbates focal ischemic brain damage supposedly through various mechanisms. One such mechanism is oxidative stress involving reactive oxygen and nitrogen species (RONS) production. Nitrones attenuate oxidative stress in various models of brain injury. Sodium 2-sulfophenyl-N-tert-butyl nitrone (S-PBN) can be administered experimentally and has been shown to be neuroprotective in experimental brain trauma. AIMS OF THE STUDY: We hypothesized that S-PBN might be neuroprotective in hyperglycemic focal cerebral ischemia. MATERIAL AND METHODS: Rats were made hyperglycemic by an intraperitoneal bolus injection of glucose (2 g/kg) and then subjected to 90 min transient middle cerebral artery occlusion (MCAO). They were randomized to a therapeutic regime of S-PBN (156 mg/kg) or saline given intravenously. Neurological testing according to Bederson and tetrazolium red staining were performed after 1 day. RESULTS: S-PBN improved the neurological performance at day 1 both in Bederson score (1.3+/-0.8 versus 2.7+/-0.48) and on the inclined plane (74.5%+/-4.6 (S-PBN) versus 66%+/-8.3 (control), P<0.05) but did not reduce the infarct size. Physiological data did not differ between groups. CONCLUSION: S-PBN may improve neurological performance at short-term survival (1 day) in the present model of hyperglycemic-ischemic brain injury in rats. This effect appeared not to be primarily related to reduced infarct size.
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| 30. |
- Morell, Arvid, et al.
(författare)
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Influence of blood/tissue differences in contrast agent relaxivity on tracer based MR perfusion measurements
- 2015
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Ingår i: Magnetic Resonance Materials in Physics, Biology and Medicine. - : Springer Science and Business Media LLC. - 0968-5243 .- 1352-8661. ; 28:2, s. 135-147
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 31. |
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| 32. |
- Reinius, Henrik, 1968-, et al.
(författare)
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Optimal PEEP during one-lung ventilation with capnothorax : An experimental study
- 2019
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 63:2, s. 222-231
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 33. |
- Reinius, Henrik, et al.
(författare)
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Real-time ventilation and perfusion distributions by electrical impedance tomography during one-lung ventilation with capnothorax
- 2015
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 59:3, s. 354-368
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Tidskriftsartikel (refereegranskat)abstract
- Background: Carbon dioxide insufflation into the pleural cavity, capnothorax, with one-lung ventilation (OLV) may entail respiratory and hemodynamic impairments. We investigated the online physiological effects of OLV/capnothorax by electrical impedance tomography (EIT) in a porcine model mimicking the clinical setting.Methods: Five anesthetized, muscle-relaxed piglets were subjected to first right and then left capnothorax with an intra-pleural pressure of 19cm H2O. The contra-lateral lung was mechanically ventilated with a double-lumen tube at positive end-expiratory pressure 5 and subsequently 10cm H2O. Regional lung perfusion and ventilation were assessed by EIT. Hemodynamics, cerebral tissue oxygenation and lung gas exchange were also measured.Results: During right-sided capnothorax, mixed venous oxygen saturation (P=0.018), as well as a tissue oxygenation index (P=0.038) decreased. There was also an increase in central venous pressure (P=0.006), and a decrease in mean arterial pressure (P=0.045) and cardiac output (P=0.017). During the left-sided capnothorax, the hemodynamic impairment was less than during the right side. EIT revealed that during the first period of OLV/capnothorax, no or very minor ventilation on the right side could be seen (33% vs. 97 +/- 3%, right vs. left, P=0.007), perfusion decreased in the non-ventilated and increased in the ventilated lung (18 +/- 2% vs. 82 +/- 2%, right vs. left, P=0.03). During the second OLV/capnothorax period, a similar distribution of perfusion was seen in the animals with successful separation (84 +/- 4% vs. 16 +/- 4%, right vs. left).Conclusion: EIT detected in real-time dynamic changes in pulmonary ventilation and perfusion distributions. OLV to the left lung with right-sided capnothorax caused a decrease in cardiac output, arterial oxygenation and mixed venous saturation.
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| 34. |
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| 35. |
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| 36. |
- Tovedal, Thomas, et al.
(författare)
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Blood Flow Quantitation by Positron Emission Tomography During Selective Antegrade Cerebral Perfusion
- 2017
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Ingår i: Annals of Thoracic Surgery. - : Elsevier BV. - 0003-4975 .- 1552-6259. ; 103:2, s. 610-616
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 37. |
- Tovedal, Thomas, et al.
(författare)
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Cerebral oxygen saturation during pulsatile and non-pulsatile cardiopulmonary bypass in patients with carotid stenosis.
- 2016
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Ingår i: Perfusion. - : SAGE Publications. - 0267-6591 .- 1477-111X. ; 31:1, s. 72-77
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 38. |
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| 39. |
- Tovedal, Thomas, 1955-
(författare)
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Cerebral Perfusion during Cardiopulmonary Bypass
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Impaired superior vena cava (SVC) cannula outflow during cardiopulmonary bypass (CPB) is a frequent issue, often manifested by only marginal changes in routine monitoring parameters. Nevertheless, significant impact on cerebral perfusion may result. When detected, remedial actions involve cannula repositioning, raising the operating table, increasing the mean arterial pressure (MAP) and adding vacuum-assisted venous drainage to the CPB system. Increased venous outflow enables increased arterial flow and thereby also increased MAP and cerebral perfusion pressure (CPP). Although representing a common clinical problem, controlled studies on SVC obstruction are few and the phenomenon has not been satisfactorily characterized. This licentiate thesis is based on two animal studies. The first (I) study describes the effects on cerebral perfusion and oxygen saturation by stepwise SVC cannula obstruction in increments of 25% until fully occluded. The second (II) study describes the effects on CPP and cerebral perfusion of two different strategies for dealing with restricted cerebral venous outflow. In Study I, ten pigs during 34 ºC CPB were examined. The animals were divided into two groups receiving either low CPB blood flow (LQ), or normal CPB blood flow (HQ). Cerebral perfusion and oxygen saturation were monitored by blood gases, near-infrared light spectroscopy (NIRS) of tissue oxygen saturation (TOI), and cerebral micro-dialysis. SVC obstruction caused increased CVP and deteriorated cerebral oxygen saturation parameters, but no metabolic effects were detectable at the group level by the micro-dialysis. However, four of ten animals showed a combined pattern of decreased TOI and SVC oxygen saturation along with increased lactate/pyruvate ratio. The phenomenon appeared in both groups and in connection with both obstruction and release of obstruction, indicating the presence of individual sensitivity to impaired cerebral perfusion. CPB tubing flow measurements revealed that the total venous drainage was preserved even with the SVC completely clamped, indicating that the drainage, but not the CVP elevation, could be fully compensated by the inferior vena cava. In Study II, intracranial pressure monitoring, NIRS, and cerebral laser-Doppler flow measurements were used for surveillance along with blood gases and analysis of the glial cellmarker S100ß in sagittal sinus blood. A SVC obstruction of 75% was applied in order to achieve a distinct CPP reduction in fourteen pigs subjected to 34 ºC CPB. Two randomly assigned strategies for restoration of the CPP were examined; vasopressor treatment (VP)and partial release of obstruction (PR) mimicking a successful repositioning of the SVC cannula. Both strategies successfully restored the CPP to baseline levels, without immediate signs of severe ischemia, although intracranial and central pressures remained elevated in the VP group throughout the experiments. The analysis of S100ß showed no signs of brain damage. In conclusion, SVC congestion may impair cerebral perfusion during CPB. Reduced SVC cannula flow may pass undetected during bi-caval CPB due to a compensatory increase in IVC flow. Experimental SVC obstruction during CPB may reduce the CPP, resulting in impaired cerebral perfusion. Both vasopressor therapy and improved venous drainage can in the short term individually restore the CPP during these circumstances.
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| 40. |
- Tovedal, Thomas, 1955-
(författare)
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Cerebral perfusion during cardiopulmonary bypass with special reference to blood flow
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cardiopulmonary bypass (CPB) is an important method that enables open heart surgery. There is a risk of neurological complications, and efforts to minimize those include optimization of the cerebral perfusion during CPB. This thesis focuses on such optimization of flow conditions in case of obstructed venous drainage, carotid stenosis and during selective antegrade cerebral perfusion (SACP).In a pig model of impaired venous drainage from the superior vena cava (SVC), stepwise obstruction increased the central venous pressure (CVP) and caused impaired oxygenation. Cerebral micro-dialysis revealed ischemic responses in some but not all of the pigs.Further experiments, using the same model, aimed to restore cerebral perfusion pressure (CPP) reduced by 75% superior venous obstruction. Both vasopressor treatment and increased venous drainage were effective in normalizing the CPP and improving the cerebral oxygenation. The intracranial pressure was elevated in the vasopressor group, but no signs of brain damage were observed.The arterial flow during CPB can be altered between pulsatile and non-pulsatile profiles. Switching between these modes was performed during CPB in 20 patients with or without carotid stenosis. The effects on cerebral oxygenation and mean arterial pressure (MAP) were examined. The MAP was significantly lowered by pulsatile flow, but the flow profile did not affect the cerebral oxygenation. No differences were seen between patients with or without carotid stenosis.SACP is used to ensure the cerebral perfusion during deep hypothermic circulatory arrest (HCA). The cerebral blood flow (CBF) was examined using positron-emission tomography (PET) technique in 8 pigs divided into HCA and HCA+SACP groups. The CBF was downregulated by 70% to 0.10 ml/cm3/min by 20°C hypothermia. A pump flow of 6 ml/kg/min preserved the CBF level without signs of cerebral desaturation. The fluorodeoxyglucose (FDG) uptake after re-warming to 37°C was similar after SACP compared with HCA alone.In conclusion, experimental SVC obstruction may impair the cerebral perfusion. Vasopressors can restore the CPP during SVC obstruction and improve cerebral oxygenation. In patients, pulsatile flow can lower the MAP in absence of effects on the cerebral oxygenation. During experimental HCA, SACP at 6 ml/kg/min can preserve the CBF at 0.10 ml/cm3/min.
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| 41. |
- Tovedal, Thomas, 1955-, et al.
(författare)
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Experimental treatment of superior venous congestion during cardiopulmonary bypass
- 2013
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Ingår i: European Journal of Cardio-Thoracic Surgery. - : Oxford University Press (OUP). - 1010-7940 .- 1873-734X. ; 44:3, s. E239-E244
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES:Superior venous outflow obstruction affects cerebral perfusion negatively by reducing cerebral perfusion pressure (CPP). We present a randomized study designed to compare two alternative strategies to preserve the CPP during superior vena cava (SVC) congestion and cardiopulmonary bypass (CPB).METHODS:Fourteen pigs on bi-caval CPB were subjected to 75% occlusion of the SVC flow. CPP was restored either by vasopressor treatment (VP, n = 7) or by partial relief (PR) of the congestion (n = 7). The cerebral effects of the interventions were studied for 60 min with intracranial pressure (ICP) monitoring, cerebral blood flow measurement, the near-infrared light spectroscopy tissue oxygen saturation index (StO2), arterial and venous blood gas analyses and serial measurements of the glial cell damage marker protein S100β.RESULTS:Both strategies restored the CPP to baseline levels and no signs of severe ischaemia were observed. In the PR group, the venous and ICPs were normalized in response to the intervention, while in the VP group those parameters remained elevated throughout the experiment. The haemoglobin oxygen saturation in the sagittal sinus (SsagO2) was increased by both VP and PR, while significant improvement in the StO2 was observed only in the PR group. The S100β concentrations were similar in the two groups.CONCLUSIONS:Experimental SVC obstruction during CPB may reduce the CPP, resulting in impaired cerebral perfusion. Both vasopressor treatment and improved venous drainage can, in the short term, individually restore the CPP during these circumstances.
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| 42. |
- Tovedal, Thomas, 1955-, et al.
(författare)
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Venous obstruction and cerebral perfusion during experimental cardiopulmonary bypass
- 2010
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Ingår i: Interactive Cardiovascular and Thoracic Surgery. - : Oxford University Press (OUP). - 1569-9293 .- 1569-9285. ; 11:5, s. 561-566
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the effects on cerebral perfusion by experimental venous congestion of the superior vena cava (SVC) during bicaval cardiopulmonary bypass (CPB) at 34 °C, pigs were subjected to SVC obstruction at levels of 75%, 50%, 25% and 0% of baseline SVC flow at two arterial flow levels (low, LQ, high, HQ). The cerebral perfusion was examined with near-infrared spectroscopy (NIRS), cerebral microdialysis and blood gas analysis. SVC obstruction caused significant decreases in the NIRS tissue oxygenation index (TOI) and in SVC oxygen saturations (P<0.05, both groups), while the mixed venous saturation was decreased only in the LQ group. Sagittal sinus venous saturations were measured in the HQ group and found significantly reduced in response to venous congestion (P<0.05). No microdialysis changes were seen at the group level, however, individual ischemic patterns in terms of concomitant venous desaturation, decreased TOI and increased lactate/pyruvate occurred in both groups. The total venous drainage remained stabile throughout the experiment, indicating increased flow in the inferior vena cava cannula. The results indicate that SVC congestion may impair cerebral perfusion especially in the case of compromised arterial flow during CPB. Reduced SVC cannula flow may pass undetected during bicaval CPB, if SVC flow is not specifically monitored.
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| 43. |
- Zoerner, Frank, et al.
(författare)
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Milrinone and esmolol decrease cardiac damage after resuscitation from prolonged cardiac arrest
- 2015
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 59:4, s. 465-474
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Tidskriftsartikel (refereegranskat)abstract
- 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: Twenty-six immature male piglets were subjected to 12 min VF followed by 8 min CPR. The treatment group (n=13) received i.v. boluses vasopressin 0.4 U∙kg−1, esmolol 250 μg∙kg−1 and milrinone 25 μg∙kg−1 after 13 min, followed by i.v. boluses esmolol 375 μg∙kg−1 and milrinone 25 μg∙kg−1 after 18 min and continuous esmolol 15 μg∙kg−1∙h−1 infusion during 180 min reperfusion, while controls (n=13) received equal amounts of vasopressin and saline. A 200J monophasic counter-shock was delivered to achieve resumption of spontaneous circulation (ROSC) after 8 min CPR. If ROSC was not achieved, another 200J defibrillation and bolus vasopressin 0.4 U∙kg−1 were administered in both groups. DC shocks at 360J were applied as one shot min−1 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.Conclusions: The combination of milrinone, esmolol and vasopressin decreased cardiac injury compared with vasopressin alone.
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| 44. |
- Zoerner, Frank, 1973-
(författare)
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Novel Interventions in Cardiac Arrest : Targeted Temperature Management, Methylene Blue, S-PBN, Amiodarone, Milrinone and Esmolol, Endothelin and Nitric Oxide In Porcine Resuscitation Models
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is a major clinical problem that survival rates after out-of-hospital cardiac arrest have not markedly improved during the last decades, despite extensive research and the introduction of new interventions. However, recent studies have demonstrated promising treatments such as targeted temperature management (TTM) and methylene blue (MB).In our first study, we investigated the effect of MB administered during experi-mental cardiopulmonary resuscitation (CPR) in the setting of postponed hypother-mia in piglets. We set out to study if MB could compensate for a delay to establish targeted TTM. The study demonstrated that MB more than compensated for 30 min delay in induction of TTM. The effect of MB added to that of TTM.The second study examined the effects of TTM and S-PBN on the endothelin system and nitric oxide synthases (NOS) after prolonged CA in a porcine CPR mod-el. The study was designed to understand the cardioprotective mechanism of S-PBN and TTM by their influence on the endothelin system and NOS regulation. We veri-fied for the first time, that these two cardioprotective postresuscitative interventions activate endothelin-1 and its receptors concomitantly with eNOS and nNOS in the myocardium. We concluded that nitric oxide and endothelin pathways are implicated in the postresuscitative cardioprotective effects of TTM.The third study compared survival and hemodynamic effects of low-dose amio-darone and vasopressin to vasopressin in a porcine hypovolemic CA model. The study was designed to evaluate whether resuscitation with amiodarone and vasopressin compared to vasopressin alone would have an impact on resuscitation success, survival, and hemodynamic parameters after hemorrhagic CA. We found that combined resuscitation with amiodarone and vasopressin after hemorrhagic circulatory arrest resulted in greater 3-hour survival, better preserved hemodynamic parameters and smaller myocardial injury compared to resuscitation with vasopressin only.In our fourth study we planned to compare hemodynamic parameters between the treatment group (milrinone, esmolol and vasopressin; MEV) and control group (vasopressin only) during resuscitation from prolonged cardiac arrest in piglets. The study was designed to demonstrate if MEV treatment improved hemodynamics or cardiac damage compared to controls. We demonstrated that MEV treatment reduced cardiac injury compared with vasopressin alone.
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