| 1. |
- Alenius Dahlqvist, Jenny, 1972-, et al.
(författare)
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Changes in Heart Rate and Heart Rate Variability During Surgical Stages to Completed Fontan Circulation
- 2021
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Ingår i: Pediatric Cardiology. - : Springer Science and Business Media LLC. - 0172-0643 .- 1432-1971. ; 42:5, s. 1162-1169
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Tidskriftsartikel (refereegranskat)abstract
- Arrhythmia is related to heart rate variability (HRV), which reflects the autonomic nervous regulation of the heart. We hypothesized that autonomic nervous ganglia, located at the junction of the superior vena cava's entrance to the heart, may be affected during the bidirectional Glenn procedure (BDG), resulting in reduced HRV. We aimed to investigate changes in heart rate and HRV in a cohort of children with univentricular heart defects, undergoing stepwise surgery towards total cavopulmonary connection (TCPC), and compare these results with healthy controls. Twenty four hours Holter-ECG recordings were obtained before BDG (n = 47), after BDG (n = 47), and after total cavopulmonary connection (TCPC) (n = 45) in patients and in 38 healthy controls. HRV was analyzed by spectral and Poincare methods. Age-related z scores were calculated and compared using linear mixed effects modeling. Total HRV was significantly lower in patients before BDG when compared to healthy controls. The mean heart rate was significantly reduced in patients after BDG compared to before BDG. Compared to healthy controls, patients operated with BDG had significantly reduced heart rate and reduced total HRV. Patients with TCPC showed reduced heart rate and HRV compared with healthy controls. In patients after TCPC, total HRV was decreased compared to before TCPC. Heart rate was reduced after BDG procedure, and further reductions of HRV were seen post-TCPC. Our results indicate that autonomic regulation of cardiac rhythm is affected both after BDG and again after TCPC. This may be reflected as, and contribute to, postoperative arrhythmic events.
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| 2. |
- Almby, Kristina E., et al.
(författare)
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Effects of Gastric Bypass Surgery on the Brain : Simultaneous Assessment of Glucose Uptake, Blood Flow, Neural Activity, and Cognitive Function During Normo- and Hypoglycemia
- 2021
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 70:6, s. 1265-1277
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Tidskriftsartikel (refereegranskat)abstract
- While Roux-en-Y gastric bypass (RYGB) surgery in obese individuals typically improves glycemic control and prevents diabetes, it also frequently causes asymptomatic hypoglycemia. Previous work showed attenuated counterregulatory responses following RYGB. The underlying mechanisms as well as the clinical consequences are unclear. In this study, 11 subjects without diabetes with severe obesity were investigated pre- and post-RYGB during hyperinsulinemic normo-hypoglycemic clamps. Assessments were made of hormones, cognitive function, cerebral blood flow by arterial spin labeling, brain glucose metabolism by F-18-fluorodeoxyglucose (FDG) positron emission tomography, and activation of brain networks by functional MRI. Post- versus presurgery, we found a general increase of cerebral blood flow but a decrease of total brain FDG uptake during normoglycemia. During hypoglycemia, there was a marked increase in total brain FDG uptake, and this was similar for post- and presurgery, whereas hypothalamic FDG uptake was reduced during hypoglycemia. During hypoglycemia, attenuated responses of counterregulatory hormones and improvements in cognitive function were seen postsurgery. In early hypoglycemia, there was increased activation post- versus presurgery of neural networks in brain regions implicated in glucose regulation, such as the thalamus and hypothalamus. The results suggest adaptive responses of the brain that contribute to lowering of glycemia following RYGB, and the underlying mechanisms should be further elucidated.
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| 3. |
- Almby, Kristina E., et al.
(författare)
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Time course of metabolic, neuroendocrine, and adipose effects during 2 years of follow-up after gastric bypass in patients with type 2 diabetes
- 2021
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Oxford University Press. - 0021-972X .- 1945-7197. ; 106:10, s. E4049-E4061
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Tidskriftsartikel (refereegranskat)abstract
- Context: Roux-en-Y gastric bypass surgery (RYGB) markedly improves glycemia in patients with type 2 diabetes (T2D), but underlying mechanisms and changes over time are incompletely understood.Objective: Integrated assessment of neuroendocrine and metabolic changes over time inT2D patients undergoing RYGB.Design and Setting: Follow-up of single-center randomized study.Patients: Thirteen patients with obesity andT2D compared to 22 healthy subjects.Interventions: Blood chemistry, adipose biopsies, and heart rate variability were obtained before and 4, 24, and 104 weeks post-RYGB.Results: After RYGB, glucose-lowering drugs were discontinued and hemoglobin A1c fell from mean 55 to 41 mmol/mol by 104 weeks (P < 0.001). At 4 weeks, morning cortisol (P < 0.05) and adrenocorticotropin (P = 0.09) were reduced by 20%. Parasympathetic nerve activity (heart rate variability derived) increased at 4 weeks (P < 0.05) and peaked at 24 weeks (P < 0.01). C-reactive protein (CRP) and white blood cells were rapidly reduced (P < 0.01). At 104 weeks, basal and insulin-stimulated adipocyte glucose uptake increased by 3-fold vs baseline and expression of genes involved in glucose transport, fatty acid oxidation, and adipogenesis was upregulated (P < 0.01). Adipocyte volume was reduced by 4 weeks and more markedly at 104 weeks, by about 40% vs baseline (P < 0.01).Conclusions: We propose this order of events: (1) rapid glucose lowering (days); (2) attenuated cortisol axis activity and inflammation and increased parasympathetic tone (weeks); and (3) body fat and weight loss, increased adipose glucose uptake, and whole-body insulin sensitivity (months-years; similar to healthy controls).Thus, neuroendocrine pathways can partly mediate early glycemic improvement after RYGB, and adipose factors may promote long-term insulin sensitivity and normoglycemia.
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| 4. |
- Andersen, Leon, et al.
(författare)
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Our initial experience of monitoring the autoregulation of cerebral blood flow during cardiopulmonary bypass
- 2023
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Ingår i: The journal of extra-corporeal technology. - : EDP Sciences. - 0022-1058. ; 55:4, s. 209-217
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cerebral blood flow (CBF) is believed to be relatively constant within an upper and lower blood pressure limit. Different methods are available to monitor CBF autoregulation during surgery. This study aims to critically analyze the application of the cerebral oxygenation index (COx), one of the commonly used techniques, using a reference to data from a series of clinical registrations.METHOD: CBF was monitored using near-infrared spectroscopy, while cerebral blood pressure was estimated by recordings obtained from either the radial or femoral artery in 10 patients undergoing cardiopulmonary bypass. The association between CBF and blood pressure was calculated as a moving continuous correlation coefficient. A COx index > 0.4 was regarded as a sign of abnormal cerebral autoregulation (CA). Recordings were examined to discuss reliability measures and clinical feasibility of the measurements, followed by interpretation of individual results, identification of possible pitfalls, and suggestions of alternative methods.RESULTS AND CONCLUSION: Monitoring of CA during cardiopulmonary bypass is intriguing and complex. A series of challenges and limitations should be considered before introducing this method into clinical practice.
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| 5. |
- Andersson, Urban, et al.
(författare)
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Nurses’ experiences of informal coercion on adult psychiatric wards
- 2020
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Ingår i: Nursing Ethics. - : SAGE Publications. - 0969-7330 .- 1477-0989. ; 27:3, s. 741-753
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Tidskriftsartikel (refereegranskat)abstract
- Background:Informal coercion, that is, situations where caregivers use subtle coercive measures to impose their will on patients, is common in adult psychiatric inpatient care. It has been described as ‘a necessary evil’, confronting nurses with an ethical dilemma where they need to balance between a wish to do good, and the risk of violating patients’ dignity and autonomy.Aim:To describe nurses’ experiences of being involved in informal coercion in adult psychiatric inpatient care.Research design:The study has a qualitative, inductive design.Participants and research context:Semi-structured interviews with 10 Swedish psychiatric nurses were analysed with qualitative content analysis.Ethical considerations:The study was performed in accordance with the Declaration of Helsinki. In line with the Swedish Ethical Review Act, it was also subject to ethical procedures at the university.Findings:Four domains comprise informal coercion as a process over time. These domains contain 11 categories focusing on different experiences involved in the process: Striving to connect, involving others, adjusting to the caring culture, dealing with laws, justifying coercion, waiting for the patient, persuading the patient, negotiating with the patient, using professional power, scrutinizing one’s actions and learning together.Discussion:Informal coercion is associated with moral stress as nurses might find themselves torn between a wish to do good for the patient, general practices and ‘house rules’ in the caring culture. In addition, nurses need to be aware of the asymmetry of the caring relationship, in order to avoid compliance becoming a consequence of patients subordinating to nurse power, rather than a result of mutual understanding. Reflections are thus necessary through the process to promote mutual learning and to avoid violations of patients’ dignity and autonomy.Conclusion:If there is a need for coercion, that is, if the coercion is found to be an ‘unpleasant good’, rather than ‘necessary evil’ considering the consequences for the patient, it should be subject to reflecting and learning together with the patient
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| 6. |
- Carlsson, Jenny, 1984-, et al.
(författare)
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Investigating tool engagement in groundwood pulping : finite element modelling and in-situ observations at the microscale
- 2020
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 74:5, s. 477-487
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Tidskriftsartikel (refereegranskat)abstract
- With industrial groundwood pulping processes relying on carefully designed grit surfaces being developed for commercial use, it is increasingly important to understand the mechanisms occurring in the contact between wood and tool. We present a methodology to experimentally and numerically analyse the effect of different tool geometries on the groundwood pulping defibration process. Using a combination of high-resolution experimental and numerical methods, including finite element (FE) models, digital volume correlation (DVC) of synchrotron radiation-based X-ray computed tomography (CT) of initial grinding and lab-scale grinding experiments, this paper aims to study such mechanisms. Three different asperity geometries were studied in FE simulations and in grinding of wood from Norway spruce. We found a good correlation between strains obtained from FE models and strains calculated using DVC from stacks of CT images of initial grinding. We also correlate the strains obtained from numerical models to the integrity of the separated fibres in lab-scale grinding experiments. In conclusion, we found that, by modifying the asperity geometries, it is, to some extent, possible to control the underlying mechanisms, enabling development of better tools in terms of efficiency, quality of the fibres and stability of the groundwood pulping process.
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| 7. |
- Carlsson, Jenny, 1984-
(författare)
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On Crack Dynamics in Brittle Heterogeneous Materials
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Natural variation, sub-structural features, heterogeneity and porosity make fracture modelling of wood and many other heterogeneous and cellular materials challenging. In this thesis, fracture in such complicated materials is simulated using phase field methods for fracture. Phase field methods have shown promise in simulations of complex geometries as well as dynamics and require few additional parameters; only the material toughness and a length parameter, determining the width of a regularised crack, are needed.First, a dynamic phase field model is developed and validated against experiments performed on homogeneous brittle polymeric materials, wood fibre composites and polymeric materials with different hole patterns. Then, a high-resolution model of wood is developed and related to experiments, this time without considering fracture. Attention is finally focussed on high-resolution numerical analyses of fracture in wood and other cellular microstructures, considering both heterogeneity and relative density.The phase field model is found to reproduce crack paths, velocities and energy release rates well in homogeneous samples both with and without holes. In more complicated heterogeneous and porous materials, the model is also able to simulate crack paths, but the interpretation of the length scale is complicated by the inherent lengths of the micro-structural geometry. In sum, the thesis points to possibilities with the proposed method, as well as limitations in our current understanding of both quasistatic and dynamic fracture of heterogeneous and cellular materials. The findings of this thesis can contribute to an improved understanding of fracture in such materials.
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| 8. |
- Erelund, Sofia, et al.
(författare)
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Are ECG changes in heart-healthy individuals of various ages related to cardiac disease 20 years later?
- 2021
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Ingår i: Upsala Journal of Medical Sciences. - : Upsala Medical Society. - 0300-9734 .- 2000-1967. ; 126:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: This research study aimed at assessing the electrocardiographic (ECG) changes caused by ageing in a cohort of healthy subjects with normal echocardiographic examinations.Methods: A total of 219 healthy individuals (119 males and 100 females) were evaluated for possible arrhythmias with a standard 12-lead resting ECG and 24-h Holter ECG. As the recordings were performed between 1998 and 2000, a 20-year follow-up study was carried out by assessing the local medical records to investigate whether the subjects had experienced any cardiovascular health complications or disease since the baseline assessment.Results: Eighty-three subjects (45 males and 38 females) presented with pathological ECG findings at baseline. The most common finding on analysis of Holter ECG recordings was premature atrial contractions, and the most severe pathological finding was episodes of ventricular tachycardia (eight subjects). Regarding the analysis of the standard 12-lead ECG, the most common finding was left ventricular hypertrophy, and the most severe pathological findings were ST-T changes and prolongation of the QT interval. Despite other cardiac examinations performed on these patients showing normal results, in combination with a strict inclusion criterion, this study showed that 28% of all subjects had pathological resting 12-lead ECGs at rest and 35% had pathological heart rhythms when assessed by 24-h Holter ECG. At follow-up, 21% of females and 43% of males had presented with ECG abnormalities, and 30% of females and 36% of males had cardiovascular disease. There was hypertension in 45% of females and in 58% of males. However, no association was found between the follow-up findings and ECG changes seen at baseline.Conclusion: Although most ECG changes found at baseline could be considered as a normal variation, they may progress to more severe heart complications as the subject ages. The results of this study also validate ECG findings of previous studies and underline that diagnostic criteria should be based on gender and age.
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| 9. |
- Erelund, Sofia, 1983-
(författare)
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Heart and lung function - in health and disease : methodological studies in clinical physiology
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The human heart and lungs constitute an intricate and dynamic system. Various clinical physiological examinations can be used to evaluate cardio-pulmonary function and identify abnormalities. Thus, it is important to understand how normal physiology presents, to be able to identify pathological findings. To distinguish normal from abnormal findings in a patient population compared to healthy controls, adequate, accurate and up-to-date reference materials are required. There is currently a lack of well-established sex and age specific reference materials that clearly state boundaries of normality for electrocardiography (ECG) variables. For lung function examinations there are several different reference materials available, being discordant between ethnicities. In addition, the relation between lung function, age, sex, and height has generally been difficult to model in an optimal way. This highlights the need for more adequate sex-specific models regarding age- and height-dependency of spirometry variables. Heart rate variability (HRV) is a method for evaluating the autonomic nervous system (ANS) and its influence on heart rate and blood pressure. Autonomic disturbances are characterized by an imbalance between the sympathetic and the parasympathetic nervous systems. It is well known that decreased HRV is associated with increased mortality. Autonomic imbalances are also associated with various pathological conditions, of which rheumatoid arthritis (RA) and ischemic heart disease (IHD) are studied in this thesis.The purpose of this thesis was to describe the properties of different clinical physiological examinations and to investigate reference values relating to cardiovascular and pulmonary function in healthy individuals regarding age and sex. In addition, the aim was to assess the relationship between HRV, RA and CVD both cross sectionally and longitudinally. In a subjectively healthy population (n=219) of varying age, there were age and sex-dependent differences in ECG examinations. This emphasizes former findings and supports the need to establish age- and sex-specific reference values in the future. Lung function examinations in subjectively healthy persons (n=285) support and emphasize that the reference values presented by the Global Lung function Initiative (GLI) underestimate the pulmonary function in the adult Swedish population. The study showed that the model used in GLI can be updated with new values that are specific for the Caucasian population in Sweden. Patients with RA (n=50) presented with lower HRV than healthy controls (n=100) during autonomic provocation tests, both at baseline examinations and after five years. This indicates a cardiac autonomic imbalance. Furthermore, increased systolic blood pressure was associated with reduced HRV, thus a decrease in HRV could be a risk marker for developing arterial hypertension in this patient group.Females with IHD (n=197) presented with lower HRV compared to controls (n=141) at baseline, and a higher mortality rate after 15 years. The higher mortality rate was only present in females < 60 years of age. For measurements obtained in the upright position, HRV was higher in females that died during follow-up compared to those who were alive. This thesis emphasizes the importance of validated and updated sex- and age- specific reference materials, and models that are well suited for different clinical physiological examinations. Additionally, HRV examinations exposed changes in the ANS related to RA as well as IHD, where findings were shown to be persistent over time and particularly pronounced during provocations. In the future, HRV assessment could be a useful tool to identify the increased risk of developing hypertension in patients with RA, or to customize treatment based on ANS response as the field of personalized medicine continues to evolve.
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| 10. |
- Erelund, Sofia, et al.
(författare)
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Heart rate variability and cardiovascular risk factors in patients with rheumatoid arthritis : a longitudinal study
- 2023
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Ingår i: Autonomic Neuroscience. - : Elsevier. - 1566-0702 .- 1872-7484. ; 249
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Tidskriftsartikel (refereegranskat)abstract
- Background: It is established that the risk of cardiovascular disease (CVD) is increased in patients with Rheumatoid Arthritis (RA). Heart rate variability (HRV) is a method for evaluating the activity in the cardiac autonomic nervous system. Our aim was to assess the longitudinal development of HRV in patients with RA and compare with healthy controls. Furthermore, we wanted to investigate associations between HRV, inflammatory disease activity and cardiovascular complications in patients with RA over time.Method: HRV was assessed with frequency-domain analysis at baseline and after five years in 50 patients with early RA, all being younger than 60 years. HRV indices were age-adjusted based on the estimated age-dependency in 100 age and sex matched healthy controls. Additionally, clinical data including serological markers, disease activity, and blood pressure were collected from the patients. Eleven years after inclusion CVD was assessed.Results: At baseline, patients with RA presented with lower HRV compared to controls during deep breathing (6 breaths/min), paced normal breathing (12 breaths/min) and after passive tilt to the upright position. No significant change in HRV was observed at the five-year follow-up. A significant negative correlation was found between HRV parameters and systolic blood pressure (SBP) at baseline. A significant positive correlation was found between heart rate and inflammatory markers at baseline but not after five years. Nine patients had developed CVD after 11 years, but no significant association was found with baseline HRV data.Conclusion: This study showed that patients with RA have autonomic imbalance both at an early stage of the disease and after five years, despite anti-rheumatic medication, but no correlation between HRV and inflammation markers were observed. Reduced HRV was also significantly negatively correlated with increased SBP. Hypertension is a common finding in patients with RA. Thus, significant decline of HRV could be a useful early marker for development of hypertension in patients with RA.
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