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| 2. |
- Jideus, Lena, et al.
(author)
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Thoracic epidural anesthesia does not influence the occurrence of postoperative sustained atrial fibrillation
- 2001
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In: Annals of Thoracic Surgery. - 0003-4975 .- 1552-6259. ; 72:1, s. 65-71
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Journal article (peer-reviewed)abstract
- Background. To evaluate whether thoracic epidural anesthesia (TEA) can reduce the incidence of atrial fibrillation (AF) after coronary artery bypass grafting (CABG).Methods. Forty-one patients undergoing CABG were treated with TEA intraoperatively and postoperatively. Another 80 patients served as the control group. The sympathetic and parasympathetic activities were evaluated by analysis of neuropeptides, catecholamines and heart rate variability (HRV), preoperatively and postoperatively.Results. Postoperative AF occurred in 31.7% of the TEA-treated patients and in 36.3% of the untreated patients (p = 0.77). TEA significantly suppressed sympathetic activity, as indicated by a less pronounced increase of norepinephrine and epinephrine (p = 0.03, p = 0.02) and a significant decrease of neuropeptide Y (p = 0.01) postoperatively in TEA-treated patients compared to untreated patients. The HRV variable expressing sympathetic activity was significantly lower and the postoperative increase in heart rate was significantly less in the TEA group than in the control group after surgery (p = 0.01, p < 0.001). Among patients developing AF, the maximal number of supraventricular premature beats per minute increased significantly in untreated patients postoperatively but remained unchanged in TEA-treated patients (p = 0.004 versus p = 0.86).Conclusions. TEA has no effect on the incidence of postoperative sustained AF, despite a significant reduction in sympathetic activity.
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| 3. |
- Arnqvist, Per, 1963-
(author)
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Functional clustering methods and marital fertility modelling
- 2017
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Doctoral thesis (other academic/artistic)abstract
- This thesis consists of two parts.The first part considers further development of a model used for marital fertility, the Coale-Trussell's fertility model, which is based on age-specific fertility rates. A new model is suggested using individual fertility data and a waiting time after pregnancies. The model is named the waiting model and can be understood as an alternating renewal process with age-specific intensities. Due to the complicated form of the waiting model and the way data is presented, as given in the United Nation Demographic Year Book 1965, a normal approximation is suggested together with a normal approximation of the mean and variance of the number of births per summarized interval. A further refinement of the model was then introduced to allow for left truncated and censored individual data, summarized as table data. The waiting model suggested gives better understanding of marital fertility and by a simulation study it is shown that the waiting model outperforms the Coale-Trussell model when it comes to estimating the fertility intensity and to predict the mean and variance of the number of births for a population.The second part of the thesis focus on developing functional clustering methods.The methods are motivated by and applied to varved (annually laminated) sediment data from lake Kassj\"on in northern Sweden. The rich but complex information (with respect to climate) in the varves, including the shapes of the seasonal patterns, the varying varve thickness, and the non-linear sediment accumulation rates makes it non-trivial to cluster the varves. Functional representations, smoothing and alignment are functional data tools used to make the seasonal patterns comparable.Functional clustering is used to group the seasonal patterns into different types, which can be associated with different weather conditions.A new non-parametric functional clustering method is suggested, the Bagging Voronoi K-mediod Alignment algorithm, (BVKMA), which simultaneously clusters and aligns spatially dependent curves. BVKMA is used on the varved lake sediment, to infer on climate, defined as frequencies of different weather types, over longer time periods.Furthermore, a functional model-based clustering method is proposed that clusters subjects for which both functional data and covariates are observed, allowing different covariance structures in the different clusters. The model extends a model-based functional clustering method proposed by James and Suger (2003). An EM algorithm is derived to estimate the parameters of the model.
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| 4. |
- Bagge, Louise, et al.
(author)
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Epicardial off-pump pulmonary vein isolation and vagal denervation improve long-term outcome and quality of life in patients with atrial fibrillation
- 2009
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In: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier BV. - 0022-5223 .- 1097-685X. ; 137:5, s. 1265-1271
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Journal article (peer-reviewed)abstract
- OBJECTIVES: The limited information available on thoracoscopic pulmonary vein isolation combined with ganglionated plexi ablation and the lack of studies regarding its effect on quality of life and physical capacity urged us to study its acute and long-term results in patients with atrial fibrillation. METHODS: Forty-three patients (mean age 57.1 years) with symptomatic atrial fibrillation referred for thoracoscopic off-pump epicardial pulmonary vein isolation and ganglionated plexi ablation using radiofrequency energy were included. RESULTS: The physical capacity improved significantly at 6-month follow-up compared with baseline (mean +/- standard deviation, 165.2 +/- 65 Watt versus 155.9 +/- 57 Watt, P = .02). Quality of life (Short Form-36 health survey) significantly improved 12 months after surgery compared with baseline in all subscales except for bodily pain. The symptom severity questionnaire score decreased significantly from mean 15.2 +/- 4.0 points to 10.7 +/- 4.8 points (P = .02). Overall, 25 of 33 patients (76%) followed up for 12 months had no symptomatic atrial fibrillation recurrences or atrial fibrillation episodes on 24-hour Holter recordings. The corresponding figures were 79% (19/24) for patients with paroxysmal atrial fibrillation, 100% (2/2) for persistent atrial fibrillation, and 57% (4/7) for permanent atrial fibrillation. The most common complication was bleeding events (9%) during pulmonary vein dissection. CONCLUSIONS: Epicardial off-pump pulmonary vein isolation combined with ganglionated plexi ablation improved quality of life, symptoms, and exercise capacity and therefore may be considered for patients with atrial fibrillation who fail endocardial pulmonary vein ablation or as a first-line procedure if left atrial appendage exclusion is warranted.
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| 5. |
- Blomström-Lundqvist, Carina, et al.
(author)
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A randomized double-blind study of epicardial left atrial cryoablation for permanent atrial fibrillation in patients undergoing mitral valve surgery: the SWEDish Multicentre Atrial Fibrillation study (SWEDMAF).
- 2007
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In: European heart journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 28:23, s. 2902-8
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Journal article (peer-reviewed)abstract
- AIMS: The efficacy of epicardial left atrial (LA) cryoablation in eliminating atrial fibrillation (AF) in patients undergoing mitral valve surgery (MVS) is unknown. We hypothesized that MVS combined with LA cryoablation is superior to MVS alone. METHODS AND RESULTS: Sixty-nine patients with permanent AF, included at four centres, underwent MVS with or without epicardial LA cryoablation. The primary endpoint was regained sinus rhythm. Risk factors for failed AF cryoablation were elucidated. Sixty-five out of 69 patients reached the primary endpoint. At 6 and 12 months follow-up, 73.3% of patients who underwent cryoablation had regained sinus rhythm at both follow-ups, compared with 45.7 and 42.9% of patients, respectively, who underwent MVS alone (group differences, at 6 months P = 0.024, after 12 months P = 0.013). The in-hospital complication rate was 11.4% in the MVS group and 26.5% in the cryoablation group (P = 0.110). Risk factors for failed elimination of AF by cryoablation were duration of permanent AF (P = 0.012) and presence of coronary artery disease (P = 0.047), according to multiple logistic regression analysis. CONCLUSION: This first prospective randomized study showed that combining MVS with epicardial LA cryoablation is significantly better in eliminating pre-operative permanent AF than MVS alone.
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| 6. |
- Borowiec, Jan W., et al.
(author)
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Influence of two blood conservation techniques (cardiotomy reservoir versus cell-saver) on biocompatibility of the heparin coated cardiopulmonary bypass circuit during coronary revascularization surgery
- 1997
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In: Journal of cardiac surgery. - : Hindawi Limited. - 0886-0440 .- 1540-8191. ; 12:3, s. 190-197
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Journal article (peer-reviewed)abstract
- Blood conservation during cardiac surgery is critically important because of the inherent risks in homologous blood transfusions. Two techniques for the intraoperative conservation of blood--retransfusion of the red cells using a cell-saver (CS), or retransfusion of the blood using a cardiotomy suction (CTR) system--were compared using biocompatibility markers, granulocyte activation, and production of oxygen-free radicals (OFR). In the CTR group, heparin coated circuits with an uncoated cardiotomy reservoir were used. For the CS group, identical heparin coated cardiopulmonary bypass (CPB) sets, without a cardiotomy reservoir but with a CS, were used. In each group, eight patients had coronary artery bypass grafting performed. The capacity of the whole blood and the granulocytes to produce OFR was estimated by a chemiluminescence, and granulocyte activation was measured as release of the granulocyte granule proteins myeloperoxidase (MPO) and lactoferrin. A significantly reduced capacity to produce OFR by the whole blood was noted at 45 minutes of CPB in the CTR group (68% +/- 17% vs 94% +/- 16% in the CS group). MPO release was higher after 3 hours (p = 0.05) and 20 hours (p < 0.05), postoperatively, in the CTR group (417 +/- 77 micrograms/L and 257 +/- 31 micrograms/L vs 246 +/- 25 micrograms/L and 164 +/- 12 micrograms/L, respectively, in the CS group). We conclude that the heparin coated CPB circuit with the uncoated cardiotomy reservoir may be less biocompatible than the identical CPB set used together with the CS.
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| 7. |
- Brorsson, Camilla, et al.
(author)
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Adrenal response after trauma is affected by time after trauma and sedative/analgesic drugs
- 2014
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In: Injury. - : Elsevier. - 0020-1383 .- 1879-0267. ; 45:8, s. 1149-1155
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Journal article (peer-reviewed)abstract
- BACKGROUND: The adrenal response in critically ill patients, including trauma victims, has been debated over the last decade. The aim of this study was to assess the early adrenal response after trauma. METHODS: Prospective, observational study of 50 trauma patients admitted to a level-1-trauma centre. Serum and saliva cortisol were followed from the accident site up to five days after trauma. Corticosteroid binding globulin (CBG), dehydroepiandrosterone (DHEA) and sulphated dehydroepiandrosterone (DHEAS) were obtained twice during the first five days after trauma. The effect of time and associations between cortisol levels and; severity of trauma, infusion of sedative/analgesic drugs, cardiovascular dysfunction and other adrenocorticotropic hormone (ACTH) dependent hormones (DHEA/DHEAS) were studied. RESULTS: There was a significant decrease over time in serum cortisol both during the initial 24 h, and from the 2nd to the 5th morning after trauma. A significant decrease over time was also observed in calculated free cortisol, DHEA, and DHEAS. No significant association was found between an injury severity score >/= 16 (severe injury) and a low (< 200 nmol/L) serum cortisol at any time during the study period. The odds for a serum cortisol < 200 nmol/L was eight times higher in patients with continuous infusion of sedative/analgesic drugs compared to patients with no continuous infusion of sedative/analgesic drugs. CONCLUSION: Total serum cortisol, calculated free cortisol, DHEA and DHEAS decreased significantly over time after trauma. Continuous infusion of sedative/analgesic drugs was independently associated with serum cortisol < 200 nmol/L.
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| 8. |
- Brorsson, Camilla, et al.
(author)
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Saliva stimulation with glycerine and citric acid does not affect salivary cortisol levels
- 2014
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In: Clinical Endocrinology. - : Wiley. - 0300-0664 .- 1365-2265. ; 81:2, s. 244-248
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Journal article (peer-reviewed)abstract
- OBJECTIVE:In critically ill patients with hypotension, who respond poorly to fluids and vasoactive drugs, cortisol insufficiency may be suspected. In serum over 90% of cortisol is protein-bound, thus routine measures of total serum cortisol may yield 'false lows' due to hypoproteinaemia. Thus, the occurrence of cortisol insufficiency could be overestimated in critically ill patients. Salivary cortisol can be used as a surrogate for free serum cortisol, but in critically ill patients saliva production is decreased, and insufficient volume of saliva for analysis is a common problem. The aim of this study was to investigate if a cotton-tipped applicator with glycerine and citric acid could be used for saliva stimulation without affecting salivary cortisol levels.DESIGN:Prospective, observational study.PARTICIPANTS:Thirty-six volunteers (six males, 30 females), age 49 ± 9 years, without known oral mucus membrane rupture in the mouth.MEASUREMENTS:Forty-two pairs of saliva samples (22 paired morning samples, 20 paired evening samples) were obtained before and after saliva stimulation with glycerine and citric acid. Salivary cortisol was analysed using Spectria Cortisol RIA (Orion Diagnostica, Finland).RESULTS:The paired samples correlated significantly (P < 0·0001) and there was no significant difference between un-stimulated and stimulated salivary cortisol levels.CONCLUSIONS:Saliva stimulation with a cotton-tipped applicator containing glycerine and citric acid did not significantly influence salivary cortisol levels in healthy volunteers. This indicates that salivary cortisol measurement after saliva stimulation may be a useful complement when evaluating cortisol status in critically ill patients.
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| 9. |
- Ekbom, Tomas, et al.
(author)
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Methanol production from steel-work off-gases and biomass based synthesis gas
- 2012
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In: International Conference on Applied Energy, ICAE 2012.
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Conference paper (peer-reviewed)abstract
- The main objective has been to describe different cases of the methanol production from steel-work off gases (Coke oven gas and Basic oxygen furnace gas) and biomass based synthesis gas. The SSAB steel mill in the town of Luleå, Sweden has been used as a basis to analyze four different methanol production cases.The studied biomass gasification technology is based on a fluidized bed gasifier unit, where the production capacity is determined from case to case coupled to the heat production required to satisfy the local district heating demand. Critical factors are the integration of the gases with availability to the synthesis unit, to balance the steam system of the biorefinery and to meet the district heat demand of Luleå.For each case, the annual production potential of methanol, the overall production efficiencies and the effects on the total steel plant have been estimated.
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