| 1. |
- Marchesi, Silvia, MD, 1985-
(författare)
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The effect of mechanical ventilation on abdominal organs : Analysing the role of PEEP and perfusion.
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: The effect of mechanical ventilation on abdominal organs is not well understood and investigated yet. Previous studies, using an animal sepsis-like model, found an association between mechanical ventilation (MV) and abdominal edema and inflammation.The presented thesis was aimed to investigate the role of perfusion in edema formation and inflammation, and to study the abdomen during mechanical ventilation in an ARDS model to reduce the confounding effect of inflammation related to sepsis.Methods: In the first paper presented, inflammation and edema in the abdomen were investigated in an endotoxin model. The study subjects were divided into two groups with different mean arterial pressures (MAP), another small group of healthy controls were studied as well. MRI analyses were used to measure perfusion in the different abdominal organs. In the second paper presented, differences in abdominal edema and inflammation were assessed in two groups of subjects, one group underwent MV and one group had spontaneously breathing.Results: In the first study, MRI analyses confirm that the group with higher MAP had better perfusion than the low MAP group. In the liver, perfusion was lower in LowMAP group compared to HighMAP group, but the HighMAP group had lower perfusion than the healthy controls. However, in the other studied organs HighMAP group and healthy controls had similar perfusion.Edema did not differ between the groups. Inflammation was globally higher in LowMAP group and correlated with hemodynamics. TNFα in liver tissue and portal vein serum correlated with intra-abdominal pressure (IAP).In the second study, the cytokine concentration was higher in serum in the MV group. MV did not increase abdominal edema or inflammation, compared to spontaneous breathing. Discussion and conclusion: Abdominal edema and inflammation are multifactorial phenomena, and many elements have to be included in the analysis. Perfusion plays an important role in determining inflammation and IAP. MV per se was not found to be related to increased edema and inflammation. In a previous study, the role of different levels of PEEP and different respiratory rate between mechanically ventilated and spontaneously breathing animals were not analyzed, but could have contributed to the results. The efforts made in this study to maintain similar respiratory rate and PEEP in both groups, could have contributed to the presented results.It is important to underline that, even if MV was not related to inflammation in abdomen, it was related to an increase in systemic inflammation, most probably because of an enhanced lung production of inflammatory mediators.Further studies, focusing on the role of respiratory rate and PEEP on abdomen, as well as the analysis of the inter-relations among inflammation, perfusion and edema, are needed to increase the pathophysiological understanding of these phenomena.
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| 2. |
- Olsson, Karl Wilhelm, 1985-
(författare)
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Persistent ductus arteriosus in extremely preterm infants
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Patent ductus arteriosus (PDA) is common in infants born <28 weeks gestational age (GA) and associated with significant morbidity. Despite extensive research efforts, the indications for PDA treatment remain controversial. The aims of these studies were to gain knowledge of factors affecting ductal closure during the early postnatal period and provide better means for identification of preterm infants that may benefit from PDA treatment.In Paper I, infants born <28 weeks GA and pharmacologically treated for PDA were retrospectively identified and their echocardiographic examinations were reviewed. Twenty-nine (52%) infants successfully closed and 27 (48%) infants failed to close PDA during treatment. High maximal ductal flow velocity (Vmax) was independently associated with closure (OR 3.04, p=0.049).Paper II prospectively included infants born <28 weeks GA and assessed early respiratory, circulatory and echocardiographic parameters. PDA was persistent in 18 (30%) and ultimately closed or insignificant in 42 (70%) infants. Echocardiographic criteria for hemodynamically significant PDA on days 2-7 did not predict persistent PDA (p=1.000). Mechanical ventilation (p=0.025), high mean airway pressure (p=0.020) and low Vmax (p=0.024) during day two were associated with future persistent PDA.Blood samples were obtained during the second day of life from 47 of the infants in Paper II and serum markers previously associated with PDA or factors affecting PDA were analyzed for Paper III. Inflammatory markers and erythropoietin (EPO) were elevated in infants with future persistent PDA. EPO levels were also higher in infants that did not close PDA during pharmacological treatment.In Paper IV, 44 infants born <28 weeks GA with surgically ligated PDA were retrospectively compared to non-surgically treated controls. Ligated infants had larger ductal diameter prior to, and lack of diameter decrease after pharmacological treatment for PDA (p=0.048 and p=0.022 respectively), and higher incidence of severe bronchopulmonary dysplasia (p=0.025). Longer periods with invasive ventilation was independently associated with ligation (OR 1.04, p=0.018).In conclusion, early hsPDA do not predict persistence of ductus arteriosus in extremely preterm infants, but Vmax and EPO are promising early markers for prediction of persistence and should be subjects of future studies.
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| 3. |
- Almgren, Birgitta, 1958-
(författare)
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Endotracheal Suction a Reopened Problem
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During mechanical ventilation, patients are connected to the ventilator by an endotracheal tube. The tube needs to be cleaned from mucus by suction, which can cause negative effects such as lung collapse, hypoxemia and desaturation. These can be avoided by preoxygenation, change of ventilator settings, use of closed suction systems and recruitment manoeuvres. The aim of the study was to investigate the effects of endotracheal suction during different ventilator settings and by different suction methods. A method to reverse side effects was investigated.In anaesthetized pigs, the effect of suction during volume and pressure-controlled ventilation was investigated, and the effect of different suction systems and catheter sizes were compared. Suction efficacy was investigated in a bench study. The effect of recruitment manoeuvre added after suction, i.e. post-suction recruitment manoeuvre was evaluated.Endotracheal suction causes lung volume loss leading to impaired gas exchange, an effect that is more severe in pressure-controlled ventilation than in volume-controlled ventilation. When 14 French suction catheters were used more side effects were found compared to 12 French catheters, but no difference was found between open and closed suction system in pressure-controlled ventilation. Open suction system was more effective to remove mucus compared to closed system. Post-suction recruitment manoeuvre restored the side effects after the first recruitment when it was applied directly after suction.In conclusion, open endotracheal suction causes impairment in gas exchange and lung mechanics, and more so in pressure-controlled than in volume-controlled mode. These changes can be minimized if smaller suction catheters are used. A post-suction recruitment manoeuvre applied directly after suction restores lung function. It is obvious that the recruitment manoeuvre should be added directly after suction, because if the manoeuvre is delayed and the lung is collapsed and left collapsed, it will be more difficult to recruit the lung.
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| 4. |
- Befekadu Wodajo, Rahel, 1968-
(författare)
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Analysis of new biomarkers and their kinetics in connection with ST-elevation myocardial infarction and percutaneous coronary intervention
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis studies different biomarkers in a cohort of patients suffering from ST-elevation myocardial infarction (STEMI) who underwent Percutaneous coronary intervention (PCI) in Örebro in 2011-2012. Blood samples were collected at three time points, at the arrival at the hospital, 1-3 days after PCI and for a smaller group of patients also 3 months after PCI. The study is a sub-study of the TASTE study, so half of the patients were also randomized to thrombus aspiration in conjunction with their PCI. For all patients, it was also recorded whether the culprit coronary vessel was totally occluded or partially patent. In total, there are samples from 165 patients, but not all markers have been measured in all patients, and 3-month samples are only available from those who had their follow-up in Örebro. The plasma levels of the biomarkers have also been measured in plasma from blood donors for comparison. In March 2019, a follow-up was made of the patients' survival, and the time of death was noted in cases where this had occurred.The markers studied are the lysosome protein Cathepsin S (Cat-S), the platelet granule protein thrombospondin 1 (TSP-1), the pentraxins C-reactive protein (CRP) and pentraxin 3 (PTX3), the endopeptidase neprilysin, the soluble forms of TNF-receptor 1 and 2 (sTNFR1 and sTNFR2), markers showing activation of the lectin pathway for complement activation (MASP-1/AT, MASP-1/C1-INH, MASP-2/C1-INH, MASP-2/AT) and common activation markers for complement activation (C3a and sC5b-9).In summary, the thesis shows that the plasma levels of all markers, except neprilysin and sC5b-9, are elevated at the time of arrival compared to healthy blood donors. Neprilysin is at the same level, and sC5b-9 is lower compared to blood donors. 1-3 days after PCI, the levels for CRP, sTNFR1 and sC5b-9 have risen strongly (>50%) compared to the levels at arrival. MASP-1/AT and MASP-2/AT have fallen moderately (about 50%), Cat-S and TSP-1 have decreased strongly, while the remaining markers are relatively similar to the levels at arrival (± 25%). The levels for CRP, PTX3, sTNFR1, sTNFR2 and neprilysin decreased even further between 1-3 days and 3 months, sC5b-9 rises slightly while the other markers remain at roughly the same levels. At 3 months, most markers still show higher levels compared to corresponding levels in blood donors, only MASP-2/C1-INH has the same level, while neprilysin is slightly lower and TSP-1 much lower compared to blood donors (the latter presumably an effect of ongoing medication with platelet inhibitors in the patients). No relevant differences were observed between patients with and without thrombus aspiration, and few differences were seen between patients with occluded or partially patent vessels. This may indicate that these factors were of minor importance for the levels of the analyzed markers. In contrast, analysis of survival showed that individuals with plasma levels above the median value for PTX3, sTNFR1 and sTNFR2 at admission and/or at 1-3 days had a significantly increased mortality compared to those with levels below the median value, which indicates that these markers could be interesting for further studies in a material where also analysis of possible interfering factors can be implemented.
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| 5. |
- Bolander, Åsa, 1977-
(författare)
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Prognostic Factors in Malignant Melanoma
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Because of the failure so far to find effective treatment for patients with advanced stages of melanoma, increasing efforts have been made to find prognostic factors identifying patients in the risk zone for development of metastasis.This thesis investigates the prognostic powers of a few selected serological and immunohistochemical biomarkers.In the first and second study, patients operated on for localized malignant melanoma were investigated regarding the prognostic impact of angiogenic serological markers and circulating levels of S100. We concluded that the S100 assays, especially S100BB, are potential biomarkers in patients with malignant melanoma, correlated to both survival and disease free survival. However, no such conclusion could be drawn from the first study, where we found no correlation to survival and investigated angiogenic markers.In the third and fourth study four new potential immunohistochemical biomarkers where investigated in collaboration with the Swedish Human Protein Atlas Program, and those where TRP-1, galectin-1, DLG5 and syntaxin-7.We found that TRP-1 correlated inversely with tumor stage and galectin-1 correlated to Ki-67.DLG5 showed a significant inverse correlation to Ki67 and the expression of STX7 was inversely correlated to tumor stage, suggesting that decreased expression is associated with more aggressive tumors.None of the investigated markers in study III and IV correlated with disease free survival or overall survival.In the fifth and last study, we examined the expression of SOX10, a transcription factor, in different melanocytic lesions. Also, a proliferation assay was carried out in a human melanoma cell line. The results reveal the presence of SOX10 in different melanocytic lesions, with a weak inverse correlation to survival and a significant inverse correlation to T-stage. A significant decrease in proliferation rate for SOX10 silenced cells was found and our data also suggests an increased migratory response in SOX10 silenced cells.
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| 6. |
- Bülow Anderberg, Sara
(författare)
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Inflammatory aspects of acute kidney injury development during severe infections
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Acute kidney injury is common in intensive care. In this setting sepsis, by definition a dysregulated inflammatory response secondary to infection, is the most common cause. Sepsis associated acute kidney injury is in turn linked to worse outcome. The syndrome is considered to be the result of multiple mechanisms elicited by the inflammatory response and not merely hypoperfusion. COVID-19 has become an additional cause of acute kidney injury in critically ill patients. The present thesis focused on investigating contributing aspects of the inflammatory response in regard to acute kidney injury development in sepsis and COVID-19.The innate immune response recognizes invading pathogens through preserved molecular structures. When detected small and short-acting immunomodulatory molecules, cytokines, are produced shaping the reaction. Neutrophils are quickly mobilized. They engage in degranulation and expulsion of extracellular traps aiming at eradicating pathogens but may in doing so cause collateral tissue damage. Neutrophils are proposed contributors to renal dysfunction during sepsis and COVID-19.We investigated the effect of hydrocortisone, a glucocorticoid, on renal function and neutrophil infiltration in an ovine sepsis model with associated renal impairment. The observed reduction in glomerular filtration and tubular sodium transport efficiency during sepsis was ameliorated. Neutrophil infiltration which was observed post mortem in renal tissue was not reduced by hydrocortisone.The progression of organ dysfunction and by extension also acute kidney injury during severe COVID-19 was early on considered caused by a hyperinflammatory state. We analysed plasma cytokine concentrations in patients admitted to intensive care because of respiratory failure secondary to COVID-19. Only a moderate increase of theses mediators was found. The majority of the cytokines analysed were in turn associated with acute kidney injury development.Human neutrophil lipocalin is a neutrophil granular protein. It was used to first evaluate neutrophil reactivity by measuring its concentration after ex vivo stimulation and second systemic activity by estimating its concentration in plasma. In turn the association with renal dysfunction in severe COVID-19 was explored. Increased concentrations in both instances were linked to a greater risk of developing severe acute kidney injury.Lastly, the effect of dexamethasone, another glucocorticoid, on AKI development and neutrophil extracellular markers including histones and myeloperoxidase-DNA in critical COVID-19 was investigated. Dexamethasone was associated with lower AKI incidence and reduced extracellular trap formation.
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| 7. |
- Dubois, Louise
(författare)
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Prostasomes as Diagnostic, Prognostic and Therapeutic Vesicles
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis explores prostasomes and their ability to be used as a new diagnostic tool for prostate cancer. Alongside diagnosis, this thesis also suggests prostasomes as a tool for prognosis and therapeutic treatment in patients with prostate cancer. By further characterizing prostasomes we can identify a biomarker and also a method of visualizing and interpreting the information provided in order to conduct a correct and fast diagnosis for prostate cancer.In Paper I, we show that the prostasomal bilayered membrane consists of lipid rafts, clusters that holds cholesterol, sphingolipids and gives receptors a rigid platform upon which to work. We compare the proteomic content of prostasome lipid rafts with the entire prostasome membrane in the search for a specific biomarker. In Paper II, we show that purified lipid rafts from the prostasome membrane can re-vesiculate and create new bioengineered vesicles. These new vesicles can carry different agents inside them and we find that the method is also applicable to blood cells. This suggests a new method for cell-specific delivery of drugs and cancer therapy. In Paper III, we further characterize the prostasome membrane, this time mapping purinergic receptors. This could be used in the development of prostate cancer treatment and to gain better understanding of how prostasomes interact with surrounding cells in their ambient environment.In Paper IV, we investigate the difference in thymidine kinase 1 (TK1) enzyme activity between prostasomes and malignant exosomes. TK1 is considered to be a biomarker of cell proliferation and could therefore be used as a biomarker for prostate cancer diagnosis and progression.In summary, this thesis contributes to the puzzle of how to better diagnose, prognose and treat prostate cancer. Although it is mainly pre-clinical research it opens up new possibilities for the diagnosis and treatment of prostate cancer.
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| 8. |
- Engström, Joakim, 1983-
(författare)
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Patient safety in the Intensive Care Unit : With special reference to Airway management and Nursing procedures
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of the present thesis was to study aspects of patient safety in critically ill patients with special focus on airway management, respiratory complications and nursing procedures. Study I describes a method called pharyngeal oxygen administration during intubation in an experimental acute lung injury model. The study showed that pharyngeal oxygenation prevented or considerably increased the time to life-threatening hypoxemia at shunt fractions by at least up to 25% and that this technique could be implemented in airway algorithms for the intubation of hypoxemic patients. In study II, we investigated short-term disconnection of the expiratory circuit from the ventilator during filter exchange in critically ill patients. We demonstrated that when using pressure modes in the ventilator, there was no indication of any significant deterioration in the patient's lung function. A bench test suggests that this result is explained by auto-triggering with high inspiratory flows during the filter exchange, maintaining the airway pressure. Study III was a clinical observational study of critically ill patients in which adverse events were studied in connection with routine nursing procedures. We found that adverse events were common, not well documented, and potentially harmful, indicating that it is important to weigh the risks and benefits of routine nursing when caring for unstable, critically ill patients. In study IV, we conducted a retrospective database study in patients with pelvis fractures treated in the intensive care unit. We found that the incidence of respiratory failure was high, that the procedure involved in surgical stabilization affected the respiratory status in patients with lung contusion, and that the mortality was low and probably not influenced by the respiratory condition. In conclusion, the results obtained in the present thesis have increase our knowledge in important areas in the most severely ill patients and have underlined the need for improvements in the field of patient safety.
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| 9. |
- Höstman, Staffan, 1979-
(författare)
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Minimal volume ventilation in lung injury : With special reference to apnea and buffer treatment
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A fairly large portion of patients receiving surgical or intensive care will need mechanical ventilation at some point. The potential ventilator-induced lung injury (VILI) is thus of interest. One of the main causal factors in VILI is the cyclic energy shifts, i.e. tidal volumes, in the lung during mechanical ventilation. The problem can be approached in two ways. Firstly, one can utilize apneic oxygenation and thus not cause any tidal injuries at all. Secondly, and more traditionally, one can simply lower the tidal volumes and respiratory rates used. The following describes a series of animal experiments exploring these options.In the first two papers, I explored and improved upon the methodology of apneic oxygenation. There is a generally held belief that it is only possible to perform apneic oxygenation by prior denitrogenation and by using 100% oxygen during the apnea. As 100% oxygen is toxic, this has prevented apneic oxygenation from more widespread use. The first paper proves that it is indeed possible to perform apneic oxygenation with less than 100% oxygen. I also calculated the alveolar nitrogen concentration which would conversely give the alveolar oxygen concentration. The second paper addresses the second large limitation of apneic oxygenation, i.e. hypercapnia. Using a high dose infusion of tris(hydroxymethyl)aminomethane (THAM) buffer, a pH > 7.2 could be maintained during apneic oxygenation for more than 4.5 hours.In the last two papers, THAM’s properties as a proton acceptor are explored during respiratory acidosis caused by very low volume ventilation. In paper III, I found that THAM does not, in the long term, affect pH in respiratory acidosis after stopping the THAM infusion. It does, however, lower PVR, even though the PaCO2 of THAM-treated animals had rebounded to levels higher than that of the controls. In the last experiment, I used volumetric capnography to confirm our hypothesis that carbon dioxide elimination through the lungs was lower during the THAM infusion. Again, the PaCO2 rebounded after the THAM infusion had stopped and I concluded that renal elimination of protonated THAM was not sufficient.
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| 10. |
- Kawati, Rafael, 1967-
(författare)
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Evaluation of Respiratory Mechanics by Flow Signal Analysis : With Emphasis on Detecting Partial Endotracheal Tube Obstruction During Mechanical Ventilation
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Evaluating respiratory mechanics during dynamic conditions without interrupting ongoing ventilation and flow, adds to the information obtained from the mechanics derived from static (= no flow) conditions, i.e., the flow signal has the potential to provide information on the properties of the respiratory system (including the tubing system). Hence monitoring the changes in the flow signal during ongoing mechanical ventilation would give information about the dynamic mechanics of the respiratory system. Any change in the mechanics of the respiratory system including the endotracheal tube (ETT) and the ventilatory circuit would affect the shape of the flow signal. Knowledge of the airway pressure distal to the ETT at the carina level (= tracheal pressure) is required for calculating the extra resistive load exerted by the endotracheal tube in order to compensate for it. In a porcine model, the flow signal was used to non-invasively calculate tracheal pressure. There was good agreement between calculated and measured tracheal pressure with different modes of ventilation. However, calculation of tracheal pressure assumes that the inner diameter of the ETT is known, and this assumption is not met if the inner diameter is narrowed by secretions. Flow that passes a narrowed tube is decelerated and this is most pronounced with the high flow of early expiration, yielding a typical time constant over expiratory volume pattern that is easy to recognize during mechanical ventilation. This pattern reliably detected partial endotracheal obstruction during volume and pressure controlled mechanical ventilation. A change in compliance of the respiratory system modifies the elastic recoil and this also affects the rate of the expiratory flow and the shape of its signal. In a porcine model, lung volume gains on the flow signal generated by the heartbeats (cardiogenic oscillations) provided information about the compliance of the respiratory system during ongoing mechanical ventilationIn conclusion analyzing the flow signal during ongoing ventilation can be a cheap, non-invasive and reliable tool to monitor the elastic and resistive properties of the respiratory system including the endotracheal tube.
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