| 11. |
- 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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| 12. |
- 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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| 13. |
- 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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| 14. |
- Kostic, Peter, 1970-
(författare)
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New methods for optimization of mechanical ventilation
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mechanical ventilation saves lives, but it is an intervention fraught with the potential for serious complications. Prevention of these complications has become the focus of research and critical care in the last twenty years. This thesis presents the first use, or the application under new conditions, of three technologies that could contribute to optimization of mechanical ventilation.Optoelectronic plethysmography was used in Papers I and II for continuous assessment of changes in chest wall volume, configuration, and motion in the perioperative period. A forced oscillation technique (FOT) was used in Paper III to evaluate a novel positive end-expiratory pressure (PEEP) optimization strategy. Finally, in Paper IV, FOT in conjunction with an optical sensor based on a self-mixing laser interferometer (LIR) was used to study the oscillatory mechanics of the respiratory system and to measure the chest wall displacement.In Paper I, propofol anesthesia decreased end-expiratory chest wall volume (VeeCW) during induction, with a more pronounced effect on the abdominal compartment than on the rib cage. The main novel findings were an increased relative contribution of the rib cage to ventilation after induction of anesthesia, and the fact that the rib cage initiates post-apneic ventilation. In Paper II, a combination of recruitment maneuvers, PEEP, and reduced fraction of inspired oxygen, was found to preserve lung volume during and after anesthesia. Furthermore, the decrease in VeeCW during emergence from anesthesia, associated with activation of the expiratory muscles, suggested that active expiration may contribute to decreased functional residual capacity, during emergence from anesthesia.In the lavage model of lung injury studied in Paper III, a PEEP optimization strategy based on maximizing oscillatory reactance measured by FOT resulted in improved lung mechanics, increased oxygenation, and reduced histopathologic evidence of ventilator-induced lung injury.Paper IV showed that it is possible to apply both FOT and LIR simultaneously in various conditions ranging from awake quiet breathing to general anesthesia with controlled mechanical ventilation. In the case of LIR, an impedance map representing different regions of the chest wall showed reproducible changes during the different stages that suggested a high sensitivity of the LIR-based measurements.
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| 15. |
- Kretzschmar, Moritz Andreas
(författare)
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Ventilation/Perfusion Matching and its Effect on Volatile Pharmacokinetics
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The mismatching of alveolar ventilation and perfusion (VA/Q) is the major determinant of impaired gas exchange. The gold standard for analyzing VA/Q distribution is the multiple inert gas elimination technique (MIGET), conventionally based on gas chromatography (GC), and, although simple in principle, a technically demanding procedure limiting its use. A new technique based on micropore membrane inlet mass spectrometry (MMIMS) combined MIGET with mass spectrometry, simplifying the sample handling process, and potentially providing VA/Q distributions for a general clinical approach.The kinetics of volatile anesthetics are well known in patients with healthy lungs. The uptake and distribution of inhaled anesthetics have usually been modeled by physiologic models. However, these models have limitations, and they do not consider ventilation/perfusion matching. Respiratory diseases account for a large part of morbidity and mortality and are associated with pulmonary VA/Q mismatch that may affect uptake and elimination of volatile anesthetics.The objectives of the studies were firstly to investigate assessment of VA/Q mismatch by MMIMS and secondly to investigate the effects of asthma-like VA/Q mismatch on the kinetics of volatile anesthetics in an experimental porcine model.Anesthetized and mechanically ventilated piglets were studied.In study I, a direct comparison of MIGET by MMIMS with the conventional MIGET by GC in three animal models that covered a wide range of VA/Q distributions was preformed. The two methods agreed well, and parameters derived from both methods showed good agreement with externally measured references.In studies II–IV, a stable method of inducing and maintaining asthma-like VA/Q mismatch with methacholine (MCh) administration was established, and the effect of VA/Q mismatch on the pharmacokinetics of desflurane and isoflurane was investigated. The present model of bronchoconstriction demonstrates a delay in volatile anesthetic uptake and elimination, related to the heterogeneity of MCh-inhalation induced ventilation. The difference in solubility of volatile anesthetics has a significant influence on their uptake and elimination under VA/Q mismatch. The higher blood soluble isoflurane is affected to a lesser degree than the fairly insoluble desflurane.
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| 16. |
- Lannergård, Anders, 1953-
(författare)
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Serum Amyloid A Protein (SAA) in Healthy and Infected Individuals
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Serum amyloid A protein (SAA) is an acute phase protein that has recently gained increasing interest as a potential marker for disease and treatment monitoring. We investigated SAA and CRP levels in (a) patients with various common infectious diseases (n=98), (b) patients with pyelonephritis (n=37) versus patients with cystitis (n=32), (c) healthy individuals of varying ages (n=231), (d) very immature newborn infants with or without nosocomial infections (NIs) (n=72) and (e) patients with bacterial infections treated with cefuroxime (n=81). SAA significantly correlated with CRP in viral as well as in bacterial infections (for the total group: r2=0.757, p<0.0001) and showed a systemic inflammatory response in 90% of the patients with cystitis as compared with 23% for CRP. Equally high efficiencies (0.96 and 0.94 for SAA and CRP, respectively) were observed in discriminating between pyelonephritis and cystitis. SAA and high sensitive (hs) CRP were lower in umbilical cords (p<0.0001) and higher in elderly adults (p<0.0001-0.03) than in the other age groups; higher in immature newborn infants than in term infants; and higher in the NI group than in the non-NI group. Interindividual variabilities of the time course of the biomarkers SAA and CRP were considerable. Because of the smoothed distribution of SAA and CRP (i.e. elevations were both essentially unchanged during the first 3 days of cefuroxime treatment), these markers were not useful when deciding parenteral-oral switch of therapy, which occurred within this time period in most cases.SAA is a sensitive systemic marker in cystitis. SAA and hsCRP in umbilical cord blood are close to the detection limit and increase with age. They increase in relation to NI in very immature newborn infants and might therefore be used in diagnosis and monitoring. Finally, SAA and CRP in adults with bacterial infections could not predict an early parenteral-oral switch of antimicrobial therapy.
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| 17. |
- Larsson, Anders, 1977-
(författare)
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Androgen receptors and endocrine disrupting substances
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Throughout the animal kingdom, organisms are dependent on substances such as steroid hormones to help them maintain internal balances. Examples of important tasks that are under regulation of steroid hormones are somatic and gonadal development, sexual performance and behavior (both social and sexual) as well as sex differentiation. Balance in the biology of reproduction is important for all organisms, and is sensitive to alterations and disturbances. If the environment is altered in a manner that lead to higher estrogenic or androgenic levels, the sex ratio of organisms that do not rely on genetic differences in the sex differentiation, will be biased towards more females or males in the population. It has been known for some time that there are pollutants in the environment that affect steroid pathways, such as the estrogenic and thyroid systems, but not much has been known about the androgenic systems. Examples of populations being masculinized have been recorded, and estrogenic compounds have been known to act as antiandrogens, but not until recently the first androgen agonist was identified. We used a combination of in vitro and computational modeling to identify the brominated flame retardant, 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane, as a potent androgen agonist to the human androgen receptor.In addition to this we cloned and characterized the androgen receptor from, a frequently used model organism, zebrafish (Danio rerio) as a receptor primarily activated by 11-ketotestosterone. This is a feature the zebrafish share with several other teleost fishes, such as the three-spined stickleback. Thus fish androgen receptors differ from most mammalian androgen receptors, where dihydrotestosterone is the most potent activator.
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| 18. |
- Larsson, Anders, 1954-
(författare)
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Att vara – tillsammans : Människosyn och medborgarskapsideal i den politiska idéhistorien
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is focused on two phenomena: normative citizenship ideals and onto-logical notions of man. The study is an inductive search for different attributes to describe a variation of these phenomena. The search is conducted from several different perspectives: Current research within citizenship theory, history in a material sense, the history of political ideas, the philosophy of science and thematic analyses of important aspects of the two phenomena.Throughout the thesis attributes are collected and sorted in order to build typologies that can define the variation.In the end the attributes of normative citizenship ideals are sorted into three groups. The ideals are explained in three ways: why they came in to existence, how the transition from one ideal to another took place and how the idealistic content of the ideals were transformed.The attributes of ontological notions of man are sorted into sex types and four of them are defined to have relevance for an existing variation today.Finally the relations between the two typologies are analyzed and ten combinations are found to be possibly useful in studies of contemporary societal contexts.Together, the results are contributing to theories of citizenship.Apart from the results of the study it is argued for a broader definition of politics in political science, for more specific ways to handle egalitarian questions in the field rights of man / citizenship rights and finally against the possibility of a neutral order, for example a neutral state.
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| 19. |
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| 20. |
- Larsson, Anders
(författare)
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Inhibited electrical discharges in air
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modem society requires a stable electricity supply, the reliability of which is partlydetermined by the dielectric strength of the outdoor high-voltage insulation systems.This thesis concentrates upon one particular discharge phenomenon that occurs whensuch a system is subjected to rain, namely the inhibited discharge. This is a dischargewhere the energy input into the discharge channel is limited by the presence of a largeseries resistor in the discharge circuit.Two experimental arrangements have been used: A quasi-uniform 10 mm electrodegap (simulating discharges between water drops) and a rod-to-plane 1 m electrode gap(simulating the flashover of a high-voltage post insulator).The presence of the series resistance caused no increase in the disruptive dischargevoltage for the 10 mm gap, but for the 1 m gap it induced an increase that was morepronounced for negative than positive polarity.The transition from a cold discharge to a hot plasma was significantly prolongedwhen a large series resistance was introduced in the discharge circuit. This is interestingfor engineering purposes since it increases the time window in which action can betaken before the end of the disruptive discharge.A five order-of-magnitude difference in the peak streamer-to-spark transition current(1 mA - 100 A) was found in the literature for 10 mm gaps. This difference has notbeen thoroughly investigated previously. Here an explanation is suggested for thisphenomenon.The experimental results revealed that the streamer propagation was not inhibited bythe presence of a large series resistance in the discharge circuit, but the final jump was.The effect upon streamer propagation was confirmed by calculations using a well-established streamer model. A final-jump model was derived as part of the work presented here and good agreement was obtained between the experiments and the calculations. This model should be useful in the design of high-voltage insulators.
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