The most commonly used method of euthanasia of laboratory rodents is exposure to carbon dioxide (CO₂), but recent studies have shown that rodents find this gas aversive. The aim of my thesis was to evaluate rat aversion to inhalant agents that could be used as humane alternatives to CO₂. The first study used approach-avoidance testing to examine rat responses to argon-induced hypoxia when argon was introduced at flow rates of 40-239% of the test cage volume per min. Rats never remained in the test cage long enough to lose consciousness when tested with argon. They consumed fewer reward items, stopped eating sooner, and left the test cage more quickly than when tested with air. Rats stopped eating and left the test cage when the oxygen (O₂) concentration had dropped to about 7.7 and 6.8%, respectively, but these O₂ concentrations are too high to cause unconsciousness. Although humans exposed to hypoxia report only subtle symptoms that include cognitive impairments and light headedness, rats are burrowing rodents and could therefore be more sensitive to these effects. I conclude that argon is not a humane alternative to CO₂. The second study used approach-avoidance testing to evaluate rat responses to different concentrations of the inhalant anaesthetics halothane and isoflurane introduced with vaporizers or from soaked cotton balls. On the first day of exposure to anaesthetics, most rats remained in the test cage until they were ataxic and showing difficulty returning to the home cage. On subsequent days of testing most rats left the test cage within seconds, but if given the option, all promptly returned and stayed until they were ataxic, indicating that the learned aversion is transient. Rats were likely sedated by the time they chose to leave, suggesting that forced exposure from the onset of aversion until loss of consciousness is less of a welfare concern than forced exposure to non-sedating agents. I suggest that the use of inhalant anaesthetics for inducing unconsciousness prior to euthanasia is a more humane method than the commonly used CO₂.

Atelektaser uppstår inom tio minuter hos 90 % av alla patienter som sövs och leder till försämrad syresättning men kan även leda till postoperativa lungkomplikationer. Syftet med studien var att beskriva hur anestesisjuksköterskan med olika ventilationsstrategier kan förebygga atelektasbildning under generell anestesi. Studien genomfördes som en litteraturstudie där 19 vetenskapliga artiklar granskades och analyserades. Resultatet visar att när 100 % syrgas ges under induktionen av anestesi ökar uppkomsten av atelektaser. Om positive end-expiratory pressure (PEEP) 6-10 cmH2O används tillsammans med 100 % syrgas motverkas detta. Det är mer oklart vilken effekt PEEP har efter induktionen av anestesi. PEEP bör kombineras med rekryteringsmanöver för att effektivt motverka atelektasbildning. Olika metoder för att genomföra rekryteringsmanöver finns beskrivna men gemensamt är att topptrycket ska nå upp till cirka 40 cmH2O. Efter induktionen kan anestesisjuksköterskan även förebygga uppkomst av atelektaser genom använda 40 % syrgas. I den kliniska verksamheten saknas ofta riktlinjer för vilken ventilationsstrategi som ska användas. För att kunna arbeta preventivt med att förebygga atelektasbildning måste anestesisjuksköterskan diskutera ventilationsstrategi med anestesiläkaren innan problem med syresättningen uppstår. För framtida forskning skulle det kunna vara av intresse att undersöka hur olika ventilationsinställningar påverkar patientens upplevelse under preoxygenering.

The most commonly used method of euthanasia of laboratory rodents is exposure to carbon dioxide (CO₂), but recent studies have shown that rodents find this gas aversive. The aim of my thesis was to evaluate rat aversion to inhalant agents that could be used as humane alternatives to CO₂. The first study used approach-avoidance testing to examine rat responses to argon-induced hypoxia when argon was introduced at flow rates of 40-239% of the test cage volume per min. Rats never remained in the test cage long enough to lose consciousness when tested with argon. They consumed fewer reward items, stopped eating sooner, and left the test cage more quickly than when tested with air. Rats stopped eating and left the test cage when the oxygen (O₂) concentration had dropped to about 7.7 and 6.8%, respectively, but these O₂ concentrations are too high to cause unconsciousness. Although humans exposed to hypoxia report only subtle symptoms that include cognitive impairments and light headedness, rats are burrowing rodents and could therefore be more sensitive to these effects. I conclude that argon is not a humane alternative to CO₂. The second study used approach-avoidance testing to evaluate rat responses to different concentrations of the inhalant anaesthetics halothane and isoflurane introduced with vaporizers or from soaked cotton balls. On the first day of exposure to anaesthetics, most rats remained in the test cage until they were ataxic and showing difficulty returning to the home cage. On subsequent days of testing most rats left the test cage within seconds, but if given the option, all promptly returned and stayed until they were ataxic, indicating that the learned aversion is transient. Rats were likely sedated by the time they chose to leave, suggesting that forced exposure from the onset of aversion until loss of consciousness is less of a welfare concern than forced exposure to non-sedating agents. I suggest that the use of inhalant anaesthetics for inducing unconsciousness prior to euthanasia is a more humane method than the commonly used CO₂.

The most commonly used method of euthanasia of laboratory rodents is exposure to carbon dioxide (CO₂), but recent studies have shown that rodents find this gas aversive. The aim of my thesis was to evaluate rat aversion to inhalant agents that could be used as humane alternatives to CO₂. The first study used approach-avoidance testing to examine rat responses to argon-induced hypoxia when argon was introduced at flow rates of 40-239% of the test cage volume per min. Rats never remained in the test cage long enough to lose consciousness when tested with argon. They consumed fewer reward items, stopped eating sooner, and left the test cage more quickly than when tested with air. Rats stopped eating and left the test cage when the oxygen (O₂) concentration had dropped to about 7.7 and 6.8%, respectively, but these O₂ concentrations are too high to cause unconsciousness. Although humans exposed to hypoxia report only subtle symptoms that include cognitive impairments and light headedness, rats are burrowing rodents and could therefore be more sensitive to these effects. I conclude that argon is not a humane alternative to CO₂. The second study used approach-avoidance testing to evaluate rat responses to different concentrations of the inhalant anaesthetics halothane and isoflurane introduced with vaporizers or from soaked cotton balls. On the first day of exposure to anaesthetics, most rats remained in the test cage until they were ataxic and showing difficulty returning to the home cage. On subsequent days of testing most rats left the test cage within seconds, but if given the option, all promptly returned and stayed until they were ataxic, indicating that the learned aversion is transient. Rats were likely sedated by the time they chose to leave, suggesting that forced exposure from the onset of aversion until loss of consciousness is less of a welfare concern than forced exposure to non-sedating agents. I suggest that the use of inhalant anaesthetics for inducing unconsciousness prior to euthanasia is a more humane method than the commonly used CO₂. / Land and Food Systems, Faculty of / Graduate

Sample preparation as the first step in an analytical procedure has an important role, particularly in bioanalysis, because of the complexity of biological samples (blood plasma and urine). Biological matrix such as plasma and blood contains proteins, organic and inorganic salts, acids, bases and various organic compounds with similar chemistry to the analytes of interest. Thus the basic concept of a sample preparation method is to convert a real matrix into a format that is suitable for analysis by an analytical technique. Therefore the choice of an appropriate sample preparation method greatly influences the reliability and accuracy of the analysis results. The aim of this thesis was to develop and validate of microextraction by packed syringe (MEPS) as a fast, selective, accurate and fully automated sample preparation technique for determination of BAM peptides in human plasma and local anaesthtics in human plasma and urine samples using silica and polymer sorbents. First work presents use of MEPS technique online with LC-MS/MS as a tool for the quantification of BAM peptide in plasma samples. MEPS technique provides significant advantages such as the speed and the simplicity of the sample-preparation process. Compared with other extraction techniques, such as protein precipitation and ultrafiltration, MEPS gave cleaner samples and higher recovery. In the second work, MEPS technique was developed by using synthesized molecularly imprinted polymer (MIP) as a sorbent for selective quantification of a homologous series of local anaesthetics, containing lidocaine, ropivacaine, mepivacaine, and bupivacaine in human plasma and urine samples. Compared with other conventional sorbent, the use of MIP provides high selectivity of the extraction and decrease the matrix effect.

Chronic neuropathic pain affects up to 8% of the United Kingdom population and is a difficult condition to manage. It is established and maintained through many mechanisms, including central sensitisation (CS) in the spinal cord and brainstem. Neuropathic pain manifests as spontaneous pain, sensory loss and evoked hypersensitivity. The development of novel treatments for neuropathic pain is challenging, in part due to inadequate experimental models of clinically relevant pain. The use of functional magnetic resonance imaging (fMRI) techniques for imaging acute and increasingly tonic states enables the assessment of the neural correlates of evoked hypersensitivity and persistent pain, with the goal of developing appropriate biomarkers to test new therapies. This thesis develops novel techniques for the assessment of ongoing pain states and their modulation by therapies. We first identified a suitable human experimental model of CS using topical capsaicin, and an fMRI pipeline for the investigation of supraspinal involvement in pain hypersensitivity. In a placebo-controlled study, we then demonstrated the improved sensitivity of fMRI above subjective reports in detecting the efficacy of a known analgesic as compared to an ineffective active compound in a small cohort. To translate this to the more clinically relevant symptom of spontaneous pain, we developed and validated the use of a multi-inversion time pseudo-continuous arterial spin labelling (ASL) imaging and analysis pipeline for the neural assessment of tonic states and the absolute quantification of cerebral blood flow (CBF). Current evidence from structural and functional studies suggests a direct role for the posterior insula cortex in the encoding of nociception and pain. Using the ASL pipeline, we found that only a CBF change in the posterior insula region was correlated with the changing perception of persistent capsaicin-induced pain, and in a separate experiment showed that suppression of CBF in this region by gabapentin was related to the drug's suppression of subjective pain perception. We also demonstrated in a cohort of phantom limb patients that pain relief resulting from transcranial direct current stimulation of the deprived sensorimotor cortex is neurally represented by a decrease in posterior insula CBF. In a separate study, we showed that baseline CBF in the periaqueductal grey can predict individuals who are most vulnerable to pain and hypersensitivity following the induction of capsaicin-related CS. Taken together, these findings suggest that fMRI can be used as a tool to assess the efficacy of established and novel analgesics, with the midbrain reticular formation and posterior insula cortex being prime candidates as biomarkers of CS mechanisms and persistent pain respectively. Relatedly, ASL-fMRI may also be an effective technique for evaluating individuals' susceptibility to pain following inflammation or injury.

Introduction: Trauma is the main cause of death in working-age adults in the UK. Multiple organ failure (MOF) is associated with a high proportion of late trauma deaths, and MOF survivors have poor long-term outcomes. Early prediction of patients at risk of MOF would assist treatment decisions and allow targeted interventions. Methods: A cohort of major trauma patients requiring intensive care unit (ICU) treatment at the John Radcliffe Hospital was identified. Data were obtained from the two national databases of the Trauma Audit Research Network and the Intensive Care National Audit and Research Centre, and from a local ICU database with hourly data recording. Literature review and questionnaire analysis of trauma clinicians identified candidate predictors of MOF, grouped into patient, injury, physiological, laboratory and management variables. MOF scoring systems were reviewed to determine the most appropriate for use in trauma patients. Prediction models of post-trauma MOF were developed using logistic regression at a range of times from 0 to 48 hours after injury. Models were internally validated using bootstrapping. Results: 517 adult trauma patients were identified from 2003-2011. Overall mortality was 14.9%, with 491 patients surviving more than 48 hours, and therefore being at risk of MOF development. For these 491 patients, MOF incidence depended on the definition, and ranged from 23% (Denver score) to 58% (SOFA score). MOF was associated with mortality, time to ICU admission, and length of ICU and hospital stay. MOF could be predicted with an accuracy of up to 81.3% at 2 hours post-injury, and 84.2% at 12 hours post-injury using small numbers of clinical variables. Age, head injury, abdominal injury, maximum heart rate and the need for vasopressors were strong predictors of all definitions of MOF. Conclusions: Post-trauma MOF can be predicted early after injury using combinations of clinical variables. Further validation of the identified variables on external populations would allow development of a clinical score to assist clinicians in trauma management.

Clinical and behavioural evidence has shown that the threat value of pain biases decisions about whether a stimulus is perceived as painful or not, and if yes, how intense is the sensation. This thesis aims to investigate the neural mechanisms underlying the effect of perceived threat on perceptual decisions about pain. The first study investigates the neural mechanisms underlying the effect of threat on the decision about the quality of the sensation, i.e., whether it is perceived as painful or not. The perception of pain (relative to no pain) was associated with activation in the anterior insula as well as an increased connectivity between this region and the mid-cingulate cortex (MCC). Activity in the MCC was correlated with the threat-related bias to perceived pain. In the second study, probabilistic tractography was performed with diffusion tensor imaging to investigate the structural connectivity between subdivisions of the insula and other pain-related regions. Additional analyses revealed that the structural connectivity between the anterior insula and the MCC, and between the posterior insula and somatosensory cortices, is positively correlated with the threat-related bias toward pain. In the third study, a multivariate pattern analysis (MVPA) was performed to investigate whether pain can be decoded from functional neuroimaging data acquired during the anticipation and during the receipt of pain. The results show that pain can be predicted by the pattern of neural activity in the right anterior insula during anticipation and stimulation. The fourth study investigated the effect of uncertainty about the stimulation intensity as a form of threat on the perceived intensity of pain. Uncertainty was found to be associated with an increased activation in the anterior insula. Overall, these findings suggest that a neural network consisting of the anterior insula and the MCC plays a key role in decisions about the quality and the quantity of nociceptive sensation. Results from the MVPA analysis support the notion that perceptual decisions are encoded by a distributed network of brain regions. The variability in anatomical connections between these regions may account for the individual differences in the susceptibility to a threat-mediated bias toward pain.

L’anesthésie-réanimation est une discipline qui n’a acquis son autonomie que récemment. Jadis sous la direction du chirurgien, l’anesthésiste-réanimateur est, comme son nom l’indique, au cœur d’une profession multidisciplinaire. Si l’acte anesthésique suppose, en aval, l’application de techniques de réanimation, l’inverse n’est pas systématiquement le cas. En effet, l’anesthésiste-réanimateur peut être confronté, dans sa fonction de réanimateur, à la problématique du prélèvement d’organes dont la pratique fait appel à la définition de la mort, définition nécessairement sujette à discussion. Par son objet même, le contentieux civil en anesthésie-réanimation est particulièrement vaste. Son étude mettra en évidence l’élaboration des normes encadrant la discipline, sur laquelle le contexte professionnel exerce une influence déterminante, leur mise en pratique par l’anesthésiste-réanimateur, puis leur adéquation au cas clinique par le juge civil, lorsqu’un patient exercera une action en responsabilité / Anaesthetics and intensive care are closely linked in the French health care system and are always carried out by the same professional. Anaesthetics and intensive care thus form a common discipline which has acquired only recently its autonomy. Formerly under the direction of the surgeon, the anaesthetist is at the core of a multidisciplinary profession. If the anaesthetic treatment supposes, down the line, application of techniques of intensive care, the opposite is not systematically true. Indeed, the anaesthetist, taken as a member of an intensive care unit, can be confronted with the issue of organ removal which practice necessarily relates back to the difficult definition of death. Concerning its object itself, civil dispute regarding anaesthetics and intensive care covers a large-scale field. This in-depth study would highlight the drafting of norms ruling the discipline upon which the professional context has a decisive influence, then their practice by the anaesthetist itself, and finally their appropriateness to the clinical case as considered by the civil judge whenever a patient had brought legal action in responsibility before a tribunal

<p>Introduktion: Patientkontrollerad epidural smärtlindring (PCEA) är idag en vedertagen metod för postoperativ smärtlindring med få komplikationer. Försök har gjorts för att titrera fram den mest gynnsamma kombinationen med fokus på att maximera smärtlindringen och minimera sidoeffekterna. Syftet med studien är att identifiera smärta, sidoeffekter och behandlingstid samt patientens subjektiva skattning av smärtlindring vid postoperativ PCEA-behandling med bupivacaine, fentanyl och epinephrine.</p><p>Metod: Studien är retrospektiv inkluderande 1088 patienter vilka postoperativt behandlats med PCEA och kombinationslösningen bupivacaine (1mg/ml), fentanyl (2μg/ml) och epinephrine (2μg/ml). Studien har undersökt skillnaden mellan kön, ålder och typ av kirurgi avseende smärta i vila respektive smärta vid mobilisering/hosta, infusionshastighet, givna och begärda bolusdoser, behandlingstid, sidoeffekter samt patientens subjektiva skattning av smärtlindringen.</p><p>Resultat: Smärta i vila och vid mobilisering/hosta var under de studerade dygnen generellt låg, smärtan kulminerade under dygn 2. De yngre patienterna visade sig skatta smärta högre under behandlingstiden. Studien visade att smärta vid mobilisering/hosta var högre vid längre behandlingstid. Kvinnor hade mer illamående och klåda, vilket inte entydigt påverkade behandlingstiden. Patienter vilka hade haft smärta både i vila och vid mobilisering/hosta skattade ett lägre betyg gällande smärtlindringen vid hemgång. Andelen patienter som avslutade PCEA-behandlingen relaterat till minskat behov var 78%.</p><p>Konklusion: Patienterna upplevde att den postoperativa smärtlindringen med PCEA med kombinationslösningen var mycket god. Typ av kirurgi, kön och smärta vid mobilisering/hosta visade sig påverka behandlingstiden. Förekomsten av sidoeffekter var hög men påverkade inte patientens betyg negativt. Smärtan hos patienterna var generellt låg.</p>