I dagsläget står det svenska kraftnätet inför en stor utmaning om det ska kunna klara av att tillgodose Sveriges växande elbehov. Stora delar av kraftnätet måste förnyas samtidigt som det byggs ut. Vid projektering av nya kraftledningsgator måste geografisk information samlas in för att kunna planera arbetet och representera de möjliga kraftledningsgatorna som höjdmodeller. Det är då viktigt att denna data är korrekt. LiDAR-data är ett bra alternativ då det kan ge en bra bild av marken trots vegetation som kan befinna sig i en eventuell kraftledningsgata. I dagsläget används antingen Lantmäteriets Nationella Höjdmodellen (NH-modellen), eller så genomförs en luftburen laserskanning med hjälp av flygplan. Då NH-modellen ibland kan upplevas som otillräcklig på grund av sin låga upplösning, samtidigt som luftburen laserskanning kan vara kostsamt både ekonomiskt och ur en miljösynpunkt är det intressant att utforska alternativa metoder.    Syftet med detta examensarbete är att genomföra en jämförelseanalys av höjdmodeller genererade med LiDAR-data insamlade med UAV och flygplan för att få svar på vad som väsentligt skiljer dem åt och ifall LiDAR-data insamlat med UAV kan vara ett alternativ till LiDAR-data insamlat med flygplan. Detta görs tillsammans med företagen Nektab och Swescan för att undersöka möjligheterna att kunna erbjuda en ny produkt till sina kunder och uppdragsgivare. Ett tidigare projekterat område utanför Horndal i Dalarna, undersöktes då det fanns tillgängliga LiDAR-data från en tidigare luftburen laserskanning gjord med flygplan. LiDAR-data samlades in med drönare med två olika skanningsmetoder, repetitive och non-repetitive, den 3:e maj 2023. Bearbetning av punktmolnet genomfördes i DJI Terra och Terrasolids programvaror Terrascan och Terramatch. Kvalitetsberäkningar genomfördes i Excel. Höjdmodeller skapades i Esris Arcmap 10.8 och analyser gjordes för att jämföra de olika höjdmodellernas höjdvärden, lutning samt profiler.     Punktmolnen genererade med UAV-LiDAR hade en lägesnoggrannhet i höjd som uppfyllde kraven för HMK-standardnivå 3, och punktmolnet genererat med skanningsmetoden non-repetitive hade en bättre lägesnoggrannhet i höjd än punktmolnet genererat med flygplans-LiDAR. Skillnaderna som kunde upptäckas mellan de olika höjdmodellerna var små och påverkades både av skillnader i klassning och insamlingsmetod. Slutsatsen som drogs är att insamling av LiDAR-data med UAV och generering av kvalitativa höjdmodeller med dessa data är fullt möjligt för mindre områden så som det i det här arbetet. / The Swedish power grid is currently facing a big challenge if it’s going to be able to meet Sweden’s growing demand for electricity. While large parts of the power grid must be updated, there also needs to be a big expansion. When planning new corridors for the powerlines, geographical information must be collected to be able to visualize said corridors as Digital Elevation Models (DEMs) and it is thus important that the data is correct. LiDAR-data is a suitable alternative for this as it can represent the ground well despite any vegetation that might be present in the planned corridor. Currently open-source data from the Swedish National Land Survey, the National Elevation Model (the NH-model), is often used, or the area is mapped with airborne laser-scanning from a plane. However, the NH-model is sometimes not a suitable alternative due to its low resolution, while airborne laser-scanning can be both environmentally and economically costly. It is therefore interesting to explore alternative methods.    The aim of this bachelor thesis is to conduct a comparative analysis between DEMs generated by LiDAR-data collected by UAV and by plane to see where they differ, and if LiDAR-data collected by UAV is a potential alternative to LiDAR-data collected by plane. This will be done in collaboration with Nektab and Swescan to explore the possibility of being able to offer a new product to their customers and clients. A previously planned area outside the Swedish town of Horndal in the county of Dalarna, was used due to already existing plane-collected LiDAR-data. LiDAR-data was collected with an UAV through two different scanner-methods, repetitive and non-repetitive, on the 3rd of May 2023. The processing of the pointclouds were performed in DJI Terra and Terrasolids software Terrascan and Terramatch. Quality calculations and control was done in Excel. DEMs were created in Esris software Arcmap 10.8 and different analyses were performed to compare the DEMs elevation, slope, and profiles.    The point clouds generated from the UAV-LiDAR had a positional accuracy equivalent to the Swedish HMK-standard level 3, and the pointcloud generated from the non-repetitive­ scanner-method had a better positional accuracy for the z-value than the pointcloud generated from the plane-LiDAR. The differences between the DEMs were small and were caused both by difference in classification of the point clouds and collection method. The conclusion is that collection of LiDAR-data through UAV and the generation of high quality DEMs from this data is fully possible for smaller areas such as the one in this thesis.

Abstract Impact cratering is a fundamental geomorphic process on planetary surfaces. More than 60% of known hypervelocity impact craters on Earth are either partially or completely buried beneath post-impact sediments and one-third have been discovered with geophysical methods. In this thesis, geophysical surveys (gravity, magnetics, seismic, bathymetric mapping) were conducted at the deeply buried (>400 m) Holleford impact crater (~2.35 km) and two probable impact structures (Charity Shoal, Skeleton Lake) in southern Ontario, Canada. 3-D potential field models were constructed to determine the subsurface geology and buried crater morphology, and to evaluate evidence for possible impact versus endogenic origins. Holleford Crater is a deeply buried, Late Proterozoic-Early Cambrian (ca. 550 ±100 Ma) simple impact crater (~2.4 km) in southeastern Ontario, Canada. Land-based magnetic and gravity surveys and modelling were conducted in this study, recorded a ~ -3 mGal Bouguer anomaly and small (~30 nT) magnetic anomaly over the crater basin. 3-D gravity modelling revealed a deeply buried simple impact basin in Mesoproterozoic basement with an estimated rim-to-rim diameter (D) of 1.8-2 km, a residual rim height of ~20-30 m and true depth (dt) >400 m. The southeast crater rim is dissected by a 150 m deep, 400 m wide erosional channel produced by fluvial rim dissection. The outflow is infilled by >50 m of Late Cambrian clastic sediments, indicating a probable Late Proterozoic to Early Paleozoic impact event. Charity Shoal is a 1.2-km-diameter, 20 m deep, circular bedrock shoal in eastern Lake Ontario. Marine seismic profiling and total field magnetic surveys (140-line km) were conducted over a 9-km2 area and combined with available multi-beam bathymetric data to evaluate the subsurface geology and structure origin. Seismic surveys revealed ~30 m of Quaternary sediments overlying Middle Ordovician (Trenton Group) carbonates in the central basin and evidence for folding and faulting of the structure rim. Magnetic surveys recorded an annular magnetic high (> 600 nT) and a central magnetic low (~500-600 nT) coincident with a ~-1.7 mGal Bouguer gravity anomaly. The continuity of Middle Ordovician bedrock below the structure rules out a post-Paleozoic intrusion and a pre-Paleozoic intrusion is ruled out with the gravity anomaly. A deeply-buried (> 450 m) impact crater is the only scenario consistent with geophysical evidence. The crater has a rim-to-rim diameter of ~1.2 km, and rim height of ~15-20 m. A 100-m wide breach in the southwestern rim records a possible outflow channel. Skeleton Lake is a suspected (~4.0 km) Paleozoic-age impact structure in Muskoka, Ontario. The lakebed morphology, subsurface structure and possible impact origin were investigated with high-resolution geophysical surveys (magnetics, bathymetry; ~140 line-km) and 3-D magnetic modelling. Bathymetric data reveal a deep (>65 m) central basin with arcuate (Paleozoic?) bedrock ridges that rise >30 m above the southwestern lakebed. Magnetic surveys recorded a >700 nT magnetic low, which truncates northwest-southeast regional magnetic trends. Low-amplitude, northwest-trending magnetic lineaments delineate basement shear zones below the basin centre. Through-going magnetic lineaments and lack of thermal alteration (e.g., dikes, fenitization) in Mesoproterozoic rocks indicate a volcanic origin is unlikely. A 1.2 km diameter volcanic plug with an Early Cambrian remanence (D = 82.2°, I = 82.7°) can reproduce some aspects of the magnetic anomaly but is at odds with the Bouguer gravity anomaly (~ -3 mGal). Forward modelling of a crater-form basin with induction and remanence magnetization yielded an estimated structure depth of ~1200 m. The basement surface model shows a complex basement topography with no apparent rim structure and elevated ‘pinnacles’ that may represent eroded remnants of a central uplift or a highly-dissected basement topography. The structure apparent diameter (> 4.2 km) and complex basement topography suggest a heavily-modified transitional crater, similar with the Gow (Saskatchewan, Canada) and Kärdla (Estonia) impact structures. This thesis demonstrates the subsurface exploration of confirmed and suspected impact structures, integrating seismic, potential field (magnetics, gravity) and digital elevation data within a 3-D geophysical modelling workflow. The approach provides important new insights into the surface and subsurface geology, morphology, and post-emplacement modification of the Holleford impact crater, and new geophysical constraints for evaluating two suspected impact structures. Geophysical data confirm that Charity Shoal and Skeleton Lake are deep-seated, crater-form depressions in Mesoproterozoic basement rocks. The weight of geophysical and geological evidence points to impact cratering processes as opposed to an endogenic (volcanic) origin for both structures. / Thesis / Doctor of Science (PhD)

Digitala terrängmodeller (DTM:er) används i samhället för många viktigafunktioner och behöver därför hållas uppdaterade när förändringar sker.Sverige har en nationell höjdmodell (NH) som innehåller höjddata över helalandet. Uppdateringen av NH förlitar sig mestadels på flygburen laserskanning(FLS). Den flygburna laserskanningsmetoden har generellt en högremätosäkerhet i tätbevuxen skog. Vid exploateringar eller framtida planeradeförändringar i skogsområden kan en mer exakt modell behövas. En utvärdering har genomförts av den handhållna laserskannern ZEB-REVO med syfte att bestämma vilken mätosäkerhet som kan uppnås i tätbevuxenskog, undersöka hur mätosäkerheten förändras med punktavståndet i denproducerade DTM:en samt vilken mätosäkerhet ZEB-REVO har i jämförelsemed NH i samma område. I studien har två skogstyper inkluderats bestående av granskog och tallskog.Mätosäkerheten har bestämts genom att mäta in terrestra kontrollprofiler medtotalstation. För att kunna genomföra en inmätning av kontrollprofiler har ettbruksnät etablerats genom ett fullständigt anslutet polygontåg viahelsatsmätning. De kända punkterna som polygontåget anslutits mot har mättsin med fri stationsetablering via SmartWorx. Resultatet visar att mätosäkerheten förbättras när punktavståndet reduceras.Mätningarna med ZEB-REVO har potential att uppnå en lägre mätosäkerhetän NH i båda skogstyperna. Resultatet för tallskogen visar att ZEB-REVO kanuppnå en lägesosäkerhet på 4-centimetersnivå och en medelavvikelse i höjd på0,018 m mot inmätta kontrollprofiler. Jämförelsen mot kontrollprofiler förområdet i granskogen visar att en medelavvikelse i höjd på 0,058 m gick attuppnå där. ZEB-REVO har potential att förbättra data i NH och data insamlad med ZEBREVOkan ligga till grund för terrängmodellering för projektering.Instrumentet kan även uppnå den bästa noggrannhetsklassningen, klass 1 i SISTS21144:2016 där en maximal medelavvikelse i höjd inte får överstiga 0,02m. / Digital terrain models (DTMs) are used in society for many importantfunctions and therefore need to be kept up to date when changes occur.Sweden has a national height model (NH) that provides height data across thewhole country. The update of NH mostly relies on airborne laser scanning(ALS). The airborne laser scanning method generally has a highermeasurement uncertainty in dense forests. When exploitation or futureplanned changes in forest areas occur, a more accurate model may need to beproduced. An evaluation has been carried out of the handheld laser scanner ZEB-REVO with the aim of determining the instrument's measurement uncertainty indense forests, evaluating how the measurement uncertainty changes with thepoint distance in the produced DTM and the measurement uncertainty ZEBREVOmay achieve in comparison with NH in the same area. The study included two different types of forest consisting of spruce and pineforest trees, respectively. Measurement uncertainty has been determined bymeasuring terrestrial control profiles with a total station. In order to be ableto carry out the measurement of control profiles, a working control networkhas been established through a fully connected traverse using full rounds ofmeasurement. The known points to which the traverse is connected have beenmeasured as free stations using SmartWorx. The results show that the measurement uncertainty improves when the pointdistance is reduced. The measurements with ZEB-REVO have the potential toachieve a lower measurement uncertainty than NH in both forest types. Theresults for the pine forest show that ZEB-REVO can achieve a 4 centimetrelevel uncertainty and an average deviation of height of 0,018 m against themeasured control profiles. The comparison with control profiles for the areain the spruce forest shows that an average deviation in height of 0,058 m wasachievable. ZEB-REVO has the potential to improve data in NH and data collected withZEB-REVO can form the basis for terrain modelling for projectionwork. Theinstrument can also achieve the best accuracy rating 1, for which themaximum mean deviation in height must not exceed 0.02 m.

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Résumé : Le contexte récent d’accélération de la fonte des glaciers et calottes glaciaires (GCG) de l’archipel arctique canadien, jumelé aux difficultés de suivi des GCG de cette région, rendent essentiels le développement et l’utilisation de nouvelles approches innovatrices de suivi. Le potentiel de la stéréo radargrammétrie (SRG) RADARSAT-2 est ici caractérisé pour l’extraction d’élévations et le calcul de changements d’élévation et de bilans de masse (historiques et récents) sur les calottes glaciaires Barnes et Penny (Nunavut, Canada). Par la méthode semi-automatisée de recherche de corrélation à partir de couples stéréoscopiques RADARSAT-2 de 2013 (mode wide ultra-fin; résolution spatiale de 3 m; taille d’image de 50 km x 50 km), une précision verticale de ~7 m (LE68) est mesurée sur la terre ferme, et cette valeur de précision est possiblement légèrement supérieure sur la calotte Barnes, étant donné la variabilité de profondeur de pénétration. Par captage 3D, une précision altimétrique de ~3-4 m (LE68) est mesurée par différents photo-interprètes à partir de couples RADARSAT de 2012 en zone d’ablation de la calotte Penny. Sur la calotte Barnes, les changements d’élévation mesurés par rapport aux premiers modèles numériques de terrain disponibles permettent de mesurer un bilan de masse spécifique historique (1960-2013) de -0,49 ± 0,20 m w.e./année, pour un bilan de masse total de -2,9 Gt/année. Entre 2005 et 2013, le bilan de masse spécifique de cette calotte augmente significativement à -1,20 ± 0,86 m w.e./année, pour un bilan de masse total de -7 Gt/année. En zone d’ablation de la calotte Penny, un changement d’élévation annuel moyen de -0,59 m/année est mesuré entre 1958 et 2012. Parallèlement, plusieurs aspects méthodologiques et techniques sont discutés et analysés. Des profondeurs de pénétration nulles (bande C) sont mesurées à partir des images acquises sur la calotte Barnes à la toute fin de la saison d’ablation (fin septembre/début octobre), alors que cette profondeur augmente à ~2,5-3 m pour des images acquises à la fin octobre/début novembre (période de gel). Nos résultats suggèrent aussi que le modèle de fonction rationnelle, lorsqu’utilisé avec des images RADARSAT-2 en mode wide ultra-fin, permet d’obtenir des précisions plus constantes que le modèle hybride de Toutin. De par son indépendance des conditions météorologiques, son utilisation possible sans point de contrôle et sa simplicité de traitement, la SRG RADARSAT-2 s’avère donc être une excellente alternative aux technologies actuelles pour le suivi de GCG situés dans des régions affectées par des contraintes opérationnelles importantes. / Abstract : Given the recent melt acceleration of the Canadian arctic archipelago’s ice caps and the monitoring difficulties of this remote region, the development of new innovative monitoring tools has become essential. Here, the potential of the RADARSAT-2 stereo radargrammetry (SRG) is characterized for elevations extraction, as well as for elevation changes/mass balances calculations (historical and recent) on Barnes and Penny ice caps (Nunavut, Canada). Using the semi-automatic approach of correlation search from RADARSAT-2 stereoscopic couples of 2013 (wide ultra-fine mode; spatial resolution of 3 m; coverage of 50 km x 50 km), a vertical precision of ~7 m (LE68) is measured on ice-free terrain and this precision is possibly slighty worse on the ice cap because of the penetration depth’s variability. On the other hand, the 3D vision extraction approach reveals an altimetric precision of ~3-4 m (LE68) on the ablation area of the Penny Ice Cap. On the Barnes Ice Cap, elevation changes calculated relative to the oldest digital elevation models available allows to calculate an historical specific mass balance (1960-2013) of -0,49 ± 0,20 m w.e./year, resulting in a total annual mass balance of -2,9 Gt/year. Between 2005 and 2013, the specific mass balance of this ice cap increases to -1,20 ± 0,86 m w.e./year, which equals to a total annual mass balance f -7 Gt/year. On Penny Ice Cap’s ablation area, an average elevation change of -0,59 m/year is measured between 1958 and 2012. As also suggested in the literature, the recent melt acceleration is highly linked to warmer summer temperatures. Methodological and technical aspects are also presented and analyzed. No penetration depth (C band) is perceived on elevations derived from late ablation season images (late September/beginning of October), while a penetration of ~2,5-3 m is measured from images acquired in late October/beginning of November (freeze period). Our results also suggest the superiority and better consistency of the rational function model for geometrical correction of wide ultra-fine mode RADARSAT-2 images, compared to the hybrid Toutin’s model. Because of its all-weather functionality, its possible use without any ground control point and the simplicity and facility of its treatment, the RADARSAT-2 SRG represents a really good technology for glacier monitoring in regions affected by serious operational constraints.

Objectifs. L'infarctus aigu du myocarde (IDM) touche chaque année plus de 120 000 personnes en France. Nous nous sommes intéressés à la prise en charge du SCA avec sus-décalage du segment ST (ST+). Deux stratégies de revascularisation coronaires s'offrent à nous : la thrombolyse intraveineuse et l'angioplastie primaire. Notre travail a évalué l'impact du choix de ces stratégies dans la phase aiguë de l'infarctus du myocarde, à travers la mise en place d'un réseau associant la médecine d'urgence et la cardiologie interventionnelle autour d'un référentiel partagé. Méthode. Nous avons mis en place un réseau cardiologie - urgence (RESCUe), qui a fédéré au sein d'une association 37 structures d'urgence (SU), 19 structures mobiles d'urgence et de réanimation (SMUR) et 10 centres de cardiologie interventionnelle (CCI) dans un bassin géographique de 3 millions d'habitants. Notre méthode de travail s'articulait autour de trois axes : édition de référentiels partagés, formation et évaluation. Résultats. Dès la mise en place de RESCUe, nous avons lancé un essai multicentrique, contrôlé et randomisé, l'étude AGIR². En douze mois 320 SCA ST+ ont été inclus. Dès la prise en charge en SMUR tous les patients ont reçu 250 mg d'aspirine, 600 mg de clopidogrel, un bolus intraveineux de 60 IU/kg d'héparine avant d'être transférés en CCI pour une angioplastie primaire. Si le bénéfice d'une administration de tirofiban en SMUR n'était pas supérieur à son administration en CCI, AGIR² a conforté les bases d'une collaboration en réseau entre médecine d'urgence et cardiologie interventionnelle autour d'un référentiel thérapeutique partagé. Depuis, l'angioplastie primaire est progressivement devenue la stratégie de reperfusion de référence du SCA ST+ sur notre bassin. Pour évaluer son impact nous avons mis en place un registre observationnel couvrant l'ensemble des SU, SMUR et CCI du réseau. Entre 2009 et 2013 nous avons pris en charge 2418 patients en SMUR avec un diagnostic d'infarctus aigu du myocarde. Parmi eux, 2119 (87.6%) ont bénéficié d'une angioplastie primaire et 299 (12.4%) d'une thrombolyse intraveineuse. Nous avons observé une augmentation du recours à l'angioplastie primaire de 78.4% en 2009 à 95.9% en 2013 (P<0.001). Le délai médian ECG - arrivée en CCI était de 48 min, ECG - angioplastie 94 min et arrivée – angioplastie 43 min. Les délais symptôme – ECG et ECG – thrombolyse sont restés stables de 2009 à 2013, mais les délais symptôme – angioplastie et ECG – arrivée en CCI – angioplastie ont diminué (P<0.001). Au total 2146 (89.2%) patients avaient un délai ECG – arrivée en CCI ≤90 min, un délai confortant le choix d'une angioplastie primaire chez 97.7% d'entre eux en 2013, conformément aux recommandations. De 2009 à 2013, la mortalité hospitalière (4-6%) et celle à 30 jours (6-8%) est restée stable. Nous avons complété notre travail par une analyse de la conformité des mesures de prévention secondaire aux recommandations. A un an post-IDM, l'association bétabloquants – aspirine – statines – inhibiteurs de l'enzyme de conversion et la correction des facteurs de risque était liée à une meilleure survie. Parmi les 5161 patients pris en charge dans nos SU et en SMUR et sortis vivant de CCI, 2991 (58%) ont bénéficié de cette stratégie optimale avec un HR de 0.12 (95% CI 0.07–0.22; P<0.001). Les patients les plus graves étaient ceux les moins bien traités, à cause des contre-indications aux traitements (insuffisance rénale, risque hémorragique). Conclusion. Dans notre bassin géographique, la mise en place d'un réseau cardiologie urgence a abouti à l'augmentation du recours à l'angioplastie primaire, conformément aux recommandations. Il n'y a pas eu d'effet sur la mortalité précoce. Un bénéfice sur la mortalité à un an est observé chez les patients qui ont bénéficié de mesures de prévention secondaire optimales / Objective. Acute myocardial infarction (AMI) annually affects more than 120 000 people in France. We studied the management of ST elevation MI (STEMI). Two reperfusion strategies are available: intravenous thrombolysis (TL) and primary percutaneous coronary intervention (PPCI). Our study aimed to evaluate the impact of these strategies in the acute phase of myocardial infarction through the establishment of an emergency network based on a shared protocol with interventional cardiology. Methods. We established a regional emergency cardiovascular network (RESCUe Network) that covers a population of 3 million inhabitants across five administrative counties, including urban and rural territories. All nineteen MICUs, thirty seven emergency departments and 10 catheterization laboratories participate in the network. We edited regularly updated guidelines, set up a doctors’ training program and implemented an evaluation registry. Results. We setup the AGIR-2 study, a multicenter, controlled, randomized study, to explore prehospital high-dose tirofiban in patients undergoing PPCI. Three hundred and twenty patients with STEMI were included over a period of 12 months. All of them received 250 mg of aspirin, 600 mg of clopidogrel and 60 IU/kg bolus of high molecular weight heparin before admission to the catheterization laboratory. If prehospital initiation of high-dose bolus of tirofiban did not improve outcome, AGIR-2 study reinforced the collaborative network between emergency medicine and interventional cardiology. Since then, PPCI has gradually become the reference reperfusion strategy for STEMI in our network. Using data from our registry, we studied STEMI patients treated in mobile intensive care units (MICUs) between 2009 and 2013. Among 2418 patients, 2119 (87.6%) underwent PPCI and 299 (12.4%) prehospital TL (94.0% of whom went on to undergo PPCI). Use of PPCI increased from 78.4% in 2009 to 95.9% in 2013 (Ptrend<0.001). Median delays included: first medical contact (FMC)–PCI centre 48 min, FMC–balloon inflation 94 min, and PCI centre– balloon inflation 43 min. Times from symptom onset to FMC and FMC to TL remained stable during 2009 to 2013, but times from symptom onset to first balloon inflation and FMC to PCI centre to first balloon inflation decreased (P<0.001). In total, 2146 (89.2%) had an FMC–PCI centre delay ≤90 min with PPCI use up to 97.7% in 2013 in accordance with guidelines. Inhospital (4–6%) and 30-day (6–8%) mortalities remained stable from 2009 to 2013. Finally, we sought to assess the effect of strict adherence to current international guidelines on 1-year all-cause mortality in a prospective cohort of patients with STEMI. After multivariable adjustment, the association between the optimal therapy (OT) group (Betablockers, Antiplatelet agents, Statins, angiotensin-converting enzyme [ACE] Inhibitors, and Correction of all risk factors) and survival remained significant, with a hazard ratio of 0.12 (95% CI 0.07–0.22; P<0.001). Of the 5161 patients discharged alive, 2991 (58%) were prescribed OT. Patients characteristics in the under treatment (UT) group were worse than those in the OT group because of contraindications to optimal treatment (renal failure, bleeding risk). Conclusion. The establishment of an emergency network in our area resulted in an increased use of PPCI in accordance with ESC guidelines with no effect on early mortality. Reduction of one year mortality was observed in patients who received optimal secondary prevention treatment

Introduction: The most appropriate airway management technique for use by paramedics in out-of-hospital cardiac arrest is yet to be determined and evidence relating to the influence of airway management strategy on outcome remains equivocal. In cases where return of spontaneous circulation (ROSC) occurs following out-of-hospital cardiac arrest, patients may undergo direct transfer to a specialist heart attack centre (HAC) where the post resuscitation 12 lead ECG demonstrates evidence of ST elevation myocardial infarction. To date, no studies have investigated the role of airway management strategy on outcomes in this sub-set of patients. The AMICABLE (Airway Management In Cardiac Arrest, Basic, Laryngeal mask airway, Endotracheal intubation) study therefore sought to investigate the influence of prehospital airway management strategy on outcomes in patients transferred by the ambulance service directly to a HAC post ROSC. Methods: Adults with ROSC post out-of-hospital cardiac arrest who met local criteria for transfer to a HAC were identified prospectively. Ambulance records were reviewed to determine prehospital airway management approach and collect physiological and demographic data. HAC notes were obtained to determine in-hospital course and quantify neurological outcome via the Cerebral Performance Category (CPC) scale. Neurologically intact survivors were contacted post discharge to assess quality of life via the SF-36 health survey. Statistical analyses were performed via Chi-square, Mann Whitney U test, odds ratios, and binomial logistic regression. Results: A total of 220 patients were recruited between August 2013 and August 2014, with complete outcome data available for 209. The age of patients ranged from 22-96 years and 71.3% were male (n=149). Airway management was undertaken using a supraglottic airway (SGA) in 72.7% of cases (n=152) with the remainder undergoing endotracheal intubation (ETI). There was no significant difference in the proportion of patients with good neurological outcome (CPC 1&2) between the SGA and ETI groups (p=.286). Similarly, binomial logistic regression incorporating factors known to influence outcome demonstrated no significant difference between the SGA and ETI groups (Adjusted OR 0.725, 95% CI 0.337-1.561). Clinical and demographic variables associated with good neurological outcome included the presence of a shockable rhythm (p < .001), exposure to angiography (p < .001), younger age (p < .001) and shorter time to ROSC (p < .001). Due to an inadequate response rate (25.4%, n=15) analysis of SF36 data was limited to descriptive statistics. Limitations: The study only included patients who achieved ROSC and met the criteria for direct transfer to a HAC. Results are therefore not generalisable to more heterogenous resuscitation populations. Accuracy of clinical decision making and ECG interpretation were not assessed and therefore some patients included in the study may have been inappropriately transferred to a HAC. The low SF-36 survey response rate limited the level of neurological outcome analysis that could be undertaken. Conclusion: In this study, there was no significant difference in the proportion of good neurological outcomes in patients managed with SGA versus ETI during cardiac arrest. Further research incorporating randomised controlled trials is required to provide more definitive evidence in relation to the optimal airway management strategy in out-of-hospital cardiac arrest.

Topographic depressions are naturally occurring low land areas surrounded by areas of high elevations, also known as “pits” or “sinks”, on terrain surfaces. Traditional watershed modeling often neglects the potential effects of depressions by implementing removal (mostly filling) procedures on the digital elevation model (DEM) prior to the simulation of physical processes. The assumption is that all the depressions are either spurious in the DEM or of negligible importance for modeling results. However, studies suggested that naturally occurring depressions can change runoff response and connectivity in a watershed based on storage conditions and their spatial arrangement, e.g., shift active contributing areas and soil moisture distributions, and timing and magnitude of flow discharge at the watershed outlet. In addition, recent advances in remote sensing techniques, such as LiDAR, allow us to examine this modeling assumption because naturally occurring depressions can be represented using high-resolution DEM. This dissertation provides insights on the effects of depressions on overland flow processes at multiple spatial scales, from internal depression areas to the watershed scale, based on hydrologic connectivity metrics. Connectivity describes flow pathway connectedness and is assessed using geostatistical measures of heterogeneity in overland flow patterns, i.e., connectivity function and integral connectivity scale lengths. A new algorithm is introduced here to upscale connectivity metrics to large gridded patterns (i.e., with > 1,000,000 cells) using GPU-accelerated computing. This new algorithm is sensitive to changes of connectivity directions and magnitudes in spatial patterns and is robust for large DEM grids with depressions. Implementation of the connectivity metrics to overland flow patterns generated from original and depression filled DEMs for a study watershed indicates that depressions typically decrease overland flow connectivity. A series of macro connectivity stages based on spatial distances are identified, which represent changes in the interaction mechanisms between overland flow and depressions, i.e., the relative dominance of fill and spill, and the relative speed of fill and formation of connected pathways. In addition, to study the role of spatial resolutions on such interaction mechanisms at watershed scale, two revised functional connectivity metrics are also introduced, based on depressions that are hydraulically connected to the watershed outlet and runoff response to rainfall. These two functional connectivity metrics are sensitive to connectivity changes in overland flow patterns because of depression removal (filling) for DEMs at different grid resolutions. Results show that these two metrics indicate the spatial and statistical characteristics of depressions and their implications on overland flow connectivity, and may also relate to storage and infiltration conditions. In addition, grid resolutions have a more significant impact on overland flow connectivity than depression removal (filling).