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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Comparing the supine and erect pelvis radiographic examinations: an evaluation of anatomy, image quality and radiation dose

Flintham, K., Alzyoud, K., England, A., Hogg, P., Snaith, Beverly 16 June 2021 (has links)
Yes / Objectives: Pelvis radiographs are usually acquired supine despite standing imaging reflecting functional anatomy. We compared supine and erect radiographic examinations for anatomical features, radiation dose and image quality. Methods: 60 patients underwent pelvis radiography in both supine and erect positions at the same examination appointment. Measures of body mass index and sagittal diameter were obtained. Images were evaluated using visual grading analysis and pelvic tilt was compared. Dose–area product values were recorded and inputted into the CalDose_X software to estimate effective dose (ED). The CalDose_X software allowed comparisons using data from the erect and supine sex-specific phantoms (MAX06 & FAX06). Results: Patient sagittal diameter was greater on standing with an average 20.6% increase at the iliac crest (median 30.0, interquartile range [26.0 to 34.0] cm), in comparison to the supine position [24.0 (22.3 to 28.0) cm; p < 0.001]. 57 (95%) patients had posterior pelvic tilt on weight-bearing. Erect image quality was significantly decreased with median image quality scores of 78% (69 to 85) compared to 87% for the supine position [81 to 91] (p < 0.001). In the erect position, the ED was 47% higher [0.17 (0.13 to 0.33) mSv vs 0.12 (0.08 to 0.18) mSv (p < 0.001)], influenced by the increased sagittal diameter. 42 (70%) patients preferred the standing examination. Conclusion: Patient diameter and pelvic tilt were altered on weightbearing. Erect images demonstrated an overall decrease in image quality with a higher radiation dose. Optimal acquisition parameters are required for erect pelvis radiography as the supine technique is not directly transferable. / College of Radiographers Industry Partnership Scheme grant.
12

Sleep apnea and sleep : diagnostic aspects

Sahlin, Carin January 2009 (has links)
Background: Patients with sleep apnea have frequent apneas and hypopneas during sleep. Apneas can be either central or obstructive. The apnea-hypopnea index (AHI) is the mean number of apneas and hypopneas per hour of sleep. Aims: 1) To evaluate the effect of a mandibular advancement device on obstructive apneas and sleep; 2) to evaluate the influence of body position on central apnea frequency; 3) to investigate whether obstructive or central apnea is related to mortality in patients with stroke; and 4) to investigate sleep and sleeping positions in women. Methods: Subjects were investigated during whole-night sleep respiratory recordings, either polysomnography including continuous recordings of EEG, EOG, EMG, airflow, respiratory effort, ECG, pulse oximetry and body position, or simplified sleep apnea recordings without EEG, EOG and EMG. Results: The frequency of obstructive apneas, hypopneas and arousals decreased and rapid eye movement (REM) sleep increased in patients with mild, moderate and severe sleep apnea during treatment with a mandibular advancement device. Central apneas were more prevalent in the supine position compared with the non-supine position in patients with Cheyne-Stokes respiration. The mean ± SD central AHI was 41 ± 13 in the supine position and 26 ± 12 in the non-supine position, p&lt;0.001. Stroke patients with obstructive sleep apnea ran an increased risk of death during 10 ± 0.6 years of follow-up with an adjusted hazard ratio of 1.76 (95% CI 1.05-2.95) compared with controls, independent of hypertension, age, body mass index, gender, smoking, diabetes mellitus, atrial fibrillation, Mini-Mental State Examination and Barthel-ADL. Central apnea was not related to early death. Total sleep time, sleep efficiency, rapid eye movement sleep, slow wave and time in the supine position decreased with age in women. Sleep quality in women was reduced with age, body mass index, obstructive sleep apnea, smoking, alcohol and hypertension. Conclusions: Obstructive sleep apneas and arousals are reduced and REM sleep is increased using a mandibular advancement device in patients with mild, moderate and severe sleep apnea. The frequency of central apneas and hypopneas is increased in the supine position in patients with Cheyne-Stokes respiration. Stroke patients with obstructive sleep apnea run an increased risk of early death. Central sleep apnea was not related to early death among the present patients. Normal values for sleep stages and sleeping positions are presented in a population-based sample of women. Age, body mass index, obstructive sleep apnea, smoking, alcohol and hypertension reduce sleep quality in women.
13

Padronização da medição da frequência cardíaca de repouso

Lima Júnior, Luizir Alberto de Souza 27 March 2012 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-05-16T13:02:47Z No. of bitstreams: 1 luiziralbertodesouzalimajunior.pdf: 1017703 bytes, checksum: f428c0dd46d8e916774da450732d3c28 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T16:14:41Z (GMT) No. of bitstreams: 1 luiziralbertodesouzalimajunior.pdf: 1017703 bytes, checksum: f428c0dd46d8e916774da450732d3c28 (MD5) / Made available in DSpace on 2017-05-17T16:14:41Z (GMT). No. of bitstreams: 1 luiziralbertodesouzalimajunior.pdf: 1017703 bytes, checksum: f428c0dd46d8e916774da450732d3c28 (MD5) Previous issue date: 2012-03-27 / Durante o repouso, a atividade colinérgica predomina sobre o nódulo sinoatrial. Assim o mecanismo de controle da Frequência Cardíaca pela atividade vagal, juntamente com a diminuída demanda energética, irão determinar a frequência cardíaca de repouso (FCR) de um indivíduo fisiologicamente íntegro. A FCR possui importância reconhecida como indicador independente de saúde cardiovascular, relação com doenças não cardiovasculares, além da sua utilização em fórmulas, questionários e protocolos relacionados ao exercício físico. Apesar da reconhecida notoriedade da FCR na prática clínica e física, ainda não foi estabelecido um modo de medição com evidências científicas, que sustentam a existência de um padrão. Desta forma o presente estudo procurou investigar, através de dois artigos, de que forma a FCR vem sendo utilizada na prática profissional de profissionais de Educação Física, no que tange as formas de medição (tempo, posição), cuidados pré e durante (substâncias interferentes e condições ambientais) e objetivos da medição. Além disso, testar e propor aplicações práticas da FCR mediante tempo e postura corporal de medição. No primeiro estudo foram entrevistados profissionais de Educação Física, através de um questionário composto por oito questões sobre a forma de utilização da FCR, tais como, importância da variável, período de repouso antes e durante a mensuração, posição corporal, equipamento, e condições ambientais (temperatura, luminosidade, substâncias interferentes). De acordo com os resultados apresentados pelas respostas dos questionários, pôde-se concluir que o uso da FCR pelos profissionais de Educação Física, não possui uma padronização para sua medição, havendo divergências estatisticamente significativas nos critérios de utilização e avaliação. No segundo estudo foram avaliados 39 indivíduos jovens (21 homens e 18 mulheres), submetidos a avaliações em repouso em duas posições, supina e sentada, cada uma com a duração de 60 minutos. Os resultados mostraram que as medições realizadas em apenas cinco minutos não eram diferentes estatisticamente das medições realizadas nos 60 minutos. Além disso, na posição sentada a FCR é 12% maior que na posição supina, retratando diferença estatística. Estes resultados se repetiram entre gêneros e entre indivíduos mais e menos ativos. Portanto, de acordo com os resultados dos estudos, pôde- se verificar a inexistência de consensos para a medição da FCR entre os profissionais de educação física. Entretanto o presente estudo propõe a medição para homens e mulheres jovens mais e menos ativos, utilizando 5 minutos de repouso, registrandose a média deste período e observando a posição medida para as devidas correções. / During rest, cholinergic activity predominates over the sympathetic system. Thus the control mechanism of Heart Rate by vagal activity, together with the reduced energy requirements, will determine the frequency resting heart rate (RHR) of an individual physiologically intact. The RHR has recognized as important independent predictor of health cardiovascular disease compared with non-cardiovascular, beyond its use in formulas, questionnaires and protocols related to exercise physical. Despite the notoriety of the RHR recognized in clinical practice and physical not yet established a method of measuring with scientific evidence that support the existence of a pattern. Thus the present study sought investigate, by means of two articles, how the RHR has been used in professional practice of physical education professionals, regarding the forms of measurement (time, location), and during antenatal care (substances interference and environmental conditions) and objective measurement. Furthermore, test and propose practical applications of RHR through time and body posture measurement. In the first study were interviewed education professionals Physics, through a questionnaire consisting of eight questions on how to use of the RHR, such as importance of the variable, rest period before and during the measurement, body position, equipment, and conditions environmental (temperature, light, interfering substances). According with the results presented by the questionnaire responses, we conclude that the use of RHR by physical education professionals, has no a standard for its measurement, with differences statistically significant use and the criteria for evaluation. In the second study were studied 39 young subjects (21 men and 18 women) who underwent evaluations at rest in two positions, supine and sitting positions, each with for 60 minutes. The results show that measurements made on only five minutes were not statistically different measurements performed in 60 minutes. Furthermore, in the sitting position is 12% higher HRH that in the supine position, portraying statistical difference. These results repeated between genders and between more and less active individuals. Therefore the According to the results of the studies, it was possible to verify the absence of consensus for the measurement of HRH among physical education teachers. However the present study proposes to measure for young men and women more and less active, using 5-minute rest, recording the average this period and noting the position measured for the corrections.
14

Efeitos agudos da administraÃÃo de pressÃo positiva contÃnua em vias aÃreas de modo nÃo invasivo sobre o parÃnquima pulmonar de voluntÃrios sadios nas posiÃÃes supina e prona: alteraÃÃes na tomografia computadorizada de alta resoluÃÃo / Effects of noninvasive continuous positive airway pressure on pulmonary inflation in normal subjects in supine and prone positions evaluated by high resolution computed tomography

Georgia Freire Paiva Winkeler 27 October 2006 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / IntroduÃÃo: A ventilaÃÃo nÃo invasiva com pressÃo positiva (VNI) vem tendo uma crescente utilidade na prÃtica clÃnica e o seu uso està bem estabelecido em casos de edema agudo de pulmÃo e nas exacerbaÃÃes da doenÃa pulmonar obstrutiva crÃnica (DPOC), diminuindo a necessidade de intubaÃÃo orotraqueal e melhorando a sobrevida. AlÃm disso, a pressÃo positiva contÃnua em vias aÃreas (CPAP) â modo de VNI â constitui o tratamento de escolha para pacientes portadores da sÃndrome de apnÃia obstrutiva do sono (SAOS), onde geralmente nÃo hà alteraÃÃo no parÃnquima pulmonar. Ainda a aplicaÃÃo de nÃveis elevados de pressÃo positiva expiratÃria final (PEEP) no manejo da sÃndrome do desconforto respiratÃrio agudo (SDRA) està associada tanto ao recrutamento alveolar como à hiperdistensÃo de Ãreas previamente normoaeradas, com resultados ainda indefinidos quanto ao impacto na sobrevida. Um dos recursos para melhora da oxigenaÃÃo nestes pacientes à a posiÃÃo prona e os efeitos da associaÃÃo desta manobra com pressÃo positiva permanecem controversos. A tomografia computadorizada de alta resoluÃÃo (TCAR) constitui um excelente mÃtodo de imagem para avaliaÃÃo qualitativa e quantitativa do parÃnquima pulmonar. O emprego da TCAR pode auxiliar na investigaÃÃo dos efeitos da CPAP de modo nÃo invasivo sobre o parÃnquima pulmonar, contribuindo para a elucidaÃÃo dos efeitos fisiolÃgicos da pressÃo positiva e da posiÃÃo prona. Objetivos: Avaliar e comparar os efeitos de diferentes nÃveis de CPAP de modo nÃo invasivo sobre o parÃnquima pulmonar em indivÃduos sadios nas posiÃÃes supina e prona. CasuÃstica e mÃtodos: Estudo intervencionista com oito voluntÃrios sadios, sem doenÃa cardiopulmonar. Foram realizados cortes tomogrÃficos de alta resoluÃÃo em trÃs regiÃes: Ãpice (2 cm acima do arco aÃrtico), hilo (1 cm abaixo da carina) e base (2 cm acima do diafragma) na posiÃÃo supina, sem CPAP (basal) e com CPAP de 5, 10 e 15 cmH2O; e na posiÃÃo prona, corte em base, sem CPAP e com CPAP de 10 cmH2O. A seqÃÃncia das posiÃÃes e da ordem das pressÃes aplicadas foi randomizada. Aguardava-se um perÃodo de no mÃnimo 5 minutos apÃs completa adaptaÃÃo da mÃscara para realizaÃÃo do exame e o mesmo perÃodo de tempo entre um nÃvel de pressÃo e outro. Os dados foram analisados agrupando-se os cortes tomogrÃficos das trÃs regiÃes e por subdivisÃes em regiÃes ventral, medial e dorsal, sendo calculadas as mÃdias das densidades pulmonares e o percentual do nÃmero de unidades com densidade menor que -950 UH (hiperaeradas) para cada uma das regiÃes. Resultados: NÃo houve diferenÃa das mÃdias das densidades pulmonares entre Ãpice, hilo e base para o mesmo nÃvel de pressÃo. Na posiÃÃo supina, houve reduÃÃo da densidade pulmonar e aumento do percentual de pixels nas Ãreas hiperaeradas com nÃveis crescentes de pressÃo: basal -761 UH e 7,25%; CPAP 5: -780 UH e 8,57%; CPAP 10: -810 UH e 11,62%; CPAP 15: -828 UH e 14,65% (p < 0,05). O mesmo foi observado na posiÃÃo prona: basal -759 UH e 6,30%; CPAP 10: -803 UH e 9,94% (p < 0,05). Este aumento da aeraÃÃo tambÃm foi observado nas regiÃes ventral, medial e dorsal. Foi encontrado um gradiente crescente no sentido ventro-dorsal de densidades pulmonares na posiÃÃo supina e o inverso na posiÃÃo prona. A CPAP de 10 cmH2O, na posiÃÃo prona, ocasionou menor aumento do percentual de pixels nas Ãreas hiperaeradas em relaÃÃo à supina. Nas regiÃes nÃo dependentes do pulmÃo (ventral em supina e dorsal em prona), observou-se um menor percentual de pixels nas Ãreas hiperaeradas e aumento nas normoaeradas na posiÃÃo prona em relaÃÃo à supina, praticamente sem diferenÃa nas regiÃes dependentes. ConclusÃes: A aplicaÃÃo de diferentes nÃveis de CPAP, de modo nÃo invasivo, em voluntÃrios sadios, resultou em maior aeraÃÃo com nÃveis crescentes de pressÃo e maior homogeneizaÃÃo da aeraÃÃo pulmonar, tanto na posiÃÃo supina como na prona. Houve menor hiperaeraÃÃo nas regiÃes nÃo dependentes na posiÃÃo prona, em relaÃÃo à supina, sem CPAP e com CPAP de 10 cmH2O, com melhor distribuiÃÃo da aeraÃÃo pulmonar naquela posiÃÃo. / Introduction: Noninvasive positive-pressure ventilation (NIPPV) is an effective means of treating patients with acute respiratory failure and its use has been well established in cardiogenic pulmonary edema and in exacerbations of chronic obstructive pulmonary disease (COPD), reducing the need for endotracheal intubation and improving survival. Furthermore the continuous positive airway pressure (CPAP) â a mode of NIPPV â is the recommended treatment for obstructive sleep apnea syndrome (OSAS), where frequently there is no abnormality in pulmonary parenchyma. Also in the acute respiratory distress syndrome (ARDS), the application of positive end-expiratory pressure (PEEP) may result in alveolar recruitment of nonaerated units as well as in overinflation of the aerated lung areas. Alveolar overinflation is considered an important factor related to ventilator-induced lung injury causing higher mortality. The prone position has beneficial effects on oxygenation in these patients and the additive effect of PEEP with this maneuver is debatable. High resolution computed tomography (HRCT) is an excellent imaging method to evaluate the effects of positive pressure and prone position on pulmonary parenchyma. Objectives: To evaluate the effects of CPAP applied by a nasal mask on pulmonary inflation in normal subjects in supine and prone positions. Patients and methods: This is an interventionist study that evaluated eight healthy volunteers. A protocol of HRCT of the lung was performed in three regions: at the apex (2 cm above the aortic level), hilum (1 cm below the carina) and basis (2 cm above the right diaphragm) in the supine position, without and with CPAP of 5, 10 and 15 cmH2O. Also HRCT slices were performed in the prone position at the lung basis, without and with CPAP of 10 cmH2O. All HRCT slices were obtained at the functional residual capacity. Each CPAP level was maintened at least five minutes and the period between the different levels of CPAP was similar. For analysis the results were divided into regions ventral, medial and dorsal and with slices of apex, hilum and basis together. The mean lung densities (MLD) and the percentual of units with densities lower than -950 UH (overinflated) were calculated for each region. Results: There was no difference between the MLD of apex, hilum and basis for the same level pressure. In the supine position, there were a MLD reduction and an increase of the number of pixels on hyperinflated areas according to CPAP levels: without CPAP -761 HU e 7,25%; CPAP 5: -780 HU e 8,57%; CPAP 10: -810 HU e 11,62%; CPAP 15: -828 UH e 14,65% (p< 0,05). The same occurred in the prone position without CPAP: -759 UH e 6,30% and with CPAP 10: -803 UH e 9,94% (p < 0,05). It was observed a crescent ventro-dorsal density gradient in supine position that was inverse in prone position. At CPAP of 10 cmH2O there was lower percentage of pixels on hyperinflated areas in the prone position than in supine. In the non dependent lung regions (ventral in supine and dorsal in prone) there were lower percentage of pixels on hyperinflated areas and higher on normoaerated areas in the prone position than in supine with little differences in the dependent regions. Conclusions: Non invasive CPAP in normal subjects induces progressive overdistension with increase of pressure levels in supine and prone positions. CPAP of 10 cmH2O causes less overdistension of the non dependent regions than the same level of CPAP in supine position, without inducing significant overinflation of the dependent regions. So that the prone position causes a more homogeneous air distribution through the lungs.
15

Deckengestaltung für Liegendpatient:innen: Gestaltungsmöglichkeiten der Decken von Notaufnahmen mit Grafik, Licht und Farbe

Luo, Xiao 08 July 2022 (has links)
Patient:innen, die in der Notaufnahme liegen, stehen vor dem Problem, eine ungewohnte Umgebung aus einer veränderten Perspektive zu erleben. Die Umgebung der Notaufnahme ist für diese Patientengruppe nicht immer freundlich und zumeist wenig gestaltet. Liegende Patient:innen können sich in den verschiedenen Bereichen ängstlich und unbehaglich fühlen. Die Deckengestaltung von drei Bereichen wurde aufgrund von Patientenabläufen für die Analyse gewählt: der Flur, der Überwachungsbereich und der Untersuchungsraum. Daraus ergibt sich die Forschungsfrage, welche Deckengestaltungen die negativen Gefühle liegender Patient:innen in den drei Bereichen der Notaufnahme mildern würden. Um die Kriterien für die Analyse der Deckengestaltung festzulegen, werden aus der Literatur Faktoren ermittelt, die sich positiv auf Patient:innen auswirken. Dabei werden die drei Grundkriterien Licht, Farbe und Grafik ermittelt. Anhand von Beispielen aus der Praxis wird gezeigt, dass die drei Gestaltungsprinzipien in verschiedenen Bereichen unterschiedlich Anwendung finden. Die Ergebnisse zeigen die Verwendung von einzelnen Farbtönen und natürlichem Licht im Flur. Im Überwachungsbereich kann der aktive Einsatz von Farben und Grafik festgestellt werden. Die geeignete Anordnung von künstlicher Beleuchtung und die Auswahl geeigneter Grafik im Untersuchungsraum wird gezeigt.
16

Comparison of Radiation Treatment Plans for Breast Cancer between 3D Conformal in Prone and Supine Positions in Contrast to VMAT and IMRT Supine Positions

Bejarano Buele, Ana Isabel January 2015 (has links)
No description available.
17

The inferior vena caval compression theory of hypotension in obstetric spinal anaesthesia : studies in normal and preeclamptic pregnancy : a literature review and revision of fundamental concepts

Sharwood-Smith, Geoffrey H. January 2011 (has links)
Three clinical investigations together with a combined editorial and review of the cardiovascular physiology of spinal anaesthesia in normal and preeclamptic pregnancy form the basis of a thesis to be submitted for the degree of Doctor of Medicine at the University of St Andrews. First, the longstanding consensus that spinal anaesthesia could cause severe hypotension in severe preeclampsia was examined using three approaches. The doses of ephedrine required to maintain systolic blood pressure above predetermined limits were first compared in spinal versus epidural anaesthesia. The doses of ephedrine required were then similarly studied during spinal anaesthesia in preeclamptic versus normal control subjects. The principal outcome of these studies, that preeclamptic patients were resistant to hypotension after a spinal anaesthetic, was then further investigated by studying pulse transit time (PTT) changes in normal versus preeclamptic pregnancy. PTT was explored both as beat-to-beat monitor of cardiovascular function and also as an indicator of changes in arterial stiffness. The cardiovascular physiology of obstetric spinal anaesthesia was then reviewed in the light of the three clinical investigations, developments in reproductive vascular biology and the regulation of venous capacitance. It is argued that the theory of a role for vena caval compression as the single cause of spinal anaesthetic induced hypotension in obstetrics should be revised.
18

Goldmann and error correcting tonometry prisms compared to intracameral pressure

McCafferty, Sean, Levine, Jason, Schwiegerling, Jim, Enikov, Eniko T. 04 January 2018 (has links)
Background: Compare Goldmann applanation tonometer (GAT) prism and correcting applanation tonometry surface (CATS) prism to intracameral intraocular pressure (IOP), in vivo and in vitro. Methods: Pressure transducer intracameral IOP was measured on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically to 10, 20, and 40 mmHg. Simultaneously, IOP was measured using a Perkins tonometer with a standard GAT prism and a CATS prism at each of the intracameral pressures. Statistical comparison was made between true intracameral pressures and the two prism measurements. Differences between the two prism measurements were correlated to central corneal thickness (CCT) and corneal resistance factor (CRF). Human cadaver eyes were used to assess measurement repeatability. Results: The CATS tonometer prism measured closer to true intracameral IOP than the GAT prism by 1.7+/-2.7 mmHg across all pressures and corneal properties. The difference in CATS and GAT measurements was greater in thin CCT corneas (2.7+/-1.9 mmHg) and low resistance (CRF) corneas (2.8+/-2.1 mmHg). The difference in prisms was negligible at high CCT and CRF values. No difference was seen in measurement repeatability between the two prisms. Conclusion: A CATS prism in Goldmann tonometer armatures significantly improve the accuracy of IOP measurement compared to true intracameral pressure across a physiologic range of IOP values. The CATS prism is significantly more accurate compared to the GAT prism in thin and less rigid corneas. The in vivo intracameral study validates mathematical models and clinical findings in IOP measurement between the GAT and CATS prisms.
19

Goldmann applanation tonometry error relative to true intracameral intraocular pressure in vitro and in vivo

McCafferty, Sean, Levine, Jason, Schwiegerling, Jim, Enikov, Eniko T. 25 November 2017 (has links)
Background: Goldmann applanation tonometry (GAT) error relative to intracameral intraocular pressure (IOP) has not been examined comparatively in both human cadaver eyes and in live human eyes. Futhermore, correlations to biomechanical corneal properties and positional changes have not been examined directly to intracameral IOP and GAT IOP. Methods: Intracameral IOP was measured via pressure transducer on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically on each patient alternately to 10, 20, and 40 mmHg. IOP was measured using a Perkins tonometer in the supine position on 58 eyes and upright on a subset of 8 eyes. Twenty one (21) fresh human cadaver globes were Intracamerally IOP adjusted and measured via pressure transducer. Intracameral IOP ranged between 5 and 60 mmHg. IOP was measured in the upright position with a Goldmann Applanation Tonometer (GAT) and supine position with a Perkins tonometer. Central corneal thickness (CCT) was also measured. Results: The Goldmann-type tonometer error measured on live human eyes was 5.2 +/- 1.6 mmHg lower than intracameral IOP in the upright position and 7.9 +/- 2.3 mmHg lower in the supine position (p <.05). CCT also indicated a sloped correlation to error (correlation coeff. = 0.18). Cadaver eye IOP measurements were 3.1+/-2. 5 mmHg lower than intracameral IOP in the upright position and 5.4+/- 3.1 mmHg in the supine position (p <.05). Conclusion: Goldmann IOP measures significantly lower than true intracameral IOP by approximately 3 mmHg in vitro and 5 mmHg in vivo. The Goldmann IOP error is increased an additional 2.8 mmHg lower in the supine position. CCT appears to significantly affect the error by up to 4 mmHg over the sample size.
20

Assessment of cerebral venous return by a novel plethysmography method

Zamboni, P., Menegatti, E., Conforti, P., Shepherd, Simon J., Tessari, M., Beggs, Clive B. January 2012 (has links)
BACKGROUND: Magnetic resonance imaging and echo color Doppler (ECD) scan techniques do not accurately assess the cerebral venous return. This generated considerable scientific controversy linked with the diagnosis of a vascular syndrome known as chronic cerebrospinal venous insufficiency (CCSVI) characterized by restricted venous outflow from the brain. The purpose of this study was to assess the cerebral venous return in relation to the change in position by means of a novel cervical plethysmography method. METHODS: This was a single-center, cross-sectional, blinded case-control study conducted at the Vascular Diseases Center, University of Ferrara, Italy. The study involved 40 healthy controls (HCs; 18 women and 22 men) with a mean age of 41.5 +/- 14.4 years, and 44 patients with multiple sclerosis (MS; 25 women and 19 men) with a mean age of 41.0 +/- 12.1 years. All participants were previously scanned using ECD sonography, and further subset in HC (CCSVI negative at ECD) and CCSVI groups. Subjects blindly underwent cervical plethysmography, tipping them from the upright (90 degrees ) to supine position (0 degrees ) in a chair. Once the blood volume stabilized, they were returned to the upright position, allowing blood to drain from the neck. We measured venous volume (VV), filling time (FT), filling gradient (FG) required to achieve 90% of VV, residual volume (RV), emptying time (ET), and emptying gradient (EG) required to achieve 90% of emptying volume (EV) where EV = VV - RV, also analyzing the considered parameters by receiver operating characteristic (ROC) curves and principal component mathematical analysis. RESULTS: The rate at which venous blood discharged in the vertical position (EG) was significantly faster in the controls (2.73 mL/second +/- 1.63) compared with the patients with CCSVI (1.73 mL/second +/- 0.94; P = .001). In addition, respectively, in controls and in patients with CCSVI, the following parameters were highly significantly different: FT 5.81 +/- 1.99 seconds vs 4.45 +/- 2.16 seconds (P = .003); FG 0.92 +/- 0.45 mL/second vs 1.50 +/- 0.85 mL/second (P < .001); RV 0.54 +/- 1.31 mL vs 1.37 +/- 1.34 mL (P = .005); ET 1.84 +/- 0.54 seconds vs 2.66 +/- 0.95 seconds (P < .001). Mathematical analysis demonstrated a higher variability of the dynamic process of cerebral venous return in CCSVI. Finally, ROC analysis demonstrated a good sensitivity of the proposed test with a percent concordant 83.8, discordant 16.0, tied 0.2 (C = 0.839). CONCLUSIONS: Cerebral venous return characteristics of the patients with CCSVI were markedly different from those of the controls. In addition, our results suggest that cervical plethysmography has great potential as an inexpensive screening device and as a postoperative monitoring tool.

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