Silicone oil (SO) is widely used as the long-term intraocular tamponade in treating various eye diseases such as complicated retinal detachment, proliferative vitreoretinopathy, proliferative diabetic retinopathy, giant retinal tear and ocular trauma. However, its propensity to emulsify is an inherent problem of its long-term use in-vivo. Dispersal of SO into many tiny oil droplets causes numerous complications such as inflammation, glaucoma and reproliferation. It may also be responsible for possible toxicity to both retina and optic nerve. Emulsification is one of the problems associated to the use of SO as a long-term intraocular tamponade. This study focused on the understanding on the physical nature and formation of in-vivo SO emulsion and the development of methods to reduce the complications associated with emulsification of SO by engineering approaches. A stepper motor driven mechanical platform was built to study the fluid flow of SO within an eye model chamber during eye-like movements and a quantitative method was established to study SO emulsification, both in-vivo and in-vitro. This method was used to compare the relative resistance of different SO against emulsification. In the last part of the thesis a novel rinse was proposed which aimed at removing the emulsified SO droplets in-vivo in an effective way. In the dynamic eye model experiment, both the increase in shear viscosity of SO and the extent of SO fill had an effect in reducing the shear. These effects were small compared to the effect of indents at reducing shear rate during eye-like movements. When SO emulsions from patients were analyzed it was found that over 90% of the emulsified droplets were outside the observable range under slit-lamp biomicroscopy. When the emulsification resistance of SO was tested using the quantitative method the result confirmed that SO with high-molecular-weight component (HMWC) was more emulsification resistant than SO with the same shear viscosity. The addition of HMWC increases the elasticity and thus increasing its resistance against emulsification. A novel rinse was also proposed to remove the emulsified droplets using physical phenomenon of double emulsification. To conclude, this study improved the understanding of the formation of SO emulsification. The clinical observable emulsified droplets are probably in all cases that was just the tip of the iceberg. Three practical suggestions were made: Firstly, the use of SO and encircling scleral buckling procedure in combination might reduce the shear rate. Secondly, the use of HMWC can reduce emulsification. Lastly, there may be a role in rinsing out the emulsified droplets using the proposed novel solution. The novel solution is going to fully developed and commercialized in the near future. / published_or_final_version / Ophthalmology / Doctoral / Doctor of Philosophy

M.Cur. / In the cardiothoracic critical care unit, the respiratory management, post-extubation forms an important component of the total nursing care of the patient. To ensure optimal respiratory management the critical care nurse needs guidelines through which quality and continuity of nursing care can be ensured. Through the effective management of the respiratory system of the patient the critical care nurse contributes to maintaining, promoting and restoring health. In this way the critical care nurse facilitates the patient's strive towards reaching his/her objective of obtaining wholeness and he/she obtains his/her objective of quality nursing. The aim of this study is to formulate guidelines for the respiratory mangement of the cardiothoracic patient, post-extubation. A qualitative-descriptive contextual spesific reseach was followed in which a focus group interview, the opinions of field specialists and the deductive analysis of a literture study were used to formulate guidelines for the respiratory management of the cardiothoracic patient, post-extubation. An analysis was done through which the focus group interview was coded and categories were formulated. These main categories and subcategories were then further explored and described by the literature and by die opinions of the field specialists. The guidelines which were formulated must relieve the uncertainty that exists among different critical care nurses and it must ensure continuity of nursing care. After the guideliness have been established to promote the nursing practice recommendations were made for nursing practice, nursing education and for further research.

By observing these warning criteria, surgery can be safely carried out if changes of signal amplitudes are within the threshold boundary. Future studies should aim to validate and refine the "warning criteria" for intraoperative neurophysiologic monitoring in different surgery. / During stable anesthesia, experiments were completed in 31 pigs. A decrease in SEP amplitude > 25% and / or TceMEP amplitude > 65% was associated with substantial risk of postoperative motor deficit. In addition, rapid deterioration of signal within 5 min of an event, and / or a lack of signal recovery within 30 min after the initial deterioration were also predictors of postoperative paraplegia or weakness. These findings also correlated well with radiological changes in the spinal cord. The sensitivity and specificity for TceMEP to predict adverse neurologic outcome were 100% and 90.5%, respectively. / In a porcine model of direct compression and distraction of the exposed spinal cord, we measured the perioperative changes in SEP and TceMEP. This was correlated with postoperative motor function using the modified Tarlov scale. Magnetic resonance diffusion tensor imaging of the spinal cord was also performed to assess the anatomical extent of injury three days after surgery. / The spinal cord is at risk of injury during complex operations of the spine or aorta, and may result in catastrophic long term disability. Intraoperative monitoring with somatosensory evoked potential (SEP) and transcranial electric motor evoked potential (TceMEP) are commonly performed to assess the integrity of the sensory and motor pathways, respectively. The purpose of this study was to identify the minimum changes in signal amplitudes, beyond which postoperative neurologic deficit may occur. / Liu, Quanmeng. / Adviser: Matthew Tu Chan. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 87-103). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Background: Beta blockers are recommended by the American College of Cardiology/American Heart Association Guidelines for high and intermediate-risk cardiac patients undergoing non-cardiac surgery. Beta blockers are a class of drugs that moderate the effects of increased catecholamine levels on the heart by selectively blocking beta receptors in the heart and blood vessels, resulting in a lower heart rate and blood pressure. Beta blocker use perioperatively has been shown to reduce the risk of ischemia and infarction. Purpose: The purpose of this project is to address beta blocker use in a group of anesthesia providers who routinely attend to high-risk and intermediate-risk cardiac patients undergoing non-cardiac surgery in a medium-sized private hospital in suburban South Florida. There are barriers to the implementation of the published guidelines for beta blocker administration, including lack of awareness of the best current practice and a lack of a formal beta blocker protocol at the institutional level. Methods: A simple and inexpensive beta blocker protocol was implemented and evaluated by various means. Beta blocker administration practices were examined and documented prior to and after protocol implementation. Beta blocker usage was examined prior to and after protocol implementation Findings/Implications: It was hypothesized that increased anesthesia provider awareness would lead to increased administration of perioperative beta blockers to high-risk and intermediate-risk cardiac patients undergoing non-cardiac procedures. Although there was a knowledge increase related to the new beta blocker protocol, no change in practice was observed.