Introduction of Doppler ultrasound techniques into the Intensive Care setting has revolutionised the way haemodynamic status is monitored in the critically ill. However, in order to increase the usefulness of these techniques, the Doppler signal and its spectrum need to be further analysed in ways to facilitate a better clinical response. Extensive processing of the Doppler spectrum on Diagnostic ultrasound machines is limited by the real time performance considerations. It was therefore proposed that the spectral information from these systems be extracted off-line and full set of analytical tools be made available to evaluate this information. This was achieved by creating an integrated and modular software tool called Spectron, which was intended as an aid in the overall management of the patients. The modular nature of Spectron was intended to ensure that new analytical tools and techniques could be easily added and tested. The software provides its users with considerable latitude in choosing various data acquisition and analysis parameters to suit various clinical situations and patient requirements. Spectron was developed under the Windows environment to provide a user friendly interface and to address a range of programming problems such as memory management and the size of the colour palettes. Spectron is able to detect the maximal velocities and compute the mean and median velocities. Relative increases in maximal velocities in cardiac blood flows after the administration of inotropic drugs have been shown in the pilot studies that were conducted. Spectron is able to help in obtaining estimates of the aortic blood flows and in other applications such measuring vascular impedance. Stenotic blood flows can be detected by using the spectral broadening index and blood flow characteristics can be studied by using various blood flow indices. Thus, this project attempted to help in patient management by providing clinicians with a range of blood flow parameters and has succeeded in meeting its objective to a large extent / Master of Engineering (Hons)

abstract: Background. Despite research aimed at understanding the mechanisms of essential hypertension, instances of this condition continue to rise. Recent findings indicate that the administration of dietary nitrates, in the form of beetroot juice and other nitrate-rich vegetables, may offer anti-hypertensive effects in various study populations. Objective. This randomized, placebo-controlled, crossover trial sought to compare the effects of high-nitrate vegetable salads to the effects of low-nitrate canned vegetables on plasma nitrate/nitrite concentration, peripheral and central-aortic systolic and diastolic blood pressures, pulse wave velocity, and flow-mediated dilation. Methods. Healthy, post-menopausal women (n=5; 80% Caucasian; 52.6 ± 5.7 years) with mildly elevated blood pressure (mean blood pressure ≥ 115/70 mm Hg and < 140/80 mm Hg) were randomly assigned to ingest a fresh, high-nitrate vegetable salad or a low-nitrate vegetable medley, twice per day, for a total of 10 consecutive days. Given the crossover design of the trial, participants observed a two to three week washout period followed by reassignment to the opposite condition. Findings were considered significant at a p-value < 0.05, and Wilcoxon Signed-Rank tests compared mean differences between conditions. Results. Plasma nitrate/nitrite concentration was significantly higher following consumption of the high-nitrate versus the low-nitrate condition (p = 0.043). Conversely, the differences in peripheral systolic and diastolic blood pressures were not statistically significant (p = 0.345 and p = 0.684 for systolic and diastolic pressures, respectively) nor were the differences in central-aortic systolic and diastolic blood pressures statistically significant (p = 0.225 and p = 0.465 for systolic and diastolic pressures, respectively). Similarly, when comparing the effects of the high-nitrate condition to the low-nitrate condition, the difference in pulse wave velocity was not statistically significant (p = 0.465). Finally, flow-mediated dilation tended to improve following consumption of the high nitrate condition (p = 0.080). Conclusion. Twice daily consumption of a fresh, high-nitrate vegetable salad significantly increased plasma nitrate/nitrite concentration. Although the trial was underpowered, there was a trend for improved flow-mediated dilation. Finally, twice daily consumption of a fresh, high-nitrate vegetable salad did not significantly lower peripheral or central-aortic systolic or diastolic blood pressures or pulse wave velocity. / Dissertation/Thesis / Masters Thesis Nutrition 2017

Background: Arterial and venous thromboses associated with the coronavirus disease 2019 (COVID-19) have been well described. These events are caused by a hypercoagulable state due to endotheliopathy and infection-driven coagulopathy. There has been an ever-increasing number of documented cases of aortic thrombosis (AoT) in COVID-19 patients. We conducted a systematic review of current scientific literature to identify and consolidate evidence of AoT in COVID-19 patients. Methods: A systematic review of literature was conducted between March 15, 2020, and May 1, 2021, on PubMed and Cochrane databases. Additionally, a case from our facility was included. Results: A total of 38 studies (12 case series and 26 case reports) and a case from our facility describing AoT in 56 COVID-19 patients were included. Patients were aged 64.8 ± 10.5 years, were predominantly male (75%), and had several comorbidities. AoT was symptomatic in 82,14% of patients; however, when D dimers were reported, they were significantly elevated even in otherwise asymptomatic patients. Most patients had no previous history of aortic disease. Thrombosis was described in all parts of the aorta, with several cases reporting multiple locations. The median reported time until development of AoT was 10 days. Peripheral thrombosis occurred in 73.21% of cases, most commonly causing lower limb ischemia. Mortality rate was 30.4%. Conclusions: AoT can occur with no clinical symptoms or as a primary symptom in otherwise asymptomatic COVID-19 patients. D dimers are a highly sensitive diagnostic tool. Diagnosis of this condition prior to development of complications could be instrumental in saving many lives.