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Now showing 1 - 5 of 20884
  • Item
    Anaesthetists’ knowledge of pulse contour cardiac output monitoring in a department of anaesthesiology
    (2022) Mandebvu, Takudzwa Richard
    Background An acceptable understanding of cardiac output measuring devices is essential for anaesthetists in order to appreciate their limitations and to safely apply their use during patient care. The aim of this study was to describe the knowledge of PiCCO among anaesthetists’ working in the Department of Anaesthesiology at the University of the Witwatersrand. Methods A cross-sectional, contextual research design was employed in this study using a self-administered questionnaire. The study population consisted of all anaesthetists working in the department. Convenience sampling was used, and completion of the questionnaire implied consent. Adequate knowledge was determined as ≥62% using the Angoff method. Results Themean (SD)score obtained was 44.5% (17.6%), with seniors obtaining a significantly higher score than juniors (51.2% vs 39.1, p =0.0001). Of the 21 (14.0%) anaesthetists who had adequate knowledge, more seniors achieved an adequate score than juniors (76.2% vs 23.8%, p=0.0022). Sixteen registrars had adequate knowledge of which 12 (75%) had completed a cardiac rotation and 4 (25%) had not, with those having completed a cardiac rotation significantly achieving an adequate score than those that had not (p=0.0005). All anaesthetists with adequate knowledge had ICU exposure (p=0.0355). Anaesthetists scored the lowest in the performing of the transpulmonary thermodilution section with a mean (SD) score of 41.6% (21.9%). Conclusion Knowledge of the PICCO cardiac output monitoring technique was inadequate in a sample of anaesthetists in an academic anaesthesiology department. Seniority, experience in cardiac anaesthesia or ICU are factors improving knowledge adequacy.
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    Clinicopathological and molecular analysis of serrated lesions of the appendix
    (2022) Keyter, Mark Andrew Robson
    A clinicopathological and molecular analysis of serrated lesions of the appendix and the prevalence of incidentally detected serrated lesions of the appendix seen in the Division of Anatomical Pathology, National Health Laboratory Services, Johannesburg, over a five-year period, was performed. To date, there is limited data on the molecular events in serrated proliferations of the appendix, with most data being extrapolated from studies on colorectal serrated proliferations. The demographics of the patients and the histopathologic characteristics of the serrated lesions were evaluated. Molecular characterisation included immunohistochemistry, polymerase chain reaction and sequence analysis. A total of ten cases were identified over a period of five years. Sessile serrated lesions/sessile serrated adenomas were seen in 0.14% of all the appendixes received over the five-year study period. All ten cases had characteristic morphological features consistent with a sessile serrated lesion/sessile serrated polyp. The molecular findings were inconclusive, with no definitive association with either BRAF V600E or KRAS codon 12 and 13 mutations. A single case contained a well-described KRAS codon 12 mutation. MLH-1 expression by immunohistochemistry was retained in all ten cases. Two of the ten patients showed microsatellite instability low (MSI-L), with both cases showing a dual peak at the BAT-25 locus. One of the sessile serrated lesions with the MSI-L also had associated BRAF mutations at nucleotide position 1732 (C>Y) and 1798 (A >W). An overall higher occurrence of sessile serrated lesions compared to other serrated proliferations of the appendix was found. This study highlights the importance of alterations in the MAP Kinase pathway and subsequent microsatellite instability in the pathogenesis of serrated proliferations in the appendix.
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    The use of point of care testing for the diagnosis of chronic kidney disease
    (2022) Currin, Sean
    Article 1 Introduction: The prevalence of chronic kidney disease is rising rapidly in low- and middle-income countries. Serum creatinine and estimation of glomerular filtration rate (GFR) are critical diagnostic tools, yet access to centralised laboratory services remains limited in primary care resource-limited settings. The aim of this study was to evaluate point-of-care (POC) technologies for serum creatinine measurement and to compare their performance to a gold standard measurement using iohexol mGFR. Methods: POC creatinine was measured using iSTAT® and StatSensor® devices in capillary and venous whole blood, and laboratory creatinine was measured using the compensated kinetic Jaffe method in 670 participants from a rural area in South Africa. GFR estimating equations (CKD-EPI and MDRD) for POC and laboratory creatinine were compared to iohexol mGFR. Results: Calculated GFR for laboratory and POC creatinine measurements overestimated GFR (positive bias of 1.9 - 34.1ml/min/1.73m2). However, all POC devices had less positive bias than the laboratory Jaffe method (1.9 - 14.7 vs 34.1 for MDRD, and 8.4 – 19.9 vs 28.6 for CKD-EPI). Accuracy within 30% of mGFR ranged from 0.56 – 0.72 for POC devices and from 0.36 – 0.43 for the laboratory Jaffe method. POC devices showed wider imprecision with coefficients of variation ranging from 4.6 - 10.2% compared to 3.5% for the laboratory Jaffe method. Conclusion: POC eGFR showed improved performance over laboratory Jaffe eGFR, however POC devices suffered from imprecision and large bias. The laboratory Jaffe method performed poorly, highlighting the need for laboratories to move to enzymatic methods to measure creatinine. Article 2 Background: the prevalence of chronic kidney disease (CKD) is predicted to rise over the next few decades. In resource-limited settings access to central laboratory services is limited. Point-of-care (POC) urine dipstick testing offers the potential to detect markers of kidney damage (albuminuria) as well as markers of other disease processes. We evaluated the diagnostic accuracy of the semiquantitative albumin-creatinine ratio (ACR) Sysmex UC-1000 POC urine dipstick system as well as the extent of other abnormal dipstick findings in urine. Methods: 700 participants from a rural area in South Africa were screened for albuminuria. A spot urine sample was used to measure POC and central laboratory ACR. We determined the sensitivity, specificity, positive predictive value and negative predictive value of the POC ACR, and recorded dipstick parameters. Results: the prevalence of albuminuria was 11.6% (95%CI; 9.3 – 14.2). Those with albuminuria had higher mean diastolic (82 vs 79mmHg, p=0.019) and systolic (133 vs 128mmHg, p=0.002) blood pressures and a higher proportion of diabetes mellitus (17.6 vs 4.9%, p<0.001). The sensitivity of the POC ACR system was 0.79, specificity 0.84, positive predictive value 0.39 and negative predictive value 0.97. The sensitivity improved to 0.80, 0.85, 0.85 and 0.89 in those with elevated blood pressure, diabetes mellitus, HIV positive status, and those 65 years and older, respectively. Abnormalities other than albuminuria were detected in 240 (34.3%) of the samples; 88 (12.6%) were positive for haematuria, 113 (16.1%) for leucocytes, 66 (9.4%) for nitrites and 27 (3.9%) for glycosuria. Conclusion: our study shows that POC ACR has good negative predictive value and could be used to rule out albuminuria when screening for CKD. Additionally, a high proportion of participants had other urine abnormalities detected with dipsticks which may reflect kidney disease or co-morbid untreated genitourinary pathology such as urinary tract infections or endemic schistosomiasis with important implications for CKD.
  • Item
    Familial hypercholesterolemia identification by machine learning using lipid profile data performs as well as clinical diagnostic criteria
    (2022) Hesse, Reinhardt
    Background Familial hypercholesterolemia (FH) is a common monogenic disorder and, if not diagnosed and treated early, results in premature atherosclerotic cardiovascular disease. Most individuals with FH are undiagnosed due to limitations in current screening and diagnostic approaches, but the advent of machine learning (ML) offers a new prospect to identify these individuals. Our objective was to create a ML model from basic lipid profile data with better screening performance than low-density lipoprotein cholesterol (LDL-C) cut-off levels and diagnostic performance comparable to the Dutch Lipid Clinic Network (DLCN) criteria. Methods The ML model was developed using a combination of logistic regression, deep learning and random forest classification and was trained on a 70% split of an internal dataset consisting of 555 individuals clinically suspected of having FH. The performance of the model, as well as that of the LDL-C cut-off and DLCN criteria, were assessed on both the internal 30% testing dataset and a high prevalence external dataset by comparing the area under the receiver operator characteristic (AUROC) curves. All three methodologies were measured against the gold standard of FH diagnosis by mutation identification. Furthermore, the ML model was also tested on two lower prevalence datasets derived from the same external dataset. Results The ML model achieved an AUROC curve of 0.711 on the high prevalence external dataset (n=1376; FH prevalence=64%), which was superior to that of the LDL-C cut off alone (AUROC=0.642) and comparable to that of the DLCN criteria (AUROC=0.705). The model performed even better when tested on the medium prevalence (n=2655; FH prevalence=20%) and low prevalence (n=1616; FH prevalence=1%) datasets, with AUROC curve values of 0.801 and 0.856 respectively. Conclusions Despite the absence of clinical information, the ML model was better at correctly identifying genetically confirmed FH in a cohort of individuals suspected of having FH than the LDL-C cut-off tool and comparable to the DLCN criteria. The same ML model performed even better when tested on two cohorts with lower FH prevalence. The application of ML is therefore a promising tool in both the screening for, and diagnosis of, individuals with FH.
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    Anaesthetists’ knowledge and frequency of use of neuromuscular monitoring at the University of the Witwatersrand
    (2022) Setsomelo, Michael Kgowe
    Background Neuromuscular blocking agents (NMBA) are commonly administered during general anaesthesia (GA). The use of these agents can result in postoperative residual neuromuscular blockade (PRNMB) as a complication. Studies have shown that such complication can be reduced with the use of neuromuscular monitors (NMM). Data from South Africa as to the knowledge and use of NMM is scanty. Therefore, the aim of this study is to assess the knowledge and the frequency of use of NMM in the Department of Anaesthesia at the University of the Witwatersrand (Wits). Methods A prospective, contextual study design was used. Data was collected using a selfadministered online questionnaire developed by the researcher with the assistance of senior anaesthetists. The study population consisted of all anaesthetists working in the Department of Anaesthesia at Wits. A convenience sampling method was used and a completion with return of the online questionnaire implied consent to participate in the study. Adequate knowledge was defined by a score of 65.5% as determined by the Angoff method. Results Two hundred and eight anaesthetists were available during the period of data collection. Of these, 126 anaesthetists completed the questionnaire. There was inadequate level of knowledge of NMM among anaesthetists in our department. Sixty-four percent of the anaesthetists achieved less than the set Angoff score of 65.5%. The anaesthetist’ mean score of the questionnaire was also 57%. The level of knowledge differs significantly depending on professional designation with p-value <0.009. Medical Officers and second year registrars scored significantly below the Angoff score with p-values of 0.0005 and 0.02 respectively, while first year registrars recorded the highest score, followed by fourth year registrars. The frequency of use of NMM in the department is low at 13%. Conclusion The level of knowledge among anaesthetists with respect to NMM was inadequate. There is a need for improvement of knowledge regarding NMM use, by ongoing education in our anaesthesia department. Formulating evidence-based guidelines which support the use of NMM in all patient who received NMBA will be beneficial. The use of NMM in our department is also low. The commonest reason for not using NMM was unavailability of these monitors. Healthcare authorities have the obligation to increase the availability and accessibility of NMM. A national study in this subject is warranted to see if this is any different among anaesthetists in South Africa.