Medicine & Health

Publication Search Results

Now showing 1 - 10 of 16
  • (2017) Aggarwal, Gunjan
    Thesis
    Abstract Aims: Assessment of the differences in diagnostic performance and radiation dose between Adaptive Statistical Iterative Reconstruction (ASIR) and High Definition (HD) CT coronary angiography (CTCA) compared with Filtered Back Projection (FBP) and Standard Definition (SD) CTCA using invasive coronary angiography as a reference standard. Methods: Data from 2069 consecutive patients undergoing CTCA was collected over a period of 2 years. A total of 30 patients were separately enrolled if they had a significant stenosis and underwent invasive coronary angiogram within 3 months. All 30 patients were scanned in high definition and then had 5 reconstructions performed using SD0%ASIR, SD50%ASIR, SD70%ASIR, HD50%ASIR and HD70% ASIR. Results: Median and total (including CACS) angiographic radiation dose for 2069 patients was 2.1 mSv and 2.7 mSv respectively. Determinants of radiation dose on multivariate regression analysis were scan voltage, tube current, padding, scan length and heart rate. The mean difference in adjusted angiographic radiation dose using ANCOVA between the ASIR cohort (n=624, mean 2.2 mSv) and FBP (n=572, mean 2.29 mSv) was 0.09 mSv (P 0.0008). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and Area under the curve (AUC) values using Receiver Operator Characteristic (ROC) curves on an intention to diagnose analysis were highest for the reconstruction HD with 70% ASIR at 94%, 89%, 75%, 98% and 0.93 for a >50% obstructive stenosis threshold on a per artery basis; and 88%, 88%, 64%, 97% and 0.91 for a >70% stenosis on a per artery basis; 100%, 67%, 96%, 100% and 0.83 for a >50% stenosis on a per patient basis; and 95%, 67%, 87%, 86% and 0.81 for a >70% stenosis on a per patient basis. The greatest benefit for HD with 70% ASIR was in patient subgroups of CACS>200, BMI>25 and stented arteries with AUC values of 0.93, 0.89 and 0.83 respectively. Conclusions: ASIR resulted in a lower adjusted angiographic radiation dose than FBP although the reduction of 4.2% was less than that observed in other studies due to the tube current reduction with ASIR scans being smaller in our study. HD with 70% ASIR reconstruction demonstrated the most robust diagnostic performance with higher specificity, PPV and AUC values than all other reconstructions due to a lower false positive rate. These benefits were the most pronounced in patients with a CACS>200, BMI>25 and stented arteries.

  • (2015) Gomes, Sean
    Thesis
    Abstract 350 words maximum: (PLEASE TYPE) Background Indications for cardiac implantable electronic devices (CIED’s) continue to expand. Increases in the number of devices implanted have resulted in an increased incidence of complications. These complications sometime require extraction of CIED leads for definitive treatment. I explore the indications, complications, microbiology and success rates involved with lead extraction in a high volume centre over a 20 year period. I also report long term follow up of these patients including mortality, recurrent device infection and need for repeat procedures Methods and Results Retrospective analysis was reported of all consecutive patients undergoing lead extraction between 1992 and 2012. 1006 leads were extracted from 510 patients. The clinical success rate was 98.2% and complete procedural success rate was 92.2%. There was one intra-procedural death. Infection was the only identified predictor of increased complication (χ² for difference between groups 20, P < 0.0001). The mean follow up was 5.5+/-4.9 years (range 0.2 – 18 years). Cumulative mortality was 10.0% at 1 year and 33.0% at 10 years. Factors associated with increased long term mortality included cardiac device infection (CDI) (33% vs 17% for non-CDI; χ² 13.8, P = 0.0003), procedural complications (43% vs 27% for no complications; χ² 4.2, P = 0.04), age (75.0 +/- 10.9 years in patients who died vs 62.7 +/- 17.2 years, P < 0.0001) and impaired renal function (Creatinine 142.5 +/- 106.4 umol/L in patients who died vs 106.3 +/- 90.7 umol/L, P = 0.001). There was comparable mortality in those patients who did not have a replacement device after transvenous lead extraction (TLE) compared with a replacement (27 % vs 24 %, P = 0.72). The rate of CDI after TLE was 3.9 % (mean 11.6 months post extraction, range 0.3 to 84 months) and is higher in patients with retained lead fragments (13.5% vs 3.0% % with complete removal; χ² 10.7 P = 0.001). Conclusion Pacing and ICD leads can be safely extracted with mechanical techniques. Long term mortality following TLE is high particularly in those with systemic infection, procedural complications, advanced age and renal impairment. Device therapy can be safely withdrawn in some patients. Finally; retained fragments are a risk factor for CDI post extraction.

  • (2002) Bell, James
    Thesis

  • (2004) Macartney, Kristine Kay
    Thesis


  • (2007) Ho, Ken Choong Khoon
    Thesis
    This is an original study to quantify and grade defect healing in a large animal cranial bone substitute model. The study of various therapies to heal cranial defects requires an appropriate ?critical? animal model. An experimental animal model should be analogous and recognizable as an appropriate challenge to human physiology. In addition, the defect must fail to heal unless treated with the tissue engineering therapy under study. Sheep as a large animal model was chosen because of its ability to tolerate creation of large skull defects analogous to clinical scenario, and its biology of healing as a high order mammal would be closer human beings. There is no agreement on the critical size limits for cranial defects. Various sizes have been termed "critical" in publications utilizing sheep. These ranged from 20-22mm. This study will investigate whether a 20mm defect is adequate. Bilateral circular cranial defects of 10, 20 and 25mm diameters were created in 12 adult sheep. Based on guided tissue engineering principles, defect protection was utilized to prevent in-growth of fibroblasts and other connective tissue cells from the surroundings. As bone tissue regeneration strategies usually involve osteoconduction element, an animal model that considered the defect protection role of osteoconduction would be more appropriate. Repopulation and regeneration of the defect was maximized as an added challenge Bioresorbable polylactic acid co-polymer mesh (MacroPoreTM) and Titanium mesh (TiMeshTM) was used as defect protection. The cranial defects were harvested at 8 and 16 weeks. The end-point analysis included Faxitron X-ray images, DEXA (Dual Energy X-ray Absorptiometry), and histology. The defects were graded to assess their ability to eventually heal. 10mm defects fully healed at 16 weeks. There was new bone formation spanning the entire defect seen on histology. 25mm defects were spanned by thin fibrous tissue only. There was variability in the healing potential of 20mm defect. Based on presence of bone islands within the defect, half of the 20mm defects demonstrated ability to heal while the other half actually had new bone spanning the defects on histology. Critical size cranial defect in sheep for the study of bone graft substitute has to be larger than 25mm diameter. The model is then utilized to study the use of Pro Osteon and AGF compared with the gold standard of autologous bone graft.

  • (2019) Blyth, Kerri
    Thesis
    Background Patellofemoral pain (PFP) is a complex musculoskeletal condition that can be challenging for the clinician to manage effectively. The use of patella taping as an adjunct treatment option is common practice however the traditional rigid taping materials (RT) are somewhat restrictive in nature when performing high level activities. The introduction of highly elastic taping material Dynamic Tape™ (DT) provides positive feedback from individuals in the clinical setting however there is no supporting evidence available for ongoing use in this management of PFP. Objective The aim of this study was to compare the knee kinematics of 30 individuals with PFP during 3 functional tasks (walking, step descent and single leg squat) under 3 taping conditions (no tape, dynamic tape and rigid tape) using 3D motion tracker analysis Design Crossover design with randomized but counterbalanced AB/BA order of intervention Results Variant knee motion demonstrated by individuals with PFP in the transverse and frontal plane during walking, step and squat were immediately altered following the application of both a localised dynamic tape and rigid tape method to the patella. Gender differences were evident in the outcomes with females demonstrating greater differences in both abduction and rotation ranges compared to the male subjects in both the untaped and taped data sets. Perceived pain levels while performing loaded closed chain activities were reduced with dynamic tape compared to no tape conditions (p=0.010) Conclusion This is the first paper to support the use of dynamic tape in the conservative management of PFP as it may allow the individual to participate in higher level activities due to its unique stretch/recoil material. Further research must be completed to investigate the diversity of taping styles that could be incorporated into clinical practice.

  • (2017) Abeygoonawardana, Dasun
    Thesis
    Despite advances in technology and surgical procedures, periprosthetic infection of orthopaedic implants remains a common and costly cause of implant failure and revision. Novel materials and coatings have been developed in an effort to improve implant resistance to the onset of infection, including those utilising the antimicrobial properties of silver ions. The aims of this study were to evaluate the osseointegration of a novel silver-doped hydroxyapatite coating and a second acid-etching process, applied to a titanium implant substrate implanted using a well-established ovine model. The subsequent results from the silver-doped coating could be compared to conventional hydroxyapatite coatings, to evaluate the effect of silver ions upon potential bone ongrowth. In this study, the silver HA coated implants demonstrated significantly higher shear stresses of mechanical pushout when compared to the acid etched implants after 4 weeks and 12 weeks in situ. Similarly, the bone-implant contact percentage was significantly higher for the silver HA coated implants indicating greater osseointegration at both timepoints. When compared to conventional HA coated implants in an identical ovine model, there was no significant difference observed in mechanical pushout or bone-implant contact of the silver HA coated implants. These results indicate that the novel silver-doped HA coating does not adversely affect the osseointegration of titanium implants. Therefore, this represents a viable solution for an antimicrobial implant coating which continues to facilitate effective osseointegration following implantation.

  • (2014) Harris, Carole
    Thesis
    In the last two decades the development of targeted cancer therapies has lead to a paradigm shift in the way cancers are being treated. Targeted cancer therapies work differently to traditional cytotoxic chemotherapy by stopping the proliferation and growth of cancer cells by acting on specific molecules in a complex pathway that leads to cancer development. As targeted cancer therapies differ from chemotherapy, it is necessary to rethink the traditional model of drug testing. The aim of this thesis was to describe the way in which the use and outcomes of targeted cancer therapies are measured in clinical trials and in routine clinical care. Whilst this thesis focuses on HER2 breast cancer, although the work detailed in this these has broader applicability across other targeted therapies. Three approaches were used to highlight these issues: a meta analysis of published clinical trials; a routine care study using a clinical audit of prescription data at four cancer centres in NSW, Australia; and a comparison of this prescription data with dispensing claims data in a matched cohort. Whilst ideally studies of routine care are conducted at a whole of population level, this third study helped to assess how well claims data reflects actual practice before undertaking a population level study. This thesis demonstrates the strengths and weaknesses of clinical trials and real world data in measuring targeted cancer therapies to treat HER2 positive breast cancer in both the adjuvant and metastatic setting. Whilst clinical trials remain the gold standard, real world studies can provide a complement to clinical trials in assessing pattern of care. This research will enable a reliable study to be undertaken into adjuvant HER2 patterns of care based on the comparison of prescription and dispensing data undertaken in this thesis.

  • (2017) O'Hagan, Edel
    Thesis
    Abstract Background Research has identified that sleep and pain have a bidirectional relationship. Understanding this relationship specifically between chronic low back pain (LBP) and sleep may lead to improved management of painful conditions such as chronic LBP and postoperative pain. As pain is typically more difficult to manage the longer it persists; an advantageous approach to management of chronic pain may be to intervene early to prevent the transition from an acute episode to a chronic problem. Targeting sleep during an acute episode of pain may provide an option to accelerate recovery and prevent chronicity. Methods This project included 3 studies. The first study used a cross-sectional design to investigate the bi-directional relationship between chronic LBP pain and sleep. Correlations were used to determine whether pain intensity during the day was associated with differences in sleep architecture and whether these differences were associated with pain intensity the following day. The second study used a systematic review with meta-analysis to investigate whether managing sleep in the acute postoperative period improved postoperative pain. The third study was a pilot randomised controlled trial that investigated the feasibility of managing sleep in participants with acute low back pain. Results This research found that: 1.For people with LBP, slow wave sleep (SWS) and sleep quality were significantly associated with next day pain intensity such that people with LBP who spent less time in SWS reported both higher pain intensity the following day and worse sleep quality for the same night. 2. Hypnotic drugs in combination with other analgesics significantly improve pain and sleep post-operatively, however the effects were modest. 3. The pilot study identified barriers to recruitment necessary to address in a large trial in order to ensure completion in a practical timeframe, in a sample of Australian primary care practitioners. Those enrolled found the questionnaires suitable and the follow-up rates were good. Conclusions This research is a useful platform to better understand the complex relationship between pain and sleep. It provides a guide for future research in the area. Enhancing sleep quality continues to be a potentially undervalued resource in improving LBP and postoperative pain.