A Multicenter Trial of Vena Cava Filters in Severely Injured Patients.

BACKGROUND: Whether early placement of an inferior vena cava filter reduces the risk of pulmonary embolism or death in severely injured patients who have a contraindication to prophylactic anticoagulation is not known. METHODS: In this multicenter, randomized, controlled trial, we assigned 240 severely injured patients (Injury Severity Score >15 [scores range from 0 to 75, with higher scores indicating more severe injury]) who had a contraindication to anticoagulant agents to have a vena cava filter placed within the first 72 hours after admission for the injury or to have no filter placed. The primary end point was a composite of symptomatic pulmonary embolism or death from any cause at 90 days after enrollment; a secondary end point was symptomatic pulmonary embolism between day 8 and day 90 in the subgroup of patients who survived at least 7 days and did not receive prophylactic anticoagulation within 7 days after injury. All patients underwent ultrasonography of the legs at 2 weeks; patients also underwent mandatory computed tomographic pulmonary angiography when prespecified criteria were met. RESULTS: The median age of the patients was 39 years, and the median Injury Severity Score was 27. Early placement of a vena cava filter did not result in a significantly lower incidence of symptomatic pulmonary embolism or death than no placement of a filter (13.9% in the vena cava filter group and 14.4% in the control group; hazard ratio, 0.99; 95% confidence interval [CI], 0.51 to 1.94; P = 0.98). Among the 46 patients in the vena cava filter group and the 34 patients in the control group who did not receive prophylactic anticoagulation within 7 days after injury, pulmonary embolism developed in none of those in the vena cava filter group and in 5 (14.7%) in the control group, including 1 patient who died (relative risk of pulmonary embolism, 0; 95% CI, 0.00 to 0.55). An entrapped thrombus was found in the filter in 6 patients. CONCLUSIONS: Early prophylactic placement of a vena cava filter after major trauma did not result in a lower incidence of symptomatic pulmonary embolism or death at 90 days than no placement of a filter. (Funded by the Medical Research Foundation of Royal Perth Hospital and others; Australian New Zealand Clinical Trials Registry number, ACTRN12614000963628.).

Cost-effectiveness of early placement of vena cava filters to prevent symptomatic pulmonary embolism in patients with contraindications to prophylactic anticoagulant.

INTRODUCTION: Vena cava filters have been used as a primary means to prevent symptomatic pulmonary embolism (PE) in trauma patients who cannot be anticoagulated after severe injury, but the economic implications for this practice remain unclear. METHODS: Using a healthcare system perspective to analyze the a priori primary outcome of the da Vinci trial, we report the cost-effectiveness of using vena cava filters as a primary means to prevent PE in patients who have contraindications to prophylactic anticoagulation after major trauma. RESULTS: Of the 240 patients enrolled, complete, prospectively collected, hospital cost data during the entire hospital stay - including costs for the filter, medical/nursing/allied health staff, medical supplies, pathology tests, and radiological imaging - were available in 223 patients (93%). Patients allocated to the filter group (n = 114) were associated with a reduced risk of PE (0.9%) compared to those in the control group (n = 109, 5.5%; p = 0.048); and the filter's benefit was more pronounced among those who could not be anticoagulated within 7 days (filter: 0% vs control: 16%, Bonferroni-corrected p = 0.02). Overall, the cost needed to prevent one PE was high (AUD $379,760), but among those who could not be anticoagulated within 7 days, the costs to prevent one PE (AUD $36,156; ~ USD $26,032) and gain one quality-adjusted life-year (AUD $30,903; ~ USD $22,250) were substantially lower. CONCLUSION: The cost of using a vena cava filter to prevent PE for those who have contraindications to prophylactic anticoagulation within 3 days of injury is prohibitive, unless such contraindications remain for longer than 7 days. (Australian New Zealand Clinical Trials Registry no.: ACTRN12614000963628).

Double interatrial septum with persistent interatrial chamber: A rare but clinically significant anomaly.

Double interatrial septum is an extremely rare congenital anomaly which forms a distinguished midline interatrial chamber between the two atria. The objective of this case report is to highlight this unusual anomaly and to discuss the potential complications of this condition. We report the case of a 6-year-old asymptomatic child who underwent cardiac evaluation for a soft systolic murmur eventually being diagnosed with double interatrial septum.

Design considerations in clinical trials with cure rate survival data: A case study in oncology.

For clinical trials with time-to-event as the primary endpoint, the clinical cutoff is often event-driven and the log-rank test is the most commonly used statistical method for evaluating treatment effect. However, this method relies on the proportional hazards assumption in that it has the maximal power in this circumstance. In certain disease areas or populations, some patients can be curable and never experience the events despite a long follow-up. The event accumulation may dry out after a certain period of follow-up and the treatment effect could be reflected as the combination of improvement of cure rate and the delay of events for those uncurable patients. Study power depends on both cure rate improvement and hazard reduction. In this paper, we illustrate these practical issues using simulation studies and explore sample size recommendations, alternative ways for clinical cutoffs, and efficient testing methods with the highest study power possible.

Blunt Traumatic Abdominal Wall Hernias: A Surgeon's Dilemma.

BACKGROUND: Traumatic abdominal wall hernias (TAWH) have been recognized for more than a century since they were first reported by Selby (JAMA 47:1485-1486, 1906). They continue to be a rare diagnosis, encountered in approximately 1% blunt trauma admissions. The present study is a 10-year retrospective review of patients presenting with TAWH to a State Major Trauma Unit in Western Australia. We hypothesized that the timing of the repair of TAWH was dependent on the severity of the abdominal wall injury, as well as associated injuries, and in turn, this may affect patient outcomes. MATERIALS AND METHODS: The Trauma Registry at Royal Perth Hospital (the only Level I Trauma Centre for adults in Western Australia) was scrutinized for TAWH, between 2003 and 2013. The injuries were graded by the classification system of Dennis et al. (Am J Surg 197:413-417, 2009). Patients with TAWH following penetrating trauma were excluded. RESULTS: During the study period, 44 patients were diagnosed to have TAWH accounting for 0.08% of admissions. Thirty (68%) of the patients were male and the median age was 36 years (IQR 24-54). The median BMI was between 25 and 30. The majority of the patients sustained trauma secondary to motor vehicle crashes and the commonest associated injury was a pelvic fracture. Grades 3 and 4 injuries were found to have an association with a pelvic fracture (p < 0.001). No association was seen in the present study between seat belt use and the development of TAWH or between the location of TAWH and seat belt pattern. The median time of diagnosis of TAWH following arrival to hospital was 18 hours while the median time of surgery from diagnosis was 15.5 hours. Forty-one (93%) of the patients underwent surgery. Of these, 8 (20%) were emergent due to a simultaneous bowel perforation and another five had primary mesh repairs. Three of the patients suffered superficial complications (7.5%) and there were 3 (7%) recurrences at a mean time of 7.25 months from the first repair. The follow-up period ranged from 1 to 51 months with an average time of 16 months. CONCLUSION: This series is the largest single institution study conducted on TAWH to date. Despite its retrospective nature and small numbers, it has generated some important questions. A larger prospective study with a longer follow-up period is required to generate reliable treatment algorithms as well as to standardize the management of TAWH.

Trans-radial percutaneous intervention for thrombosed hemodialysis access: A single-center experience.

BACKGROUND: Traditionally, percutaneous transluminal angioplasty (PTA) is a first-line approach for stenosed dialysis accesses and has been performed through the non-thrombosed vein segment. For thrombosed accesses, thrombectomy (whether open or percutaneous) is a standard approach. The primary objective of our study is to determine the clinical and technical outcomes of the trans-radial approach of PTA among thrombosed dialysis accesses, in terms of safety and feasibility, technical and clinical aspects and factors influencing them, as well as assisted primary patency, secondary patency at 6 and 12 months. METHODS: This is a single-center retrospective study that included 150 patients over 3 years. About 123 patients underwent successful percutaneous balloon angioplasty through the radial access. RESULTS: We report an overall technical and clinical success rate of 82%, assisted primary patency rate of about 90.25% at 3 months, 82.93% at 6 months, 73.18% at 1 year, and secondary patency rate of 94% at 1 year. Twenty-seven patients were referred for surgical revisions/creation of a new fistula for reasons like inability to pass wire (6 patients), unfavorable anatomical variations like aneurysms at the proximal segments (5 patients), inability to cross the fistula (5 patients), and persistent fistula dysfunction with no flow after initial balloon dilatation (11 patients). Three patients had hematoma at the radial access site (2.5%) while two patients had the AV fistula segment rupture and were successfully treated conservatively. CONCLUSION: We conclude that PTA through the trans-radial approach to completely thrombosed hemodialysis accesses is a good alternative to transvenous access and has a very good assisted primary patency and secondary patency at 1 year without major complications.

Association of ABO blood groups with the severity of coronary artery disease in southern India population: A prospective cross-sectional study.

This study aimed to find an association between ABO blood groups with presence and severity of Coronary artery disease (CAD) among Indian population. 1500 patients undergoing elective coronary angiogram (CAG) at a tertiary care hospital in Karnataka were enrolled in the study. Baseline demographic data and the presence of cardiac comorbidities were documented. Data from baseline echocardiography and angiographic studies were compiled. The incidence of CAD was higher among patients with blood group A. Blood group A also showed a higher incidence of acute coronary syndrome (ACS), left ventricular dysfunction, triple vessel disease, and severe CAD among the patients who underwent CAG.

An injury awareness education program on outcomes of juvenile justice offenders in Western Australia: an economic analysis.

BACKGROUND: Injury is a major cause of mortality and morbidity of young people and the cost-effectiveness of many injury prevention programs remains uncertain. This study aimed to analyze the costs and benefits of an injury awareness education program, the P.A.R.T.Y. (Prevent Alcohol and Risk-related Trauma in Youth) program, for juvenile justice offenders in Western Australia. METHODS: Costs and benefits analysis based on effectiveness data from a linked-data cohort study on 225 juvenile justice offenders who were referred to the education program and 3434 who were not referred to the program between 2006 and 2011. RESULTS: During the study period, there were 8869 hospitalizations and 113 deaths due to violence or traffic-related injuries among those aged between 14 and 21 in Western Australia. The mean length of hospital stay was 4.6 days, a total of 320 patients (3.6%) needed an intensive care admission with an average length of stay of 6 days. The annual cost saved due to serious injury was $3,765 and the annual net cost of running this program was $33,735. The estimated cost per offence prevented, cost per serious injury avoided, and cost per undiscounted and discounted life year gained were $3,124, $42,169, $8,268 and $17,910, respectively. Increasing the frequency of the program from once per month to once per week would increase its cost-effectiveness substantially. CONCLUSIONS: The P.A.R.T.Y. injury education program involving real-life trauma scenarios was cost-effective in reducing subsequent risk of committing violence or traffic-related offences, injuries, and death for juvenile justice offenders in Western Australia.

Characteristics of kangaroo-related motor vehicle crashes.

BACKGROUND: Kangaroo-related motor vehicle collisions are common but there is limited literature on this topic. Drivers confronted by kangaroos may choose to swerve or to directly collide with the kangaroo. The effect of these differing crash mechanisms, along with the effect of vehicle type or time of day, has not yet been reported. METHODS: A retrospective cohort study was performed, examining patients admitted to our tertiary trauma centre for kangaroo-related motor vehicle collisions between 2000 and 2020. Data on patient demographics, crash characteristics, and hospital stay were collected and analysed. RESULTS: A total of 366 patients were included and were predominantly male (76%) with an median age of 40. Swerve crashes were more common (59%) than direct impact and swerving was a statistically significant predictor of reduced injury severity score on multivariable analysis (other significant factors were female sex and no rollover). Motor vehicle crashes and motorbike crashes had differing crash characteristics. Motor vehicle crashes were more likely the result of swerving, and swerving was less likely to cause ejection or require extrication but more likely to cause rollover. Motorbike crashes however, were more likely the result of head on collision and riders were more likely to be ejected from the vehicle, require extrication, or be involved in a rollover. In terms of time of day, there were more crashes at dawn and there was a trend towards higher injury severity score and length of stay for night-time crashes. CONCLUSION: For kangaroo-related motor vehicle crashes, predictors of increased injury severity score on multivariable analysis were male sex, direct impact, and rollover. Motorbikes and motor vehicles had differing crash mechanisms and characteristics, as did night-time crashes when compared to daytime or twilight crashes. LEVEL OF EVIDENCE: IV, prognostic.

Transformation and fate of urea in pit-toilet blackwater after discharge to environment.

Studies on urea transformation reactions in blackwater are limited as urea rapidly hydrolyses under anaerobic condition. Since ammonium content of blackwater mainly originates from urine-urea, studying urea hydrolysis reactions is important to predict potential nitrate loads in aquifers from on-site sanitation facilities. In this study, urea spiked blackwater samples from pour flush pit toilet are used to examine the urea-ammonium pathways at varying initial urea concentrations and temperature. Based on laboratory results, the annual nitrate load imposed by the urea constituent of blackwater in a hard rock aquifer is predicted. Laboratory results illustrated that experimental temperature of 37 °C and pH range of 6.7 to 8.1 facilitated optimum urease enzyme activity at the initial substrate concentration of 500 mg/L. The Q10 value for urea transformation reactions indicated that increase in temperature has positive influence on enzyme activity. The reduction in urea concentration with time followed first-order kinetics. Part of ammonium ions in blackwater oxidises as nitrate ions that travel to the aquifer. Upon mixing and dilution, the nitrate concentration in 1 km2 of hard rock aquifer would annually increase by 0.004 mg/L due to blackwater infiltration from single household pour flush toilet.

Validation of the geriatric trauma outcome scores in predicting outcomes of elderly trauma patients.

BACKGROUND: Using three patient characteristics, including age, Injury Severity Score (ISS) and transfusion within 24 h of admission (yes vs. no), the Geriatric Trauma Outcome Score (GTOS) and Geriatric Trauma Outcome Score II (GTOS II) have been developed to predict mortality and unfavourable discharge (to a nursing home or hospice facility), of those who were ≥65 years old, respectively. OBJECTIVES: This study aimed to validate the GTOS and GTOS II models. For the nested-cohort requiring intensive care, we compared the GTOS scores with two ICU prognostic scores - the Acute Physiology and Chronic Health Evaluation (APACHE) III and Australian and New Zealand Risk of Death (ANZROD). METHODS: All elderly trauma patients admitted to the State Trauma Unit between 2009 and 2019 were included. The discrimination ability and calibration of the GTOS and GTOS II scores were assessed by the area under the receiver-operating-characteristic (AUROC) curve and a calibration plot, respectively. RESULTS: Of the 57,473 trauma admissions during the study period, 15,034 (26.2%) were ≥65 years-old. The median age and ISS of the cohort were 80 (interquartile range [IQR] 72-87) and 6 (IQR 2-9), respectively; and the average observed mortality was 4.3%. The ability of the GTOS to predict mortality was good (AUROC 0.838, 95% confidence interval [CI] 0.821-0.855), and better than either age (AUROC 0.603, 95%CI 0.581-0.624) or ISS (AUROC 0.799, 95%CI 0.779-0.819) alone. The GTOS II's ability to predict unfavourable discharge was satisfactory (AUROC 0.707, 95%CI 0.696-0.719) but no better than age alone. Both GTOS and GTOS II scores over-estimated risks of the adverse outcome when the predicted risks were high. The GTOS score (AUROC 0.683, 95%CI 0.591-0.775) was also inferior to the APACHE III (AUROC 0.783, 95%CI 0.699-0.867) or ANZROD (AUROC 0.788, 95%CI 0.705-0.870) in predicting mortality for those requiring intensive care. CONCLUSIONS: The GTOS scores had a good ability to discriminate between survivors and non-survivors in the elderly trauma patients, but GTOS II scores were no better than age alone in predicting unfavourable discharge. Both GTOS and GTOS II scores were not well-calibrated when the predicted risks of adverse outcome were high.

Development and validation of a risk-adjustment model for mortality and hospital length of stay for trauma patients: a prospective registry-based study in Australia.

OBJECTIVES: Adequate risk adjustment for factors beyond the control of the healthcare system contributes to the process of transparent and equitable benchmarking of trauma outcomes. Current risk adjustment models are not optimal in terms of the number and nature of predictor variables included in the model and the treatment of missing data. We propose a statistically robust and parsimonious risk adjustment model for the purpose of benchmarking. SETTING: This study analysed data from the multicentre Australia New Zealand Trauma Registry from 1 July 2016 to 30 June 2018 consisting of 31 trauma centres. OUTCOME MEASURES: The primary endpoints were inpatient mortality and length of hospital stay. Firth logistic regression and robust linear regression models were used to study the endpoints, respectively. Restricted cubic splines were used to model non-linear relationships with age. Model validation was performed on a subset of the dataset. RESULTS: Of the 9509 patients in the model development cohort, 72% were male and approximately half (51%) aged over 50 years . For mortality, cubic splines in age, injury cause, arrival Glasgow Coma Scale motor score, highest and second-highest Abbreviated Injury Scale scores and shock index were significant predictors. The model performed well in the validation sample with an area under the curve of 0.93. For length of stay, the identified predictor variables were similar. Compared with low falls, motor vehicle occupants stayed on average 2.6 days longer (95% CI: 2.0 to 3.1), p<0.001. Sensitivity analyses did not demonstrate any marked differences in the performance of the models. CONCLUSION: Our risk adjustment model of six variables is efficient and can be reliably collected from registries to enhance the process of benchmarking.

Extracranial injuries are important in determining mortality of neurotrauma.

OBJECTIVE: This study aimed to assess the significance of extracranial injuries, as measured by Injury Severity Score, on 6-mo and 9-yr mortality of neurotrauma. DESIGN: Retrospective linked data cohort study. SETTING: A major neurotrauma center in Western Australia. PATIENTS: Six hundred eighty-three adult neurotrauma patients. MEASUREMENTS AND MAIN RESULTS: Data were first used to validate the largest published international neurotrauma "extended" mortality prognostic model, in which extracranial injuries are considered significant if the patient has hypoxemia or hypotension on admission. Logistic and Cox regression, incorporating bootstrap techniques to adjust for overfitting, were used to assess the significance of Injury Severity Score in determining 6-mo and 9-yr mortality, respectively. Among a total of 683 patients admitted between 1994 and 2002, 636 (93.1%) had extracranial injuries. The international neurotrauma "extended" mortality prognostic model was poorly calibrated and underestimated the observed mortality (slope and intercept of the calibration curve were 2.14 and 0.35, respectively) when applied to our patients. Incorporating Injury Severity Score into the model improved its calibration. Injury Severity Score accounted for 11% of the variability and was the third most important factor after Marshall computed tomographic grading (17.8%) and pupil reactivity (14.5%) in determining 6-mo mortality. There was a notable increase in mortality between 6-mo (19.2%) and 24-mo follow-up (25.8%). Injury Severity Score remained important and accounted for 9.2% of the variability in determining 9-yr mortality after the injury. CONCLUSIONS: Hypotension and hypoxemia on admission were inadequate markers of extracranial injuries; incorporating more comprehensive extracranial injury assessment by the Injury Severity Score to the standard neurologic prognostic factors improved the accuracy of predictions on mortality after neurotrauma.

Identifying the dominant mode of moisture transport during drying of unsaturated soils.

Diffusion of capillary water and water vapor during moisture loss in an unsaturated soil is impeded by the chemical and geometrical interactions between water molecules/vapor and the soil structure. A reduction in moisture content contracts the diffuse and adsorbed water layers in the partly saturated soil and disturbs the connected capillary network for flow of liquid water. With further drying, the dry soil layer expands and moisture is predominantly lost as vapor through continuous air-flow channels. The water-filled capillary network and air-filled channels are moisture conduits during different stages of soil drying. It is important to identify zones of dominant moisture transport and to select appropriate tortuosity equations for correct prediction of moisture flux. Laboratory experiments were performed to determine moisture flux from compacted soil specimens at environmental relative humidity of 33, 76 and 97% respectively. Analysis of the resultant τ - θ (tortuosity - volumetric water content) relations, illustrated the existence of a critical water content (θcr), that delineates the dominant zones of capillary liquid flow and vapor diffusion. At critical water content, the pore-size occupied by the capillary water is governed by the generated soil suction. Generalized equations are proposed to predict tortuosity factor in zones of dominant capillary liquid flow and vapor transport over a wide range of relative humidity (33 to 97%).

Factors affecting severity of bicycle-related injuries: the role of helmets in preventing head injuries.

OBJECTIVES: To identify factors that affect the severity of bicycle-related injuries in patients with head injury compared with those without, so as to find whether the effect of using helmets extends beyond head protection, and to explore a direct protective effect of helmets on head injuries. METHODS: A total of 297 patients with bicycle-related injuries were studied. A generalized linear model was used to test the effect of age, sex, helmet use, cause of injury, year of injury, place of injury and whether the injury occurred on public or school holidays on the Injury Severity Score (ISS) in those patients who had head injury and those without. A logistic regression model was used to define the factors that contribute to head injury, while adjusting for ISS. RESULTS: Factors affecting ISS in the generalized linear model in those who had head injury were: cause of injury (P = 0.01) and there was a trend for helmet use (P = 0.06). The significant factors that have affected ISS in the no head injury group were age (P = 0.002) and place of accident (P = 0.03). Logistic regression has shown that with each increase of 1 point in the ISS the odds of head injury increases by a factor of 1.22 (95% confidence interval 1.13-1.31) and the use of helmets reduces the odds of head injury by a factor of 0.48 (95% confidence interval 0.23-1.03). CONCLUSIONS: The reduced severity of injury in helmeted patients is because of protection of the head and not other body regions.

Effect of preoperative biliary stenting on post-operative infectious complications in pancreaticoduodenectomy.

BACKGROUNDS/AIMS: The impact of pre-operative biliary stenting (PBS) in patients undergoing pancreaticoduodenectomy on post-operative infectious complications is unclear. Therefore, the purpose of this study is to investigate the relationship between PBS and post-operative infectious complications, to determine the effect of PBS on bile bacteriology, and to correlate the bacteriology of bile and bacteria cultured from post-operative infectious complications in our institute. METHODS: Details of 51 patients undergoing pancreaticoduodenectomy January 2011-April 2015 were reviewed. Of 51 patients, 30 patients underwent pre-operative biliary stenting (PBS group) and 21 patients underwent pancreaticoduodenectomy without pre-operative biliary stenting. Post-operative infectious complications were compared between the two groups. RESULTS: Overall post-operative infectious complication rate was 77% and 67% in the PBS and non-PBS groups respectively. Wound infection was the main infectious complication followed by intraabdominal abscess. The rate of wound infection doubled in the PBS group (50% vs 28%). There was slight increase in incidence of intraabdominal abscess in PBS group (53% vs 46%). 80% of PBS patients had positive intraoperative bile culture as compared to 20% in non-PBS group. CONCLUSIONS: Preoperative biliary drainage prior to pancreaticoduodenectomy increases risk of developing post-operative wound infections and intra-abdominal collections.

Increased detection of blunt carotid and vertebral artery injury after implementation of diagnostic imaging pathway in level 1 trauma centre in Western Australia.

BACKGROUND: The incidence of Blunt Carotid Artery and Vertebral Artery Injury (BCVI) is relatively low in modern trauma practice. However, these injuries may be associated with severe neurological consequences. Following the introduction of a Diagnostic Imaging Pathway in Department of Health of Western Australia, we hypothesized that this injury would be less likely to be missed, and accordingly diagnosed more frequently. METHOD: A review of all major trauma (Injury Severity Scale>15) admissions at the State Major Trauma Centre in Royal Perth Hospital was undertaken from 1995 until 2013. BCVI was identified from the hospital's trauma registry. The medical records of these patients were then reviewed. RESULT: 58 of 7451 (0.78%) major trauma patients were diagnosed of BCVI during the study period. An increased incidence, from 0.52% (20/3880) to 1.06% (38/3571), was seen after the introduction of the Diagnostic Imaging Pathway in 2007 (p=0.010). The majority of the cases were caused by motor vehicle crashes, with 66% (n=38) of the cases sustaining concomitant head or cervical spine injury. Other commonly associated injuries included chest, extremity and thoracic spine injury. CONCLUSION: Our study reports a significant increase in the diagnosis of BCVI among major traumas after the introduction of a Diagnostic Imaging Pathway for the screening of this injury in 2007. The previously low incidence of BCVI compared with other centres' reports indicated possible previous under-screening and diagnosis of this injury.

Detailed assessment of benefits and risks of retrievable inferior vena cava filters on patients with complicated injuries: the da Vinci multicentre randomised controlled trial study protocol.

INTRODUCTION: Retrievable inferior vena cava (IVC) filters have been increasingly used in patients with major trauma who have contraindications to anticoagulant prophylaxis as a primary prophylactic measure against venous thromboembolism (VTE). The benefits, risks and cost-effectiveness of such strategy are uncertain. METHODS AND ANALYSIS: Patients with major trauma, defined by an estimated Injury Severity Score >15, who have contraindications to anticoagulant VTE prophylaxis within 72 hours of hospitalisation to the study centre will be eligible for this randomised multicentre controlled trial. After obtaining consent from patients, or the persons responsible for the patients, study patients are randomly allocated to either control or IVC filter, within 72 hours of trauma admission, in a 1:1 ratio by permuted blocks stratified by study centre. The primary outcomes are (1) the composite endpoint of (A) pulmonary embolism (PE) as demonstrated by CT pulmonary angiography, high probability ventilation/perfusion scan, transoesophageal echocardiography (by showing clots within pulmonary arterial trunk), pulmonary angiography or postmortem examination during the same hospitalisation or 90-day after trauma whichever is earlier and (B) hospital mortality; and (2) the total cost of treatment including the costs of an IVC filter, total number of CT and ultrasound scans required, length of intensive care unit and hospital stay, procedures and drugs required to treat PE or complications related to the IVC filters. The study started in June 2015 and the final enrolment target is 240 patients. No interim analysis is planned; incidence of fatal PE is used as safety stopping rule for the trial. ETHICS AND DISSEMINATION: Ethics approval was obtained in all four participating centres in Australia. Results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: ACTRN12614000963628; Pre-results.

Predicting the compressibility behaviour of tire shred samples for landfill applications.

Tire shreds have been used as an alternative to crushed stones (gravel) as drainage media in landfill leachate collection systems. The highly compressible nature of tire shreds (25-47% axial strain on vertical stress applications of 20-700 kPa) may reduce the thickness of the tire shred drainage layer to less than 300 mm (minimum design requirement) during the life of the municipal solid waste landfill. There hence exists a need to predict axial strains of tire shred samples in response to vertical stress applications so that the initial thickness of the tire shred drainage layer can be corrected for compression. The present study performs one-dimensional compressibility tests on four tire shred samples and compares the results with stress/strain curves from other studies. The stress/strain curves are developed into charts for choosing the correct initial thickness of tire shred layers that maintain the minimum thickness of 300 mm throughout the life of the landfill. The charts are developed for a range of vertical stresses based on the design height of municipal waste cell and bulk unit weight of municipal waste. Experimental results also showed that despite experiencing large axial strains, the average permeability of the tire shred sample consistently remained two to three orders of magnitude higher than the design performance criterion of 0.01cm/s for landfill drainage layers. Laboratory experiments, however, need to verify whether long-term chemical and bio-chemical reactions between landfill leachate and the tire shred layer will deteriorate their mechanical functions (hydraulic conductivity, compressibility, strength) beyond permissible limits for geotechnical applications.