An LCA of the Pelamis wave energy converter.

PURPOSE: To date, very few studies have attempted to quantify the environmental impacts of a wave energy converter, and almost all of these focus solely on the potential climate change impacts and embodied energy. This paper presents a full life cycle assessment (LCA) of the first-generation Pelamis wave energy converter, aiming to contribute to the body of published studies and examine any potential trade-offs or co-benefits across a broad range of environmental impacts. METHODS: The process-based attributional LCA was carried out on the full cradle-to-grave life cycle of the Pelamis P1 wave energy converter, including the device, its moorings and sub-sea connecting cable up to the point of connection with the grid. The case study was for a typical wave farm located off the north-west coast of Scotland. Foreground data was mostly sourced from the manufacturer. Background inventory data was mostly sourced from the ecoinvent database (v3.3), and the ReCiPe and CED impact assessment methods were applied. RESULTS AND DISCUSSION: The Pelamis was found to have significantly lower environmental impacts than conventional fossil generation in 6 impact categories, but performed worse than most other types of generation in 8 of the remaining 13 categories studied. The greatest impacts were from steel manufacture and sea vessel operations. The device performs quite well in the two most frequently assessed impacts for renewable energy converters: climate change and cumulative energy demand. The carbon payback period is estimated to be around 24 months (depending on the emissions intensity of the displaced generation mix), and the energy return on investment is 7.5. The contrast between this and the poor performance in other impact categories demonstrates the limitations of focussing only on carbon and energy. CONCLUSIONS: The Pelamis was found to generally have relatively high environmental impacts across many impact categories when compared to other types of power generation; however, these are mostly attributable to the current reliance on fossil fuels in the global economy and the early development stage of the technology. Opportunities to reduce this also lie in reducing requirements for steel in the device structure, and decreasing the requirements for sea vessel operations during installation, maintenance and decommissioning.

Aortic Dehiscence During Endovascular Sealing for Ruptured Abdominal Aortic Aneurysms.

PURPOSE: To present a case of aneurysm disruption during endovascular sealing of a ruptured abdominal aortic aneurysm. CASE REPORT: A 91-year-old woman presented with a ruptured abdominal aortic aneurysm. Her aneurysm morphology was unsuitable for standard or fenestrated endovascular repair, whereas open repair was considered to have an increased perioperative risk owing to multiple comorbidities. The Nellix endovascular sealing system was used. The balloon-expandable stent-grafts were deployed, but in the presence of aneurysm rupture, it was decided not to prefill the endobags with saline. The patient developed hypotension during endobag filling, which resolved once target pressure was reached. The procedure was completed uneventfully, and the completion angiogram revealed no endoleak. The time from guidewire insertion to completion angiogram was 24 minutes. Over the following days, she developed a gradual drop in hemoglobin, and computed tomographic angiography revealed an increased retroperitoneal hematoma and pronounced disruption of the calcified rim of the aortic sac compared to the preoperative imaging. She was managed with supportive treatment, demonstrating remarkable progress. She remains in good health 4 months later. CONCLUSION: Endovascular sealing can be used in patients with ruptured abdominal aortic aneurysm. Intraoperative endobag saline prefill should be avoided to minimize the risk of aortic wall disruption.

Closure technique after carotid endarterectomy influences local hemodynamics.

BACKGROUND: Meta-analysis supports patch angioplasty after carotid endarterectomy (CEA); however, studies indicate considerable variation in practice. The hemodynamic effect of a patch is unclear and this study attempted to elucidate this and guide patch width selection. METHODS: Four groups were selected: healthy volunteers and patients undergoing CEA with primary closure, trimmed patch (5 mm), or 8-mm patch angioplasty. Computer-generated three-dimensional models of carotid bifurcations were produced from transverse ultrasound images recorded at 1-mm intervals. Rapid prototyping generated models for flow visualization studies. Computational fluid dynamic studies were performed for each model and validated by flow visualization. Mean wall shear stress (WSS) and oscillatory shear index (OSI) maps were created for each model using pulsatile inflow at 300 mL/min. WSS of <0.4 Pa and OSI >0.3 were considered pathological, predisposing to accretion of intimal hyperplasia. The resultant WSS and OSI maps were compared. RESULTS: The four groups comprised 8 normal carotid arteries, 6 primary closures, 6 trimmed patches, and seven 8-mm patches. Flow visualization identified flow separation and recirculation at the bifurcation increased with a patch and was related to the patch width. Computational fluid dynamic identified that primary closure had the fewest areas of low WSS or elevated OSI but did have mild common carotid artery stenoses at the proximal arteriotomy that caused turbulence. Trimmed patches had more regions of abnormal WSS and OSI at the bifurcation, but 8-mm patches had the largest areas of deleteriously low WSS and high OSI. Qualitative comparison among the four groups confirmed that incorporation of a patch increased areas of low WSS and high OSI at the bifurcation and that this was related to patch width. CONCLUSIONS: Closure technique after CEA influences the hemodynamic profile. Patching does not appear to generate favorable flow dynamics. However, a trimmed 5-mm patch may offer hemodynamic benefits over an 8-mm patch and may be the preferred option.

Defining a role for contrast-enhanced ultrasound in endovascular aneurysm repair surveillance.

OBJECTIVE: Endovascular aneurysm repair (EVAR) surveillance includes duplex ultrasound, abdominal radiography, and computed tomography angiography. Contrast-enhanced ultrasound (CEUS) has emerged as an additional modality whose role remains undefined. We evaluated whether a potential role for CEUS was the elucidation of unresolved issues following standard surveillance modalities. METHODS: All patients undergoing EVAR at a tertiary referral center had surveillance based on plain abdominal radiograph and duplex ultrasound, with single arterial phase computed tomography angiography reserved for abnormalities or nondiagnostic imaging. In this prospective evaluation, from April 2010 to July 2011, discordance between imaging modalities or unresolved surveillance issues prompted CEUS. Cases and imaging were discussed in a multidisciplinary setting and outcomes recorded. RESULTS: During the study period, 539 patients underwent EVAR surveillance, of whom 33 (6%) had CEUS for unresolved issues (median age, 79; range, 66-90; 28 male). Median follow-up after EVAR was 23 months (range, 0-132). In all cases, CEUS was able to resolve the clinical issue, resulting in secondary intervention in 10 patients (30%). The remaining patients were returned to surveillance. Within the cohort of 33 patients, the clinical issues were categorized into three groups. Group 1: Endoleak of uncertain classification (n = 27: 21 type II, four type I, two had endoleak excluded). Group 2: Significant aneurysm expansion (≥ 5 mm) without apparent endoleak (n = 4: one type II, three had endoleak excluded). Group 3: Target vessel patency following fenestrated EVAR (n = 2: patency confirmed in both). CONCLUSIONS: CEUS can enhance EVAR surveillance through clarification of endoleak and target vessel patency when standard imaging modalities are not diagnostic.

Guidewire stiffness: what's in a name?

PURPOSE: To measure the stiffness of commonly used "stiff" guidewires in terms of their flexural modulus, an engineering parameter related to bending stiffness. METHODS: Eleven different intact stiff guidewires were selected to undergo a 3-point bending test performed using a tensile testing machine. Testing was performed on 3 new and intact specimens of each guidewire at 10 locations along the wire's length, excluding the floppy tip. The flexural modulus (in gigapascals, GPa) was calculated from the results of the bending test. RESULTS: The flexural modulus of the plain Amplatz wire was 9.5 GPa compared to 11.4 to 14.5 GPa for the "heavy duty" wires. Within the Amplatz family of guidewires, the flexural modulus was 17 GPa for the "stiff," 29.2 GPa for the "extra stiff," 60.3 GPa for the "super stiff," and 65.4 GPa for the "ultra stiff." The Backup Meier measured 139.6 GPa and the Lunderquist Extra Stiff 158.4 GPa. CONCLUSION: The Instructions for Use of some endovascular devices specify a wire type selected from a range of undefined "stiffness" descriptors. These descriptors have little correlation with the measured flexural modulus. Two guidewires with the description "extra stiff" can have a 5-fold difference in flexural modulus. We recommend that guidewire catalogues and packaging include the flexural modulus and that device manufacturers amend their Instructions for Use accordingly.

Arranging university semester date to minimize annual CO2 emission: A UK university case study.

Existing methods of reducing carbon emissions on campus often require substantial investment, and the potential opportunities for carbon dioxide and energy savings in universities with existing infrastructure have not been considered in much detail. This work fills this gap by considering an indirect and soft demand response strategy, i.e., semester arrangement. To identify the optimal operational strategy of a realistic campus-level multi vector energy system (MES) in Scotland based on CO2 emissions, an original tool is presented. Two conclusions can be drawn safely from the case study. Firstly, changing the operational mode of the university could significantly reduce CO2 emissions. Secondly, considering the difference between average emission factor (AEF) and marginal emission factor (MEF) in the power grid, the different operational modes will bring different electricity/heat demands and also affect carbon emissions. The work opens up a new perspective for worldwide university operators who are considering reducing CO2 emissions.

Endovascular Aneurysm Repair and Sealing (EVARS): A Useful Adjunct in Treating Challenging Morphology.

An 81-year-old male with previous open abdominal aortic aneurysm repair presented with asymptomatic large pseudoaneurysms at both ends of an open surgical tube graft. Endovascular aneurysm sealing (EVAS) in combination with the iliac limbs of a standard endovascular aneurysm repair (EVAR) successfully excluded both pseudoaneurysms from circulation. We describe the combination of elements of EVAS and EVAR and have termed this endovascular aneurysm repair and sealing (EVARS). EVARS has the advantage of harnessing the benefits of endobag sealing in aortic necks unsuitable for standard EVAR whilst providing the security of accurate stent placement within short common iliac arteries. In conclusion, EVAS may be combined with standard endovascular iliac limbs and is a possible treatment option for pseudoaneurysm following open aneurysm repair.

Reduction of surgical site infection using a novel intervention (ROSSINI): study protocol for a randomised controlled trial.

BACKGROUND: Surgical site infection (SSI) is a common complication following abdominal surgery. It is associated with considerable morbidity and mortality, and its management results in significant cost to health services within both primary and secondary care. Some surgeons believe that the use of a wound-edge protection device may reduce the incidence of SSI. Whilst there is some encouraging evidence showing that such devices may lead to a reduction in SSI, there are no controlled trials of sufficient size or quality to support their routine use. METHODS/DESIGN: 750 patients will be recruited from around 20 surgical units within the United Kingdom. Patients undergoing laparotomy through any major abdominal incision for any indication, elective or emergency, are eligible. Patients under the age of 18, those undergoing a laparoscopic assisted procedure or who have undergone laparotomy within the previous 3 months, and those who are unable to give informed consent will be excluded. Patients will be randomised (1:1 ratio) to the use of a wound-edge protection device or no wound-edge protection device during surgery. Follow up will consist of blinded clinical wound reviews at 5-7 days and 30-33 days postoperatively with a self-completed questionnaire covering the intervening period. Quality of life questionnaires will be completed prior to surgery and at the subsequent wound review points and information on resource usage will also be captured.The primary outcome measure is SSI within 30 days of surgery. Secondary outcomes include the impact of the degree of wound contamination, patient comorbidity, and operative characteristics on the efficacy of a wound-edge protection device in reducing SSI and whether the use of a wound-edge protection device has an effect on health-related quality of life or length of hospital stay and is cost-effective. DISCUSSION: Rossini is the first multicentre observer-blinded randomised controlled trial of sufficient size and quality to establish whether the use of a wound-edge protection device in adult patients undergoing abdominal surgery leads to a lower rate of SSI. The results of this study will be used to inform current surgical practice and may potentially benefit patients undergoing surgery in the future. TRIAL REGISTRATION NUMBER: Current Controlled Trials ISRCTN: ISRCTN40402832.