Optical Tests on a Curve Fresnel Lens as Secondary Optics for Solar Troughs

A curve Fresnel lens is developed as secondary concentrator for solar parabolic troughs to reduce the number of photovoltaic cells. Specific measurements and optical tests are used to evaluate the optical features of manufactured samples. The cylindrical Fresnel lens transforms the focal line, produced by the primary mirror, into a series of focal points. The execution of special laboratory tests on some secondary concentrator samples is discussed in detail, illustrating the methodologies tailored to the specific case. Focusing tests are performed, illuminating different areas of the lens with solar divergence light and acquiring images on the plane of the photocell using a CMOS camera. Concentration measurements are carried out to select the best performing samples of curve Fresnel lens. The insertion of the secondary optics within the concentrating photovoltaic (CPV) trough doubles the solar concentration of the system. The mean concentration ratio is 1.73, 2.13, and 2.09 for the three tested lenses. The concentration ratio of the solar trough is 140 and approaches 300 after the introduction of the secondary lens

The distance walked daily as a post-operative measure after pulmonary endarterectomy

Background: Pulmonary endarterectomy (PEA) is recognized as the best surgical choice for treatment of chronic thromboembolic pulmonary hypertension caused by pulmonary vascular occlusion in eligible patients. This study aims to describe correlations between the daily walk (DW), and the demographic and clinical characteristics of patients undergoing pulmonary endarterectomy. Methods: This was a cross-sectional study using data from 32 consecutive patients who had undergone PEA operations and were admitted to the cardiac ward to complete their post-operative rehabilitation. Results: Those with a body mass index of 6525 walked a greater distance during the post-operative rehabilitation phase after PEA compared with those with body mass index <25. We also found differences in daily walk distances between women and men: by day 3, the men had already walked a median distance of 240 metres, while women had walked a median distance of 15 metres. Conclusions: The authors found that estimation of the DW was a simple, inexpensive, and reliable measure that can help professionals to evaluate patients' post-operative course after PE

Risk factors for acute kidney injury after surgery of the thoracic aorta using antegrade selective cerebral perfusion and moderate hypothermia

BACKGROUND: The development of acute kidney injury (AKI) in cardiac surgery is associated with increased morbidity and mortality. The aim of the study was to assess the incidence and risk factors for AKI after thoracic aorta surgery, using antegrade selective cerebral perfusion (ASCP) and moderate hypothermia.METHODS: We reviewed 641 patients undergoing thoracic aortic surgery, using ASCP and moderate hypothermia, from November 1996 to December 2012. Patient preoperative, intraoperative, and postoperative variables were evaluated for association with AKI with logistic regression analysis. Models including all variables and models, after the sequential removal of postoperative, and both postoperative and intraoperative variables, were assessed using receiver operating characteristic analysis.RESULTS: The mean age of the patients was 62.9 years, and 194 patients (30%) were women. The overall incidence of AKI was 19.0%. In-hospital mortality was significantly higher in the AKI group (33.6% vs 6.7%; P < .001). Logistic regression analysis identified 8 predictors of AKI: 4 of them were preoperative (priority, diabetes, preoperative glomerular filtration rate, and weight); 2 intraoperative (mitral valve and aortic valve replacement); and 2 postoperative (overall neurologic complication and reoperation for bleeding). Model-discrimination performance improved from an area under the curve (AUC) of 0.737, for the model including only preoperative variables, to an AUC of 0.798 for the model including all variables (P = .012).CONCLUSIONS: The incidence of AKI after thoracic aorta surgery is fairly common, and its occurrence strongly affects outcomes. Preoperative renal status and preoperative conditions are the main influences on AKI development. Predictive models can be improved by adding intraoperative and postoperative variables

Elective Aortic Arch Repair: Factors Influencing Neurologic Outcome in 791 Patients

Background The aim of this study was to determine perioperative factors influencing neurologic outcome in a single-center cohort of patients undergoing elective aortic arch operations. Methods From January 2005 to June 2015, 791 consecutive patients received open aortic arch operations with either antegrade selective cerebral perfusion (ASCP) (636 patients [80.4%]) or deep hypothermic circulatory arrest (DHCA) (155 patients [19.6%]). Main indications were degenerative aneurysm (85%) and chronic postdissection aneurysm (9.1%). Results Hospital mortality (30 days) was 5.3%. Permanent neurologic dysfunction (PND) was observed in 42 patients (5.3%). Significant risk factors for PND appeared to be femoral artery cannulation (p = 0.003), progressive cardiopulmonary bypass (p = 0.001), circulatory arrest (p = 0.001), and ASCP time (p = 0.011). ASCP, in contrast to DHCA, was protective against PND (odds ratio [OR], 0.37; p = 0.003). Temporary neurologic dysfunction (TND) was observed in 49 patients (6.2%). Preoperative transient ischemic attack (TIA) (p = 0.001), progressive EuroSCORE (p = 0.001), left ventricular ejection fraction (LVEF) less than 50% (p = 0.003), and the use of femoral artery cannulation (p = 0.049) showed correlation in the univariate analysis. Stepwise logistic regression indicated TIA (p = 0.002; OR, 3.24) and the EuroSCORE (p = 0.003; OR, 1.23) as independent predictors of TND. Conclusions Contemporary elective aortic arch repair can be achieved with low mortality and a low incidence of neurologic dysfunction. ASCP was confirmed to be the safest method of cerebral protection. The extent of aortic arch replacement (apart from the frozen elephant trunk [FET] procedure) was not related to increased rates of TND or PND

Extracorporeal membrane oxygenation for the treatment of refractory cardiogenic shock in adults: strategies, results, and predictors of mortality = Sistemi di ossigenazione a membrana extracorporea come trattamento per lo shock cardiogeno refrattario nella popolazione adulta: strategie, risultati e predittori di mortalit\ue0

The RotaFlow (Maquet, Jostra Medizintechnik AG, Hirrlingen, Germany) and Levitronix CentriMag (Levitronix LCC, Waltham, MA, USA) veno-arterial extracorporeal membrane oxygenation (ECMO) support systems have been investigated as treatment for refractory cardiogenic shock. METHODS: Between 2004 and 2012, 119 consecutive adult patients were supported on RotaFlow (n=104) or CentriMag (n=15) ECMO at our Institution (79 men; mean age 57.3 \ub1 12.5 years, range 19-78 years). Indications for support were: failure to wean from cardiopulmonary bypass in the setting of postcardiotomy (n=47) and primary graft failure (n=26); post-acute myocardial infarction cardiogenic shock (n=11); acute myocarditis (n=3), and cardiogenic shock on chronic heart failure (n=32). RESULTS: A central ECMO setting was established in 64 (53.7%) patients while peripherally in 55 (46.2%). Overall mean support time was 10.9 \ub1 8.7 days (range 1-43 days). Forty-two (35.2%) patients died on ECMO. Overall success rate, in terms of survival on ECMO (n=77), weaning from mechanical support (n=51; 42.8%) and bridge to heart transplantation (n=26; 21.8%), was 64.7%. Sixty-eight (57.1%) patients were successfully discharged. Stepwise logistic regression identified blood lactate levels and creatine kinase-MB relative index at 72h after ECMO initiation, and number of packed red blood cells (PRBCs) transfused on ECMO as significant predictors of mortality. Central ECMO population had a higher rate of continuous veno-venous hemofiltration need and bleeding events compared with the peripheral setting. CONCLUSIONS: ECMO support provides encouraging results in different subsets of patients in cardiogenic shock. Blood lactate levels, creatine kinase-MB relative index and PRBCs transfused should be strictly monitored during veno-arterial ECMO running. Type of ECMO implantation, if peripheral or central, should be decided according to the specific patient subset