Renal Replacement Therapy for Acute Kidney Injury in COVID-19 Patients in Latin America

The incidence of acute kidney injury (AKI) in hospitalized patients with COVID-19 is broad and ranges from 0.5 to 29% according to early reports from China and Italy [1, 2]. A recent multicenter retrospective cohort in New York showed a higher incidence (37%) and mortality (35%). AKI was primarily seen in COVID-19 patients with respiratory failure; 89.7% of patients who were on mechanical ventilation developed AKI as compared to just 21.7% of non-ventilated patients. Furthermore, 96.8% of patients who required renal replacement therapy (RRT) were on ventilators [3]. From these first reports, AKI emerges at the same time as the acute respiratory distress syndrome, and the development of AKI is usually found in patients who progress to phase 3 of the extra-pulmonary systemic hyper-inflammation syndrome [4]. Hirsch et al. [3] reported that up to 37.3% of AKI cases occurred within the first 24 h of hospital admission, and AKI frequently coincides with the development of the hyperinflammation phas

Latin American registry of renal involvement in COVID-19 disease. The relevance of assessing proteinuria throughout the clinical course

The Latin American Society of Nephrology and Hypertension conducted a prospective cohort, multinational registry of Latin American patients with kidney impairment associated to COVID-19 infection with the objective to describe the characteristics of acute kidney disease under these circumstances. The study was carried out through open invitation in order to describe the characteristics of the disease in the region. Eight-hundred and seventy patients from 12 countries were included. Median age was 63 years (54–74), most of patients were male (68.4%) and with diverse comorbidities (87.2%). Acute kidney injury (AKI) was hospital-acquired in 64.7% and non-oliguric in 59.9%. Multiorgan dysfunction syndrome (MODS) due to COVID-19 and volume depletion were the main factors contributing to AKI (59.2% and 35.7% respectively). Kidney replacement therapy was started in 46.2%. Non-recovery of renal function was observed in 65.3%. 71.5% of patients were admitted to ICU and 72.2% underwent mechanical ventilation. Proteinuria at admission was present in 62.4% of patients and proteinuria during hospital-stay occurred in 37.5%. Those patients with proteinuria at admission had higher burden of comorbidities, higher baseline sCr, and MODS was severe. On the other hand, patients with de novo proteinuria had lower incidence of comorbidities and near normal sCr at admission, but showed adverse course of disease. COVID-19 MODS was the main cause of AKI in both groups. All-cause mortality of the general population was 57.4%, and it was associated to age, sepsis as cause of AKI, severity of condition at admission, oliguria, mechanical ventilation, non-recovery of renal function, in-hospital complications and hospital stay. In conclusion, our study contributes to a better knowledge of this condition and highlights the relevance of the detection of proteinuria throughout the clinical course

Increasing access to integrated ESKD care as part of Universal Health Coverage

The global nephrology community recognizes the need for a cohesive strategy to address the growing problem of end-stage kidney disease (ESKD). In March 2018, the International Society of Nephrology hosted a summit on integrated ESKD care, including 92 individuals from around the globe with diverse expertise and professional backgrounds. The attendees were from 41 countries, including 16 participants from 11 low- and lower-middle–income countries. The purpose was to develop a strategic plan to improve worldwide access to integrated ESKD care, by identifying and prioritizing key activities across 8 themes: (i) estimates of ESKD burden and treatment coverage, (ii) advocacy, (iii) education and training/workforce, (iv) financing/funding models, (v) ethics, (vi) dialysis, (vii) transplantation, and (viii) conservative care. Action plans with prioritized lists of goals, activities, and key deliverables, and an overarching performance framework were developed for each theme. Examples of these key deliverables include improved data availability, integration of core registry measures and analysis to inform development of health care policy; a framework for advocacy; improved and continued stakeholder engagement; improved workforce training; equitable, efficient, and cost-effective funding models; greater understanding and greater application of ethical principles in practice and policy; definition and application of standards for safe and sustainable dialysis treatment and a set of measurable quality parameters; and integration of dialysis, transplantation, and comprehensive conservative care as ESKD treatment options within the context of overall health priorities. Intended users of the action plans include clinicians, patients and their families, scientists, industry partners, government decision makers, and advocacy organizations. Implementation of this integrated and comprehensive plan is intended to improve quality and access to care and thereby reduce serious health-related suffering of adults and children affected by ESKD worldwide

Non-Traditional Shape GFRP Rebars for Concrete Reinforcement

The use of glass-fiber-reinforced-polymer (GFRP) composites as internal reinforcement (rebars) for concrete structures has proven to be an alternative to traditional steel reinforcement due to significant advantages such as magnetic transparency and, most importantly, corrosion resistance equating to durability and structural life extension. In recent years, the number of projects specifying GFRP reinforcement has increased dramatically leading the construction industry towards more sustainable practices. Typically, GFRP rebars are similar to their steel counterparts having external deformations or surface enhancements designed to develop bond to concrete, as well as having solid circular cross-sections; but lately, the worldwide composites industry has taken advantage of the pultrusion process developing GFRP rebars with non-traditional cross-sectional shapes destined to optimize their mechanical, physical, and environmental attributes. Recently, circular GFRP rebars with a hollow-core have also become available. They offer advantages such as a larger surface area for improved bond, and the use of the effective cross-sectional area that is engaged to carry load since fibers at the center of a solid cross-section are generally not fully engaged. For a complete understanding of GFRP rebar physical properties, a study on material characterization regarding a quantitative cross-sectional area analysis of different GFRP rebars was undertaken with a sample population of 190 GFRP specimens with rebar denomination ranging from #2 to #6 and with different cross-sectional shapes and surface deformations manufactured by five pultruders from around the world. The water displacement method was applied as a feasible and reliable way to conduct the investigation. In addition to developing a repeatable protocol for measuring cross-sectional area, the objectives of establishing critical statistical information related to the test methodology and recommending improvements to existing provisions and standards allowing for a consistent universal norm for all GFRP rebars were reached. This dissertation also presents an evaluation of the structural behavior of reinforced concrete (RC) beams and slabs using the new type of GFRP rebar consisting of a non-traditional hollow-core shape compared to “traditional” solid round rebars with equivalent cross-sectional areas within the framework of two studies, respectively. To validate the design assumptions following ACI 440.1R design guidelines, two conditions were investigated: under-reinforced (failure controlled by rupture of GFRP rebar); and, over-reinforced (failure controlled by crushing of concrete). For comparison, a cyclic three-point bending load test matrix was developed: for beams, 3 under-reinforced and 3 over-reinforced with hollow-core and solid GFRP rebars, respectively, making a total of 12 RC specimens; for slabs, 3 under-reinforced and 3 over-reinforced with hollow-core and 2 types of solid GFRP rebars, respectively, making a total of 18 RC slabs. The studies on GFRP RC beams and slabs concluded that the hollow-core GFRP rebars were as effective as their solid counterpart and ACI 440.1R design guidelines were applicable to predict their performance. It was shown that final design may be controlled by the permissible deflections as governing parameter for elements under service conditions. Also, a final study with a test matrix containing six extra specimens was generated for post-fire residual strength evaluation of fire-exposed GFRP RC slabs along with temperature gradient in the slabs and dynamic mechanical analysis (DMA) investigation on GFRP samples extracted from the fire-exposed slabs. In this study, the ability of GFRP RC slabs to retain structural integrity during a standards fire exposure as well as determining the residual structural capacity were investigated. The residual strength evaluation of the fire-exposed slabs showed a range of results varying between ± 10%, of the virgin slabs. And, 19 mm (0.75 in.) cover with normal weight concrete was shown to be adequate to provide the necessary fire protection to the GFRP rebars preventing irreversible damage for two-hour fire rated GFRP RC slabs subjected to service loads; also, from the DMA and glass transition temperature of samples extracted from the GFRP rebars, it is inferred that the resin had undergone a post curing phase

Dynamic and quasi-static design of high-rise buildings subjected to wind loads

Damage to structures recorded during recent hurricanes such as Andrew (1992), Iniki (1992), and Hugo (1989) shows dramatic examples of the vulnerability of buildings and other structures such as bridges, and highway sign support structures. Structural failure due to high winds represent a serious concern for the Florida engineering community, and the Nation at large. Especially since annual property losses resulting from such high velocity winds exceed all losses from other natural hazards put together. Moreover, in recent years the migration of people to the hurricane-prone coastal line and the development of new high-tech, lightweight, building materials create a need to investigate the vulnerability of such structures for undesirable wind effects

p Flexural and Durability Performance of Seawater-Mixed Glass Fiber-Reinforced Polymer-Reinforced Concrete Slabs

Forty-eight simply supported glass fiber-reinforced polymer (GFRP) reinforced concrete (RC) slabs made with seawater-mixed concrete were tested to study potential performance degradation over different environmental conditions for 1, 6, 12, and 24 months. The environments consisted of typical field conditions of a subtropical region and immersion in seawater at 60 degrees C (140 degrees F) as an accelerated aging regimen. The GFRP-RC slab strips were 1828 mm (72 in.) long, 304 mm (12 in.) wide, and 152 mm (6 in.) deep and were reinforced with a 9.5 mm (0.375 in.) diameter GFRP bar. All the slabs were tested under three-point flexural loading and all exhibited bar rupture as the failure mode. The test results are reported in terms of the cracking load, ultimate moment capacity, and service-load deflections. Experimental results were compared to the analytical and ACI 440.1R-15 expected values. The type of concrete mixture design as well as the accelerated aging exposure seems to affect the ultimate capacity of GFRP-RC slabs. Analytical and ACI approaches reasonably predicted the experimental failure-moment capacity of most of the seawater-mixed GFRP-RC slabs, specifically for those exposed to field conditioning. The ACI 440.1R-15 equations were in good agreement with the experimentally measured deflections, where the largest deviations were observed for accelerated-aged specimens

Bond-slip effect in flexural behavior of GFRP RC slabs

The use of glass fiber reinforced polymer (GFRP) composite bars as internal reinforcement for concrete is rapidly increasing especially in structures exposed to aggressive environments. A proper bond mechanism between GFRP bar and concrete is essential to ensure proper functioning of such structures. The slippage between the concrete and reinforcement has usually been ignored in numerical modeling of reinforced concrete (RC) structures. In this study, the effect of the bond action in flexural behavior of GFRP RC slabs was investigated. The analysis was first performed by considering a perfect bond between the concrete and reinforcement and ignoring any slippage. Next, an experimentally obtained bond-slip relation was used to replace the unrealistic perfect bond assumption. The predicted flexural load-deflection response of the slab was compared to the experimental data. The result obtained by incorporating the bond-slip model showed a better agreement with the experimental data. Hence, considering the slippage between the GFRP and concrete may be necessary when accurate deflection estimate is required under the service condition. Additionally, it was shown that the perfect bond assumption was sufficiently safe for the design of the GFRP RC slabs

Evaluation of fiber content in GFRP bars using digital image processing

The tensile strength and elastic modulus of a fiber reinforced polymer (FRP) bar are directly related to the percentage of fibers measured by weight or volume. Recognizing the increasing number of different commercially available FRP bars, the implementation of precise methods for quantification of constituent fractions is of high importance to determine physico-mechanical properties. In this study, the fiber and resin matrix contents of four commercially available glass FRP (GFRP) bars were evaluated by implementing micrograph analysis of representative cross-sectioned specimens and compared to a conventional resin matrix separation method. The micrograph analysis was performed through digital image processing (DIP) of scanning electron microscope (SEM) images, while the conventional method was achieved by applying the standardized burn-off resin technique (ASTM D2584-18). The fiber volume fractions obtained from the DIP method were converted to weight fraction through constituent relationship equations. Comparable weight fraction values were obtained from both methods. However, the DIP method has the capability to provide additional microstructural information

Durability of GFRP reinforcing bars in seawater concrete

•Physical and mechanical characterizations of aged GFRP bars were performed.•Accelerated aging exposure has an effect on tensile strength retention.•SEM images and EDS analysis were used to evaluate microstructural integrity.•No chemical degradation was detected after environmental conditioning.•Exponential degradation model is in good agreement with experimental data. This paper presents an experimental study that investigated the durability performance of unstressed glass fiber-reinforced polymer (GFRP) bars embedded in concrete mixed with seawater (seawater concrete). GFRP bars were extracted from concrete elements made with two different seawater concrete mix designs and exposed to different environmental conditions for 1, 6, 12, and 24 months. The concrete samples’ exposure environments consisted of typical field conditions of a subtropical region and seawater at 60 °C as an accelerated aging method. The mechanical test results of GFRP bars are reported in residual capacities of tensile strength, longitudinal elastic modulus, transverse shear strength, and apparent horizontal shear strength. Furthermore, the physical evaluations are in terms of glass transition temperature (Tg) and microstructural integrity through scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy (EDS) analysis. Among all tested properties, tensile strength was the most affected by environmental conditioning. Based on an exponential degradation model, the long-term prediction of the tensile strength capacity was on average 92% under typical field exposure and 72% under the more aggressive conditioning (seawater at 60 °C)

Post-Fire Behavior of GFRP Bars and GFRP-RC Slabs

AbstractTechnologies developed over the last two decades have introduced the use of glass fiber reinforced polymer (GFRP) composite bars as reinforcement in concrete structures when corrosion of the steel reinforcement is likely to occur. Fire resistance of GFRP-reinforced concrete (RC) members is a potential concern that needs to be understood and addressed because of the susceptibility of GFRP bars to degradation at elevated temperatures. In this study, the residual strength of fire-exposed GFRP-RC slabs and the GFRP mechanical properties after furnace exposure were studied. Slabs reinforced with two different types of GFRP bar were exposed to a furnace fire and sustained three-point bending, simulating the sustained service load (the moment due to dead load plus 20% of the moment due to live load at midspan), for 2 h. Upon completion of the fire test, the residual slab strength was assessed using a quasi-static flexural test up to failure. Next, GFRP bars were extracted from the selected locations of the slabs to evaluate the residual mechanical properties, including shear strength (transverse and horizontal) and glass transition temperature (Tg). The GFRP-RC slabs with both bar types did not experience apparent reduction in flexural capacity after a 2-h fire test that generated a maximum temperature of 115°C at the bar surface. The GFRP transverse shear strength decreased whereas the horizontal shear strength and Tg slightly increased