bluuebunny/crossref_metadata_2025 huggingface dataset:
Uncovering the Mechanisms of Low-Salinity Water Injection EOR Processes: A Molecular Simulation Viewpoint
Authors: Martins Ernane de Freitas , da Silva Gabriela Dias , Salvador Michele Aparecida , Baptista Alvaro David Torrez , de Almeida James Moraes , Miranda Caetano Rodrigues
Published: October 2019

In this work, we present a multiscale approach based on first-principles calculations and classical molecular dynamics methods, to investigate the enhanced oil recovery via low-salinity water injection (EOR-LSWI). Salting-in effect, wettability, pH alteration, electrical double layer and the main geochemical reactions involved in the multicomponent ionic exchanges mechanism were analyzed in order to understand their contribution, also to provide an overall phenomenological perspective of the involved phenomena with a proposed feedback control system. The first-principles calculations were based on density functional theory, carry out in the Quantum-ESPRESSO package, to determine the adsorption energies of hydrocarbons (propionic and pentanoic acids and phenol) on calcite (CaCO3) {10.4} surface. In addition, we have obtained the free energy variations for the minerals dissolution processes. The solvent effect was taken into account for the geochemical reactions through a continuum dielectric. The interface between calcite and API brine was investigated through steered classical molecular dynamics, as implemented in the LAMMPs code to evaluate the brine ions adsorption/desorption on calcite surface and characterize the electrostatic environment in the vicinity of the calcite-brine-oil interfaces. Our results showed that the adsorption energies for the deprotonated molecules were lower than the ones for the neutral cases, highlighting the pH effect in the desorption processes. The pH also played a role in the calcite dissolution, since the free energy variation (ΔG) of the dissolution process mediated by H3O+ was lower than the ΔG for the neutral pH process. We found the lowest dissolution ΔG for the MgSO4 mineral (bulk), indicating that Mg2+ and SO42- ions would be abundant in the solution. In contrast, the other minerals exhibit a positive ΔG. Ions adsorption/desorption on calcite are isoergic and suggest an equilibrium between Ca2+ and CO32- ions. In contrast, the Na+ and Cl- ions adsorption were not found to be a spontaneous process. Moreover, the potential of mean force profile for Ca2+ and CO32- ions showed a layered structuring, which indicates that the ion hydration energy is related to the adsorption/desorption process. Such results may contribute to cause-effect understanding of correlations among the mechanisms in EOR-LSWI and help to propose an optimal brine composition to maximize the oil recovery.
ScaleProTect – Scale Deposition Modeling in Pre-Salt Reservoir
Authors: Bouamra Reda , Carneiro Giovanna , Machado Patrick , Feliciano da Silva Manoel , Franquiz Gabriela , Guan Hua , Lindvig Thomas
Published: October 2019

The complexity of carbonate reservoir in pre-salt plays dictates the use of advanced inflow devices to enable optimized reservoir recovery. Intelligent Completions are considered one of the most effective systems for flow control for a production interval. Depending on the actual design and geometry of the intelligent completion tool, inorganic scale deposition can be very difficult to prevent and/or to mitigate. The failure of such equipment tools can cause severe production impairment and affect the entire field economics.

In order to provide a high accuracy assessment of the scale deposition risk, a novel methodology involving scale deposition experiments and model generation has been developed. The proposed workflow combines 1D mechanistic methods to define scaling conditions, thermodynamic models to define the scaling tendencies at these conditions and 3D models to predict particles accumulation in complex geometries using numerical techniques describing the multiphysics interactions between solid particles and live fluids. The basis of the models will be presented in this article along with numerical results of the precipitation and deposition phenomena at downhole conditions.

This work represents the first holistic approach to characterize scale build-up in the vicinity of inflow equipment walls. Numerical results are presented in this paper.
Potential Environmental Impacts of Subsea System Installation and Decommissioning: A New Tool for Comparison of Locational and Technological Alternatives in the Oil & Gas Industry
Authors: Silva Priscila Reis da , Silva Teresinha Andrea da , Nicolosi Eduardo Ribeiro , Miranda Carlos Abraham de Knegt
Published: October 2019

The environmental aspect can be critical in the decision-making process at the onset of offshore E&P projects, especially in sensitive areas. Thus, we developed a methodological framework and a web tool to support the selection of technological and locational alternatives in subsea system installation and decommissioning activities. This framework relies on the assessment of environmental pressures and biological sensitivities. Our model's main assumption is that an activity can cause a number of environmental pressures, which can have different effects on each environmental component (habitats or biological groups). In the end, a potential environmental impact of a technology can be the result of its pressures on the components at a location. The work relied on experts' judgement and it was based on some previously established criteria for the classification of these environmental pressures and components' sensitivities. Scores were set and ranked in these assessments and a formula calculated the potential environmental impact of each activity/technology. A web tool called SCENARIO was developed to incorporate these results in a user-friendly interface, where one can compare scenarios made up with different technological options and different habitats or biological groups. This tool points out the potential environmental impact of each available choice. It also details how each component relates to that impact. Finally, one can acknowledge the environmental performance of its own scenario choices within the range of the best and worst possible alternatives. The tool was tested and proved to be technically sound and capable of contributing effectively to support the decision making process in the environmental aspects of offshore E&P subsea projects. It is also flexible to incorporate any pressure review, new activities and technological updates whenever necessary.
Influence of Humidity, Moisture and Temperature on the Electric Properties of Self-Sensing Cement Pastes for Post-Abandonment Well Monitoring
Authors: Carísio Pedro de Almeida , Carvalho Carlos Pessanha Costa , Cocchiarale Marcela de Oliveira , Ferreira Lincoln Homero Thome , Mendoza Reales Oscar Aurelio , Fairbairn Eduardo de Moraes Rego , Toledo Filho Romildo Dias
Published: October 2019

The self-sensing capability is a well-studied property of carbon nanotubes blended cement pastes intended for civil construction applications. Nevertheless, most of the studies that can be found in the literature were performed at room temperature, natural humidity and atmospheric pressure. It is necessary to understand how down-hole conditions affect the electrical response of this intelligent material to identify its potential application in the oil industry. This paper presents a study on the effect of relative humidity, internal moisture and temperature on the electric properties of self-sensing cement pastes. These pastes were manufactured with class G cement blended with carbon nanotubes and are intended to be used as an intelligent material capable of auto monitoring its internal stresses and deformations during the post-abandonment phase of a well. Carbon nanotubes blended cement pastes were molded in 2.5 × 2.5 × 11.5 cm3 prisms embedded with copper electrodes. The produced samples were exposed to different relative humidity, internal moisture and temperature conditions and their electrical resistivity was measured at each condition by connecting a DC power supply and a multimeter to the embedded electrodes. Relative humidity and temperature was varied in a climate chamber, already internal moisture was varied by saturating and partially drying the material. It was found that the electrical resistivity of the studied pastes is more highly sensible to internal moisture and temperature, while relative humidity had a lower effect under the studied conditions. These results lead to the conclusions that the electrical response of carbon nanotubes blended pastes is highly affected by environmental conditions, and that for oil-well applications it is necessary to develop correction models that allow an accurate measurement of the internal stresses and deformations of the material.
Virtual Reality for Visualization of Enhanced Oil Recovery Processes at Nanoscale
Authors: de Almeida James Moraes , Miranda Caetano Rodrigues
Published: October 2019

This work provides an immersive visualization of oil & gas relevant systems and enhanced oil recovery (EOR) processes at the nanoscale by coupling molecular dynamics (MD) simulations with gamming virtual reality (VR) technologies. The main objective is to understand oil/brine/rock interfaces at molecular level and identify the underlying EOR mechanisms at the atomic scale. Within this immersive experience, the user can directly interact and enhance its perception of atomic environment for EOR applications. The experiences cover nano-EOR, nano-IOR and low-salt processes at nanoscale based on MD calculations of nanoparticles at oil-brine interfaces, oil-brine at silica nanopores and calcite-brine-oil interfaces, respectively. The MD simulations are performed with the Lammps package. The visualizations were done with an HTC Vive and Oculus Rift virtual reality headsets with the Nomad VR and Unitymol software. For the Nomad VR, the trajectories are previously saved from a Lammps molecular dynamics simulation, whereas, for the Unitymol, the simulation with Lammps is performed on-the-fly through the iMD (interactive MD) plugin. The user can visualize and navigate through the trajectories using the Nomad VR. Furthermore, the Unitymol also allows the user apply forces on selected molecules on real time during the VR experience. As means of comparison, the visualization was also performed with cell-phone based VR headsets with the Nomad VR application. Our demonstrations show that VR combined with molecular simulations can be an interesting and attractive way to improve the perception of the nanoscale for the general public. Additionally, it is an emergent tool to characterize, improve the understanding and provide molecular insights about nanosystems and the EOR methods, and also to be integrated with on-going digitalization processes within the oil & gas industry.
Multiscale Coupling between Molecular Simulations and Reservoir Simulator: Geochemical Reactions for Low Salinity Water Injection in Carbonates
Authors: Baptista Alvaro David Torrez , Salvador Michele Aparecida , Silva Gabriela Dias da , Martins Ernane de Freitas , Almeida James Moraes de , Miranda Caetano Rodrigues
Published: October 2019

This work, is based on the multiscale coupling between molecular simulations and reservoir simulators, to explore the brine composition for enhanced oil recovery via the low salinity water injection (LSWI) processes. To achieve this goal, molecular simulations were performed, providing physical-chemistry parameters to reservoir simulators and validate the proposed brine compositional model. The key data required within reservoir simulators are related to the chemical reactions, which are occurring due to the LSWI process, such as their free energies, kinetic constants, ionic strengths, chemical activities, and activation energies. To improve the accuracy of this input dataset, the main aqueous phase geochemical reactions were mapped, adsorption energies of hydrocarbons and brine ions on calcite surface were determined and ions-bearing calcium carbonate were evaluated. The calculations were based on the density functional theory (DFT) and classical molecular dynamics (MD) using Quantum-ESPRESSO and LAMMPS codes, respectively. The geochemical reactions that take place at mineral dissolution and ionic release, related to the LWSI process (MgSO4, CaSO4, BaSO4, Na2CO3, and CaCO3), were also determined. The obtained chemical equilibrium showed that the MgSO4 dissolution reaction was favored, while other minerals did not show a similar trend. Adsorption studies of organic the molecules naphthalene and anthracene over different surface sites were performed. The adsorption energies were similar for both molecules, where the most favorable configuration has the rings oriented parallel to the mineral surface. The potential of mean force obtained for brine ion adsorption suggested that there were no barriers for adsorbing Ca2+ and CO32- brine ions on calcite surface. In contrast, the other ions adsorption (Na+ and Cl-) have presented higher estimated activation energies. The energetic difference showed that the SO42- incorporation in calcite is more favorable than Mg2+. The Ba2+ showed unfavorable incorporation energy. The thermodynamic properties (free energies, entropies, and heat capacities) were calculated from the vibrational properties. Obtaining such input data by molecular simulations can significantly reduce uncertainties, by increasing the reservoir simulators predictive power, facilitating the optimization and understanding of the processes involved in the injection of low salinity fluids. From these results, the obtained equilibrium constants, free energies and adsorption energies can be used as input data in further reservoir simulators. In addition, it would allow the validation of the proposed model from the understanding of the physical processes underlying LSWI.
Decreasing Well Construction Costs for Mature Fields in the Recôncavo Basin
Authors: Loza Prado Jaime Andres , Rosales Juan , Finney Troy , Venuto Marcos , Hupp Anderson , Camara Francisco
Published: October 2019

The Recôncavo basin is located in northeast Brazil and has several mature fields that have been producing for more than 40 years. After more than three years without drilling activity, an integrated services model was implemented as a different working methodology for optimizing well construction. This work describes in detail the applied methodology and illustrates how it has positively impacted well construction times and thus costs.

An integrated services model approach was applied. Instead of many technical representatives for each specialty, as performed in previous projects in the area, an integrated services coordinator was assigned as a single contact point for the operator to improve communication, document lessons learned, support logistics, follow up with project KPI, daily reporting, operational meetings, and field support on critical operations. Furthermore, technologies that had never been used in the area were applied, such as oil based mud (OBM), electromagnetic measurement while drilling (MWD), rigless cement evaluation, PDC bits and cased hole evaluation. These logging systems were chosen because of the high risk of losing openhole wireline tools as a result of fluid-loss issues in the production hole section, and it worked very well as an innovative option in which a synthetic profile was obtained from the cased hole wireline logging data. This profile was obtained and adjusted based on information from neighboring wells in the same field.

Wells of the previous drilling campaign involved the use of traditional tools and relatively low nonproductive times, but at inefficient well construction rates. Because of the integration acquired using the integrated services approach, a more collaborative environment was created and project stakeholders collaborated to achieve project success and solve specific issues. As a result of the integrated service approach, and the application of new technologies in the area, instant improvement was observed compared to previous drilling campaigns. During project execution, drilling times were positively impacted and risk mitigated, reflecting a continuous improvement tendency and consistent learning curve.

This paper illustrates how an integrated services approach and the introduction of proven technologies were successfully applied in the Recôncavo basin, which can be used by engineers as reference to help achieve similar or better results. It also demonstrates that, even in mature fields or in very well-known areas, there is room for improvement.
Seal Qualification and Single-Trip Lockdown Sleeve Reduces Risk Through Innovative and Advanced Technology
Authors: Ellisor Scott Patrick , Queiroz Rodrigo Albani , Gaban Carlos Eduardo Martins , Eppinghaus Guilherme Pedro , Lucci Bruno Naressi
Published: October 2019

The oil and gas industry continues to face the need to reduce risk and the overall cost of operations as a means to compensate for lower oil prices. Conventional designs and methods are economically infeasible when drilling offshore in the current economic environment pushing the manufacturer to re-evaluate how to reduce risk and drive down costs. This paper describes a new and advanced way to drive down cost and reduce risk while drilling by reducing the number of trips into the well, adding significant value to the end user.

The subsea wellhead system functions in a dynamic, complex environment; however, the qualification process of this system commonly employs relatively static test fixtures. These critical seal/casing hanger barriers within this wellhead system are presented, discussed and shown with exhaustive validation efforts necessary to evaluate relevant failure modes. Within the wellhead system, loads are typically resultant of a combined state including pressure and temperature. The validation of these components is aimed at defining the performance of the system in these states while detailing the limitations that one performance aspect may have on another. (Brown, 2017)

This wellhead system offers reduced cost, simplified installation procedures and lower operational risk. Traditionally, a wellhead system would require a drilling lockdown sleeve during the drilling operations; however, prior to running the lockdown sleeve, many additional trips are made into the well to verify the position of the hanger in the wellhead. By eliminating the lockdown sleeve, the operator will save multiple trips into the well, therefore, reducing NPT and cost of operations. This is proven by performing well-defined subsea seal/casing hanger testing validation to accurately simulate the installed configuration.

Because of this innovative seal assembly design, development of a single trip lock down sleeve was designed for wellhead systems requiring extremely high lock down requirements. The lock down sleeve does not require a trip with a Lead Impression Tool to clean the wellhead and measure the position of pre-installed equipment. This allows the user to save trips previously required by legacy designs, reducing time spent down hole and reducing overall cost.

The antiquated claims of not being able to provide metal-to-metal sealing in dynamic applications are dispelled based on performed validation testing of a metal-to-metal seal (with no elastomeric/thermoplastic elements) which accurately represents field scenarios, in which combined pressure/temperature, load and hanger movement are applied. Therefore, the need for costly trips into the well is shown to be unnecessary with the installation of the single trip lockdown sleeve and/or high capacity casing hanger/seal assembly.
Libra Digital: An Integrated View
Authors: Silva Flavia Pacheco , Anjos Sylvia Couto , Ferreira Ana Cristina Florentino , Wambersie Olivier Edward , Moura Daniela Gonçalves , Pinheiro Luciana Frechette , Santos Bruno Evione , Oliveira Thais Eleuterio R.
Published: October 2019

Digital transformation has revolutionized the way companies operate in the market, changing their work processes with the inclusion of new technologies and thus influencing their culture. In the oil and gas industry, this phenomenon is more recent and is increasingly accentuating. Its importance is such that companies are adjusting their structure to accelerate the implementation of this new culture.

At Petrobras this movement was no different, the corporate area responsible for the digital transformation in the company orchestrates this movement, identifying new opportunities, coordinating corporate initiatives and following the fronts already being implemented in other areas, ensuring alignment with institutional guidelines.

Libr@Digital program aligned with Petrobras’ Digital Transformation corporate initiative and it has been working as a testing environment to validate the solutions before scaling them up to Petrobras operations. This is so, because Libra in its structe congragates all disciplines that integrate the E&P activities, from exploration to oil offloading.
Improved Reamer Cutter Blocks Optimizes the Brazilian's Pre Salt Well Construction
Authors: Silva Leonardo Pacheco da , da Mata Pedro Oliveira , Oliveira Raphael Cristiano , Almeida Junior Carlos Alberto , Benitez Matamoros Alina Meylin , Florido Jorge de Carvalho Lopes
Published: October 2019

This paper will describe the improvement made to the reamer cutter blocks to enhance its durability and optimize the Pre-salt Well Construction

Currently, most of the Brazilian's Pre-Salt wells have the last phase built-in 12.25in. In some situations, it is necessary to drill oil wells in a giant offshore field wells with five phases, enlarging the third phase from 18.125in to 22in. The high abrasiveness encountered at this phase increased the number of runs needed to drill it and, consequently, time and costs that encouraged the development of solutions.

This work relates what has been observed during the last years about reaming difficulties, specifically, in the enlargement from 18.125in to 22in when facing abrasive formations. Petrobras specialists analyzed these events and concluded the matrix of the reamer's cutter blocks was wearing faster and losing the capacity to hold the PDC cutters. The hole enlargement company, that Petrobras works for nowadays, developed a process that increased the resistance of the cutter blocks by increasing the hardness of the surface material prior to the brazing of the cutters. Then, Petrobras has had the opportunity to use both modified and common cutter blocks in a challenging operation to compare their durability and the results were completely satisfactory. The modified cutter blocks had much less wearing on the same formations. Based on this operation, we can conclude this process is validated since improved the reamer cutter blocks quality and its lifetime.

This paper can serve as a guide to reduce operations costs and to optimize well construction when there are concrete possibilities to enlarge abrasive formations.
Some Design Criteria and Operational Characteristics of High Performance Naval VTOL Aircraft
Authors: Duvivier J. F.
Published: October 2019

This paper examines critically the effect of design and mission requirements on the weight penalties claimed for jet VTOL tactical aircraft, the effect of design trade‐offs between structure and powerplant and the relationship of approach speed to landing accident rates, most
of which have not generally been considered in comparisons made between VTOL and CTOL jet aircraft.
Prop‐Rotor Stability at High Advance Ratios
Authors: Hall W. Earl
Published: October 2019

An analytical method for determining the stability of wing‐mounted prop‐rotor pylon systems in fully converted airplane configuration has been developed and is described. Application of this method to an existing tilt‐rotor VTOL configuration, the Bell <emph
type="4">XV‐3, and to subsequently tested scale models, has indicated that the method simulates the instabilities arising from the coupling of prop‐rotor flapping motions to pylon motions. It has been found that the principal destabilizing factor in these pylon
motions is the inplane force generated by blade flapping at high advance ratios. The stability of the prop‐rotor pylon system is decreased with decrease in pylon mounting stiffness and damping and with increase in speed and pitch‐flap coupling (delta‐three). Stability
of the system may generally be increased by Proper controls coupling, such as lagging swashplate coupled to pylon displacements.
Review of Rotary‐Wing V/STOL Dynamic and Aeroelastic Problems
Authors: Loewy Robert G.
Published: October 2019

Rotary‐wing and propeller instabilities are reviewed with three objectives: 1) to increase insight into the sources of prop‐rotor problems, 2) to catalogue a variety of instabilities to which prop‐rotors are subject and 3) to suggest several important subjects for
research in this general area. Thc first objective is approached by contrasting prop‐rotor static aeroelastic problems with those encountered with fixed‐wing aircraft; the second by a selective literature review which groups the dynamic phenomena of interest according to the
kind of differential equation which characterizes them; and the third attempts to anticipate sources of difficulty either with new configurations or in flight regimes for which we presently have very limited experience.
Helicopter Rotor Noise Prediction and Control
Authors: Schlegel Ronald G. , Bausch William E.
Published: October 2019

This paper summarizes the results of Sikorsky Aircraft's research in the prediction and control of helicopter rotor noise. The work to he discussed was partly funded by the U.S. Army Aviation Material Laboratories under Contracts DA 44‐177‐AMC‐141(T) and DA 44‐177‐AMC‐448(T).
An improved procedure has been developed for the prediction of main rotor vortex noise under conditions of uniform inflow for a single rotor helicopter. Both the overall sound pressure level and the spectrum shape of the vortex noise from square tipped blades can be calculated as a function
of tip speed, blade area, and thrust. The geometry of the blade tip can alter both levels and spectrum shape appreciably. The USAAVLABS contracts also resulted in two computerized analyses for rotational noise prediction. Both analyses extend the work of Gutin to include the noise produced
by harmonics of airload acting on the rotor blades. These analyses have demonstrated the importance of the higher harmonics of airload and the chordwise distribution of loading for accurate rotational noise prediction.
The Art and Science of Rotary Wing Data Correlation
Authors: Drees Jan M.
Published: October 2019

This paper presents an overview of the correlation of helicopter rotor performance and loads data from various tests and analyses. Information is included from U.S. Army‐sponsored tests conducted by Bell Helicopter Company for free‐flight full‐scale tests in the
NASA‐Ames 40 × 80 wind tunnel, one‐fifth scale tests in the NASA‐Langley Transonic Dynamics Tunnel, and small‐scale tests of a rotor in air. These test data are compared with each other, where appropriate, and with calculated results. Typical examples illustrate
the state of the art for correlation and indicate anomalies encountered. It is concluded that a procedure using theoretical analyses to aid in interpretation and evaluation of test results is essential to developing a science of correlation.
Don’t forget the jumper’s knee in the young sportsman: evaluation of patellar tendinopathy with a high frequency ultrasound probe
Authors: Ruaro B. , Cutolo M. , Alessandri E. , Zaottini F. , Picasso R. , Pistoia F. , Ferrari G. , Martinoli C.
Published: October 2019

Patellar tendinopathy, or Jumper’s knee, is a painful knee condition caused by inflammation of the patella tendon. This condition is most frequently observed in subjects who play sports that require repetitive regular jumping. Jumper’s knee is frequently misdiagnosed as a minor injury and many athletes, like our patient, keep on training and competing and either tend to ignore the injury or attempt to treat it themselves. However, jumper’s knee is a serious condition that requires a correct and timely diagnosis, which often necessitates ultrasound investigation in order to start the most appropriate treatment.
The avifauna of the forest mosaic habitats of the Mariarano region, Mahajanga II district, north-west Madagascar
Authors: Palfrey Rachel H. , Baddams Jack , Raveloson Bruno A. , Rasamison Solohery , Ó Marcaigh Fionn , Neaves Jamie , Long Peter R. , Martin Thomas E.
Published: October 2019

Background: The West Malagasy dry forests support numerous endemic species and experience heavy anthropogenic pressures, yet remain very poorly studied. Further research is required to understand species distributions and overall diversity in these threatened forest ecosystems.Objectives: We aimed to provide a description of the avifaunal community of a particular dry forest, Mariarano forest, north-western Madagascar, as well as other habitats that are heavily integrated with these Forests. The study site possesses a highly endemic bird community and is under severe environmental pressure, but remains poorly explored.Method: We compiled all records from a 9-year (2010–2018) bird survey data set (the most extensive compiled from a Madagascan dry forest to date), which yielded data from a combination of point count and mist-netting protocols. This was further supplemented by approximately 4384 h of opportunistic observation effort.Results: In total, 95 species were detected, including 63 regional endemics (66.3% of all species), 2 local endemics and 7 Threatened or Near-Threatened species.Conclusion: We highlight the forest mosaic habitats of Mariarano as a potential new Important Bird Area, given the regional importance of its endemic avifauna.
Role of neuroimaging and electroencephalogram in first unprovoked seizures in children from Cairo
Authors: Elfeshawy Mohamed S , Afia Ali A , Alsawah Ahmed Y , Mohammed Mahmoud I , Abdelkader Ann A
Published: October 2019

Background

First unprovoked seizure (FUS) and complex febrile seizure (CFS) are common pediatric issues of great debate with respect to the role of electroencephalogram (EEG) and neuroimaging in their diagnosis.

Aim

To determine the frequency of abnormal EEG and neuroimaging results in children with FUS and CFS and to detect the correlation between EEG and neuroimaging results.

Patients and methods

A total of 100 children (6 months to 12 years of age), who presented with first afebrile or CFS underwent EEG and neuroimaging (computed tomography and/or MRI). This was a prospective randomized controlled trial.

Results

A total of 100 cases within the age group 6 months to 12 years were recruited. FUS was seen in 63 cases and CFS in 37 cases. Overall, 69.8% cases of FUS were generalized and 30.2% were focal. The prevalence of EEG abnormality was found in 33% of the whole studied population: 44.4% in patients with FUS and 13.5% in patients with CFS. The prevalence of neuroimaging abnormality was found in 15% of the whole studied population: 20.6% in patients with FUS and 5.4% in patients with CFS. Neuroimaging abnormality was seen more commonly in those patients who had an abnormal EEG, with a statistically significant increase in cases with FUS.

Conclusion

EEG and neuroimaging abnormalities were more prevalent in children with FUSs than those with CFSs. Abnormal EEG and neuroimaging were more common in children with partial seizures than those with generalized seizures. Neuroimaging was abnormal in a significant number of children having abnormal EEG, so neurologically free patients having normal EEG can be safely discharged without neuroimaging, if follow-up is assured. When EEG is abnormal in FUS, the probability of having abnormal neuroimaging increases as compared with those cases where EEG is normal. In case of generalized seizures, patients with abnormal EEG may have abnormal computed tomography/MRI scans, but there are fewer possibilities of a patient with abnormal EEG to have a normal neuroimaging. In partial seizures, abnormal EEG increases the risk of having abnormal neuroimaging than in generalized seizures, and normal EEG in partial seizures markedly decreases the risk of having an abnormal neuroimaging generalized seizures. CFSs in otherwise neurologically free children rarely indicate the presence of lesion on neuroimaging even if associated with EEG abnormalities. Neuroimaging abnormalities in neurologically free children with FUS and CFSs do not require urgent intervention.
The role of dexmedetomidine infusion on intraoperative desflurane and fentanyl requirement in spine surgery
Authors: Elsayed Ruqaya M , Shabaan Amira A
Published: October 2019

Introduction

Dexmedetomidine is a potent selective agonist of α2 adrenoceptor having sedative, amnestic, sympatholytic, and pain-relieving properties without producing significant respiratory depression and promotes hemodynamic stability when used as an adjuvant during general anesthesia.

Aim

The objective of this study was to evaluate the effect of dexmedetomidine infusion on desflurane consumption, intraoperative fentanyl requirement, and hemodynamic changes.

Patients and methods

Sixty patients of American Society of Anesthesiologists I and II enlisted for elective spine surgery were randomly classified into two groups: group D dexmedetomidine group received preoperative intravenous dexmedetomidine 0.5 μg/kg over 10 min followed by 0.25 μg/kg/h (1 ml, 100 μg diluted with normal saline in 20 ml syringe) intraoperative infusion till the end of surgery and group P, the placebo group received a similar volume of normal saline. Desflurane consumption and intraoperative fentanyl requirement were recorded as well as intraoperative hemodynamic changes.

Results

Desflurane consumption and intraoperative fentanyl requirement were significantly lower in group D (P<0.001) as well as there was a significant decrease in heart rate and mean arterial blood pressure (P<0.05) in D group

Conclusion

Dexmedetomidine infusion resulted in significant reduction of desflurane consumption and intraoperative fentanyl requirement with significant decrease in heart rate and mean arterial blood pressure.
Open mesh versus laparoscopic mesh repair of inguinal hernia
Authors: Abd El-Ghaffar Ahmed Abd E , Elshafey Mohammed H , Abd El-Moneam Ghonaim Amer Y
Published: October 2019

Introduction

Inguinal hernia repair is the most frequently performed operation in general surgery. The standard method for inguinal hernia repair had changed little over a hundred years until the introduction of synthetic mesh which can be placed by either using an open or a laparoscopic approach. The cause of groin hernia is probably multifactorial, with one or more factors applying in any particular case. Among the factors predisposing to groin hernia are persistence of the processus vaginalis, weakness of the shutter mechanism of the inguinal canal, raised intraabdominal pressure, heavy physical exertion, loss of integrity of the fascia transversalis, metabolic factors leading to the production of abnormal collagen fibers, cigarette smoking, genetic influences, spontaneous or iatrogenic abdominal wall trauma, aging, and general factors causing weakness of the abdominal wall muscles and fascia.

Aim

To compare the merits and potential risks between cases subjected to open mesh repair versus cases subjected to laparoscopic mesh repair of inguinal hernia.

Patients and methods

The patients were selected from those attending the surgical outpatient clinics of Al-Azhar University Hospitals (El-Hussein and El Sayed Galal), during the period from January 2017 till January 2019.

Results

This study includes 100 patients with inguinal hernias, where 50 of them were repaired laparoscopically by the transabdominal preperitoneal technique whereas the other 50 were repaired through the Lichtenstein tension-free repair. Patients were followed up by routine clinical examination for 6–18 months (with mean 12 months of follow-up) to calculate the incidence of postoperative complications and recurrence rate during the relatively short period of follow-up.

Conclusion

The Lichtenstein tension-free hernioplasty is the gold standard of groin hernia repair owing to the simplicity of the technique, the short learning curve, the low incidence of recurrence, and the low incidence of easily controllable postoperative complications as well as the relative low price and less expensive instruments required. However, transabdominal preperitoneal repair should be reserved for bilateral and recurrent inguinal hernias as long as the case is fit for general anesthesia or it is best suited to the younger patients in good general health who cannot afford an extended time away from work or who are suspected for a contralateral inguinal defect, and that it should be performed by an experienced surgeon to decrease the risk of complications and the operative time as well as the recurrence rates.
Elective and emergency repair of umbilical hernia in cirrhotic patients with ascites
Authors: Attia Radwa M , Kotb Fatma M
Published: October 2019

Background

Umbilical hernia is a common finding in cirrhotic patients with ascites. The incidence of umbilical hernia is 20–40% in cirrhotic patients, and emergency repair is indicated in critical cases if there is ascites leakage, irreducibility, and infection, with high rate of morbidity and mortality than elective cases.

Aim

To evaluate the effectiveness of elective hernioplasty rather than emergent one.

Patients and methods

A total of 50 patients were included in this study between December 2017 and December 2018 at Al Zahraa University Hospital. They were divided into two groups: (a) elective group included 25 patients with moderate to severe ascites, and (b) emergent group included 25 patients with moderate to severe ascites, of them 10 (40%) cases presented with spontaneous eruption of umbilical hernia, whereas 15 (60%) patients presented with irreducible umbilical hernia. There were 30 (60%) males and 20 (40%) females. Their age ranged between 40 and 65 years, with an average age of 45 years. Umbilical hernioplasty was done for all patients in both groups by using polypropylene mesh after preparation.

Results

In this study, one operative procedure was done for all patients. Using polypropylene mesh with peritoneal dialysis, a catheter was placed in all cases of both groups. There is difference between elective and emergency groups in operative time, postoperative hospital stay, and also early postoperative complication. Long-term follow-up was done in both groups and revealed death owing to liver failure as a complication of cirrhosis in three (12%) patients in the emergent group and in only one (4%) patient in the elective group.

Conclusion

Higher morbidity and mortality are associated with the emergency surgery in advanced cirrhotic patients. The prognosis is favorable for patients with good hepatic reserve.
Effect of ultra-low-dose naloxone with ultrasound-guided transversus abdominis plane block on postoperative pain relief in patients undergoing laparoscopic cholecystectomy
Authors: AEl-Garhy Ahmed M , Nouh Eldesoky M
Published: October 2019

Introduction

Transversus abdominis plane (TAP) blocks have been described as an effective component of multimodal postoperative analgesia for a wide variety of abdominal procedures such as bowel resection, open/laparoscopic appendectomy, cesarean delivery, hysterectomy, laparoscopic cholecystectomy, open prostatectomy, renal transplant surgery, and abdominoplasty. Various adjuvants have been added to augment the effect and prolong the duration of action of analgesia in TAP block. The mechanism of action of ultra-low-dose naloxone includes selective inhibition of the impulses from excitatory opioid receptors and release of encephalin.

Aim

This study investigated the effect of ultra-low-dose naloxone on intensity and duration of analgesia of transversus abdominis plane block (TAP block). The primary outcome of the work is to assess the quality of TAB block with addition of ultra-low-dose naloxone in terms of time to first analgesic request (rescue analgesia) and visual analogue score (VAS) score. The secondary outcome is to assess opioid consumption and occurrence of complications (nausea and vomiting).

Patients and methods

A total of 100 elective laparoscopic cholecystectomy patients were included in our study who were divided randomly into two groups: in the naloxone group (N) (50 patients), bilateral ultrasound-guided subcostal TAP block was done with injection of bupivacaine 0.25% in the plane +100 ng naloxone with total volume of 20 ml in each side, and in the control group (C) (50 patients), bilateral ultrasound-guided subcostal TAP block was done with injection of bupivacaine 0.25% in the plane with total volume 20 ml in each side. Then, the patients were assessed for postoperative pain after full recovery as baseline and then every 4 h for 24 h by VAS. Time to first analgesic request (rescue analgesia), postoperative opioid consumption for the first 24 h, and any adverse effects (nausea and vomiting) were noted.

Results

We found, a highly significant decrease in VAS scores at 12, 16, 20, and 24 h in naloxone group compared with the control group (P<0.01). There was a nonsignificant difference regarding VAS scores at PACU, 4, and 8 h (P>0.05). Moreover, there was a highly significant increase in time to first analgesic request in naloxone group compared with the control group (P<0.01). Regarding secondary outcomes, there was a highly significant decrease in postoperative opioid consumption in naloxone group compared with the control group (P<0.01), and nonsignificant difference regarding nausea and vomiting (P>0.05).

Conclusion

Ultra-low-dose naloxone usage in TAP block helps in reducing postoperative pain scores and postoperative opioid consumption in patients who underwent laparoscopic cholecystectomy.
Comparative study between Limberg flap and local rotation flap for pilonidal sinus, as a new modified technique
Authors: El Fattah Morsi Abd
Published: October 2019

Introduction

Pilonidal sinus is a common chronic disease of the sacrococcygeal region. Treatment varies according to the clinical presentation of the disease. Although many surgical methods have been suggested, an ideal method is still lacking because of high recurrence rates. Recurrent disease causes significant morbidity and consequent time off work.

Aim

The aim of this study was to assess the role of the local rotation flap in promoting primary healing in pilonidal disease and to evaluate morbidity and recurrence in comparison with Limberg flap.

Patients and methods

This prospective study was conducted at Al-Azhar University Hospitals, from April 2015 to July 2018. It involved 80 patients with pilonidal disease. There were 56 males and 24 females aged between 21 and 42 years old. They were divided randomly into two groups, with 40 patients each. Group A underwent Limberg flap, whereas group B underwent a local rotation flap closure for sacrococcygeal pilonidal sinus.

Results

The operative time was ∼1.5 h in group A, whereas in group B was ∼45–60 min. The duration of hospital stay was 1 day, as all patients were discharged on the same day of surgery in both groups. In group A, there was no wound infection, but two cases had wound dehiscence, one case flap necrosis, and two cases with seroma after removal of drain. In group B, there was no wound infection, flap necrosis, or wound dehiscence, but there were six cases with seroma in the follow-up period. There was one case of recurrence in group A and no recurrence in group B.

Conclusion

This study favors the local rotation flap for sacrococcygeal pilonidal sinus because it had the same outcomes as in Limberg flap, in addition to its simplicity and short operative time.
Fetuin-A
Authors: El-Sayed Huda M , El-Sayd Zeinab H , Megahed Tarek G , El-Nabi Mohammed M. Abd El-Wahab H
Published: October 2019

Introduction

Helicobacter pylori infection has been associated with many extragastrointestinal diseases such as cardiovascular and neurological diseases. Recently, several studies have reported a relationship between nonalcoholic fatty liver disease and H. pylori infection. Indeed, H. pylori infection is involved in the pathogenesis of insulin resistance (IR), which is closely linked with nonalcoholic fatty liver disease. Furthermore, fetuin-A has been linked with impaired insulin sensitivity.

Aim

Therefore, we aimed to evaluate fetuin-A as a possible link between H. pylori infection and IR.

Patients and methods

A total of 160 patients included in our study were divided into two groups according to the presence or absence of H. pylori infection. We determined serum fetuin-A, serum insulin, homeostasis model assessment-IR, and liver and kidney functions. Upper gastrointestinal tract endoscopy and antral biopsy was taken for H. pylori examination.

Results

We found that fetuin-A was significantly elevated in H. pylori-positive group when compared with H. pylori-negative group, and a significant positive correlation of fetuin-A was observed with fasting insulin levels and homeostasis model assessment-IR.

Conclusion

We conclude that fetuin-A was implicated as a possible link between H. pylori infection and the development of nonalcoholic steatohepatitis through its effect on IR.
Relationship among cognitive function, depression, and vitamin D in a sample of Egyptian patients with migraine
Authors: Maabady Manal H , Elattar Rasha S , Elaidy Asmaa M , Elshennawy Salwa I
Published: October 2019

Background

Migraine is the second most common cause of headache worldwide. Recently, vitamin D deficiency has been considered as a global health problem. Cognitive impairment and depression are common comorbidities with both migraine and vitamin D deficiency. Some studies have shown relationship between vitamin D deficiency and migraine; however, the available evidence on association among vitamin D, migraine, and those comorbidities is limited.

Objective

To study the relation between vitamin D and migraine and to explore its relation to depression and cognitive impairment as comorbidities of migraine.

Patients and methods

This was a cross-sectional comparative case–control study. A total of 30 patients with migraine aged 18–41 years were included along with 30 controls, who were age and sex matched. All patients were assessed for frequency, duration of migraine attacks, and Migraine Disability Assessment Scale (MDAS). All patients with chronic migraine were not on prophylactic treatment. Moreover, patients and control were exposed to Hamilton Depression Rating scale (HAM-D) and Montreal Cognitive Assessment (MoCA) to assess depression and cognition, respectively. Serum vitamin D level was also measured.

Results

Serum vitamin D was significantly decreased in migraineurs with negative correlation to duration of disease and frequency of attacks; however, it was not significant to cognitive impairment or depression. MoCA and HAM-D were significantly affected in patients with migraine than control with significant decline in chronic form of migraine; however, there was no significant difference between migraine with aura or without. MoCA and HAM-D were also related to MDAS but not to vitamin D.

Conclusion

Serum vitamin D is deficient in migraineurs and was related to frequency of attacks but not to the severity of migraine, associated depression, or cognitive impairment. Cognitive impairment and depression were explored in migraineurs and related to MDAS. Cognitive impairment is related to both migraine with aura or without aura, and patients with chronic migraine are affected more than those with episodic migraine.