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1.
Surg Oncol ; 52: 102039, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38301449

RESUMEN

BACKGROUND AND OBJECTIVES: Recurrent isolated pancreatic metastasis from Renal Cell Carcinoma (RCC) after pancreatic resection is rare. The purpose of our study is to describe a series of cases of relapse of pancreatic metastasis from renal cancer in the pancreatic remnant and its surgical treatment with a repeated pancreatic resection, and to analyse the results of both overall and disease-free survival. METHODS: Multicenter retrospective study of patients undergoing pancreatic resection for RCC pancreatic metastases, from January 2010 to May 2020. Patients were grouped into two groups depending on whether they received a single pancreatic resection (SPS) or iterative pancreatic resection. Data on short and long-term outcome after pancreatic resection were collected. RESULTS: The study included 131 pancreatic resections performed in 116 patients. Thus, iterative pancreatic surgery (IPS) was performed in 15 patients. The mean length of time between the first pancreatic surgery and the second was 48.9 months (95 % CI: 22.2-56.9). There were no differences in the rate of postoperative complications. The DFS rates at 1, 3 and 5 years were 86 %, 78 % and 78 % vs 75 %, 50 % and 37 % in the IPS and SPS group respectively (p = 0.179). OS rates at 1, 3, 5 and 7 years were 100 %, 100 %, 100 % and 75 % in the IPS group vs 95 %, 85 %, 80 % and 68 % in the SPS group (p = 0.895). CONCLUSION: Repeated pancreatic resection in case of relapse of pancreatic metastasis of RCC in the pancreatic remnant is justified, since it achieves OS results similar to those obtained after the first resection.


Asunto(s)
Carcinoma de Células Renales , Neoplasias Renales , Neoplasias Pancreáticas , Humanos , Carcinoma de Células Renales/cirugía , Carcinoma de Células Renales/patología , Estudios Retrospectivos , Pancreatectomía/métodos , Neoplasias Pancreáticas/patología , Neoplasias Renales/cirugía , Neoplasias Renales/patología , Recurrencia
3.
Sci Rep ; 13(1): 18623, 2023 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-37903833

RESUMEN

Over million years, convergence between the Nazca and South America tectonic plates results in Andean orogeny. Over decades/centuries, it fuels the earthquake cycle of the Andean megathrust. It is well recognised that, over the geologically-long term of million years, Andean orogeny feeds back onto plate convergence rates, generating temporal changes documented throughout the Neogene. In contrast, no feedback mechanism operated over the geologically-short term by the earthquake cycle is currently contemplated. In fact, it is commonly assumed that the rates of contemporary convergence, which are accurately measured via geodesy, remain steady during the megathrust earthquake cycle. Here we investigate whether the contemporary Nazca/South America plate motion varies over year-/decade-long periods in response to megathrust stress variations associated with the earthquake cycle. We focus on the decade preceding the three largest and most recent [Formula: see text] earthquakes (2010 [Formula: see text] Maule, 2014 [Formula: see text] Iquique, 2015 [Formula: see text] Illapel), and find slowdowns of both Nazca and South America whole-plate motions that exceed the impact of data uncertainty or noise. We show that the torque variations required upon Nazca and South America to generate the slowdowns are consistent with that arising from the buildup of interseismic stress preceding the earthquakes.

4.
Crit Care Explor ; 4(11): e0796, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36440062

RESUMEN

Timing of tracheostomy in patients with COVID-19 has attracted substantial attention. Initial guidelines recommended delaying or avoiding tracheostomy due to the potential for particle aerosolization and theoretical risk to providers. However, early tracheostomy could improve patient outcomes and alleviate resource shortages. This study compares outcomes in a diverse population of hospitalized COVID-19 patients who underwent tracheostomy either "early" (within 14 d of intubation) or "late" (more than 14 d after intubation). DESIGN: International multi-institute retrospective cohort study. SETTING: Thirteen hospitals in Bolivia, Brazil, Spain, and the United States. PATIENTS: Hospitalized patients with COVID-19 undergoing early or late tracheostomy between March 1, 2020, and March 31, 2021. INTERVENTIONS: Not applicable. MEASUREMENTS AND MAIN RESULTS: A total of 549 patients from 13 hospitals in four countries were included in the final analysis. Multivariable regression analysis showed that early tracheostomy was associated with a 12-day decrease in time on mechanical ventilation (95% CI, -16 to -8; p < 0.001). Further, ICU and hospital lengths of stay in patients undergoing early tracheostomy were 15 days (95% CI, -23 to -9 d; p < 0.001) and 22 days (95% CI, -31 to -12 d) shorter, respectively. In contrast, early tracheostomy patients experienced lower risk-adjusted survival at 30-day post-admission (hazard ratio, 3.0; 95% CI, 1.8-5.2). Differences in 90-day post-admission survival were not identified. CONCLUSIONS: COVID-19 patients undergoing tracheostomy within 14 days of intubation have reduced ventilator dependence as well as reduced lengths of stay. However, early tracheostomy patients experienced lower 30-day survival. Future efforts should identify patients most likely to benefit from early tracheostomy while accounting for location-specific capacity.

5.
Eur J Surg Oncol ; 48(1): 133-141, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34417061

RESUMEN

BACKGROUND: Renal Cell Carcinoma (RCC) occasionally spreads to the pancreas. The purpose of our study is to evaluate the short and long-term results of a multicenter series in order to determine the effect of surgical treatment on the prognosis of these patients. METHODS: Multicenter retrospective study of patients undergoing surgery for RCC pancreatic metastases, from January 2010 to May 2020. Variables related to the primary tumor, demographics, clinical characteristics of metastasis, location in the pancreas, type of pancreatic resection performed and data on short and long-term evolution after pancreatic resection were collected. RESULTS: The study included 116 patients. The mean time between nephrectomy and pancreatic metastases' resection was 87.35 months (ICR: 1.51-332.55). Distal pancreatectomy was the most performed technique employed (50 %). Postoperative morbidity was observed in 60.9 % of cases (Clavien-Dindo greater than IIIa in 14 %). The median follow-up time was 43 months (13-78). Overall survival (OS) rates at 1, 3, and 5 years were 96 %, 88 %, and 83 %, respectively. The disease-free survival (DFS) rate at 1, 3, and 5 years was 73 %, 49 %, and 35 %, respectively. Significant prognostic factors of relapse were a disease free interval of less than 10 years (2.05 [1.13-3.72], p 0.02) and a history of previous extrapancreatic metastasis (2.44 [1.22-4.86], p 0.01). CONCLUSIONS: Pancreatic resection if metastatic RCC is found in the pancreas is warranted to achieve higher overall survival and disease-free survival, even if extrapancreatic metastases were previously removed. The existence of intrapancreatic multifocal compromise does not always warrant the performance of a total pancreatectomy in order to improve survival.


Asunto(s)
Carcinoma de Células Renales/cirugía , Neoplasias Renales/patología , Metastasectomía , Pancreatectomía , Neoplasias Pancreáticas/cirugía , Complicaciones Posoperatorias/epidemiología , Anciano , Carcinoma de Células Renales/secundario , Femenino , Humanos , Neoplasias Renales/cirugía , Masculino , Persona de Mediana Edad , Nefrectomía , Neoplasias Pancreáticas/secundario , España/epidemiología , Resultado del Tratamiento
7.
World J Surg ; 45(8): 2408-2414, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-33939010

RESUMEN

BACKGROUND: Future navy officers require unique training for emergency medical response in the isolated maritime environment. The authors issued a workshop on extremity bleeding control, using four different commercial extremity tourniquets onboard a training sail ship. The purposes were to assess participants' perceptions of this educational experience and evaluate self-application simplicity while navigating on high seas. METHODS: A descriptive observational study was conducted as part of a workshop issued to volunteer training officers. A post-workshop survey collected their perceptions about the workshops' content usefulness and adequacy, tourniquet safety, self-application simplicity, and device preference. Tourniquet preference was measured by frequency count while the rest of the studied variables on a one-to-ten Likert scale. Frequencies and percentages were calculated for the studied variables, and application simplicity means compared using the ANOVA test (p < 0.05). RESULTS: Fifty-one Spanish training naval officers, aged 20 or 21, perceived high sea workshop content's usefulness, adequacy, and safety level at 8.6/10, 8.7/10, and 7.5/10, respectively. As for application simplicity, CAT and SAM-XT were rated equally with a mean of 8.5, followed by SWAT (7.9) and RATS (6.9), this one statistically different from the rest (p < 0.01). Windlass types were preferred by 94%. CONCLUSIONS: The training sail ship's extremity bleeding control workshop was perceived as useful and its content adequate by the participating midshipmen. Windlass types were regarded as easier to apply than elastic counterparts. They were also preferred by nine out of every ten participants.


Asunto(s)
Hemorragia , Torniquetes , Extremidades , Humanos , Encuestas y Cuestionarios , Voluntarios
8.
Eur J Trauma Emerg Surg ; 47(3): 621-629, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33047158

RESUMEN

PURPOSE: The COVID-19 pandemic has changed working conditions for emergency surgical teams around the world. International surgical societies have issued clinical recommendations to optimize surgical management. This international study aimed to assess the degree of emergency surgical teams' adoption of recommendations during the pandemic. METHODS: Emergency surgical team members from over 30 countries were invited to answer an anonymous, prospective, online survey to assess team organization, PPE-related aspects, OR preparations, anesthesiologic considerations, and surgical management for emergency surgery during the pandemic. RESULTS: One-hundred-and-thirty-four questionnaires were returned (N = 134) from 26 countries, of which 88% were surgeons, 7% surgical trainees, 4% anesthetists. 81% of the respondents got involved with COVID-19 crisis management. Social media were used by 91% of the respondents to access the recommendations, and 66% used videoconference tools for team communication. 51% had not received PPE training before the pandemic, 73% reported equipment shortage, and 55% informed about re-use of N95/FPP2/3 respirators. Dedicated COVID operating areas were cited by 77% of the respondents, 44% had performed emergency surgical procedures on COVID-19 patients, and over half (52%), favored performing laparoscopic over open surgical procedures. CONCLUSION: Surgical team members have responded with leadership to the COVID-19 pandemic, with crisis management principles. Social media and videoconference have been used by the vast majority to access guidelines or to communicate during social distancing. The level of adoption of current recommendations is high for organizational aspects and surgical management, but not so for PPE training and availability, and anesthesiologic considerations.


Asunto(s)
Anestesiología , COVID-19 , Urgencias Médicas/epidemiología , Control de Infecciones , Grupo de Atención al Paciente/organización & administración , Procedimientos Quirúrgicos Operativos , Anestesiología/métodos , Anestesiología/tendencias , COVID-19/epidemiología , COVID-19/prevención & control , COVID-19/transmisión , Servicio de Urgencia en Hospital , Humanos , Control de Infecciones/instrumentación , Control de Infecciones/métodos , Control de Infecciones/normas , Cooperación Internacional , Relaciones Interprofesionales , Exposición Profesional/clasificación , Exposición Profesional/prevención & control , Manejo de Atención al Paciente/métodos , Manejo de Atención al Paciente/tendencias , Equipo de Protección Personal/normas , Equipo de Protección Personal/provisión & distribución , SARS-CoV-2 , Servicio de Cirugía en Hospital , Procedimientos Quirúrgicos Operativos/métodos , Procedimientos Quirúrgicos Operativos/estadística & datos numéricos , Encuestas y Cuestionarios
9.
Rev Esp Cardiol ; 73(12): 985-993, 2020 Dec.
Artículo en Español | MEDLINE | ID: mdl-32963419

RESUMEN

INTRODUCTION AND OBJECTIVES: Despite advances in treatment, patients with acute myocardial infarction (AMI) still exhibit unfavorable short- and long-term prognoses. In addition, there is scant evidence about the clinical outcomes of patients with AMI and coronavirus disease 2019 (COVID-19). The objective of this study was to describe the clinical presentation, complications, and risk factors for mortality in patients admitted for AMI during the COVID-19 pandemic. METHODS: This prospective, multicenter, cohort study included all consecutive patients with AMI who underwent coronary angiography in a 30-day period corresponding chronologically with the COVID-19 outbreak (March 15 to April 15, 2020). Clinical presentations and outcomes were compared between COVID-19 and non-COVID-19 patients. The effect of COVID-19 on mortality was assessed by propensity score matching and with a multivariate logistic regression model. RESULTS: In total, 187 patients were admitted for AMI, 111 with ST-segment elevation AMI and 76 with non-ST-segment elevation AMI. Of these, 32 (17%) were diagnosed with COVID-19. GRACE score, Killip-Kimball classification, and several inflammatory markers were significantly higher in COVID-19-positive patients. Total and cardiovascular mortality were also significantly higher in COVID-19-positive patients (25% vs 3.8% [P < .001] and 15.2% vs 1.8% [P = .001], respectively). GRACE score > 140 (OR, 23.45; 95%CI, 2.52-62.51; P = .005) and COVID-19 (OR, 6.61; 95%CI, 1.82-24.43; P = .02) were independent predictors of in-hospital death. CONCLUSIONS: During this pandemic, a high GRACE score and COVID-19 were independent risk factors associated with higher in-hospital mortality.Full English text available from:www.revespcardiol.org/en.

10.
Rev Esp Cardiol (Engl Ed) ; 73(12): 985-993, 2020 Dec.
Artículo en Inglés, Español | MEDLINE | ID: mdl-32839121

RESUMEN

INTRODUCTION AND OBJECTIVES: Despite advances in treatment, patients with acute myocardial infarction (AMI) still exhibit unfavorable short- and long-term prognoses. In addition, there is scant evidence about the clinical outcomes of patients with AMI and coronavirus disease 2019 (COVID-19). The objective of this study was to describe the clinical presentation, complications, and risk factors for mortality in patients admitted for AMI during the COVID-19 pandemic. METHODS: This prospective, multicenter, cohort study included all consecutive patients with AMI who underwent coronary angiography in a 30-day period corresponding chronologically with the COVID-19 outbreak (March 15 to April 15, 2020). Clinical presentations and outcomes were compared between COVID-19 and non-COVID-19 patients. The effect of COVID-19 on mortality was assessed by propensity score matching and with a multivariate logistic regression model. RESULTS: In total, 187 patients were admitted for AMI, 111 with ST-segment elevation AMI and 76 with non-ST-segment elevation AMI. Of these, 32 (17%) were diagnosed with COVID-19. GRACE score, Killip-Kimball classification, and several inflammatory markers were significantly higher in COVID-19-positive patients. Total and cardiovascular mortality were also significantly higher in COVID-19-positive patients (25% vs 3.8% [P <.001] and 15.2% vs 1.8% [P=.001], respectively). GRACE score> 140 (OR, 23.45; 95%CI, 2.52-62.51; P=.005) and COVID-19 (OR, 6.61; 95%CI, 1.82-24.43; P=.02) were independent predictors of in-hospital death. CONCLUSIONS: During this pandemic, a high GRACE score and COVID-19 were independent risk factors associated with higher in-hospital mortality.


Asunto(s)
COVID-19/epidemiología , Infarto del Miocardio/mortalidad , Medición de Riesgo/métodos , SARS-CoV-2 , Anciano , Comorbilidad , Femenino , Estudios de Seguimiento , Mortalidad Hospitalaria/tendencias , Humanos , Masculino , Persona de Mediana Edad , Pandemias , Estudios Prospectivos , Estudios Retrospectivos , Factores de Riesgo , España/epidemiología
11.
World J Surg ; 44(9): 2842-2847, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32564140

RESUMEN

BACKGROUND: The Severe Acute Respiratory Syndrome Coronavirus 2 pandemic has exposed surgeons to hazardous working conditions, imposing the need for personal protective equipment (PPE) use during surgery. The use of such equipment may affect their non-technical skills, augment fatigue, and affect performance. This study aimed to assess the surgeons' perceptions of the impact of wearing PPE during emergency surgery throughout the pandemic. METHODS: An international cooperation group conducted an anonymous online survey among surgeons from over 30 countries, to assess perceptions about the impact of PPE use on non-technical skills, overall comfort, decision making, and surgical performance during emergency surgery on COVID-19 patients. RESULTS: Responses to the survey (134) were received from surgeons based on 26 countries. The vast majority (72%) were males. More than half of the respondents (54%) felt that their surgical performance was hampered with PPE. Visual impairment was reported by 63%, whereas 54% had communication impediments. Less than half (48%) felt protected with the use of PPE, and the same proportion perceived that the use of such equipment influenced their decision making. Decreased overall comfort was cited by 66%, and 82% experienced increased surgical fatigue. CONCLUSIONS: Surgeons perceived impediment for both visibility and communication, and other non-technical skills while using PPE on emergency surgery in COVID-19 patients. Their perceived lack of protection and comfort and increased fatigue may have inhibited their optimal surgical performance. More attention should be placed in the design of more user-friendly equipment, given the possibility of a second wave of the pandemic.


Asunto(s)
Actitud del Personal de Salud , Infecciones por Coronavirus/prevención & control , Pandemias/prevención & control , Equipo de Protección Personal , Neumonía Viral/prevención & control , Cirujanos , Rendimiento Laboral , Adulto , Betacoronavirus , COVID-19 , Toma de Decisiones Clínicas , Infecciones por Coronavirus/epidemiología , Fatiga/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neumonía Viral/epidemiología , SARS-CoV-2 , Encuestas y Cuestionarios
13.
Rev Esp Cardiol (Engl Ed) ; 73(5): 368-375, 2020 May.
Artículo en Inglés, Español | MEDLINE | ID: mdl-31631048

RESUMEN

INTRODUCTION AND OBJECTIVES: Ivabradine is an inhibitor of the If channel, the main determinant of the pacemaker function of the sinus node. The drug has been approved for the treatment of angina and heart failure. There is some evidence of its role as an inhibitor of atrial-ventricular node (AVN) conduction. The aim of the BRAKE-AF project is to assess ivabradine use for rate control in atrial fibrillation (AF). METHODS: A multicenter, randomized, parallel, open-label, noninferiority phase III clinical trial will be conducted to compare ivabradine vs digoxin in 232 patients with uncontrolled permanent AF despite beta-blockers or calcium channel blockers. The primary efficacy endpoint is the reduction in daytime heart rate measured by 24-hour Holter monitoring at 3 months. This clinical trial will be supported by an electrophysiological study of the effect of ivabradine on the action potential of the human AVN. To do this, an experimental model will be used with Chinese hamster ovarium cells transfected with the DNA encoding the expression of the t channels involved in this action potential and recording of the ionic currents with patch clamp techniques. RESULTS: New data will be obtained on the effect of ivabradine on the human AVN and its safety and efficacy in patients with permanent AF. CONCLUSIONS: The results of the BRAKE-AF project might allow inclusion of ivabradine within the limited arsenal of drugs currently available for rate control in AF. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov. Identifier: NCT03718273.


Asunto(s)
Antiarrítmicos/uso terapéutico , Fibrilación Atrial/tratamiento farmacológico , Fármacos Cardiovasculares/uso terapéutico , Digoxina/uso terapéutico , Frecuencia Cardíaca/efectos de los fármacos , Ivabradina/uso terapéutico , Estudios de Equivalencia como Asunto , Frecuencia Cardíaca/fisiología , Humanos , Resultado del Tratamiento
14.
J Vis Exp ; (135)2018 05 02.
Artículo en Inglés | MEDLINE | ID: mdl-29781983

RESUMEN

A well-defined experimental procedure is put forward to evaluate maximum exposure conditions in a worst-case scenario whilst avoiding the uncertainties caused by the use of personal exposimeters (PEMs) as measuring devices: the body shadow effect (BSE), the limited sensitivity range, and the non-identification of the radiation source. An upper bound for exposure levels to EMF in several indoor enclosures has been measured and simulated. The frequency used for the study is 2.4 GHz, as it is the most commonly used band in indoor communications. Although recorded values are well below the International Commission for Non-Ionizing Radiation Protection (ICNIRP) reference levels, there is a particular need to provide reliable exposure levels within particularly sensitive environments. In terms of electromagnetic field (EMF) exposure, limits established in national and international standards for health protection have been set for unperturbed exposure conditions; that is, for real and objective exposure data that have not been altered in any way.


Asunto(s)
Campos Electromagnéticos/efectos adversos , Exposición a Riesgos Ambientales/efectos adversos , Dosímetros de Radiación/efectos adversos , Humanos
16.
J Mech Behav Biomed Mater ; 75: 33-40, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28692843

RESUMEN

The present study is focused on mechanical properties that result from cold rolling and aging treatments applied to TiNbSn alloys comprising different Nb (35% and 42%) and Sn (0% and 2.5%) contents. The alloys were arc melted, homogenized, solubilized, cold rolled and aged at 400°C for different aging times. A set of characterization tests performed, included microstructural analysis, X-ray diffraction, microhardness, tensile tests and fracture analysis. The alloys contained all three ß, α" and ω phases after cold rolling, regardless of the alloying content. The solid solution effect led to changes in the alloys' mechanical behavior. Furthermore, the alloys presented α phase precipitation, and it led to a peak-aged stage after different aging times due to the Nb content. The alloys containing 42% and 35% Nb content reached the peak-aged stage within 48 and 72h, respectively. The α phase precipitation in the alloys at peak-aged stage increased the hardness, tensile strength and elastic modulus of the alloys; however, it also caused ductility to decrease. The fine dispersed precipitates of the α phase generated small and shallow dimples, which are a characteristic fracture micromechanism of peak-aged alloys.


Asunto(s)
Aleaciones/análisis , Ensayo de Materiales , Titanio/análisis , Módulo de Elasticidad , Resistencia a la Tracción , Difracción de Rayos X
18.
World J Cardiol ; 7(7): 423-30, 2015 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-26225204

RESUMEN

AIM: To assess the safety of therapeutic hypothermia (TH) concerning arrhythmias we analyzed serial electrocardiograms (ECG) during TH. METHODS: All patients recovered from a cardiac arrest with Glasgow < 9 at admission were treated with induced mild TH to 32-34 °C. TH was obtained with cool fluid infusion or a specific intravascular device. Twelve-lead ECG before, during, and after TH, as well as ECG telemetry data was recorded in all patients. From a total of 54 patients admitted with cardiac arrest during the study period, 47 patients had the 3 ECG and telemetry data available. ECG analysis was blinded and performed with manual caliper by two independent cardiologists from blinded copies of original ECG, recorded at 25 mm/s and 10 mm/mV. Coronary care unit staff analyzed ECG telemetry for rhythm disturbances. Variables measured in ECG were rhythm, RR, PR, QT and corrected QT (QTc by Bazett formula, measured in lead v2) intervals, QRS duration, presence of Osborn's J wave and U wave, as well as ST segment displacement and T wave amplitude in leads II, v2 and v5. RESULTS: Heart rate went down an average of 19 bpm during hypothermia and increased again 16 bpm with rewarming (P < 0.0005, both). There was a non-significant prolongation of the PR interval during TH and a significant decrease with rewarming (P = 0.041). QRS duration significantly prolonged (P = 0.041) with TH and shortened back (P < 0.005) with rewarming. QTc interval presented a mean prolongation of 58 ms (P < 0.005) during TH and a significant shortening with rewarming of 22.2 ms (P = 0.017). Osborn or J wave was found in 21.3% of the patients. New arrhythmias occurred in 38.3% of the patients. Most frequent arrhythmia was non-sustained ventricular tachycardia (19.1%), followed by severe bradycardia or paced rhythm (10.6%), accelerated nodal rhythm (8.5%) and atrial fibrillation (6.4%). No life threatening arrhythmias (sustained ventricular tachycardia, polymorphic ventricular tachycardia or ventricular fibrillation) occurred during TH. CONCLUSION: A 38.3% of patients had cardiac arrhythmias during TH but without life-threatening arrhythmias. A concern may rise when inducing TH to patients with long QT syndrome.

20.
Bioelectromagnetics ; 36(2): 118-32, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25399935

RESUMEN

Personal exposure meters (PEMs) used for measuring exposure to electromagnetic fields (EMF) are typically used in epidemiological studies. As is well known, these measurement devices cause a perturbation of real EMF exposure levels due to the presence of the human body in the immediate proximity. This paper aims to model the alteration caused by the body shadow effect (BSE) in motion conditions and in indoor enclosures at the Wi-Fi frequency of 2.4 GHz. For this purpose, simulation techniques based on ray-tracing have been carried out, and their results have been verified experimentally. A good agreement exists between simulation and experimental results in terms of electric field (E-field) levels, and taking into account the cumulative distribution function (CDF) of the spatial distribution of amplitude. The Kolmogorov-Smirnov (KS) test provides a P-value greater than 0.05, in fact close to 1. It has been found that the influence of the presence of the human body can be characterized as an angle of shadow that depends on the dimensions of the indoor enclosure. The CDFs show that the E-field levels in indoor conditions follow a lognormal distribution in the absence of the human body and under the influence of BSE. In conclusion, the perturbation caused by BSE in PEMs readings cannot be compensated for by correction factors. Although the mean value is well adjusted, BSE causes changes in CDF that would require improvements in measurement protocols and in the design of measuring devices to subsequently avoid systematic errors.


Asunto(s)
Electricidad , Exposición a Riesgos Ambientales/análisis , Simulación por Computador , Electricidad/efectos adversos , Campos Electromagnéticos/efectos adversos , Diseño de Equipo , Cuerpo Humano , Humanos
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