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1.
J Hosp Infect ; 145: 22-33, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38157940

RESUMO

BACKGROUND: Infection prevention and control (IPC) is a critical component of delivering safe, effective and high-quality healthcare services, and eliminating avoidable healthcare-associated infections (HAIs) in health facilities, predominantly in population-dense settings such as Bangladesh. AIM: Our study aimed to assess the effect of an integrated intervention package in improving the IPC level of the health facilities in Bangladesh. METHODS: We conducted a pre-post intervention study in six district hospitals (DHs) and 13 Upazila Health Complexes (UHCs) in the six districts of Bangladesh. Baseline and endline assessments were conducted between March and December 2021 using the adapted World Health Organization Infection Prevention and Control Assessment Framework (WHO-IPCAF) tool. The IPCAF score, ranging from 0-800, was calculated by adding the scores of eight components, and the IPC promotion and practice level was categorized as Inadequate (0-200), Basic (201-400), Intermediate (401-600) and Advanced (601-800). The integrated intervention package including IPC committee formation, healthcare provider training, logistics provision, necessary guidelines distribution, triage/flu corners establishment, and infrastructure development was implemented in all facilities. RESULTS: The average IPCAF score across all the facilities showed a significant increase from 16% (95% CI: 11.5-20.65%) to 54% (95% CI: 51.4-57.1%). Overall, the IPCAF score increased by 34 percentage points (P<0.001) in DHs and 40 percentage points (P<0.001) in UHCs. Following the intervention, 12 (three DHs, nine UHCs) of 19 facilities progressed from inadequate to intermediate, and another three DHs upgraded from basic to intermediate in terms of IPC level. CONCLUSION: The integrated intervention package improved IPCAF score in all facilities.


Assuntos
Infecção Hospitalar , Controle de Infecções , Humanos , Bangladesh , Infecção Hospitalar/prevenção & controle , Instalações de Saúde , Qualidade da Assistência à Saúde
2.
Mymensingh Med J ; 31(2): 350-354, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35383749

RESUMO

Rickettsial diseases are one of the leading causes of treatable acute febrile illness in Asia pacific region. This cross-sectional descriptive study was conducted at Department of Microbiology, Mymensingh Medical College to diagnose scrub typhus by rapid Immunochromatographic Test (ICT) and Nested PCR followed by molecular identification of possible Rickettsial coinfection among suspected febrile patients in Mymensingh, Bangladesh from March 2019 to February 2020. Among the enrolled 402 patients, 89 samples (22.13%) were seropositive by Immunochromatographic Test (ICT) and 65 samples (16.16%) were positive for O. tsutsugamushi DNA by Nested PCR, targeting 47KDa gene. Therefore, 113/402 (28.10%) samples were positive for scrub typhus by PCR and/or ICT. All the scrub typhus positive samples were further subjected to Nested PCR targeting 17 KDa gene for identification of Rickettsial co-infection and 13/113 (11.50%) were documented as positive. Then 13 Rickettsial co-infected samples were undertaken to automate sequencing and all were genetically confirmed as Rickettsia felis. Findings of the study may help clinicians to expand their list of differential diagnoses for undifferentiated fever and detection of Rickettsial co-infection may guide them to prescribe effective antimicrobials.


Assuntos
Orientia tsutsugamushi , Rickettsia felis , Rickettsia , Tifo por Ácaros , Bangladesh/epidemiologia , Estudos Transversais , Humanos , Orientia tsutsugamushi/genética , Rickettsia/genética , Tifo por Ácaros/diagnóstico , Tifo por Ácaros/microbiologia
3.
Mymensingh Med J ; 31(1): 66-71, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34999682

RESUMO

Scrub typhus is one of the leading causes of undifferentiated treatable febrile illness in Asia pacific region. It is grossly under diagnosed in many tropical countries of South Asia including Bangladesh, due to wide range of non-specific clinical presentations, low index of suspicion among clinicians, limited awareness and lack of accurate diagnostic facilities. This cross sectional observational study was conducted at department of Microbiology, Mymensingh Medical College, Mymensingh, Bangladesh from March 2019 to February 2020 enrolling 113 diagnosed cases of scrub typhus by Immunochromatographic test (ICT) and / or Nested PCR to characterize the socio-demographic and clinico-epidemiological features of scrub typhus in Mymensingh area. Majority of the scrub typhus cases came from rural areas (63.83%) and there was a slight female predominance (52.21%). The young (32.74%) and the young-adult age group (28.31%) were mostly affected. Most of the scrub typhus cases were housewives (30.98%), followed by farmers (23.89%) and students (21.23%). All the enrolled cases presented with fever. Other findings were myalgia (76.10%), headache (56.63%), cough (30.97%), vomiting (12.38%) and Respiratory distress (9.73%). Typical eschar of scrub typhus was present only in 9(7.96%) cases and 4(3.53%) patients had rashes on their skin. Few cases (3.53%) had jaundice and 15.96% cases were anaemic. Oliguria (7.96%) and neck rigidity (1.76%) were also documented. Most of the Nested PCR positive scrub typhus cases were documented during late rainy season and beginning of winter months. Findings of the study may offer increased awareness about high burden of scrub typhus as well as heightened suspicion among clinicians for early diagnosis, timely treatment and prevention of complications.


Assuntos
Tifo por Ácaros , Bangladesh/epidemiologia , Estudos Transversais , Demografia , Feminino , Humanos , Índia , Tifo por Ácaros/diagnóstico , Tifo por Ácaros/epidemiologia , Centros de Atenção Terciária
4.
Mymensingh Med J ; 30(4): 967-972, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34605464

RESUMO

Scrub typhus, caused by the bacterium- Orientia tsutsugamushi is one of the leading causes of undifferentiated treatable febrile illness in Asia pacific region. It is grossly under diagnosed in many tropical countries of South Asia including Bangladesh, due to wide range of non-specific clinical presentations, low index of suspicion among clinicians, limited awareness and lack of accurate diagnostic facilities. This cross-sectional descriptive study was conducted at Department of Microbiology, Mymensingh Medical College to diagnose scrub typhus by rapid Immunochromatographic test (ICT) as well as molecular detection of O. tsutsugamushi by Nested PCR and automated nucleotide sequencing among suspected febrile patients in Mymensingh, Bangladesh during 2019-20. Blood samples were collected from 402 febrile patients of suspected Rickettsial illness, referred from inpatient and outpatient departments of Medicine and Pediatrics, Mymensingh Medical College Hospital (MMCH). Among the enrolled 402 patients, 89 samples (22.13%) were seropositive by Immunochromatographic test (ICT) and 65 samples (16.16%) were positive for O. tsutsugamushi DNA by Nested PCR, targeting 47KDa gene. Therefore, 113/402 (28.10%) samples were positive for scrub typhus by PCR and/ or ICT. Highest number of patients was detected positive by nested PCR during the first 5-10 days of fever but only 2 cases were positive after 20 days. In case of ICT, highest positivity for only IgM (8.13%) and both antibodies (2.43%) were documented in first 5-10 days of fever, but IgG positivity was highest (41.66) in >20 days of fever. From 65 PCR positive samples, automated nucleotide sequencing was performed on 20 randomly selected samples and all were genetically confirmed to be O. tsutsugamushi.


Assuntos
Tifo por Ácaros , Anticorpos Antibacterianos , Criança , Estudos Transversais , Hospitais , Humanos , Tifo por Ácaros/diagnóstico , Tifo por Ácaros/epidemiologia , Sensibilidade e Especificidade
5.
Psychophysiology ; 56(10): e13401, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31144730

RESUMO

Recreational use of concentrated oxygen has increased. Claims have been made that hyperoxic breathing can help reduce fatigue, increase alertness, and improve attentional capacities; however, few systematic studies of these potential benefits exist. Here, we examined the effects of short-term (15 min) hyperoxia on resting states in awake human subjects by measuring spontaneous EEG activity between normoxic and hyperoxic situations, using a within-subject design for both eyes-opened and eyes-closed conditions. We also measured respiration rate, heart rate, and blood oxygen saturation levels to correlate basic physiological changes due to the hyperoxic challenge with any brain activity changes. Our results show that breathing short-term 100% oxygen led to increased blood oxygen saturation levels, decreased heart rate, and a slight, but nonsignificant, decrease in breathing rate. Changes of brain activity were apparent, including decreases in low-alpha (7-10 Hz), high-alpha (10-14 Hz), beta (14-30 Hz), and gamma (30-50 Hz) frequency ranges during eyes-opened hyperoxic conditions. During eyes-closed hyperoxia, increases in the delta (0.5-3.5 Hz) and theta (3.5-7 Hz) frequency range were apparent together with decreases in the beta range. Hyperoxia appeared to accentuate the decrease of low alpha and gamma ranges across the eyes-opened and eyes-closed conditions, suggesting that it modulated brain state itself. As decreased alpha during eyes-opened conditions has been associated with increased attentional processing and selective attention, and increased delta and theta during eyes-closed condition are typically associated with the initiation of sleep, our results suggest a state-specific and perhaps opposing influence of short-term hyperoxia.


Assuntos
Eletroencefalografia , Hiperóxia/fisiopatologia , Adolescente , Adulto , Encéfalo/fisiopatologia , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Oxigênio/sangue , Taxa Respiratória/fisiologia , Adulto Jovem
6.
J Cogn Neurosci ; 29(3): 480-494, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28129063

RESUMO

Oscillatory brain rhythms can bias attention via phase and amplitude changes, which modulate sensory activity, biasing information to be processed or ignored. Alpha band (7-14 Hz) oscillations lateralize with spatial attention and rhythmically inhibit visual activity and awareness through pulses of inhibition. Here we show that human observers' awareness of spatially unattended targets is dependent on both alpha power and alpha phase at target onset. Following a predictive directional cue, alpha oscillations were entrained bilaterally using repetitive visual stimuli. Subsequently, we presented either spatially cued or uncued targets at SOAs either validly or invalidly predicted in time by the entrainers. Temporal validity maximally modulated perceptual performance outside the spatial focus of attention and was associated with both increased alpha power and increased neural entrainment of phase in the hemisphere processing spatially unattended information. The results demonstrate that alpha oscillations represent a pulsating inhibition, which impedes visual processing for unattended space.


Assuntos
Ritmo alfa/fisiologia , Atenção/fisiologia , Encéfalo/fisiologia , Percepção Espacial/fisiologia , Percepção do Tempo/fisiologia , Percepção Visual/fisiologia , Adulto , Potenciais Evocados/fisiologia , Feminino , Lateralidade Funcional , Humanos , Masculino , Testes Neuropsicológicos , Detecção de Sinal Psicológico , Adulto Jovem
7.
Psychophysiology ; 54(1): 74-82, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-28000254

RESUMO

Dry electrodes are becoming popular for both lab-based and consumer-level electrophysiological-recording technologies because they better afford the ability to move traditional lab-based research into the real world. It is unclear, however, how dry electrodes compare in data quality to traditional electrodes. The current study compared three EEG electrode types: (a) passive-wet electrodes with no onboard amplification, (b) actively amplified, wet electrodes with moderate impedance levels, and low impedance levels, and (c) active-dry electrodes with very high impedance. Participants completed a classic P3 auditory oddball task to elicit characteristic EEG signatures and event-related potentials (ERPs). Across the three electrode types, we compared single-trial noise, average ERPs, scalp topographies, ERP noise, and ERP statistical power as a function of number of trials. We extended past work showing active electrodes' insensitivity to moderate levels of interelectrode impedance when compared to passive electrodes in the same amplifier. Importantly, the new dry electrode system could reliably measure EEG spectra and ERP components comparable to traditional electrode types. As expected, however, dry active electrodes with very high interelectrode impedance exhibited marked increases in single-trial and average noise levels, which decreased statistical power, requiring more trials to detect significant effects. This power decrease must be considered as a trade-off with the ease of application and long-term use. The current results help set constraints on experimental design with novel dry electrodes, and provide important evidence needed to measure brain activity in novel settings and situations.


Assuntos
Córtex Cerebral/fisiologia , Eletrodos , Eletroencefalografia/instrumentação , Potenciais Evocados P300 , Potenciais Evocados Auditivos , Estimulação Acústica , Adulto , Artefatos , Impedância Elétrica , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Processamento de Sinais Assistido por Computador , Razão Sinal-Ruído , Adulto Jovem
8.
Artigo em Inglês | MEDLINE | ID: mdl-23691634

RESUMO

We conducted a study of the knowledge, attitudes and practices regarding dog bites among residents of a rural community in Bangladesh from September 2006 to February 2007 using face to face interviews with 1,973 adults from five villages. The mean age of the respondents was 34+/-16 years. Sixty-eight percent of subjects were female, 7.3% of respondents reported a history of dog bite in a family member; 10% had been bitten twice. Sixty-five percent of subjects were aware of rabies and 99.1% knew a dog bite was the cause of rabies. Seventy-one percent of subjects were aware of a rabies vaccine, 77.5% of respondents stated rabies can cause death. Ninty percent of dog bite victims received treatment by traditional healers, 25% were treated with a rabies vaccine and 2.1% of victims died. Greater awareness is needed in rural Bangladesh regarding prevention of rabies.


Assuntos
Mordeduras e Picadas/tratamento farmacológico , Mordeduras e Picadas/psicologia , Conhecimentos, Atitudes e Prática em Saúde , Vacina Antirrábica/uso terapêutico , População Rural , Adulto , Animais , Bangladesh/epidemiologia , Mordeduras e Picadas/complicações , Mordeduras e Picadas/epidemiologia , Estudos Transversais , Cães , Feminino , Humanos , Masculino , Medicina Tradicional , Pessoa de Meia-Idade , Percepção , Vacina Antirrábica/administração & dosagem , Fatores Socioeconômicos
9.
Pharm Biol ; 48(7): 764-9, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20645774

RESUMO

The hepatoprotective activity of jigrine, a polypharmaceutical herbal formulation, at a dose of 1 mL/kg/day p.o. was evaluated against galactosamine (400 mg/kg b.wt.)-induced hepatopathy in rats. Biochemical parameters such as alanine trasaminase (ALT), alkaline phosphatase (ALP), and bilirubin were estimated to assess liver function. Jigrine was also evaluated for its effect on the possible behavioral alterations secondary to liver damage produced by galactosamine (d-Gal) administration in rats. The d-Gal-induced elevation in serum levels of ALT, ALP, and bilirubin was significantly reduced (p values <0.01, <0.01, and <0.05, respectively) in jigrine- and silymarin-pretreated rats. Jigrine pretreatment also exhibited beneficial effects on d-Gal-induced behavioral abnormalities in rats. Silymarin (25 mg/kg/day p.o.) was used as reference standard. The biochemical observations were supplemented with histopathological examination of rat liver sections. Histopathological evaluation showed marked improvement in the livers of jigrine- and silymarin-treated animals.


Assuntos
Comportamento Animal/efeitos dos fármacos , Hepatite/tratamento farmacológico , Fitoterapia , Extratos Vegetais/uso terapêutico , Animais , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Feminino , Galactosamina , Hepatite/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Atividade Motora/efeitos dos fármacos , Extratos Vegetais/efeitos adversos , Extratos Vegetais/farmacocinética , Extratos Vegetais/farmacologia , Distribuição Aleatória , Ratos , Ratos Wistar , Silimarina/uso terapêutico
10.
Cell Death Dis ; 1: e53, 2010 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-21364658

RESUMO

The histological manifestation of growth-regulating and differentiation-inducing signals in cancer cells is considered as a key component for clinical outcome prediction and commonly defined as tumor differentiation grade. However, the molecular and functional framework underlying this clinical parameter remains poorly understood. Our correlative data display a significant association (P>0.001) between mitochondrial uncoupling protein 2 (UCP2) and tumor grade in primary breast cancer (n=234). Through mechanistic analyses, we show a synergistic link between UCP2 and established cellular pathways in conferring grade-associated functional phenotypes. Here, the application of well to moderately differentiated primary tumor cell lines has enabled direct observation of SMAD recruitment to the UCP2 promoter underlying repression of gene transcription. In contrast, poorly differentiated tumor cells, known to be TGFß resistant, displayed aberrant UCP2 regulation, and consequently, gene overexpression, which reduced mitochondrial calcium and facilitated the maintenance of mitochondrial membrane potential, thereby significantly decreasing oxidative stress and inhibiting cell death. Conversely, UCP2 silencing in such cells rapidly led to the induction of apoptosis and cell differentiation, concurrent with reduced cell survival and proliferation, confirming gene-specific effects. Demonstration of a biologically driven role for UCP2 dysregulation in promoting multiple characteristics of tumor aggressiveness strongly endorses assessment of gene expression at clinical presentation to augment therapeutic decision-making and improve patient outcome through personalized targeting approaches.


Assuntos
Neoplasias da Mama/metabolismo , Canais Iônicos/metabolismo , Proteínas Mitocondriais/metabolismo , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismo , Apoptose , Cálcio/metabolismo , Diferenciação Celular , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Canais Iônicos/genética , Potencial da Membrana Mitocondrial , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Estadiamento de Neoplasias , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Proteína Smad4/genética , Proteína Smad4/metabolismo , Células Tumorais Cultivadas , Proteína Desacopladora 2
11.
Oncogene ; 26(43): 6269-79, 2007 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-17471242

RESUMO

An improved understanding of cell immortalization and its manifestation in clinical tumors could facilitate novel therapeutic approaches. However, only rare tumor cells, which maintain telomerase expression in vitro, immortalize spontaneously. By expression-profiling analyses of limited-life primary breast tumor cultures pre- and post-hTERT transduction, and spontaneously immortalized breast cancer cell lines, we identified a common signature characteristic of tumor cell immortalization. A predominant feature of this immortalization signature (ImmSig) was the significant overexpression of oxidoreductase genes. In contrast to epithelial cells derived from low histologic grade primary tumors, which required hTERT transduction for the acquisition of ImmSig, spontaneously immortalizing high-grade tumor cultures displayed similar molecular changes independent of exogenous hTERT. Silencing the hTERT gene reversed ImmSig expression, increased cellular reactive oxygen species levels, altered mitochondrial membrane potential and induced apoptotic and proliferation changes in immortalized cells. In clinical breast cancer samples, cell-proliferation-pathway genes were significantly associated with ImmSig. In these cases, ImmSig expression itself was inversely correlated with patient survival (P=0), and was particularly relevant to the outcome of estrogen receptor-positive tumors. Our data support the notion that ImmSig assists in surmounting normal barriers related to oxidative and replicative stress response. Targeting a subset of aggressive breast cancers by reversing ImmSig components could be a practical therapeutic strategy.


Assuntos
Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Estresse Oxidativo , Neoplasias da Mama/genética , Neoplasias da Mama/terapia , Sobrevivência Celular , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Interferência de RNA , Transdução de Sinais , Taxa de Sobrevida , Telomerase/genética , Telomerase/metabolismo , Resultado do Tratamento , Células Tumorais Cultivadas
13.
Skeletal Radiol ; 31(12): 720-3, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12483435

RESUMO

We report a case of primary hyperparathyroidism (PHPT) with advanced and unusual skeletal manifestations--a rare occurrence in developed countries nowadays. The literature is briefly reviewed.


Assuntos
Doenças Ósseas/diagnóstico por imagem , Doenças Ósseas/etiologia , Hiperparatireoidismo/complicações , Adulto , Feminino , Humanos , Hiperparatireoidismo/cirurgia , Tomografia Computadorizada por Raios X
14.
Phys Med Biol ; 47(1): 137-48, 2002 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-11814222

RESUMO

Texture analysis of positron emission tomography (PET) images of the brain is a very difficult task, due to the poor signal to noise ratio. As a consequence, very few techniques can be implemented successfully. We use a new global analysis technique known as the Trace transform triple features. This technique can be applied directly to the raw sinograms to distinguish patients with Alzheimer's disease (AD) from normal volunteers. FDG-PET images of 18 AD and 10 normal controls obtained from the same CTI ECAT-953 scanner were used in this study. The Trace transform triple feature technique was used to extract features that were invariant to scaling, translation and rotation, referred to as invariant features, as well as features that were sensitive to rotation but invariant to scaling and translation, referred to as sensitive features in this study. The features were used to classify the groups using discriminant function analysis. Cross-validation tests using stepwise discriminant function analysis showed that combining both sensitive and invariant features produced the best results, when compared with the clinical diagnosis. Selecting the five best features produces an overall accuracy of 93% with sensitivity of 94% and specificity of 90%. This is comparable with the classification accuracy achieved by Kippenhan et al (1992), using regional metabolic activity.


Assuntos
Doença de Alzheimer/diagnóstico , Doença de Alzheimer/patologia , Tomografia Computadorizada de Emissão/métodos , Adulto , Automação , Diagnóstico por Computador , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Teóricos
15.
Fitoterapia ; 72(4): 428-30, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11395271

RESUMO

The petroleum ether, chloroform and methanol extracts of the leaves and barks of Zanthoxylum budrunga have been evaluated for their antibacterial, antifungal and cytotoxic properties.


Assuntos
Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Fungos/efeitos dos fármacos , Plantas Medicinais , Rosales , Animais , Antibacterianos , Artemia/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Extratos Vegetais/farmacologia , Folhas de Planta , Caules de Planta
16.
IEEE Trans Biomed Eng ; 46(9): 1081-9, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10493071

RESUMO

Small formed elements and gas bubbles in flowing blood, called microemboli, can be detected using Doppler ultrasound. In this application, a pulsed constant-frequency ultrasound signal insonates a volume of blood in the middle cerebral artery, and microemboli moving through its sample volume produce a Doppler-shifted transient reflection. Current detection methods include searching for these transients in a short-time Fourier transform (STFT) of the reflected signal. However, since the embolus transit time through the Doppler sample volume is inversely proportional to the embolus velocity (Doppler-shift frequency), a matched-filter detector should in principle use a wavelet transform, rather than a short-time Fourier transform, for optimal results. Closer examination of the Doppler shift signals usually shows a chirping behavior apparently due to acceleration or deceleration of the emboli during their transit through the Doppler sample volume. These variations imply that a linear wavelet detector is not optimal. We apply linear and quadratic time-frequency and time-scale detectors to a set of noise-corrupted embolus data. Our results show improvements of about 1 dB using the time-scale detectors versus an STFT-based detector signifying that embolus detection is best approached as a time-scale problem. A time-scale-chirp detector is also applied and is found to have the overall best performance by about 0.5-0.7 dB while coming fairly close (about 0.75 dB) to a theoretical upper bound.


Assuntos
Embolia e Trombose Intracraniana/diagnóstico por imagem , Processamento de Sinais Assistido por Computador , Ultrassonografia Doppler/métodos , Artérias Cerebrais/diagnóstico por imagem , Análise de Fourier , Humanos , Modelos Cardiovasculares , Ultrassonografia Doppler/economia
17.
J Electrocardiol ; 28 Suppl: 53-8, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-8656129

RESUMO

A recently proposed time-frequency filtering technique has shown promising results for the enhancement of signal-averaged electrocardiograms. This method weights the short-time Fourier transform of the ensemble-averaged signal, analogous to the spectral domain Wiener filtering of stationary signals. In effect, it is a self-designing, time-varying Wiener filter applied to the high-resolution electrocardiogram (HRECG). In this study, the authors empirically show that the performance of the proposed technique is about 2-3 dB lower over the critical late-potential portion of the HRECG than the optimal fixed-window, time-frequency filter based on ideal a priori knowledge of statistics. Although this ideal knowledge and performance is unattainable in practice, these results suggest that there remains potential for modest improvement. To narrow this gap in performance, improvements based on alternative structures for the time-frequency filter, including time-varying short-time Fourier transform windows, are proposed. Simulation results show that an improved fixed-window technique can potentially yield an improvement of about 1-1.5 dB. By using properly chosen time-varying windows, the performance could potentially be improved of about 1-1.5 dB. By using properly chosen time-varying windows, the performance could potentially be improved even further. Thus, the improved techniques could produce an HRECG using fewer averages than the existing method, or that could tolerate a lower initial signal-to-noise ratio.


Assuntos
Eletrocardiografia , Processamento de Sinais Assistido por Computador , Algoritmos , Artefatos , Simulação por Computador , Eletrocardiografia/estatística & dados numéricos , Análise de Fourier , Humanos , Fatores de Tempo
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