Browsing by Author "Fonseca-Pinto, Rui"
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- Assessing autonomic control of metabolic syndrome by principal component analysis: a data driven methodologyPublication . Fonseca-Pinto, Rui; Lopes, Nuno Vieira; Brito, Gabriel; Lages, Marlene; Guarino, Maria PedroMetabolic diseases are one of the leading causes of death worldwide. Due to its lack of clinical manifestations for long periods, metabolic diseases are generally detected in advanced stages, when the risk of cardiovascular, ocular and renal complications is high. Thus, early detection of these disorders is essential to design effective health promotion strategies. Herein we provide a preliminary approach for the early diagnosis of metabolic diseases based on Principal Component Analysis (PCA) of autonomic features of sympathovagal Balance (SVB) to characterize the activity of the carotid bodies (CB). CBs are small chemoreceptors located in the bifurcation of the carotid arteries whose overactivation is intimately linked to early stages of metabolic disease through asymptomatic deregulation of the sympathetic nervous system. Herein we discuss parameters that can be extracted from these recordings using a PCA approach in response to two different challenge tests: 100% oxygen and administration of a mixed meal in healthy and type 2 diabetes volunteers. This methodology may represent a paradigm shift in the diagnosis of metabolic diseases through the characterization of CB activity, and aims to bridge the existing gap in early assessment of metabolic dysfunction.
- Autonomic nervous system monitoring in intensive care as a prognostic tool. Systematic reviewPublication . Bento, Luis; Fonseca-Pinto, Rui; Póvoa, PedroObjective: To present a systematic review of the use of autonomic nervous system monitoring as a prognostic tool in intensive care units by assessing heart rate variability. Methods: Literature review of studies published until July 2016 listed in PubMed/Medline and conducted in intensive care units, on autonomic nervous system monitoring, via analysis of heart rate variability as a prognostic tool (mortality study). The following English terms were entered in the search field: (“autonomic nervous system” OR “heart rate variability”) AND (“intensive care” OR “critical care” OR “emergency care” OR “ICU”) AND (“prognosis” OR “prognoses” OR “mortality”). Results: There was an increased likelihood of death in patients who had a decrease in heart rate variability as analyzed via heart rate variance, cardiac uncoupling, heart rate volatility, integer heart rate variability, standard deviation of NN intervals, root mean square of successive differences, total power, low frequency, very low frequency, low frequency/high frequency ratio, ratio of short-term to long-term fractal exponents, Shannon entropy, multiscale entropy and approximate entropy. Conclusion: In patients admitted to intensive care units, regardless of the pathology, heart rate variability varies inversely with clinical severity and prognosis.
- Avaliação de sistemas posturais da pélvis numa pessoa com Distrofia Muscular do tipo Cinturas: resultados da análise a três almofadas na promoção do equilíbrio dinâmicoPublication . Marques, Cíntia; Matos, Carolina; Cavaleiro, Joana; Simões, Juliana; Fonseca-Pinto, Rui; Lopes, Nuno; Ribeiro, Jaime MoreiraIntrodução: As almofadas anti-escaras são dispositivos especializados para a redistribuição de pressão e gestão da carga sobre os tecidos e do microclima. Devem manter o alinhamento postural, facilitar o movimento, criar uma base estável, aliviar a dor e serem confortáveis. Podem ser compostas exclusivamente por um material como espuma, gel, ar e fluido, ou pela combinação de dois ou mais destes materiais. As investigações concretizadas focam-se na distribuição do peso e negligenciam o comportamento dinâmico da almofada durante as atividades quotidianas. Objetivos: Avaliar a eficácia na manutenção do equilíbrio dinâmico de três tipos de almofadas de gama média-alta com diferentes composições. Métodos: Estudo com uma pessoa do sexo feminino com Distrofia Muscular do tipo Cinturas, utilizando-se: uma almofada de espuma e ar (A), uma almofada de espuma e bolsa de fluido (B) e uma de ar (C). A recolha de dados foi realizada em dois momentos: 1)recolha dados antropométricos, cinemáticos e dinâmicos, através de medição direta do alcance, videogravação e acelerómetro, e pressões exercidas sobre as almofadas, mediante um protocolo de movimentos e randomização de almofadas; 2)avaliação da perceção do utilizador com questionário e escala visual analógica de dor, após quatro horas de permanência na almofada. Resultados: A almofada A revelou melhores resultados ao nível do alcance máximo, do pico de pressão na posição inicial, do coeficiente de variação e da pressão média na flexão frontal do tronco. A almofada B apresentou resultados mais positivos na área de contacto, coeficiente de variação e na pressão média na posição inicial, no pico de pressão da flexão frontal do tronco, na variação da aceleração e na análise subjetiva. Conclusão: As almofadas anti-escaras que, na sua composição, combinam dois materiais, são mais eficazes na promoção do equilíbrio dinâmico, observando-se vantagem na utilização da almofada composta por espuma e fluido.
- Blood pressure assessment during standard clinical manoeuvres: A noninvasive PPT based approachPublication . Duarte, Diana; Lopes, Nuno Vieira; Fonseca-Pinto, RuiContinuous and reliable blood pressure (BP) monitoring during standard clinical manoeuvres provides important information about the cardiovascular system condition. Common invasive methods are accurate but denote increased risk. An alternative approach is based on changes in pulse transit time (PTT) defined as the time delay between the R-wave of the electrocardiogram (ECG) and the peak value of the photoplethysmogram (PPG) signal at the same cardiac cycle.
- Blood Pressure Regulation by the Carotid Sinus Nerve: Clinical Implications for Carotid Body NeuromodulationPublication . Conde, Silvia V; Sacramento, Joana F.; Melo, Bernardete F.; Fonseca-Pinto, Rui; Romero-Ortega, Mario I.; Guarino, Maria PedroChronic carotid sinus nerve (CSN) electrical modulation through kilohertz frequency alternating current improves metabolic control in rat models of type 2 diabetes, underpinning the potential of bioelectronic modulation of the CSN as a therapeutic modality for metabolic diseases in humans. The CSN carries sensory information from the carotid bodies, peripheral chemoreceptor organs that respond to changes in blood biochemical modifications such as hypoxia, hypercapnia, acidosis, and hyperinsulinemia. In addition, the CSN also delivers information from carotid sinus baroreceptors—mechanoreceptor sensory neurons directly involved in the control of blood pressure—to the central nervous system. The interaction between these powerful reflex systems—chemoreflex and baroreflex—whose sensory receptors are in anatomical proximity, may be regarded as a drawback to the development of selective bioelectronic tools to modulate the CSN. Herein we aimed to disclose CSN influence on cardiovascular regulation, particularly under hypoxic conditions, and we tested the hypothesis that neuromodulation of the CSN, either by electrical stimuli or surgical means, does not significantly impact blood pressure. Experiments were performed in Wistar rats aged 10–12 weeks. No significant effects of acute hypoxia were observed in systolic or diastolic blood pressure or heart rate although there was a significant activation of the cardiac sympathetic nervous system. We conclude that chemoreceptor activation by hypoxia leads to an expected increase in sympathetic activity accompanied by compensatory regional mechanisms that assure blood flow to regional beds and maintenance of hemodynamic homeostasis. Upon surgical denervation or electrical block of the CSN, the increase in cardiac sympathetic nervous system activity in response to hypoxia was lost, and there were no significant changes in blood pressure in comparison to control animals. We conclude that the responses to hypoxia and vasomotor control short-term regulation of blood pressure are dissociated in terms of hypoxic response but integrated to generate an effector response to a given change in arterial pressure.
- CBmeter study: Protocol for assessing the predictive value of peripheral chemoreceptor overactivation for metabolic diseasesPublication . Lages, Marlene; Carvalho, Lucinda; Feijó, Salvato; Vieira, Alexandra; Fonseca-Pinto, Rui; Guarino, Maria PedroEarly screening of metabolic diseases is crucial since continued undiagnostic places an ever-increasing burden on healthcare systems. Recent studies suggest a link between overactivated carotid bodies (CB) and the genesis of type 2 diabetes mellitus. The non-invasive assessment of CB activity by measuring ventilatory, cardiac and metabolic responses to challenge tests may have predictive value for metabolic diseases; however, there are no commercially available devices that assess CB activity. The findings of the CBmeter study will clarify the role of the CBs in the genesis of—metabolic diseases and guide the development of new therapeutic approaches for early intervention in metabolic disturbances. Results may also contribute to patient classification and stratification for future CB modulatory interventions.
- CBmeter- a new medical device for early screening of metabolic diseasesPublication . Guarino, Maria Pedro; Brito, Gabriel; Lages, Marlene; Fonseca-Pinto, Rui; Lopes, Nuno VieiraType 2 diabetes mellitus (T2DM) is a highly prevalent disease worldwide which is asymptomatic in about 44% of patients being critical to search for new ways of early diagnosis. Recent studies have demonstrated that the etiology of this disease may be associated with alterations in the function of the carotid body (CB), a chemosensor organ located within the bifurcation of the carotid artery. In animal models of metabolic syndrome it was observed that the CBs are overactivated, underlying diseases such as obesity, hypertension and T2DM. This discovery provided a new paradigm in the neuroendocrinology field, suggesting that diagnostic function of the CBs has predictive value for the development of metabolic diseases. Despite this fact, it is not common in clinical practice to look at the CBs as organs associated with endocrine dysfunction and we believe this is probably due to the nonexistence of a user-friendly, portable medical device that diagnosis the function of the CBs.
- Classification of reticular pattern and streaks in dermoscopic images based on texture analysisPublication . Machado, Marlene; Pereira, Jorge; Fonseca-Pinto, RuiThe early detection of melanoma is one of the greatest challenges in clinical practice of dermatology, and the reticular pattern is one of the most important dermoscopic structures to improve melanocytic lesion diagnosis. A texture-based approach is developed for the automatic detection of reticular patterns, whose output will assist clinical decision-making. Feature selection was based on the use of two algorithms by means of the classical graylevel co-occurrence matrix and Laws energy masks optimized on a set of 104 dermoscopy images. The AdaBoost (adaptive boosting) approach to machine learning was used within this strategy. Results suggest superiority of LEM for reticular pattern detection in dermoscopic images, achieving a sensitivity of 90.16% and a specificity of 86.67%. The use of automatic classification in dermoscopy to support clinicians is a strong tool to assist diagnosis; however, the use of automatic classification as a complementary tool in clinical routine requires algorithms with high levels of sensitivity and specificity. The results presented in this work will contribute to achieving this goal.
- Dermoscopic assisted diagnosis in melanoma: Reviewing results, optimizing methodologies and quantifying empirical guidelinesPublication . Lee, Huei Diana; Mendes, Ana Isabel; Spolaôr, Newton; Oliva, Jefferson Tales; Parmezan, Antonio Rafael Sabino; Wu, Feng Chung; Fonseca-Pinto, RuiEarly diagnosis is still the most important factor to deal with skin cancer, a disease that challenges physicians and researchers. It has benefited from computer-aided diagnosis methods that successfully combine dermoscopy, Digital Image Processing, and Machine Learning techniques. This paper aims to approximate medical professionals working with dermoscopy to these methods, to join the challenge of melanoma early detection. Accordingly, a proposal for extracting, selecting and combining texture and shape features from dermoscopic images is presented. The Feature Selection task is added to the learning process to potentiate the quality of classification models. Three classical Machine Learning algorithms were applied to differentiate melanoma from non-melanoma images. The models are evaluated by standard performance measures and a multi-criteria decision analysis method. This is the first time such method is used in melanoma diagnosis. As a result, we found a decision tree that performs well and allows the explicit representation and analysis of the knowledge learned from the images. In addition, the competitiveness of our decision models in comparison with literature approaches reviewed in this work encourages further applications of Machine Learning and Feature Selection to assist computer-aided diagnosis.
- Development of a mixed-meal that impacts carotid-body mediated cardiorespiratory and metabolic parameters - a pilot studyPublication . Frazão, Ana; Costa, Andreia; Teixeira, Bárbara; Santo, Marisa; Brito, Gabriel; Lages, Marlene; Lopes, Nuno Vieira; Fonseca-Pinto, Rui; Pereira, Cidália; Guarino, Maria PedroThe carotid bodies (CB) have been recently implicated in the genesis of metabolic diseases in animal models. The CBs respond to circulating insulin to increase heart rate, respiratory rate and blood glucose levels. In humans, this mechanism is not well characterized.
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