1,720,979 research outputs found
Peserico, A. Germani, P. Sanese, V. Di Virgilio, V. Grossi, M. Nicola, A.J.M. Barbosa, A. Del Rio, C. Simone
No full textECG fiducial points detection through wavelet transform
No full textAbstract: The wavelet transform is introduced as a novel method to analyze signals in both time and frequency domains, and therefore it is suitable for analysis of time-varying signals such as ECG. Detection of ECG signal characteristic patterns has been achieved using an algorithm based on the wavelet transform decomposition. ECG signals are represented by a pyramidal algorithm at successive scales into fine and coarse components used for the successive fiducial points detection. The presented time-scale diagrams illustrate the detection capability of fiducial points on ECG signal (QRS complexes, P and T waves)
Sustainable Procurement of Medical Devices in an International Context-Part 2
Full text linkBackground and Objectives: This article describes how sustainable procurement of medical devices (MDs) can be implemented in operational projects in developing countries. It also further details how sustainability principles and the needs assessment can be applied by the biomedical/clinical engineer lead (BCEL) responsible for the technical and quality aspects of the procurement process of MDs. It also emphasizes the importance of the BCEL considering the country’s or region’s specific healthcare context when working on MD procurement projects in developing countries. Material and Methods: This article describes how sustainable procurement of medical devices (MDs) can be implemented in operational projects in developing countries. It also further details how sustainability principles and the needs assessment can be applied by the biomedical/clinical engineer lead (BCEL) responsible for the technical and quality aspects of the procurement process of MDs. It also emphasizes the importance of the BCEL considering the country’s or region’s specific healthcare context when working on MD procurement projects in developing countries. Results: The BCEL has a key role in the sustainable procurement of MDs as an integrator able to understand clinical needs and translate them into requirements while being aware of the sustainability and safety risks linked to technology implemented in the fragile environment of a developing country with limited resources. This context also creates additional challenges that can be managed if the BCEL is conscious of the country’s health expenditure, geopolitical, healthcare, model of care, regulatory, infrastructure, and logistical conditions in which the MDs will be installed. Many equipment may remain unused if the technology implementation is not in line with the needs of the beneficiaries. Therefore, a thorough needs assessment performed by the BCEL to obtain the detailed list of MDs, their technological level and estimated budget is of utmost importance to increase the project’s sustainability and mitigate the risk of unused MDs. Conclusion: Besides traditional disciplines in biomedical and clinical engineering, the BCEL shall also learn at least basic principles in public health, healthcare planning, project management, health infrastructure, and development aid to facilitate the dialogue with stakeholders based on knowledge, flexibility, and capacity to anticipate and solve practical issues on the ground. To this extent, it is advisable for a BCEL new to the environment of developing countries to have progressive exposure to more complex projects and to extensively use the peer review mechanism to assure sustainability and quality during project imple-mentation. A theoretical background based on sustainable procurement principles, analysis of the local and national health context and regulations, and knowledge of lessons learned from past projects should guide the BCEL’s approach to performing the needs assessment while implementing a new project. © 2023 Global Clinical Engineering
Respiratory sinus arrhythmia and cardiovascular neural regulation in atlethes. Med Sci Sports Exerc 98;30(2):215-9.
No full textStudies using spectral analysis of cardiovascular variability as a noninvasive means for assessing autonomic nervous system activity have provided controversial results in athletes. One reason is that a slow breathing rate-a common feature in athletes-affects spectral estimation because it causes the low-frequency (LF) and high-frequency (HF) components to overlap. Low-frequency power increases during sympathetic activation; high-frequency corresponds to respiratory sinus arrhythmia. In this study, to assess how controlled respiration influences autonomic nervous system activity, we determined the effect of controlled and uncontrolled breathing conditions on cardiovascular variability. Our aim was to identify a standard respiratory rate for spectral estimation of cardiovascular neural control in athletes. During electrocardiographic recordings, subjects lay supine and breathed at their spontaneous frequency and at rates of 15, 12, and 10 to 14(random) breaths!min-1. Uncontrolled and random breathing rates significantly altered spectral sympathetic indices; conversely, 15 and 12 breaths!min-1 redistributed respiratory related power through the HF, thus yielding correct LF power estimation. None of the breathing conditions significantly changed mean heart rate, arterial blood pressure, or spectral total power of cardiovascular variability. In conclusion, when power spectral analysis is used for assessing autonomic activity in athletes, respiration should be standardized at 15 breaths!min-1. Controlled respiration at this rate leaves autonomic nervous system activity unchanged
Parameters measurement of coronary blood flow velocity using a fast wavelet transform based algorithm
No full textAbstract: An algorithm based on fast wavelet transform has been developed for detecting diastolic and systolic coronary blood flow velocity signals characteristic patterns. The fast wavelet transform is used as a denoising tool to distinguish coronary blood flow waves from major noise, artifacts and baseline drift. Start-end diastolic-systolic fiducial points have been automatically detected to measure coronary blood flow velocity characteristic parameters. Feasibilty of scientific and clinical investigation assessment of coronary artery disease is presented through phasic coronary blood flow beat-to-beat analysis
Arterial pressure control during non-hypo/hypertensive changes in central venous volume: assessment with multivariate autoregressive modeling
No full textAbstract: To evaluate how small decreases and increases of central volume influence heart rate and arterial pressure control multivariate autoregressive techniques were used to quantify the interactions between respiration, RR interval and arterial blood pressure during random interval breathing, at 3 low levels of lower body negative pressure and 3 low levels of increased central volume. In addition to the classic spectral parameters for each signal, the algorithms were used to derive the closed-loop feedforward and feedback gains for the baroreflex and the effects of respiration on RR interval. With reductions of central volume below control, baroreflex and respiratory sinus arrhythmia gains were generally reduced, while with increases of volume above control, they increased only for the first two levels, and decreased at the highest volume. These findings indicate that reflex heart rate control is maximum with mild hypervolemia, and are consistent with the presence of the Bainbridge reflex in healthy humans
Multivariate autoregressive spectral analysis: heart rate baroreflex and respiratory influence under administration of atropine and propranolol
No full textAbstract: In this study the authors introduce a trivariate autoregressive (AR) algorithm based on a model that takes into account, at the same time, all the possible interactions among heart rate (HR), arterial blood pressure (ABP), and instantaneous lung volume (ILV). Signals were acquired in 14 subjects during a tilting protocol with a random interval breathing technique and administration of atropine and propranolol. A bivariate AR algorithm was used to identify the typical HR and ABP spectral parameters of LF and HF power, and the LF/HF ratio. The cross-parameters obtained by the bivariate technique were then compared with results obtained using the trivariate model. As expected, differences were found in the comparison of the gain values. However, gain parameters were found to be good markers of autonomic activity in both techniques
A multivariate time-variant AR method for the analysis of heart rate and arterial blood pressure.
No full textContinuous quantification of respiratory and baroreflex control of heart rate: use of time-variant bivariate spectral analysis
No full textAbstract: The mutual interactions between respiration, heart rate (HR) and arterial blood pressure (ABP) can be described by parametric bivariate models. Application of these methods allows the opportunity to investigate short and long term events of pathophysiological interest occurring in the cardiovascular system. In this study, to improve the identification of respiratory control of HR (respiratory sinus arrythmia, RSA), and ABP control of HR (baroreflex), the frequency content of respiration and ABP were broadened. A bivariate autoregressive (AR) time-variant model was used to identify the typical HR and ABP spectral parameters of LF and HF power, and the LF/HF ratio. In addition, cross-parameters such as coherent power, LF and HF gain for ABP-HR, and RSA gain were computed. Similar results were obtained using a "batch" algorithm, but the time-variant technique was able to provide nearly continuous parameters, allowing for a real-time continuous monitoring of circulatory control
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