Effect of clonidine on the target dose of propofol: bispectral index evaluation

Background: The increasing evidence associating general anaesthetics with neurotoxicity and post-operative cognitive disturbances, mainly with deeper levels of anaesthetics, has led to more frequent use of adjuvants. This study aimed to analyse the effect of clonidine on the target dose of propofol in total intravenous anaesthesia. Methods: A randomised, double-blind clinical trial was performed in a large hospital located in the southern region of Ceará, Brazil. Fifty-one patients from the anaesthesia outpatient clinic were enrolled. Patients were divided into two groups: one group received 100 mL of 0.9% sterile saline, and the other group received 100 mL of 0.9% sterile saline with clonidine at a dose of 3 µg/kg. A target-controlled infusion pump was used to administer propofol, following the modified Marsh pharmacokinetic model and aiming for a bispectral index (BIS) score of approximately 40 for intubation and 45 for anaesthesia maintenance. The anaesthesiologist was informed which group the patient belonged to after completion of surgery and data recording. Results: The chi-squared test was used to evaluate the distribution of the samples with respect to gender, and the Student’s t-test was used to evaluate the parametric variables. There was no statistically significant difference between the samples. A significant difference was observed in the target dose of propofol between the two groups during the maintenance and awakening phases, but not at the time of intubation. Conclusions: Clonidine pre-operatively administered at a dose of 3 µg/kg significantly reduced the target dose of propofol needed to maintain adequate levels of anaesthesia as measured by BIS

Auditory stimulation and cardiac autonomic regulation

Previous studies have already demonstrated that auditory stimulation with music influences the cardiovascular system. In this study, we described the relationship between musical auditory stimulation and heart rate variability. Searches were performed with the Medline, SciELO, Lilacs and Cochrane databases using the following keywords: "auditory stimulation", "autonomic nervous system", "music" and "heart rate variability". The selected studies indicated that there is a strong correlation between noise intensity and vagal-sympathetic balance. Additionally, it was reported that music therapy improved heart rate variability in anthracycline-treated breast cancer patients. It was hypothesized that dopamine release in the striatal system induced by pleasurable songs is involved in cardiac autonomic regulation. Musical auditory stimulation influences heart rate variability through a neural mechanism that is not well understood. Further studies are necessary to develop new therapies to treat cardiovascular disorders

Contact Failure Identification in Multilayered Media via Artificial Neural Networks and Autoencoders

The estimation of defects positioning occurring in the interface between different materials is performed by using an artificial neural network modeled as an inverse heat conduction problem. Identifying contact failures in the bonding process of different materials is crucial in many engineering applications, ranging from manufacturing, preventive inspection and even failure diagnosis. This can be modeled as an inverse heat conduction problem in multilayered media, where thermography temperature measurements from an exposed surface of the media are available. This work solves this inverse problem with an artificial neural network that receives these experimental data as input and outputs the thermalphysical properties of the adhesive layer, where defects can occur. An autoencoder is used to reduce the dimension of the transient 1D thermography data, where its latent space represents the experimental data in a lower dimension, then these reduced data are used as input to a fully connected multilayer perceptron network. Results indicate that this is a promising approach due to the good accuracy and low computational cost observed. In addition, by including different noise levels within a defined range in the training process, the network can generalize the experimental data input and estimate the positioning of defects with similar quality.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Finance Code 001), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)Grant CAPES/PrInt No. 88887.469279/2019-00PID2020-112754 GB-I00 (Spanish Ministry of Economy and Competitiveness and funds from the European Regional Developement Fund, ERDF)B-TIC-640-UGR20 (Regional Govern of Andalusia, Spain

Prior exercise training does not prevent acute cardiac alterations after myocardial infarction in female rats

OBJECTIVE: This study aimed to investigate whether previous exercise training could prevent or attenuate acute cardiac alterations after myocardial infarction. METHODS: Female rats were submitted to swim training (1 h/day; 5 days/week) or allowed to remain sedentary for 8 weeks. Afterwards, they were randomly assigned to left coronary artery occlusion or sham surgery. After this procedure, the rats remained sedentary for one week until euthanasia. Cardiac structural and functional analyses were performed using Doppler echocardiography. The rats that had a moderate or large infarct size were included in the evaluations. The data (mean + SEM) were analyzed using a two-way ANOVA model followed byTukey's post-hoc test. RESULTS: After the surgery, no significant difference between the exercise and sedentary groups was observed in the left ventricular infarct sizes (34.58 + 3.04 vs. 37.59 + 3.07). In another group of rats evaluated with Evans blue 1 h after myocardial infarction, no siginificant difference in the area at risk was observed between the exercised and sedentary rats (49.73 + 1.52 vs. 45.48 + 3.49). The changes in the left ventricular fractional areas for the exercised and sedentary myocardial infarction groups (36 + 2% and 39 + 3%, respectively) were smaller than those for the exercise sham surgery (ES, 67+1%) and sedentary sham surgery (SS, 69 + 2%) groups. The E/A was higher in the sedentary myocardial infarction (4.4 + 0.3) and exercised myocardial infarction (5.5 + 0.3) rats than in the SS (2.4 + 0.1) and ES (2.2 + 0.1) rats. CONCLUSION: Previous swim training of female rats does not attenuate systolic and diastolic function alterations after myocardial infarction induced by left coronary artery occlusion, suggesting that cardioprotection cannot be provided by exercise training in this experimental model

Labyrinthine fístulae in chronic otitis media with cholesteatoma

The chronic otitis media with cholesteatoma (COMC) may evoluate to intracranial and extra cranial complications, including the labyrithine fístulae. In this study, we present the evolution of our patients with labyrinthine fístulae. STUDY DESIGN: Clinical prospective. MATERIAL AND METHOD: Ten out 82 patients with COMC had labyrinthine fístulae and underwent surgery from January/2001 to April/2002. They were assessed by clinical exam, computed tomography scans, and pre and postoperative audiogram. RESULTS: Hearing loss, otorrhea, tinnitus and dizziness were present in 100%, 90%,80%, and 40% of the cases. In one patient the fístulae was seen only in the coronal CT-scan, in another patient the fístulae was not seen neither in coronal nor axial images. Among the patients who had tinnitus, 66% referred improvement of this complaint after surgery. DISCUSSION: in the cases without invasion of the perilymphatic space, we noticed a tendency of improvement of the postoperative audiogram pattern and clinical outcome. In the extensive fístulae, on the other hand, there were no clinical changes. CONCLUSION: The CT-scan remains the best exam to assess the COMC with 90% of sensitivity for labyrinthine fístulae. In the stage II we had a good postoperative outcome.A otite média crônica colesteatomatosa (OMCC) pode cursar com complicações intra e/ou extracranianas, entre elas a fístula labiríntica. Neste trabalho, mostramos a incidência e a evolução dos casos de fístula labiríntica decorrentes da OMCC em nosso serviço. FORMA DE ESTUDO: Clínico prospectivo. MATERIAL E MÉTODO: Dez pacientes com fístula labiríntica, do total de 82 pacientes com OMCC, foram submetidos à cirurgia no período de janeiro de 2001 a abril de 2002 e avaliados através de exame otorrinolaringológico completo, tomografia computadorizada e audiometria pré e pós-operatória. RESULTADOS: Perda auditiva, otorréia, zumbido e vertigem estavam presentes em 100%, 90%, 80% e 40% dos casos respectivamente na avaliação clínica pré-operatória. Em um paciente a fístula aparecia apenas nos cortes tomográficos coronais e tivemos um caso de falso-negativo. Dos pacientes com zumbido, 66% apresentaram melhora deste quadro no pós-operatório. DISCUSSÃO: Nos casos de fístula sem invasão do espaço perilinfático (até grau II), notamos uma tendência de melhora dos quadros clínico e audiométrico após a cirurgia. Nas fístulas extensas, por outro lado, o resultado audiométrico se manteve inalterado. CONCLUSÃO: A tomografia continua sendo o exame de escolha para os quadros de OMCC com sensibilidade de 90% para fístulas labirínticas. Nas fístulas grau II a cirurgia apresenta bom resultado funcional.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Otorrinolaringologia e Distúrbios da Comunicação HumanaUNIFESP, EPM, Depto. de Otorrinolaringologia e Distúrbios da Comunicação HumanaSciEL

Estimativa da Variação Temporal de Condutância Térmica de Contato em Placas Termicamente Finas via Método MCMC

This work deals with the solution of an inverse heat conduction problem to estimate a time-varying thermal contact conductance, in a one-dimensional problem in a composite medium with two thermally thin layers which is heated by a heat flux applied to the upper surface and exposed thermal convection on the bottom surface. The Classic Lumped method was applied to the direct problem mathematical formulation, considering thermally thin plates. This formulation reduces the original problem into two coupled ordinary differential equations, reducing the computational cost needed to solve the associated direct problem, which is solved with the NDSolve function, intrinsic to the Mathematica software. The inverse problem was solved with the Markov Chain Monte Carlo method within a Bayesian approach, applying the classic Metropolis-Hastings algorithm. The method was analyzed from simulated temperature measurements and proved to be capable of estimating a temporal function of the contact thermal conductance. This methodology allows taking into account the uncertainties associated with the parameters present in the models, as well as those associated with the estimation of thermal conductance varying with time, which is not observed in the methods aimed at temporal estimation of the contact thermal conductance currently found in the literature.Este trabalho trata da solução de um problema inverso de condução de calor visando estimar a variação temporal de condutância térmica de contato, num problema unidimensional em um material de duas camadas termicamente finas, aquecidas por meio de um fluxo de calor aplicado na superfície superior e exposto a convecção térmica na superfície inferior. Para a formulação do problema direto, considerando placas termicamente finas, foi utilizado o método Classic Lumped. Esta formulação reduz o problema original em duas equações diferenciais ordinárias acopladas, desta forma, possibilita diminuir o custo computacional necessário para solucionar o problema direto associado, que foi resolvido utilizando a função NDSolve, intrínseca do software Mathematica. Para a solução do problema inverso foi utilizado o método Monte Carlo via Cadeias de Markov, dentro de uma abordagem Bayesiana, aplicando o algoritmo de Metropolis-Hastings. O método foi analisado a partir de medidas simuladas de temperatura e se mostrou capaz para estimar uma função temporal da condutância térmica de contato. Esta metodologia permite levar em conta as incertezas associadas aos parâmetros presentes nos modelos, bem como, àquelas associadas com a estimativa da condutância térmica variando com o tempo, o que não é observado nos métodos voltados para estimativa temporal da condutância térmica de contato encontrados atualmente na literatura

A single bout of exercise with a flexible pole induces significant cardiac autonomic responses in healthy men

OBJECTIVES: Flexible poles can provide rapid eccentric and concentric muscle contractions. Muscle vibration is associated with a "tonic vibration reflex” that is stimulated by a sequence of rapid muscle stretching, activation of the muscle spindles and stimulation of a response that is similar to the myotatic reflex. Literature studies analyzing the acute cardiovascular responses to different exercises performed with this instrument are lacking. We investigated the acute effects of exercise with flexible poles on the heart period in healthy men. METHOD: The study was performed on ten young adult males between 18 and 25 years old. We evaluated the heart rate variability in the time and frequency domains. The subjects remained at rest for 10 min. After the rest period, the volunteers performed the exercises with the flexible poles. Immediately after the exercise protocol, the volunteers remained seated at rest for 30 min and their heart rate variability was analyzed. RESULTS: The pNN50 was reduced at 5-10 and 15-20 min after exercise compared to 25-30 min after exercise (p = 0.0019), the SDNN was increased at 25-30 min after exercise compared to at rest and 0-10 min after exercise (p = 0.0073) and the RMSSD was increased at 25-30 min after exercise compared to 5-15 min after exercise (p = 0.0043). The LF in absolute units was increased at 25-30 min after exercise compared to 5-20 min after exercise (p = 0.0184). CONCLUSION: A single bout of exercise with a flexible pole reduced the heart rate variability and parasympathetic recovery was observed approximately 30 min after exercise

A single bout of exercise with a flexible pole induces significant cardiac autonomic responses in healthy men

OBJECTIVES: Flexible poles can provide rapid eccentric and concentric muscle contractions. Muscle vibration is associated with a "tonic vibration reflex” that is stimulated by a sequence of rapid muscle stretching, activation of the muscle spindles and stimulation of a response that is similar to the myotatic reflex. Literature studies analyzing the acute cardiovascular responses to different exercises performed with this instrument are lacking. We investigated the acute effects of exercise with flexible poles on the heart period in healthy men. METHOD: The study was performed on ten young adult males between 18 and 25 years old. We evaluated the heart rate variability in the time and frequency domains. The subjects remained at rest for 10 min. After the rest period, the volunteers performed the exercises with the flexible poles. Immediately after the exercise protocol, the volunteers remained seated at rest for 30 min and their heart rate variability was analyzed. RESULTS: The pNN50 was reduced at 5-10 and 15-20 min after exercise compared to 25-30 min after exercise (p = 0.0019), the SDNN was increased at 25-30 min after exercise compared to at rest and 0-10 min after exercise (p = 0.0073) and the RMSSD was increased at 25-30 min after exercise compared to 5-15 min after exercise (p = 0.0043). The LF in absolute units was increased at 25-30 min after exercise compared to 5-20 min after exercise (p = 0.0184). CONCLUSION: A single bout of exercise with a flexible pole reduced the heart rate variability and parasympathetic recovery was observed approximately 30 min after exercise