Research on Biomedical Engineering, Volume: 33, Issue: 4, Published: 2017
  • Effects of backpack loads and positions on the variability of gait spatiotemporal parameters in young adults Original Article

    Lehnen, Georgia Cristina; Magnani, Rina Marcia; Sá e Souza, Gustavo Souto de; Rodrigues, Fábio Barbosa; Andrade, Adriano de Oliveira; Vieira, Marcus Fraga

    Abstract in English:

    AbstractIntroduction: People carry backpacks of different weight in different positions every day. The effects of backpack wearing under different loads and positions were assessed according to the gait’s spatiotemporal parameters and their variability in young adults. Methods Twenty-one subjects performed trials of 4 min in the conditions: control condition with no backpack; bilateral back load consisting of 10% body weight (BW); bilateral back load of 20% BW (B20); unilateral load of 10% BW; unilateral load with 20% BW (U20); bilateral frontal load with 10% BW; bilateral frontal load with 20% BW. Results Step length (SL) and step frequency (SF) show that frontal conditions differed from others as seen in B20. Gait cycle phases showed an increase in the B20 condition for double stance phase and stance phase, swing phase presented reduction in the B20 condition. There were significant main effects in position for SL, SF, and walk ratio, in load only for stride width. The highest variability of spatiotemporal parameters occurred in the U20 condition. All load conditions with 20% BW showed a greater variability when compared to the 10% BW counterpart. Conclusion We concluded that young adults can cope with up to a 15% BW load under a bilateral back position, but in the frontal position not even a 10% BW load was proven to be a safe limit. 20% BW loads should be avoided in any position. These recommendations may assure increased gait stability, decreased trunk forward lean and decreased muscle activation and fatigue reducing back pain occurrence.
  • Correction equations to estimate body fat with plicometer WCS dual hand Original Article

    Zonatto, Hiago Augusto; Ribas, Marcelo Romanovitch; Simm, Eduardo Bolicenha; Oliveira, André Gonçalves de; Bassan, Julio Cesar

    Abstract in English:

    ABSTRACT Introduction This study aimed to propose regression equations for the correction of fat percentage values obtained with the WCS Dual Hand skinfold caliper, using the Lange skinfold caliper as a reference. Methods This study evaluated 112 undergraduate students from the Physical Education and Physical Therapy programs of the Faculdade Dom Bosco, located in Curitiba, Paraná, Brazil. Of these, 58 women were 24.9±5.8 years old and 54 men were 27.6±7.9 years old. The evaluation comprised the following measurements: height, body mass, and nine skin folds with WCS Dual Hand and Lange skinfold calipers used in biceps, triceps, subscapular, suprailiac, pectoral, average axillary, medial thigh, abdominal, and calf measurements. Results Through the simple linear regression analysis, eight equations were generated to correct the relative body fat obtained with equations commonly used in Brazil. For these correction equations, R2 was between 0.830 and 0.961 and p-value was 0.000 for all measurements. Conclusion These results indicate the use of equations for the correction of estimated values of relative body fat measured with the WCS Dual Hand skinfold caliper, whenever the Lange skinfold caliper is not available, in order to minimize the difference between them.
  • Adaptation of a smart walker for stroke individuals: a study on sEMG and accelerometer signals Original Article

    Loterio, Flávia Aparecida; Valadão, Carlos Torturella; Cardoso, Vivianne Flávia; Pomer-Escher, Alexandre; Bastos, Teodiano Freire; Frizera-Neto, Anselmo

    Abstract in English:

    Abstract Introduction: Stroke is a leading cause of neuromuscular system damages, and researchers have been studying and developing robotic devices to assist affected people. Depending on the damage extension, the gait of these people can be impaired, making devices, such as smart walkers, useful for rehabilitation. The goal of this work is to analyze changes in muscle patterns on the paretic limb during free and walker-assisted gaits in stroke individuals, through accelerometry and surface electromyography (sEMG). Methods The analyzed muscles were vastus medialis, biceps femoris, tibialis anterior and gastrocnemius medialis. The volunteers walked three times on a straight path in free gait and, further, three times again, but now using the smart walker, to help them with the movements. Then, the data from gait pattern and muscle signals collected by sEMG and accelerometers were analyzed and statistical analyses were applied. Results The accelerometry allowed gait phase identification (stance and swing), and sEMG provided information about muscle pattern variations, which were detected in vastus medialis (onset and offset; p = 0.022) and biceps femoris (offset; p = 0.025). Additionally, comparisons between free and walker-assisted gaits showed significant reduction in speed (from 0.45 to 0.30 m/s; p = 0.021) and longer stance phase (from 54.75 to 60.34%; p = 0.008). Conclusions Variations in muscle patterns were detected in vastus medialis and biceps femoris during the experiments, besides user speed reduction and longer stance phase when the walker-assisted gait is compared with the free gait.
  • Brazilian clinical engineering regulations: health equipment management and conditions for professional exercise Original Article

    Del Solar, João Gabriel Martin; Soares, Fabiano Araujo; Mendes, Cristiano Jacques Miosso Rodrigues

    Abstract in English:

    Abstract Introduction In Brazil, professionals, scientific community, and members of regulatory bodies have not yet achieved a consensus regarding who can legally perform the professional duties of a clinical engineer. We aim at clarifying this aspect, based on a detailed analysis of the pertinent regulations. Methods We acted on three fronts: (i) reviewing the current legislation regarding the clinical engineering exercise; (ii) visiting hospitals and working as trainee to understand how this exercise is implemented on Brazil’s Federal District; (iii) one of the authors participated in virtual discussion groups of clinical engineering professionals, monitoring collective understanding of regulations, checking consistency of proper knowledge, and acting as an active opinion leader in the subject among peers. Results We try to make a formal definition of clinical engineer and indicate their characteristic activities. We propose a synthesis of the regulation regarding healthcare products’ integrity protection and health technology management, identifying the engineering activities necessary to achieve those legal requirements. We analyze the legal constraints and conditions to exert engineering, indicating the necessary professionals’ attributions and the way to obtain them. Finally, we provide a brief analysis of the technical requirements presented by the Brazilian Consumer Protection Code and of the 15.943 Brazilian Standard (NBR). Discussion We conclude that, despite the lack of consensus about the Clinical Engineering activity, there exists in Brazil a Clinical Engineering regulation, but it is spread in complex laws and normative resolutions, defining compulsory responsibilities and attributions, as well as conditions and prerequisites for role performance.
  • Low cost system to measure active power in electrosurgical units Original Article

    Dums, José Flavio; Schneider, Bertoldo; Badin, Alceu André

    Abstract in English:

    Abstract Introduction: The real-time measurement of active power delivered to patients during the electrosurgical act is still an engineering challenge. Besides, there is no electrosurgical unit on the market capable of doing it according to the normative requirement. Methods This work presents the design of an electronic structure capable to probe the electrosurgical equipment output electrical signals, using low-costs very common resistors, and High Frequency distortions compensation circuits, and process them to provide an analogue signal proportional to the active power, allowing the knowledge and control of the energy delivered to the biological tissue. The reading circuits and the active power calculation method are presented. The power calculation is performed in two stages. The first one consists of a multiplier circuit that uses the readings voltage and current quantities to determine the instantaneous output power, and the second stage is formed by an integrating circuit which determines the average power value, resulting in a rippled continuous voltage, proportional to the active power delivered to the patient or biological tissue. Results Practical tests of the compensation technical are statistically evaluated by means of linear regressions. Results of 23 tests are summarized in a way to demonstrate de effectiveness of the proposed system. Conclusion Analysis of the results demonstrate the efficiency of the proposed system, whose average error is lower than 5%, and correlating them with the standard IEC 60601-2-2, that regulates the operation of electrosurgery units.
  • Proposal of surface electromyography signal acquisition protocols for masseter and temporalis muscles Original Article

    Sabaneeff, Ana; Caldas, Luciana Duarte; Garcia, Marco Antonio Cavalcanti; Nojima, Matilde da Cunha Gonçalves

    Abstract in English:

    Abstract Introduction The aim of this study was to propose a method of electrodes positioning on the superficial masseter and anterior temporalis muscles for surface electromyographic (sEMG) recordings in order to overcome some known methodological constraints. Methods Fifteen volunteers with normal occlusion participated in two experimental sessions within a 7 day-period. Surface electrodes were placed on two different locations that were based on palpable and individual anatomical references. Surface EMG signals (2000 Hz per channel; A/D: 16 bits; gain: 2000 X; band-pass filter: 20-500 Hz) were recorded under three conditions: mandibular rest position, 30% and 100% of maximum voluntary bite force. Three measurements of maximal bite force were taken by using a force transducer positioned over the lower right first molar region and the highest record was taken into account. The root mean square value was considered for analysis. Intraclass correlation coefficients (ICCs), paired t test, and the Bland-Altman method comprised the statistical analyses. The level of significance was set at 0.05. Results ICC records for right and left masseter and anterior temporalis muscles at T0 (first sEMG record) and T7 (second sEMG record) intervals were significantly different (p<0.05). The results showed satisfactory to excellent reproducibility of RMS values at rest, MVBF and 30% MVBF, as well as for MVBF in kgf. Conclusion The results showed reliable reproducibility for the sEMG signal recording in masseter and anterior temporalis muscles from the protocols presented and under the three conditions investigated.
  • The Neuroid revisited: A heuristic approach to model neural spike trains Original Article

    Prada, Erick Javier Argüello; Arteaga, Ignacio Antonio Buscema; Martínez, Antonio José D’Alessandro

    Abstract in English:

    AbstractIntroduction: Since it was introduced in 2012, the Neuroid has been used to aid in understanding how functionally different neural populations contribute to sensory information processing. However, insights about whether this neuron-model could perform better than others or about when its utilization should be considered have not been provided yet. Methods In an attempt to address this issue, a comparison between the Neuroid and the leaky-integrate-and-fire (LIF) model in terms of accuracy and computational cost was performed. Both models were tested for different stimulation amplitudes and stimulation periods, with time step sizes ranging from 10-4 to 1 ms. Results It was found that, although the Neuroid was able to produce more accurate results than its original version, its accuracy was lower than the achieved with the LIF model solved by the forward Euler method. On the other hand, the Neuroid performed its calculations in an amount of time significantly lower (Mulfactorial ANOVA test, p < 0.05) than that required by the LIF model when it was solved by using the forward Euler method. Moreover, it was possible to use Neuroid-based networks to replicate biologically relevant firing patterns produced by low-scale networks composed of more detailed neuron-models. Conclusion Results suggest that the Neuroid could be an interesting choice when computational resources are limited, although its use might be restricted to a narrow band of applications.
  • Algorithm for predicting macular dysfunction based on moment invariants classification of the foveal avascular zone in functional retinal images Original Article

    Arthur, Angélica Moises; Arthur, Rangel; Silva, Alexandre Gonçalves; Fouto, Marina Silva; Iano, Yuzo; Faria, Jacqueline Mendonça Lopes de

    Abstract in English:

    Abstract Introduction A new method for segmenting and quantifying the macular area based on morphological alternating sequential filtering (ASF) is proposed. Previous studies show that persons with diabetes present alterations in the foveal avascular zone (FAZ) prior to the appearance of retinopathy. Thus, a proper characterization of FAZ using a method of automatic classification and prediction is a supportive and complementary tool for medical evaluation of the macular region, and may be useful for possible early treatment of eye diseases in persons without diabetic retinopathy. Methods We obtained high-resolution retinal images using a non-invasive functional imaging system called Retinal Function Imager to generate a series of combined capillary perfusion maps. We filtered sequentially the macular images to reduce the complexity by ASF. Then we segmented the FAZ using watershed transform from an automatic selection of markers. Using Hu’s moment invariants as a descriptor, we can automatically classify and categorize each FAZ. Results The FAZ differences between non-diabetic volunteers and diabetic subjects were automatically distinguished by the proposed system with an accuracy of 81%. Conclusion This is an innovative method to classify FAZ using a fully automatic algorithm for segmentation (based on morphological operators) and for the classification (based on descriptor formed by Hu’s moments) despite the presence of edema or other structures. This is an alternative tool for eye exams, which may contribute to the analysis and evaluation of FAZ morphology, promoting the prevention of macular impairment in diabetics without retinopathy.
  • A model for multidimensional efficiency analysis of public hospital management Original Article

    Soares, Adeilson Barbosa; Pereira, Adriano Alves; Milagre, Selma Terezinha

    Abstract in English:

    Abstract Introduction Multidimensional efficiency analysis can provide important insights into the performance of hospitals. In this paper, we propose a multidimensional model based on Data Envelopment Analysis (DEA) to investigate and compare the efficiency of public hospitals in Brazil. Methods Data from 21 public hospitals were collected from public databases (OECD - Organization for Economic Co-operation and Development; SIH-SUS - SUS Hospital Information System, Datasus, Brazil). Four inputs (Number of medical and non-medical staff, Annual revenue, Number of beds, Average length of patient hospitalization), four Variables of Influence (Type of hospital, Accredited hospital, Number of medical specialties, Resources from government) and four Outputs (Number of outpatient care services, Number of hospitalizations, Number of surgeries, Number of exams) were used to feed the DEA model. Results Seven hospital units reach 100% efficiency and, according to DEA, can be considered efficient units. Two units were considered “almost efficient” and the remaining twelve units perform poorly, considering the data supplied to the DEA model. As a whole, the average efficiency of the hospitals investigated was 79% (0.79). Conclusion A very heterogeneous performance has been found among the Brazilian public hospitals investigated. Besides, the reasonably low average efficiency seems to indicate that the system has a large potential for improvement in almost all areas associated with the input and output variables investigated in this paper.
  • Development of a skateboarding trick classifier using accelerometry and machine learning Original Article

    Corrêa, Nicholas Kluge; Lima, Júlio César Marques de; Russomano, Thais; Santos, Marlise Araujo dos

    Abstract in English:

    Abstract Introduction Skateboarding is one of the most popular cultures in Brazil, with more than 8.5 million skateboarders. Nowadays, the discipline of street skating has gained recognition among other more classical sports and awaits its debut at the Tokyo 2020 Summer Olympic Games. This study aimed to explore the state-of-the-art for inertial measurement unit (IMU) use in skateboarding trick detection, and to develop new classification methods using supervised machine learning and artificial neural networks (ANN). Methods State-of-the-art knowledge regarding motion detection in skateboarding was used to generate 543 artificial acceleration signals through signal modeling, corresponding to 181 flat ground tricks divided into five classes (NOLLIE, NSHOV, FLIP, SHOV, OLLIE). The classifier consisted of a multilayer feed-forward neural network created with three layers and a supervised learning algorithm (backpropagation). Results The use of ANNs trained specifically for each measured axis of acceleration resulted in error percentages inferior to 0.05%, with a computational efficiency that makes real-time application possible. Conclusion Machine learning can be a useful technique for classifying skateboarding flat ground tricks, assuming that the classifiers are properly constructed and trained, and the acceleration signals are preprocessed correctly.
  • An automatic gain control circuit to improve ECG acquisition Technical Communication

    Rovetta, Marco; Baggio, João Fernando Refosco; Moraes, Raimes

    Abstract in English:

    Abstract Introduction Long-term electrocardiogram (ECG) recordings are widely employed to assist the diagnosis of cardiac and sleep disorders. However, variability of ECG amplitude during the recordings hampers the detection of QRS complexes by algorithms. This work presents a simple electronic circuit to automatically normalize the ECG amplitude, improving its sampling by analog to digital converters (ADCs). Methods The proposed circuit consists of an analog divider that normalizes the ECG amplitude using its absolute peak value as reference. The reference value is obtained by means of a full-wave rectifier and a peak voltage detector. The circuit and tasks of its different stages are described. Results Example of the circuit performance for a bradycardia ECG signal (40bpm) is presented; the signal has its amplitude suddenly halved, and later, restored. The signal is automatically normalized after 5 heart beats for the amplitude drop. For the amplitude increase, the signal is promptly normalized. Conclusion The proposed circuit adjusts the ECG amplitude to the input voltage range of ADC, avoiding signal to noise ratio degradation of the sampled waveform in order to allow a better performance of processing algorithms.
Sociedade Brasileira de Engenharia Biomédica Centro de Tecnologia, bloco H, sala 327 - Cidade Universitária, 21941-914 Rio de Janeiro RJ Brasil, Tel./Fax: (55 21)2562-8591 - Rio de Janeiro - RJ - Brazil
E-mail: rbe@rbejournal.org