Medical & biological engineering & computing
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Med Biol Eng Comput · Mar 2016
An MRI-based leg model used to simulate biomechanical phenomena during cuff algometry: a finite element study.
Cuff pressure stimulation is applicable for assessing deep-tissue pain sensitivity by exciting a variety of deep-tissue nociceptors. In this study, the relative transfer of biomechanical stresses and strains from the cuff via the skin to the muscle and the somatic tissue layers around bones were investigated. Cuff pressure was applied on the lower leg at three different stimulation intensities (mild pressure to pain). ⋯ The mean stress under the cuff position around tibia was 4.6, 4.9 and around fibula 14.8, 16.4 times greater than mean stress of muscle surface in the same section at pain threshold and intense painful stimulations, respectively. At the same stimulation intensities, the mean strains around tibia were 36.4, 42.3 % and around fibula 32.9, 35.0 %, respectively, of mean strain on the muscle surface. Assuming strain as the ideal stimulus for nociceptors the results suggest that cuff algometry is less capable to challenge the nociceptors of tissues around bones as compared to more superficially located muscles.
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Med Biol Eng Comput · Jan 2016
Hierarchical multi-class SVM with ELM kernel for epileptic EEG signal classification.
In this paper, a novel hierarchical multi-class SVM (H-MSVM) with extreme learning machine (ELM) as kernel is proposed to classify electroencephalogram (EEG) signals for epileptic seizure detection. A clinical EEG benchmark dataset having five classes, obtained from Department of Epileptology, Medical Center, University of Bonn, Germany, is considered in this work for validating the clinical utilities. Wavelet transform-based features such as statistical values, largest Lyapunov exponent, and approximate entropy are extracted and considered as input to the classifier. ⋯ Experiments have been conducted using holdout and cross-validation methods on the entire dataset. Metrics namely classification accuracy, sensitivity, specificity, and execution time are computed to analyze the performance of the proposed work. The results show that the proposed H-MSVM with ELM kernel is efficient in terms of better classification accuracy at a lesser execution time when compared to ANN, various multi-class SVMs, and other research works which use the same clinical dataset.
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Med Biol Eng Comput · Sep 2015
Influence of head mass on temporo-parietal skull impact using finite element modeling.
The effect of head mass on its biomechanical response during lateral impact to the head is investigated in this computational study. The mass of the head of a state-of-the-art validated finite element head model is altered by ± 10 % from the base value of 4.7 kg. Numerical simulations of lateral head impacts for 30 cases (representing 15 human cadaver experiments × 2 mass configurations) are performed using the LS-DYNA solver at different velocities ranging from 2.4 to 6.5 m/s and three impacting conditions representing different stiffness and shapes of the contact/impact surfaces. ⋯ Mass variations have also influence on skull strain energy. Regardless of increase/decrease in skull strain energy influenced by head mass variations used in the computational study, the 50 % fracture tolerance limit was unaltered, which was 544 mJ. The present study gives a better understanding of the mechanism of temporo-parietal skull impact.
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Med Biol Eng Comput · Jun 2015
A mechanical chest compressor closed-loop controller with an effective trade-off between blood flow improvement and ribs fracture reduction.
Chest compression (CC) is a significant emergency medical procedure for maintaining circulation during cardiac arrest. Although CC produces the necessary blood flow for patients with heart arrest, improperly deep CC will contribute significantly to the risk of chest injury. In this paper, an optimal CC closed-loop controller for a mechanical chest compressor (OCC-MCC) was developed to provide an effective trade-off between the benefit of improved blood perfusion and the risk of ribs fracture. ⋯ With a higher mean value of cardiac output (1.35 L/min) and partial pressure of end-tidal CO2 (15.7 mmHg), the OCC-MCC obtained a larger blood flow and higher BF than TMCM (5.19 vs. 3.41) in six out of a total of nine cases. Although it is relatively difficult to maintain a stable CC depth when the chest is stiff, the OCC-MCC is still superior to the TMCM for performing safe and effective CC during CPR. The OCC-MCC is superior to the TMCM in performing safe and effective CC during CPR and can be incorporated into the current version of mechanical CC devices for high quality CPR, in both in-hospital and out-of-hospital CPR settings.
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Med Biol Eng Comput · Mar 2015
Assessment of dynamic cerebral autoregulation and cerebral carbon dioxide reactivity during normothermic cardiopulmonary bypass.
Despite increased risk of neurological complications after cardiac surgery, monitoring of cerebral hemodynamics during cardiopulmonary bypass (CPB) is still not a common practice. Therefore, a technique to evaluate dynamic cerebral autoregulation and cerebral carbon dioxide reactivity (CO2R) during normothermic nonpulsatile CPB is presented. The technique uses continuous recording of invasive arterial blood pressure, middle cerebral artery blood flow velocity, absolute cerebral tissue oxygenation, in-line arterial carbon dioxide levels, and pump flow measurement in 37 adult male patients undergoing elective CPB. ⋯ CO2R was preserved during CPB, but significantly lower for hypocapnia compared with hypercapnia (p < 0.01). Conversely, cerebral autoregulation parameters such as gain, phase, and autoregulation index were significantly higher (p < 0.01) during hypocapnia compared with both normocapnia and hypercapnia. Assessing cerebral autoregulation and CO2R during CPB, by cyclic alteration of pump flow, showed an impaired cerebral autoregulation during hypercapnia.