Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference
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Conf Proc IEEE Eng Med Biol Soc · Jan 2007
The role of intracarotid cold saline infusion on a theoretical brain model incorporating the circle of willis and cerebral venous return.
This study describes a theoretical model of brain cooling by intracarotid cold saline infusion which takes into account redistribution of cold perfusate through the circle of Willis (CoW) and cold venous return (VR) from the head. This model is developed in spherical coordinates on a four tissue layer hemispherical geometrical configuration. Temperature evolution is modeled according to the Pennes bioheat transfer equation. ⋯ The temperature effect in the CoW model was present but less robust in the ipsilateral anterior region, as final temperature was 32 degrees C. However, cooling was also achieved in contralateral and posterior brain regions. This model continues to demonstrate the feasibility of intracarotid cold saline infusion for ischemic stroke therapy.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2007
Fluid resuscitation: computer simulation and animal experiments.
The purpose of this study was to investigate the hemodynamic system in hemorrhagic shock and to estimate the effects of different infusion fluids and rates on the recovery of the bleeding patient. A mathematical model of the hemodynamic system was developed including fluid transfer to and from the interstitium for different types of fluids. ⋯ The computer simulation followed successfully experimental data collected in five different experiments. Thus, it may now serve as an advanced tool for evaluating and analyzing effects of different fluids and optimize fluid regimen.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2007
Changes in Heart Rate Variability in patients under local anesthesia.
Spectral analysis of Heart Rate Variability (HRV) is widely used for the assessment of cardiovascular autonomic control. Several studies have shown the effect of anesthetic agents on HRV parameters. In this study a systematic approach of HRV analysis has been employed. ⋯ Using this methodology electrocardiogram (ECG) signals from 14 patients undergoing local anesthesia (brachial plexus block) were analyzed with parametric Autoregressive (AR) method. The results showed that the LF/HF ratio values calculated from the HRV signal decreases within an hour of the application of the brachial plexus block compared to the values at the start of the procedure. This change was noticed in approximately 80% of the patients.
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the continuous monitoring of splanchnic organ oxygen saturation (SpO2) would make the early detection of inadequate tissue oxygenation feasible, reducing the risk of hypoperfusion, severe ischemia, multiple organ failure, and, ultimately, death. In an attempt to create a splanchnic SpO2 sensor that can be used intra-operatively, pre-operatively and post-operatively this paper describes the design and technical evaluation of fiber optic based reflectance pulse oximeter sensor and processing system. In a detailed investigation to determine the optimal source-emitter spacing it was found that the optimum separation distance was between 3mm and 6mm. In vivo thermal testing showed that the rise in temperature at the tip of the fiber at both wavelengths was insignificant and therefore should have no effect in the splanchnic tissue.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2007
Automatic identification of spike-wave events and non-convulsive seizures with a reduced set of electrodes.
Epileptiform activity in the brain, whether localized or generalized, constitutes an important category of abnormal electroencephalogram (EEG). Seizures are episodes of relatively brief disturbances of mental, motor or sensory activity caused by paroxysmal cerebral activity. They are not always accompanied by the characteristic convulsions that we commonly associate with the word epilepsy. ⋯ The proposed signal processing algorithm is based on the detection of spike-wave events obtained from a wavelet analysis of the EEG signal, combined with an analysis of the complexity of the EEG using fractal dimension estimates. We show that this algorithm has excellent sensitivity and specificity. In particular, the fractal analysis is a key factor in the removal of falsely detected spike-wave events (false positives) that can be caused by voluntary or involuntary artifacts such as fast eyelid flutter.