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 2010
Robust closed-loop control of propofol administration using WAVCNS index as the controlled variable.
This paper presents a robust closed-loop strategy for control of depth of hypnosis. The proposed method regulates the electroencephalogram (EEG)-derived WAVCNS index as a hypnosis measure by manipulating intravenous propofol administration. ⋯ This closed-loop control was evaluated using simulated surgical procedures in 44 patient models whose PK and PD were identified from real clinical data. The controller can deliver consistent and acceptable closed-loop induction and maintenance phase responses for patients with wide-ranging PK and PD differences.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2010
Estimated venous return surface and cardiac output curve precisely predicts new hemodynamics after volume change.
In our extended Guyton's model, the ability of heart to pump blood is characterized by a cardiac output curve and the ability of vasculature to pool blood by a venous return surface. These intersect in a three-dimensional coordinate system at the operating right atrial pressure, left atrial pressure, and cardiac output. ⋯ Using the average values for two logarithmic function parameters, and for two slopes of a surface, we were able to estimate cardiac output curve and venous return surface. The estimated curve and surface predicted new hemodynamics after volume change precisely.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Randomized Controlled TrialEffect of remifentanil on the nonlinear electroencephalographic entropy parameters in propofol anesthesia.
Nonlinear electroencephalographic entropy parameters have been proposed for the assessment of depth of anesthesia. The influence of remifentanil, a commonly used intraoperative opioid, on these parameters, namely approximate entropy (ApEn), sample entropy (SampEn), and permutation entropy (PeEn), during induction of propofol anesthesia was studied. ⋯ No consistent influence on PeEn was observed. However, this may have been due to strong interindividual variation in PeEn values.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Revisiting the video stethoscope: an application of digital signal processing software (Goldwave) to monitoring ventilation in intubated patients.
Problems with tracheal intubation and mechanical ventilation are potentially important causes of perioperative morbidity and mortality. We have developed a method of monitoring the ventilation of both lungs during general anesthesia that is an advanced digital version of a more primitive analog technique developed over two decades ago. We used two miniature electret microphones connected to regular chest pieces, placing the assemblies on the anterior chest wall about 4 inches below the clavicle in the midclavicular line. ⋯ We also hypothesized that as a result of noise and anatomical variations that under conditions of bilateral mechanical ventilation the obtained plot would be very different from a simple 45 degree line. The data obtained supports these hypotheses. This preliminary study suggests that our technique may help provide a practical real-time warning system for detecting endotracheal tube malpositions, and may help build on the work of other investigators.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Estimating transition point of anesthetic-induced loss of consciousness in mice by detecting motion in response to forced movement.
To characterize transition periods of entrance to and emergence from anesthetic-induced unconsciousness in terms of thalamocortical neural activity, we devised a new method estimating a transition point of anesthetic-induced loss of consciousness. The method continuously monitors an animal's head motion in response to forced movement on treadmill and uses the motion signals as a criterion of the transition. ⋯ Resulting signals from the motion detector could discriminate the points of entrance into and emergence from the anesthetic-induced unconsciousness with resolution corresponding to the sampling frequency. This method makes it possible to track the anesthetic transition period continuously without contaminating EEGs and LFPs.