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 2014
Comparative StudyComparison of methods for determining pulse arrival time from Doppler and photoplethysmography signals.
The aim of this study was to compare three foot-finding methods applied to ultrasound Doppler and photoplethysmographic (PPG) signals: maximum 1st derivative, maximum 2nd derivative and an 'intersecting tangents' method. The pulse arrival times of each method were compared. ⋯ The results show that the maximum 1st derivative method produced significantly larger pulse arrival times than the other two methods. The intersecting tangents method produced greatest precision for cardiac periods compared with ECG than maximum 1st or 2nd derivatives for both Doppler (r(2) = 0.975) and PPG (r(2) = 0.987) signals.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Automatic lung tidal volumes estimation from tracheal sounds.
This paper presents a method to automatically estimate lung tidal volumes from the acoustic signals generated in the respiratory track. The signal is measured with an acoustic based sensor placed in the suprasternal notch. The method does not require any previous knowledge or modelling of the individual respiratory track, and relies on just one calibration parameter. ⋯ The subjects were simultaneously wearing a Wright respirometer which was used as a gold standard for comparison. Agreement between the two methods was assessed with Bland-Altman techniques. The results show the potential the technique has, integrated with a small acoustic sensor, for less-intrusive and even remote and/or continuous monitoring of lung tidal volumes.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Interaction between EEG and drug concentration to predict response to noxious stimulation during sedation-analgesia: effect of the A118G genetic polymorphism.
The level of sedation in patients undergoing medical procedures is affected by the interaction between the effect of the anesthetic and analgesic agents and the pain stimuli. The presence of the A118G single nucleotide polymorphism (SNP) in the OPRM1 gene affects the requirements of opioids for patients undergoing sedation-analgesia. ⋯ The proposed measures were based on power spectral density and auto-mutual information function. It was found that the statistical performances of the EEG measures improved when the presence of the SNP was taken into account (prediction probability Pk>0.9).
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Rapid and low-invasive functional brain mapping by realtime visualization of high gamma activity for awake craniotomy.
For neurosurgery with an awake craniotomy, the critical issue is to set aside enough time to identify eloquent cortices by electrocortical stimulation (ECS). High gamma activity (HGA) ranging between 80 and 120 Hz on electrocorticogram (ECoG) is assumed to reflect localized cortical processing. In this report, we used realtime HGA mapping and functional magnetic resonance imaging (fMRI) for rapid and reliable identification of motor and language functions. ⋯ Specificities of the motor and language-fMRI, however, did not reach 85%. The results of HGA mapping was mostly consistent with those of ECS mapping, although fMRI tended to overestimate functional areas. This novel technique enables rapid and accurate functional mapping.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
An adaptive brain-machine interface algorithm for control of burst suppression in medical coma.
Burst suppression is an electroencephalogram (EEG) indicator of profound brain inactivation in which bursts of electrical activity alternate with periods of isoelectricity termed suppression. Specified time-varying levels of burst suppression are targeted in medical coma, a drug-induced brain state used for example to treat uncontrollable seizures. A brain-machine interface (BMI) that observes the EEG could automate the control of drug infusion rate to track a desired target burst suppression trajectory. ⋯ We design an adaptive recursive Bayesian estimator to jointly estimate drug concentrations and system parameters in real time. We construct a controller using the linear-quadratic-regulator strategy that explicitly penalizes large infusion rate variations at steady state and uses the estimates as feedback to generate robust control. Using simulations, we show that the adaptive algorithm achieves precise control of time-varying target levels of burst suppression even when model parameters are initialized randomly, and reduces the infusion rate variation at steady state.