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
Clinical TrialA system for analyzing intraoperative B-Mode ultrasound scans of the liver.
In this article, a system for automatic analysis of intraoperative B-Mode ultrasound images of the liver is presented. The system is part of an assistance system for open liver surgery. ⋯ With this segmentation results, an ultrasound based 3D-model of the vascular structure is extracted and manually registered to a preoperative CT-based model. Anatomical landmarks like bifurcations of vessels are automatically extracted in the ultrasound-based model and will be used for an automatic registration process in further developments.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2007
Randomized Controlled TrialA new method for evaluating the performance of depth-of-hypnosis indices - the D-value.
An alternative statistic, the D-value, is presented for the evaluation of the performance of EEG-based depth-of-hypnosis measures against the Observers' Assessment of Alertness/Sedation scale. The measures considered here are spectral entropy, approximate entropy, Lempel-Ziv complexity and Higuchi fractal dimension. The study is based on recordings from 45 patients, divided into three groups of 15 recordings each. ⋯ All the patients received stepwise increased dose of propofol. The study shows that the D-value is a promising and flexible statistic for the evaluation of the discriminative power of the EEG measures with respect to the OAA/S scale. The D-value indicates well the dependence of the performance of the measures on the EEG frequency band as well as on remifentanil concentration.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2007
EEG frequency progression during induction of anesthesia: from start of infusion to onset of burst suppression pattern.
The anesthetic infusion with propofol influences EEG activity rather smoothly by changing the amplitude activity in different frequency bands. This results in a frequency progression pattern (FPP) which can be related to the depth of anesthesia. ⋯ The results reveal the underlying FPP and how the onset of the BSP is related to it. The proposed method offers potential for the development of automatic assessment systems for the depth of anesthesia.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2007
Estimation of effects of visually-induced motion sickness using independent component analysis.
To quantify the effect of visually-induced motion sickness on the autonomic nervous system, the authors previously proposed a new physiological index rho max representing the maximum cross-correlation coefficient between blood pressure variability and heart rate variability whose frequency components are limited to the Mayer wave band. However, rho max requires measurement of continuous blood pressure with an expensive and bulky measuring device. In the present study, an easier method for obtaining rho max with measurement of neither continuous blood pressure nor ECG but using finger photoplethysmography (PPG) only has been developed. ⋯ Two experiments in which subjects performed the Valsalva maneuver and then they watched a swaying video image were carried out to evaluate the adequacy of the proposed method. The experimental results have shown that the proposed method worked successfully as good as the conventional method. This means that the proposed method can contribute to increase in the number of subjects because multiple subjects can be used even in a single experiment.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2007
Comparison of cardiac output monitoring methods for detecting central hypovolemia due to lower body negative pressure.
Reduction in mean arterial pressure (MAP) is a late indictor of progressive circulatory pathology. Non-invasive monitoring methods that are superior indicators of circulatory compromise would be clinically valuable. With IRB approval, 21 healthy volunteers were subjected to progressive lower body negative pressure (LBNP) until the onset of presyncopal symptoms. ⋯ In terms of discriminating between (a) the 11 subjects who tolerated the protocol (i.e., tolerated higher levels of LBNP); versus (b) the 10 non-tolerant subjects, there was also a significant difference between MF and LTI: the ROC AUC for MF was 0.40 and for LTI was 0.66. There were no significant differences between MF nor EBI, however. In conclusion, LTI is notable as the only method which (a) correlated with decompression: (b) distinguished between decompression to -45 mmHg versus recovery; and (c) distinguished between those subjects who adequately compensated for central hypovolemia (tolerant) and those who did not have such robust physiologic compensation (non-tolerant).