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 2009
Fuzzy control for closed-loop, patient-specific hypnosis in intraoperative patients: a simulation study.
Research has demonstrated the efficacy of closed-loop control of anesthesia using bispectral index (BIS) as the controlled variable, and the recent development of model-based, patient-adaptive systems has considerably improved anesthetic control. To further explore the use of model-based control in anesthesia, we investigated the application of fuzzy control in the delivery of patient-specific propofol-induced hypnosis. In simulated intraoperative patients, the fuzzy controller demonstrated clinically acceptable performance, suggesting that further study is warranted.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Long-term assessment of post-cardiac-arrest neurological outcomes with somatosensory evoked potential in rats.
Cardiac arrest (CA) can produce complex changes in somatosensory evoked potentials (SSEPs). Somatosensory evoked potentials (SSEPs) indicate the intactness of somatosensory pathways and are commonly used for brain function monitoring during surgeries. Multiresolution biorthogonal wavelet analysis was applied to SSEPs recorded during established CA experiments and post-CA long-term recovery periods in rats. ⋯ In the long-term recovery period (within 72 hours), both the amplitudes of SSEPs and the interpeak latencies returned to the baseline. Our results suggest that the changes of SSEPs may represent the post-CA neurological injuries and recovery in the somatosensory afferent pathways. The results here lay ground work for establishing the relationship between SSEPs and post-CA neurological injuries and functional outcomes as well as deploying SSEP in clinical settings to monitor patients resuscitated from CA in the future.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Combined direct current and high frequency nerve block for elimination of the onset response.
Nerve conduction in peripheral mammalian nerves can be blocked by high frequency alternating current (HFAC) waveforms. However, one of the disadvantages of HFAC block is that it produces an intense burst of firing in the nerve when the HFAC is first turned on. This is a significant obstacle to the clinical implementation of HFAC block. ⋯ This method was experimentally evaluated in an in-vivo mammalian model. Successful no-onset HFAC block was obtained using a DC block of 200 microA and an HFAC block of 30 kHz at 10 Vp-p. This may allow HFAC block to be used in clinical applications for pain relief.
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BIS monitoring is a processed electroencephalogram (EEG) technology that is designed to follow the effects that anesthetics and sedatives have on cerebral function. Much is know about the technology, it's utility and limitations. The economic case for widespread utilization of this technology is weak. ⋯ Total cost to the heath care system would approach one billion US dollars per year, just for use during general anesthetics. More appropriate use of already available drugs and technology would most likely decrease the incidence of IR as effectively, although individual patients who are at high risk for IR may benefit from this technology. However, based on current health care economic standards general use of BIS monitoring does not seem warranted and appears not to be cost-effective.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Reduction of the onset response in high frequency nerve block with amplitude ramps from non-zero amplitudes.
High frequency alternating current (HFAC) waveforms reversibly block conduction in mammalian peripheral nerves. The initiation of the HFAC produces an onset response in the nerve before complete block occurs. An amplitude ramp, starting from zero amplitude, is ineffective in eliminating this onset response. ⋯ However, an amplitude ramp was successful in eliminating this onset. This was always possible for the ramps up from 50%, 75 % and 90% block threshold amplitude, but never from 0% or 25% of the block threshold amplitude. This maneuver can potentially be used to maintain complete nerve block, transition to partial block and then resume complete block without initiating another onset.