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
FDA regulation of clinical high intensity focused ultrasound (HIFU) devices.
In the U. S., medical devices are regulated under the authority of the 1976 Medical Device Amendments to the Food, Drug, and Cosmetic Act, with the Food and Drug Administration's Center for Devices and Radiological Health having primary responsibility. The Act defines several regulatory paths to market depending on the complexity of the device and indications for use. ⋯ Pre-clinical testing generally comprises ultrasound power measurements and field characterization, in vitro and in vivo temperature measurements, thermal computational modeling, and demonstrating the accuracy for targeting the region of interest and monitoring treatment progress. Protocols for clinical trials are developed by the device sponsor in conjunction with FDA medical and scientific staff. Currently there are no recognized guidance or standards documents for HIFU testing that could be used in the regulatory review process, but such work is underway within the International Electrotechnical Commission.
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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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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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Monitoring of human vital signs - heart rate, respiratory rate, hemoglobin oxygen saturation and others - has become an indispensable part of the standard of care in a hospital setting. For example, vital sign monitoring during administration of general anesthesia is essential, given the role that the anesthesiologist plays in assuming physiologic control. In veterinary settings, however, vital sign monitoring under anesthesia is less common, and may consist simply of a visual assessment of respiratory rate. ⋯ In this paper, we present a unique nose-cone design and associated instrumentation which allows for measurement of respiratory parameters - e.g., anesthesia gas concentration, inspiratory and expiratory O(2), and inspiratory and expiratory CO(2) (capnometry). Such instrumentation facilitates a physiologic assessment of small animals undergoing general anesthesia, an increasingly important consideration as small animals play a greater role in in vivo biomedical studies. In addition, the techniques proposed herein are suitable for measurement on small respiratory volumes associated with neonatal monitoring.
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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.