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
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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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
A wavelet based method for steady-state detection in anesthesia.
With the recent concern on patient's outcome following general anesthesia, automatic control of drugs has been a field of interest. The Bispectral Index (BIS) is an EEG based hypnosis monitor, in current use at the operating theatre as a guiding tool for the anesthesiologist to titrate drugs, and prevent awareness. ⋯ A steady-state index was obtained using a wavelet analysis technique for trend detection. This tool may be used in the future to model the drug's combined effect on the hypnosis indices, and also to bring some insight on disturbances not related to drug changes.
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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
Validation of a graphic measurement of heart rate variability to assess analgesia/nociception balance during general anesthesia.
The optimization of analgesic drugs delivery during general anesthesia (GA) requires to evaluate the pain/analgesia balance. Heart Rate Variability (HRV) analysis has long been shown to measure the autonomic nervous system tone, which is strongly influenced by anesthetic drugs. ⋯ Measurements on simulated RR series showed that the graphic assessment is independent from respiratory rate, while LF and HF spectral measurements are over- and underestimated for respiratory rates lower than 12 cycles min Clinical measurements on 49 patients during GA showed that normalized HF power was strongly related to hemodynamic responsiveness during GA, and was strongly correlated with normalized EnvTOT measurements. A real time computation of the RR series could therefore help medical staff to anticipate hemodynamic responsiveness and the analgesia/nociception balance during GA.