Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2010
Functional regeneration of severed peripheral nerve using an implantable electrical stimulator.
This paper presents functional regeneration of severed peripheral nerve using a polymer-based implantable electrical stimulator. A polyimide based conduit electrode was made by micro-fabrication and a stimulation chip was designed to generate biphasic current pulse for electrical stimulation. The stimulation chip was packaged with a battery using silicone elastomer, and integrated with the electrode. ⋯ The electrical stimulation was applied for periods of one, two and four weeks between the proximal and the distal nerve stumps. After four weeks of post-operations, the degree of regeneration was evaluated through walking track assessments and by measuring neural response of the regenerated nerve. Based on these results, electrical stimulation, especially for two weeks of stimulation, could accelerate functional regeneration of the severed nerve.
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2010
Comparative StudyTime-varying spectral analysis for comparison of HRV and PPG variability during tilt table test.
In this work we assessed the possibility of using the pulse rate variability (PRV) extracted from photoplethysmography signal as an alternative measurement of the HRV signal in non-stationary conditions. The study is based on the analysis of the changes observed during tilt table test in the heart rate modulation of 17 young subjects. Time-varying spectral properties of both signals were compared by time-frequency (TF) and TF coherence analysis. ⋯ Time-frequency analysis revealed that: the TF spectra of both signals were highly correlated (0.99 ± 0.01); the difference between the instantaneous power, in LF and HF bands, obtained from HRV and PRV was small (, 10(-3) s(-2)) and their temporal patterns were highly correlated (0.98 ± 0.04 and 0.95 ± 0.06 in LF and HF bands respectively); TF coherence in LF and HF bands was high (0.97 ± 0.04 and 0.89 ± 0.08, respectively). Finally, the instantaneous power in LF band was observed to significantly increase during head-up tilt by both HRV and PRV analysis. These results suggest that, although some small differences in the time-varying spectral indices extracted from HRV and PRV exist, mainly in the HF band associated with respiration, PRV could be used as an acceptable surrogate of HRV during non-stationary conditions, at least during tilt table test.
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2010
Clinical TrialAssessment of the depth of anesthesia based on symbolic dynamics of the EEG.
Methodologies based on symbolic dynamics have successfully demonstrated to reflect the nonlinear behavior of biological signals. In the present study, symbolic dynamics was applied to the electroencephalogram (EEG) in order to describe the level of depth of anesthesia. ⋯ Words of three symbols were built from this symbolic series. The results obtained from the EEGs of 36 patients undergoing anesthesia showed that the probabilities of the word types were able to reflect the depth of anesthesia in a similar way to the auditory evoked potential index AAI, a commercial index.
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2010
Analysis of heart rate variability dynamics during propofol and dexmedetomidine anesthesia.
It has been observed that heart rate variability (HRV) diminishes during anesthesia, but the exact mechanisms causing it are not completely understood. The aim of this paper was to study the dynamics of HRV during low dose propofol (N=9) and dexmedetomidine (N=8) anesthesia by using state-of-the-art time-varying methods, and thereby ultimately try to improve the safety of anesthesia. ⋯ For dexmedetomidine these changes are more considerable than for propofol. For dexmedetomidine the variability also seems to start decreasing right after loss of consciousness, whereas for propofol HRV continues increasing.
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2010
PhysioDoloris: a monitoring device for analgesia / nociception balance evaluation using heart rate variability analysis.
Continuous Analgesia / Nociception balance evaluation during general anesthesia could be of precious help for the optimization of analgesic drugs delivery, limiting the risk of toxicity due to the use of opioid drugs, limiting the risk of post operative hyper algesia, and, probably, reducing time of recovery after surgical procedure. Heart Rate Variability analysis has been shown in several studies to measure the Autonomic Nervous System tone, which is strongly influenced by anesthetic drugs. ⋯ We have previously developed and evaluated a pain / analgesia measurement algorithm based on the magnitude analysis of the respiratory patterns on the RR series. In this paper, we present the development of a monitoring device (PhysioDoloris), based on the previously described technology, giving in real time an Analgesia Nociception Index (ANI) which can be used during general anesthesia in order to give to the anesthetist, a complementary tool for optimized drug delivery.