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 2012
Estimation of venous oxygenation saturation using the finger Photoplethysmograph (PPG) waveform.
In this study, finger photoplethysmograph data obtained from twelve patients undergoing cardiothoracic surgery were analyzed in order to estimate the venous saturation utilizing the modulations created by the positive pressure ventilation in the AC Photoplethysmograph (PPG) signals. The PPG signals were analyzed in the time-domain using a conventional pulse oximetry algorithm to produce estimations of arterial oxygen saturation. ⋯ The results showed that there was no significant difference in the traditionally-derived (time-domain) arterial saturation and the instantaneous arterial saturation. However, the instantaneous venous saturation was found to be significantly lower than the time-domain estimated and instantaneous arterial saturation (P=<0.001).
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Wireless photoplethysmographic device for heart rate variability signal acquisition and analysis.
The photoplethysmographic (PPG) signal has the potential to aid in the acquisition and analysis of heart rate variability (HRV) signal: a non-invasive quantitative marker of the autonomic nervous system that could be used to assess cardiac health and other physiologic conditions. A low-power wireless PPG device was custom-developed to monitor, acquire and analyze the arterial pulse in the finger. The system consisted of an optical sensor to detect arterial pulse as variations in reflected light intensity, signal conditioning circuitry to process the reflected light signal, a microcontroller to control PPG signal acquisition, digitization and wireless transmission, a receiver to collect the transmitted digital data and convert them back to their analog representations. ⋯ Kubios was able to generate a report sheet with the time domain and frequency domain parameters of the acquired data. These features were then compared against those calculated by MATLAB. The preliminary results demonstrate that the prototype wireless device could be used to perform HRV signal acquisition and analysis.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Frequency dependent transmission characteristics between arterial blood pressure and intracranial pressure in rats.
The pulsatile energy transmission between arterial blood pressure (BP) and intracranial pressure (ICP) is affected by cerebrospinal fluid (CSF) and brain tissue. Studies in dogs have shown that the transfer function (TF) between BP and ICP shows damping of pulsatile energy around heart rate frequency (1-3Hz) with notch filter characteristics, and the amount of damping is sensitive to cerebral compliance. This investigation aimed to assess whether this notch filter characteristic is an intrinsic property of the brain enclosed in a rigid skull and therefore applies across species with a large difference in body size. ⋯ Findings show that the rat brain acts as a selective frequency pulsation absorber of energy centered at heart rate frequency. This similarity with larger animals indicates a possible allometric mechanism underlying this phenomenon, with notch filter characteristic frequency scaled to body size. This study suggests that the TF between arterial BP and ICP is an intrinsic property of the brain tissue and CSF enclosed in a rigid compartment and can be used to assess changes in cerebral compliance due to abnormal CSF pressure and flow as occur in hydrocephalus.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Heart rate variability analysis as an index of emotion regulation processes: interest of the Analgesia Nociception Index (ANI).
Autonomic Nervous System (ANS) variations are strongly influence by emotion regulation processes. Indeed, emotional stimuli are at the origin of an activation of the ANS and the way an individual pass from a state of alert in the case of emotional situation to a state of calm is closely coupled with the ANS flexibility. We have previously described and developed an Analgesia Nociception Index (ANI) for real time pain measurement during surgical procedure under general anesthesia. ⋯ To test this hypothesis, we analyzed ANI's response to a negative emotional stimulus. This analysis showed that the index decreases during the emotion induction phase and returns to its baseline after 2 minutes. This result confirms that ANI could be a good indicator of parasympathetic changes in emotional situation.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Prediction of extubation failure for neonates with respiratory distress syndrome using the MIMIC-II clinical database.
Extubation failure (EF) is an ongoing problem in the neonatal intensive care unit (NICU). Nearly 25% of neonates fail their first extubation attempt, requiring re-intubations that are associated with risk factors and financial costs. ⋯ From an initial list of 57 candidate features, our machine learning approach narrowed down to six features useful for building an EF prediction model: monocyte cell count, rapid shallow breathing index, fraction of inspired oxygen (FiO(2)), heart rate, PaO(2)/FiO(2) ratio where PaO(2) is the partial pressure of oxygen in arterial blood, and work of breathing index. Algorithm performance had an area under the receiver operating characteristic curve (AUC) of 0.871 and sensitivity of 70.1% at 90% specificity.