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
Discovering shared dynamics in physiological signals: application to patient monitoring in ICU.
Modern clinical databases include time series of vital signs, which are often recorded continuously during a hospital stay. Over several days, these recordings may yield many thousands of samples. In this work, we explore the feasibility of characterizing the "state of health" of a patient using the physiological dynamics inferred from these time series. ⋯ Each such "dynamic" captures a distinct pattern of evolution of BP and is possibly recurrent within the same time series and shared across multiple patients. Next, we examine the utility of this low-dimensional representation of BP time series for predicting mortality in patients. Our results are based on an intensive care unit (ICU) cohort of 480 patients (with 16% mortality) and indicate that the dynamics of time series of vital signs can be an independent useful predictor of outcome in ICU.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Model based optimization of the cardiopulmonary resuscitation (CPR) procedure.
This paper is concerned with the optimization of the cardiopulmonary resuscitation (CPR) procedure, which plays a critical rule in saving the life of patients suffering from cardiac arrest. In this paper, we define the performance index for optimization using the oxygen delivery. A model developed earlier is used to calculate the oxygen delivery through CPR. ⋯ First, a global optimization is implemented to discover the best values of the free parameters which maximize the oxygen delivery. In addition to this, a sequential optimization scheme is explored which uses a two step optimization in each CPR sequence to maximize the oxygen delivery. Results show that the sequential optimization procedure will enhance the performance of the CPR significantly.
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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
Moving coil pressure algometer produces consistent force gradient and repeated stimulation.
Computer-controlled pressure stimulation (algometry) offers seemingly good reliability when it comes to pain assessment methods. It is therefore important to ensure through methodological quantification that moving coil pressure algometer (MCPA) exhibits accurate, fast, and precise tissue stimulation techniques. ⋯ Solicited force gradients of 500, 1000, and 1800 g/s showed high correlation values (R(2) > 0.99) for both rubber mat and direct probe-to-sensor contact cases. Through fast switching between different modes of operation of the actuator, force overshoot was reduced from as much as 300 to 20% for the same force magnitude, at the expense of a slight delay in repeated pulse delivery scheme.
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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.