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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Capnography, the monitoring of expired carbon dioxide (CO2) has been employed clinically as a non-invasive measure for the adequacy of ventilation of the alveoli of the lung. In combination with air flow measurements, the capnogram can be used to estimate the partial pressure of CO2 in the alveolar sacs. In addition, physiologically relevant parameters, such as the extent of CO2 rebreathing, the airway dead space, and the metabolic CO2 production can be predicted. ⋯ In addition, this allowed for a dynamic prediction of the unmeasured alveolar CO2 tension. The method is demonstrated using simulations of the capnogram. The proposed method could aid the clinician in the interpretation of the capnogram.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2006
Continuous cardiac output and left atrial pressure monitoring by pulmonary artery pressure waveform analysis.
We introduce a novel technique for continuous (i.e., automatic) monitoring of cardiac output (CO) and left atrial pressure (LAP) by mathematical analysis of a pulmonary artery pressure (PAP) waveform. To obtain an initial evaluation of the technique, we applied it to PAP waveforms obtained from nine critically ill patients and compared the resulting CO and LAP estimates with standard operator-dependent thermodilution and pulmonary capillary wedge pressure measurements, respectively. We report that the technique achieved an overall CO error of 17.2% and an overall LAP error of 15.8%. With further testing, the technique may ultimately be employed so as to permit, for the first time, continuous CO and LAP monitoring in critically ill patients.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2006
High rate shear insult delivered to cortical neurons produces heterogeneous membrane permeability alterations.
Traumatic brain injury (TBI) occurs when brain tissue is subjected to stresses and strains at high rates and magnitudes, yet the mechanisms of injury and cellular thresholds are not well understood. The events that occur at the time of and immediately after an insult are hypothesized to initiate cell dysfunction or death following a critical cell strain and strain rate. We analyzed neuronal plasma membrane disruption in two in vitro injury models-fluid shear stress delivered to planar cultures and shear strain induction of 3-D neural cultures. ⋯ Furthermore, increased membrane permeability led to increases in electrophysiological disturbance. Specifically, cells that exhibited increased membrane permeability did not fire random action potentials, in contrast to neighboring cells that had intact plasma membranes. This approach provides an experimental framework to investigate injury tolerance criteria as well as mechanistically driven therapeutic strategies.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2006
An evaluation of a PTT-based method for noninvasive and cuffless estimation of arterial blood pressure.
The aim of this study is to determine if a noninvasive and cuffless blood pressure (BP) estimation method using pulse transit time (PTT) can accurately track the changes in BP after a treadmill exercise. Experiments were conducted on 12 healthy subjects, who were directed to run on a treadmill at 10 kph for 4 minutes. For each subject, 13 trials were recorded in total, including 11 trials obtained immediately after exercise and during the 60-minute recovery period. ⋯ Both PTT-based device and Finometer were calibrated initially and Finometer calibration was also performed after exercise to the sphygmomanometer. Experimental results showed that there was only occasional discrepancy between BPs measured by Finometer and PTT-based device during the recovery period, i.e., at 5 minutes after exercise (p=0.008 for systolic BP and p=0.03 for diastolic BP). At all other post exercise time spots there were no significant differences between BPs measured by Finometer and PTT-based device.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2006
Evaluation of external cardiac massage performance during hypogravity simulation.
Preservation of astronaut crew health during an exploration mission to the Moon or Mars will be crucial to mission success. The likelyhood of a life threatening medical condition occurring during a mission to Mars has been estimated by NASA to be 1% per year. Since basic life support is a vital skill in critical care medicine, plans must be in place for cardiopulmonary resuscitation in both microgravity and hypogravity (i.e. on the surface of the Moon or Mars). ⋯ Elbow flexion was measured using an electrogoniometer in order to assess the use of arm muscles to achieve chest compressions. This study found that depth (Lunar and Mars) and rate (Mars) of chest compression was below American Heart Association recommendations during hypogravity simulation in the female group. Furthermore, elbow flexion proved to be significantly greater during Lunar and Mars hypogravity simulation than that of the 1G control condition, suggesting that upper arm force may be used to counter the loss of body weight in an attempt to maintain adequate chest compression under these conditions.