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
Impact of obstructive sleep apnea on sleep-wake stage ratio.
Patients with obstructive sleep apnea (OSA) experience fragmented sleep and exhibit different sleep architectures. While polysomnographic metrics for quantifying sleep architecture are studied, there is little information about the impact of OSA on the ratio of different sleep-wake stages (wake, W; rapid eye movement, REM; non-REM stages 1 to 3, N1 to N3). This study, therefore, aims to investigate the relationship between apnea-hypopnea index (AHI, a measure of OSA severity) and all possible ratios of sleep-wake stages. ⋯ Results show a statistically significant positive, linear and monotonic correlation between AHI and REM/N3, as well as between AHI and N1/W (p-values < 0.05). These findings imply that patients with increased severity of OSA may spend more time in REM than deep sleep, and in light sleep than wake (or less time in deep sleep than REM, and in wake than light sleep). A power-law regression model may possibly explain the relationships of AHI-REM/N3 and AHI-N1/W, and predict the value of AHI using REM/N3 or N1/W.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
A survival prediction model of rats in hemorrhagic shock using the random forest classifier.
Hemorrhagic shock is the cause of one third of deaths resulting from injury in the world. Although many studies have tried to diagnose hemorrhagic shock early and accurately, such attempts were inconclusive due to compensatory mechanisms of humans. The objective of this study was to construct a survival prediction model of rats in hemorrhagic shock using a random forest (RF) model, which is a newly emerged classifier acknowledged for its performance. ⋯ For the LR model, sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (ROC-AUC) were 1, 0.89, 0.94, and 0.98, respectively. For the RF models, sensitivity, specificity, accuracy, and AUC were 0.96, 1, 0.98, and 0.99, respectively. In conclusion, the RF model was superior to the LR model for survival prediction in the rat model.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Effect of anesthesia on spontaneous activity and evoked potentials of the cerebellar cortex.
Cerebellum is a highly organized structure with a crystalline morphology that has always intrigued neuroscientists. Much of the cerebellar research has been conducted in anesthetized animals, particularly using ketamine and xylazine combination. ⋯ The frequency contents of the spontaneous activity suggest that ketamine/xylazine anesthesia suppresses most of the components except those below 30 Hz. This preliminary study also showed that multi channels of cerebellar cortical activity can be recorded using flexible multi-electrode arrays in behaving animals, which is very challenging task with single microelectrodes.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Comparative Study Clinical TrialThe comparison of a novel continuous cardiac output monitor based on pulse wave transit time and echo Doppler during exercise.
A new technology called estimated continuous cardiac output (esCCO) uses pulse wave transit time (PWTT) obtained from an electrocardiogram and pulse oximeter to measure cardiac output (CO) non-invasively and continuously. This study was performed to evaluate the accuracy of esCCO during exercise testing. We compared esCCO with CO measured by the echo Doppler aortic velocity-time integral (VTIao_CO). ⋯ This indicates that PEP included in PWTT has an impact on the accuracy of esCCO measurement. In this study, the validity of esCCO during exercise testing was assessed and shown to be acceptable. The result of this study suggests that we can expand its application.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Cardiac output estimation in mechanically ventilated patients: a comparison between prolonged expiration method and thermodilution.
A non-invasive method to estimate cardiac output (CO) in mechanically ventilated patients, based on prolonged expiration, has been previously described. With the aim to assess its performances, we prospectively enrolled fifteen cardiac surgery patients, and compared the results obtained with the non-invasive method with the ones obtained using two invasive approaches based on thermodilution. ⋯ These values show the slight underestimation of CO by the proposed non-invasive method with respect to the gold standard. On the other hand the described method could represent a good compromise between accuracy and non-invasiveness, which fosters the implementation of a new monitoring tool suitable for a semi-continuous CO assessment.