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
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
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.
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Sternal seismocardiogram (SCG) is the assessment of microvibrations produced by the beating heart as detected by an accelerometer positioned on the sternum. This signal reflects mechanical events of the heart contraction, including the opening and closure of mitral and aortic valves and maximal blood flow acceleration. Traditionally, SCG has been detected in a laboratory setting with the subject lying at rest in supine position. ⋯ A large number of SCG estimates could be obtained over the 24 hours. In particular, more than 100 estimates per hour were available during the day; at night this rate was three times higher. Thus our study indicates that not only the 24h SCG monitoring in daily life is feasible but also that possible changes over time in SCG and its derived parameters may be tracked with an extreme temporal detail.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Clinical TrialReal-time cardiorespiratory coherence detects antinociception during general anesthesia.
Heart rate variability (HRV) may provide anesthesiologists with a noninvasive tool for monitoring nociception during general anesthesia. A novel real-time cardiorespiratory coherence (CRC) algorithm has been developed to analyze the strength of linear coupling between heart rate (HR) and respiration. CRC values range from 0 (low coherence, strong nociception) to 1 (high coherence, no nociception). ⋯ For comparison, three traditional measures of HRV (LF/HF ratio, SDNN, and RMSSD) responded on average by only 3.8%, 14%, and 3.9%, respectively. Finally, two traditional clinical measures of nociception (HR and blood pressure) responded on average by only 3.9% and 0.91%, respectively. CRC may thus be used as a real-time nociception monitor during general anesthesia.