Journal of clinical monitoring and computing
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J Clin Monit Comput · Apr 2002
Xenon washout during in-vitro extracorporeal circulation using different oxygenators.
Xenon anesthesia is known to have no adverse influence on myocardial contractility and cardiocirculatory function even in cardiac compromised patients. To make use of this advantages for cardiac surgery patients undergoing extracorporeal circulation (ECC) it must be known if oxygenators are diffusible for xenon in order to avoid losses of the very expensive noble gas. ⋯ Using common oxygenators xenon is eliminated during ECC and lost into the atmosphere. To maintain anesthesia during ECC continuous xenon application would be necessary to compensate these losses. Due to its high price it would be too expensive to continue xenon anesthesia during ECC. Therefore it is not practicable to use the today's oxygenators and ECC equipment in xenon anesthesia.
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J Clin Monit Comput · Apr 2002
Automated evaluation of functional residual capacity by oxygen washout.
Measurement of functional residual capacity (FRC) is of considerable interest for monitoring ventilated patients in ICUs. However, the lack of instruments that can be used in the clinical setting has so far impeded the routine application of this measurement. It was the aim of our study to evaluate the accuracy and the reproducibility of a simplified oxygen washout technique (FRC[O2]). ⋯ The automated oxygen washout technique is a simple method to measure FRC in the ICU patient.
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J Clin Monit Comput · Apr 2002
A prototype device for standardized calibration of pulse oximeters II.
There is no commonly accepted in vivo calibration method for pulse oximeters available up to now. On the basis of a prototype device for the calibration of pulse oximeters which was introduced recently, a second approach based on the same concept was tackled in order to design a reliable method for standardized calibration of pulse oximeters. ⋯ Compared to the first prototype the current version is simpler and less expensive in production. Many of previously existing problems are solved and the applicability to a large variety of pulse oximeters and sensors is given. The novel concept for the calibration of pulse oximeters is a tool for assessing the performance of pulse oximeters.
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J Clin Monit Comput · Apr 2002
Comparative StudyComparison of endotracheal tube and hookwire electrodes for monitoring the vagus nerve.
Monitoring the vagus nerve and the recurrent laryngeal nerve during surgical procedures may reduce the probability of significant nerve injury. As such, a number of methods to monitor these nerves have been devised including placing electrodes directly into the vocal cords or recording from surface electrodes. In direct comparison, monitoring the identical muscles, bipolar hookwire electrodes displayed approximately one order of magnitude greater amplitude, of both spontaneously occurring and evoked electrical activity than double wire endotracheal tube electrodes. The enhanced sensitivity of the hookwire electrodes, despite the technical difficulties with placement, suggests their use when maximum sensitivity is required.
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J Clin Monit Comput · Apr 2002
Performance of a real-time dicrotic notch detection and prediction algorithm in arrhythmic human aortic pressure signals.
A novel algorithm for real-time detection and prediction of the dicrotic notch from aortic pressure waves was evaluated in arrhythmic aortic pressure signals from heart failure patients. A simplified model of the arterial tree was used to calculate real-time aortic flow from aortic pressure. The dicrotic notch was detected at the first negative dip from the calculated flow, prediction of the notch was performed using a percentage of the decreasing flow. ⋯ Prediction of the dicrotic notch was tested at 40%, 20%, and 0% of the decreasing calculated aortic flow. The mean time-delays to the notch were 68 +/- 14 ms, 55 +/- 12 ms, and 43 +/- 8 ms, respectively. Given these small variability, intra-beat prediction of the dicrotic notch may be used for real-time intra-aortic balloon counterpulsation inflation timing.