Journal of clinical monitoring and computing
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J Clin Monit Comput · Aug 2002
Clinical TrialUnconsciousness indication using time-domain parameters extracted from mid-latency auditory evoked potentials.
The mid-latency auditory evoked potential (MLAEP) has been used to indicate depth of anaesthesia, and is usually analysed in time-domain. This work compares three techniques: Wave Deformation Parameters (PDO), Auditory Evoked Potential Index (AEPidx) and an automatic Nb-wave latency estimator (Nb), in the assessment of unconsciousness onset based on EEG under auditory stimulation. ⋯ The results suggest that, at least to indicate unconsciousness, the most reliable effect of the anaesthetic drug on MLAEP would be the amplitude attenuation. Despite the high dependence on noise due to its time-domain basis, the Attenuation-PDO seems to be adequate to assess depth of anaesthesia.
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J Clin Monit Comput · Aug 2002
Temporal patient state characterization using Iterative Order and Noise (ION) estimation: applications to anesthesia patient monitoring.
As more sensors are added to increasingly technology-dependent operating rooms (OR), physicians such as anesthesiologists must sift through an ever-increasing number of patient parameters every few seconds as part of their OR duties. To the extent these many parameters are correlated and redundant, manually monitoring all of them may not be an optimal physician strategy for assessing patient state or predicting future changes to guide their actions. ⋯ This paper illustrates the use of ION to improve significantly the performance of PCA in the efficient representation of patient state and in improving the performance of linear predictors of clinically significant parameters.
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J Clin Monit Comput · Jul 2002
Comparative StudyActivated clotting time systems vary in precision and bias and are not interchangeable when following heparin management protocols during cardiopulmonary bypass.
Our aim was to test the hypothesis that new activated clotting time (ACT) technology, with modifications to instruments and reagents designed to detect earlier clot formation, would be associated with more precise but lower results. A secondary objective was to evaluate the potential impact of any change in ACT measurement on heparin requirements during cardiopulmonary bypass (CPB). ⋯ Our results support the hypothesis that the modified technology (Actalyke) is associated with more precise but lower ACT results. We estimated these lower values would lead to increased heparin dosing during CPB. The impact of this increase on bleeding after cardiac surgery with CPB is controversial and requires further study.
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J Clin Monit Comput · Jul 2002
Subcutaneous microdialysis for metabolic monitoring in abdominal aortic surgery.
Microdialysis, that is the sampling of interstitial fluid via semi-permeable tubes, has been shown to be suitable for detecting ischemic changes e.g. in brain and heart tissue. The purpose of the present study was to investigate the possibility of monitoring with subcutaneous microdialysis peri-operative metabolic sequelac of elective abdominal aortic surgery. In 22 patients microdialysis catheters were inserted subcutaneously in the lower leg as well as the shoulder serving as a reference topographic region. Lactate, pyruvate and glycerol, which indicate ischemia or reperfusion, were measured. We observed severe metabolic changes within the interstitial fluid of the lower extremity during ischemia followed by normalization during reperfusion. Despite high interstitial concentrations of lactate and glycerol indicating severe ischemia during clamping of the abdominal aorta these parameters returned to pre-operative values within 2 hrs after declamping and all patients recovered completely. ⋯ Subcutaneous microdialysis was able to detect metabolic changes due to ischemia during clamping of the abdominal aorta as well as reperfusion there after. It is a suitable technique to monitor the peri-operative course of the dependent tissue after abdominal aortic vascular surgery.
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J Clin Monit Comput · Jul 2002
Bispectral Index in ICU: correlation with Ramsay Score on assessment of sedation level.
The assessment of sedation level in critically ill patient remains a challenge for the intensivists in order to avoid over- or under-sedation phenomena. Scoring systems commonly used still show some limitation; the introduction of Bispectral Index (an EEG parameter) could bring potential advantages in monitoring sedation. According to the reports, Bispectral Index correlates with levels of sedation on the Ramsay Scale. We report our personal experience in this topic. ⋯ The results of the study are consistent with those found in the literature on this topic of study. In fact, this study demonstrates the utility of BIS to track levels of consciousness in ICU patients while still maintaining the use of the score systems to care for ICU patients.