Journal of clinical monitoring and computing
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J Clin Monit Comput · Aug 2004
The pulse in reflectance pulse oximetry: modeling and experimental studies.
Reflectance pulse oximetry permits the use of alternative monitoring sites such as the face or torso, and is the approach commonly employed in fetal pulse oximetry systems. The purpose of this study is to investigate the impact of assumptions about the nature of arterial pulsatility on the calibration of such systems. ⋯ The sensitivity of reflectance pulse oximetry calibration to the depth and magnitude of arterial pulsatility reinforces the observation that monitoring site selection is of importance in optimizing reflectance pulse oximetry performance, particularly fetal pulse oximetry. Sites with palpable pulsatility should be avoided.
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J Clin Monit Comput · Aug 2004
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of isoflurane and propofol on intraoperative neurophysiological monitoring during spinal surgery.
To compare the effects of isoflurane and propofol on intraoperative neurophysiological monitoring (IONM) during spinal surgery. ⋯ Isoflurane inhibited IONM more than propofol. Propofol is recommended for critical spinal surgery, particularly when motor pathway function is monitored.
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J Clin Monit Comput · Aug 2004
Weaning from long-term mechanical ventilation: a nonpulmonary weaning index.
Despite the extensive investigations in the area of weaning, clinicians are still struggling with the question of when to begin the process of weaning. Clinical weaning indices designed to predict the weaning potential are most frequently based on pulmonary factors. However, many physiological, respiratory, and mechanical factors also have impact on weaning, but are often overlooked. We suggest a new "nonpulmonary weaning index" (NPWI), which assesses the influence of factors such as blood albumin and total blood protein on the weaning success. ⋯ The results of this study suggest that in the decision whether to attempt weaning from long-term mechanical ventilation, more attention should be paid to the nonpulmonary factors.
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J Clin Monit Comput · Aug 2004
Clinical TrialThe correlation of the bispectral index with propofol effect site concentrations is not altered by epochs indicated as artefact-loaded by narcotrend.
Artefact detection is an essential feature of automatic EEG monitoring systems used in anaesthesia. Clinical experience indicates that Narcotrend monitoring (MonitorTechnik, Bad Bramstedt, Germany, version 4.0) excludes more EEG epochs because of artefacts than bispectral index monitoring (BIS, Aspect Medical Systems, Newton, MA, version XP). Whether this increased exclusion of epochs is justified has not been investigated yet. ⋯ Exclusion of data pairs that were detected as artefacts by Narcotrend but not by BIS did not change the performance of bispectral index as an indicator of propofol effect site concentration.
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J Clin Monit Comput · Aug 2004
Clinical TrialCorrelation of Narcotrend Index, entropy measures, and spectral parameters with calculated propofol effect-site concentrations during induction of propofol-remifentanil anaesthesia.
The aim of this study was to compare the EEG parameter Narcotrend Index with the spectral and entropy-based EEG parameters median frequency, 95% spectral edge frequency, burst-compensated 95% spectral edge frequency, spectral entropy, amplitude entropy, and approximate entropy with regard to their ability to describe cerebral anaesthetic drug effects during induction of propofol-remifentanil anaesthesia. ⋯ In all groups Narcotrend Index showed the highest correlation with the propofol effect-site concentration and the lowest variability of individual correlation values. Furthermore, only the Narcotrend Index showed a monophasic behaviour over the entire time period analysed. In the group of entropy parameters approximate entropy yielded the best results. Among the spectral parameters the burst-compensated 95% spectral edge frequency had the highest correlation with the propofol effect-site concentration. It was markedly higher than for the standard spectral edge frequency. The correlations of median frequency and amplitude entropy with propofol effect-site concentration were the lowest. CONCLUSIONS. Changes in the propofol effect-site concentration during induction of anaesthesia were best described by the multivariate Narcotrend Index compared to conventional spectral EEG parameters and different entropy measures.