Journal of clinical monitoring and computing
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J Clin Monit Comput · Jul 1999
Predicted sevoflurane partial pressure in the brain with an uptake and distribution model comparison with the measured value in internal jugular vein blood.
In order to predict the partial pressure of volatile anesthetics in brain tissue, we developed a pharmacokinetic simulation model suitable for real time application. The accuracy of this model was examined by comparing the predicted values against measured values for blood sampled from the internal jugular vein, which was used as a measure of the partial pressure in the brain. ⋯ We conclude that our model is clinically useful for predicting sevoflurane partial pressure in the brain, assuming that Pj(S) reflects the sevoflurane partial pressure in the brain.
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J Clin Monit Comput · Jul 1999
Evaluation of a new fibre-optical monitor for respiratory rate monitoring.
To present further development of a fibre-optical respiratory rate monitor and evaluate the function in the final version. ⋯ The fibre-optical monitor has sufficient accuracy for clinical monitoring. It is easy to use and inexpensive. Combinations with pulse oximetry seem attractive, to use especially for application outside "high tech areas," for example when respiratory depressant drugs are used or in ambulances.
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The increasing focus on health care costs requires that all physicians evaluate practice behaviors. The primary emphasis in anesthesia has been limiting the use of expensive medications and interventions. Reducing waste is another approach, and volatile anesthetics are an appropriate target in that simple reduction of fresh gas-flow (FGF) rates is effective. A monitor that measures and displays the cost of wasted volatile anesthetic was developed and used to determine if real-time display of the cost would result in decreased FGF rates, which, in turn, would decrease wasted anesthetic. ⋯ Nine residents were initially enrolled, but due to scheduling difficulties only five residents completed the protocol. Data from cases using the WGM demonstrated a 50% decrease (3.58 +/- 1.34 l/min vs. 1.78 +/- 0.51 l/min (p = 0.009)) in the scavenger flow rates, which resulted in a 48% ($5.28 +/- 0.68 vs. $2.72 +/- 0.80 (p = 0.002)) decrease in hourly cost of wasted volatile anesthetic. There was no difference between the Baseline and Visible phases with regard to use of nitrous oxide or intravenous anesthetic agents. CONCLUSIONS. The WGM decreased wasted volatile anesthetic by encouraging decreased FGF rates.
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J Clin Monit Comput · Jul 1999
High fidelity correction of pressure signals from fluid-filled systems by harmonic analysis.
Fluid-filled systems are generally used for invasive pressure measurements in cardiology, anesthesiology and intensive care medicine. Wave reflection and attenuation cause considerable signal distortion. ⋯ High fidelity correction of pressure signals from fluid-filled systems by harmonic analysis is feasible.
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J Clin Monit Comput · Jul 1999
Nonlinear model-based predictive control of non-depolarizing muscle relaxants using neural networks.
Neuromuscular blockade can be relatively easily measured in the clinical setting. Consequently, closed-loop control can be exercised by measuring the neuromuscular activity, calculating the dose of drug necessary to achieve a predefined degree of neuromuscular blockade and finally directing an infusion pump. Recently introduced short-acting blocking agents like mivacurium provide benefits for the clinical routine due to a small onset time and half life. ⋯ In a clinical study the EMG module within a Datex AS/3 monitor was used to measure the blockade and a Grasepy 3500 infusion pump for i.v. administration of mivacurium to 35 patients (ASA I-III). The performance of the novel system (mean of the T1 error: -0.32 +/- 1.7) compares favourably with closed-loop controllers demonstrated in the past. These promising results and the easy adaption to other blocking agents encourage to apply this technology even for delivering hypnotic drugs.