Journal of clinical monitoring and computing
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J Clin Monit Comput · Jan 1998
Clinical evaluation of tracheal pressure estimation from the endotracheal tube cuff pressure.
Air flow through an endotracheal tube causes a pressure drop across the tube. This pressure drop creates a difference between air pressure measured in the trachea and the pressure measured in the breathing circuit, which can lead to errors when calculating pulmonary mechanics and when setting ventilators. We have developed a method of estimating tracheal pressure from the pressure in the endotracheal tube cuff and tested this system in clinical trials. ⋯ The flow-based tracheal pressure estimates were accurate during intermittent spontaneous breathing, but not during spontaneous breathing or with a poorly inflated cuff. The estimates were more immune to noise than the cuff-based estimates of tracheal pressure. The estimates of tracheal pressure measured from the ETT cuff should be accurate enough for clinical use in the operating room.
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A model can be defined as an abstraction of reality which accounts for those properties ofa phenomenon that are pertinent to the purpose of the model. Models are used in anesthesia to understand the various physiologic, pharmacological and physical processes that occur during anesthesia. Indeed, many different types of models that comply with our definition can be distinguished. ⋯ Physical models of drug uptake and distribution have been developed to explain the kinetics of volatile anesthetics in the body. The goal of this paper is to introduce the reader to some of the types of models that been used to facilitate education and research in anesthesia. These examples will elucidate the steps involved in developing a model and the various types of models that have proven useful.
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J Clin Monit Comput · Jan 1998
Comparative StudyThe application of a modified proportional-derivative control algorithm to arterial pressure alarms in anesthesiology.
We have developed an arterial pressure alarm system based on a modified proportional-derivative (PD) controller algorithm, and prospectively tested its ability to predict significant hypotensive episodes, defined as systolic arterial pressure < 80 mmHg, in comparison to conventional limit alarms. ⋯ An arterial pressure alarm system design based on a closed loop control algorithm offered improved perform ance over conventional limit alarms and in addition provided a graded output of severity of the hypotension.
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J Clin Monit Comput · Jan 1998
Comparative StudyNew equipment for neuromuscular transmission monitoring: a comparison of the TOF-Guard with the Myograph 2000.
The present study is to clarify whether the bias and limits of agreement of the TOF-Guard and the mechanomyograph differ from those of two mechanomyographs on contra lateral arms. Previous studies of the bias and limits of agreement between acceleromyographical (TOF-Guard) and mechanomyographical measurements of neuromuscular transmission did not take the error introduced by using contra lateral arms into consideration. ⋯ Due to wide limits of agreement and different recovery courses, acccleromyographic and mechanomyographic recordings of neuromuscular transmission cannot be used interchangeably. The substantial variation between simultaneous mechanomyographical recordings of neuromuscular transmission obtained in contra lateral arms suggests that this factor should be taken into account when studying new neuromuscular monitoring techniques using the two-arm technique.