Journal of clinical monitoring and computing
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J Clin Monit Comput · Jan 2000
Partial CO2 rebreathing indirect Fick technique for non-invasive measurement of cardiac output.
Evaluation in animals of a non-invasive and continuous cardiac output monitoring system based on partial carbon-dioxide (CO2) rebreathing indirect Fick technique. ⋯ The partial CO2 rebreathing technique for measurement of cardiac output is non-invasive, automated, and based on the well accepted Fick principle. The limits of agreement between NICO and TDco is within the recommended value for NICO to be a clinically acceptable method for cardiac output measurement. The results of this canine study show that NICO performed as well, and in some cases better, than other currently available non-invasive cardiac output techniques over a wide range of cardiac outputs.
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J Clin Monit Comput · Jan 2000
Accuracy of deadspace free ventilatory measurements for lung function testing in ventilated newborns: a simulation study.
A deadspace free method based on simultaneous ventilatory measurements in the inspiratory and expiratory limb of the ventilator circuit was compared to the conventional endotracheal method where the flow is measured between ETT and Y-Piece. The aim of our study was to find out how the arrangement of this setup affects the measuring accuracy of 1) the ventilatory and 2) the lung mechanical parameters by means of a computer simulation. ⋯ The dead space free method can be used for accurate ventilatory measurements during mechanical ventilation. However, for lung mechanic measurements in very low birth weight infants the position of the PNTs must be as short as possible.
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J Clin Monit Comput · Jan 2000
ReviewHRCT imaging of airway responsiveness: effects of anesthetics.
The noninvasive imaging method, high resolution computed tomography (HRCT), has been developed in animal models and applied to humans with obstructive lung disease for assessing regional and individual airway responsiveness. The ability to directly view airway responses during provocations such as tracheal intubation in an asthmatic could greatly enhance our understanding and treatment of airway hyperresponsiveness. HRCT uses increased kilovoltage peak (kVp) and milliamperage (mAs) settings, thin slices, high spacial frequency reconstruction algorithms, and small fields of view to resolve structures as small as 200 microm. ⋯ HRCT allows direct in vivo measurement of airway responsiveness to pharmacological and physiological stress that induces bronchoconstriction or bronchodilation. Using HRCT, we are able to measure airway dilation at baseline airway tone with inhalation anesthetics, differentiate the bronchodilating properties of inhalational agents in airways with tone, assess bronchodilating agents commonly used as premedications prior to anesthesia, and measure airway heterogeneity at baseline tone and their response to a variety of stimuli. This ability of HRCT to measure airway caliber and response heterogeneity in vivo noninvasively will dramatically improve our understanding of pulmonary physiology in general and the effects of anesthetics on the airways specifically.
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J Clin Monit Comput · Jan 2000
Use of an anesthesia information management system (AIMS) to evaluate the physiologic effects of hypnotic agents used to induce anesthesia.
The aim of this study was to utilize an anesthesia information management system (AIMS) in investigating the effects of hypnotic agents used to induce anesthesia on blood pressure, heart rate and arterial oxygen saturation. The characteristics of these agents, known from previous studies, were compared to the effects documented in this study during routine clinical use. ⋯ The effects of the induction hypnotic agents thiopental, etomidate and propofol on blood pressure and heart rate as documented by an AIMS corresponded to those found in clinical studies. An AIMS with the corresponding documentation, software and database structure is suitable for collecting and evaluating data for dinical investigations.
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J Clin Monit Comput · Jan 2000
Bispectral index (BIS) and burst suppression: revealing a part of the BIS algorithm.
The bispectral index (BIS) is a complex EEG parameter which integrates several disparate descriptors of the EEG into a single variable. One of the subparameters incorporated in the BIS is the suppression ratio, quantifying the percentage of suppression during burst suppression pattern. The exact algorithm used to synthetize the information to the BIS value is unpublished and still unknown. This study provides insight into the integration of the suppression ratio into the BIS algorithm. ⋯ Suppression ratio values > 40% are linearly correlated with BIS values from 30 to 0. An increasing anesthetic drug effect resulting in an increase of the duration of suppression to a suppression ratio up to 40% is not adequately reflected by the BIS value.