Journal of clinical monitoring and computing
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J Clin Monit Comput · Jun 2010
Relations between respiratory changes in R-wave amplitude and arterial pulse pressure in mechanically ventilated patients.
R-wave obtained from the electrocardiogram depends on ventricular stroke volume. We assessed the relationship between respiratory variations in R-wave (DeltaRDII) and in pulse pressure (DeltaPP) during general anesthesia. ⋯ DeltaRDII and DeltaPP are related in this setting.
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J Clin Monit Comput · Jun 2010
The standard strong ion difference, standard total titratable base, and their relationship to the Boston compensation rules and the Van Slyke equation for extracellular fluid.
A general formalism for calculating physiological acid-base balance in multiple compartments is extended to the combined interstitial, plasma, and erythrocyte multicompartment system in humans using the Siggaard-Andersen approximation for interstitial fluid. The resulting equations for total titratable base and strong ion difference reproduce the experimental in vivo carbon dioxide titration curve as well as the experimental strong ion difference value of the interstitial, plasma, and erythrocyte system in normal man. The "Boston rules" for compensation in acute respiratory acidosis and alkalosis are then derived analytically from the model. The Van Slyke equation for the interstitial, plasma, and erythrocyte system is also derived and shown to approximate the Van Slyke equation for standard base excess.
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Numerous possibilities exist which may cause obstruction to ventilation under anesthesia resulting in a tight reservoir bag with low compliance. We report an interesting case where a reservoir bag twisted around its own neck and resulted in a tight bag situation. ⋯ We caution all anesthesiologists using the disposable modified Jackson-Rees breathing system to be aware of such an eventuality. We also urge the manufacturer to consider strengthening the neck of the reservoir bag by improving the quality of the material used for its construction.
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J Clin Monit Comput · Apr 2010
Comparative StudyTransthoracic electrical bioimpedence cardiac output: comparison with multigated equillibrium radionuclide cardiography.
Thoracic electrical bioimpedance (TEB) for measuring cardiac output (CO) is being explored increasingly as an alternative to pulmonary artery catheter. The major advantage of this technology is that it is non-invasive and easy to perform. Several studies have compared it to thermodilution cardiac output using PA catheter, with variable correlation. Multigated radionuclide equilibrium cardiography (RNEC) method of cardiac output measurement is known to be reliable. ⋯ This study observed a moderate correlation between TEB and RNEC methods of CO measurement. Further studies are indicated to explore the relative utility of TEB in comparison with RNEC as well as other methods of CO measurement before considering its use in patients with ischemic heart disease.
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J Clin Monit Comput · Apr 2010
Validation of arterial blood pressures observed from the patient monitor; a tool for prehospital research.
For some time, the inaccuracies of non-invasive blood pressure measurement in critically ill patients have been recognised. Measurement difficulties can occur even in optimal conditions, but in prehospital transportation vehicles, problems are exacerbated. Intra-arterial pressures must be used as the reference against which to compare the performance of non-invasive methods in the critically ill patient population. Intra-arterial manometer data observed from the patient monitor has frequently been used as the reference against which to assess the accuracy of noninvasive devices in the emergency setting. To test this method's validity, this study aimed to determine whether numerical monitor pressures can be considered interchangeable with independently sampled intra-arterial pressures. ⋯ Integrated mean arterial pressures observed from a well maintained patient monitor can be considered interchangeable with independently sampled intra-arterial pressures and may be confidently used as the reference against which to test the accuracy of non-invasive blood pressure measuring methods in the prehospital or emergency setting.