Medical & biological engineering & computing
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Med Biol Eng Comput · Sep 2004
Comparative StudyStroke volume and systolic time intervals: beat-to-beat comparison between echocardiography and ambulatory impedance cardiography in supine and tilted positions.
The aim of the study was to compare stroke volume (SV), ejection time (ET) and pre-ejection period (PEP) measurements obtained using a central haemodynamics ambulatory monitoring device based on impedance cardiography (ICG), in supine and tilted positions (60 degrees), with pulsed Doppler echocardiography as a non-invasive reference method. The Holter-type ICG device was used for off-line, beat-to-beat, automatic determination of SV, ET and PEP. ⋯ Linear regression between the measured values obtained for all subjects was described by the following formulas: SVicg= 13.9 + 0.813 x SVecho (r = 0.857, SEE = 9.03, n = 496), ETicg = 16.8 + 0.987 x ETecho (r = 0.841, SEE=21.3, n = 496), PEPicg= 22.8 + 0.890 x PEPecho (r = 0.727, SEE = 14.6, n = 496). The data showed that ambulatory impedance cardiography gives useful absolute values of SV and systolic time intervals measured in supine and tilted positions.
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Med Biol Eng Comput · Sep 2004
Reduction of false arterial blood pressure alarms using signal quality assessment and relationships between the electrocardiogram and arterial blood pressure.
The paper presents an algorithm for reducing false alarms related to changes in arterial blood pressure (ABP) in intensive care unit (ICU) monitoring. The algorithm assesses the ABP signal quality, analyses the relationship between the electrocardiogram and ABP using a fuzzy logic approach and post-processes (accepts or rejects) ABP alarms produced by a commercial monitor. ⋯ By rejecting 98.2% (159 of 162) of the false ABP alarms produced by the monitor using the test set of data, the algorithm was able to reduce the false ABP alarm rate from 26.8% to 0.5% of ABP alarms, while accepting 99.8% (441 of 442) of true ABP alarms. The results show that the algorithm is effective and practical, and its use in future patient monitoring systems is feasible.