Journal of clinical monitoring and computing
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J Clin Monit Comput · Feb 2002
Time-variant investigation of quadratic phase couplings caused by amplitude modulation in electroencephalic burst-suppression patterns.
Several studies suggest that parameters derived from bispectral analysis of the EEG can be used to characterize specific cortical activation states represented by non linear interaction between brain electrical oscillations. For example, it was shown that so-called bispectral indices can be used to assess the depth of sedation. The methods applied so far are based on interval-related procedures of bispectral analysis. Consequently, the use of the resulting parameters for on-line monitoring or investigations of signal properties during transition periods, e.g., when entering burst-suppression periods, is restricted. The objective of this paper is to provide the methodological basis for a time-continuous (on-line) investigation of quadratic phase coupling induced by amplitude modulation. ⋯ It was found that these periods are associated with increasing DAM compared with the baseline conditions.
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J Clin Monit Comput · Feb 2002
New possibilities in prognostication of hemodynamic instability during surgical operations.
The new approach to intraoperative hemodynamics disorders prognostication which caused of inadequate anaesthesiological protection is presented in this research. Hemodynamic parameters stability both with systemic homeokinesis state were investigated in 28 patients with various surgical diseases. ⋯ Instability of homeostatic regulation was controlled with special original analysis of cardiac rhythm entropy dynamics chaotisity in multidimensional faze space of existence. It is established that numerical criterion of cardiac rhythm chaotic state degree exceeds the intended acceptable level 5-10 minutes before clinical signs of hemodynamics instability developing in all inadequate anaesthesiological protection cases.
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J Clin Monit Comput · Feb 2002
Arguing for the need of triangulation and iteration when designing medical equipment.
There is a need to develop adequate methods for use by the manufacturers of medical equipment when specifying requirements for their development and in order for hospitals to critically assess their usability qualities before purchase. A Human Factors approach was used to determine requirements for the redesign of an existing volumetric infusion pump. With these requirements as a starting point, a new user interface for an infusion pump was designed. Usability tests were carried out to verify whether the new interface had better usability than the existing interface or whether further improvements were needed. This paper has two aims: 1) to compare the nature of the requirements derived from a Human Factors approach and from usability tests and 2) to evaluate the use of usability tests on existing medical equipment as a basis for redesign and for evaluating the redesign. ⋯ The requirements derived from the Human Factors approach and the usability tests are important for the development of a new and improved user interface. The requirements derived from the Human Factors approach can be attributed to contextual requirements. The requirements derived from the usability tests have a higher degree of concreteness, are more specific and focus more on design solutions compared to the requirements derived from the Human Factors approach. It is important to consider intended user groups when carrying out usability tests, as the nature of the information from the different groups can be different.
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J Clin Monit Comput · Feb 2002
Comparative StudyA comparison of two impedance cardiographs using head-up tilting and trend analysis.
To compare the performances of two impedance cardiographs, the RheoCardioMonitor (RCM) and the BoMed NCCOM3, using trend analysis. This involved a series of head-up tilts, a simulation of the stroke volume (SV) and cardiac output (CO) response, calculation of prediction errors and cumulative sums (Cusum). ⋯ Simulation of a physiological response, such as that to head-up tilting, and using a trend analysis based on prediction errors and Cusum, is a useful technique. The trending abilities of the RCM and BoMed were similar.
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J Clin Monit Comput · Feb 2002
Enamel nail polish does not interfere with pulse oximetry among normoxic volunteers.
To determine if enamel nail polish interferes with pulse oximetry. ⋯ Enamel finger nail polish pigments do not interfere with pulse oximetry as previously reported, the A660-A940 difference must be greater than 1.88 +/- 0.23 SD AU in order to affect pulse oximetry.