Journal of clinical monitoring and computing
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J Clin Monit Comput · Feb 2002
A computerized method to measure systolic pressure variation (SPV) in mechanically ventilated patients.
Intrathoracic pressure variation during mechanical ventilation has different effects on cardiac preload and stroke volume in both ventricles. Changes in left ventricle stroke volume are reflected by fluctuations of the arterial pressure waveform or Systolic Pressure Variation (SPV). SPV has been proposed as a way to evaluate vascular volume status in mechanically ventilated patients as well as responsiveness of the left ventricle stroke volume to volume loading. ⋯ The automated SPV measurement requires less time as well as human errors compared to the manual method; this makes SPV calculation a competitive alternative to methods for the measurements of stroke volume variations as arterial thermodilution technique and transesophageal echocardiography, which require sophisticated equipment and specific experience.
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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.
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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 StudyComparative provocation test of respiratory monitoring methods.
The aim of this study was to compare clinically relevant performance of: 1) a prototype respiratory sensor based on capnometry with two alternative signal receptor fixations, 2) a fiberoptic humidity sensor and 3) human visual observation. Comparative provocation tests were performed on volunteers at the Post-Anesthesia Care Unit at Västerås Central Hospital. ⋯ The capnometry and fiberoptic sensors exhibit differences in responses that may be understood from basic principles. The importance of the physical application of the sensor to the patient was clearly observed. The optimum design remains to be found.
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J Clin Monit Comput · Feb 2002
Automatic analysis and monitoring of burst suppression in anesthesia.
We studied the spectral characteristics of the EEG burst suppression patterns (BSP) of two intravenous anesthetics, propofol and thiopental. Based on the obtained results, we developed a method for automatic segmentation, classification and compact presentation of burst suppression patterns. ⋯ Our results show that burst suppression caused by the different anesthetics can be reliably detected with our segmentation and classification methods. The analysis of normal and pathological EEG, however, should include information of the anesthetic used. Knowledge of the normal variation of the EEG is necessary in order to detect the abnormal BSP of, for instance, seizure patients.