Anna-Lisa Osvalder | PubMed Health

PubMed2004

Usability evaluation of a GUI prototype for a ventilator machine.

OBJECTIVE: Information presentation on the monitor screen of ventilator machines affects nurses' response and decision-making during ventilation treatment. The purpose of this study is to evaluate whether a new GUI (graphical user interface) prototype, the so-called circular display prototype can make deviations easy to detect. METHOD: A numerical display prototype was made and used as a reference display in the evaluation. Six task scenarios that involved parameter changes were selected to simulate a real situation under volume control (VC) mode during ventilation treatment. Usability tests with the two display designs were carried out in a usability laboratory. Twenty medical nursing students participated as test subjects in the usability tests. RESULTS: The objective results showed that the graphical circular display had an advantage over the numerical display in interpreting parameter changes, but not in reducing the error rates for detecting the number of parameter changes or for forming an overall picture of the patient's situation. Furthermore, the circular display prototype did not improve the detection time. CONCLUSIONS: Although the majority of the test subjects preferred the graphical circular display, the results implied that several aspects of this prototype should be improved in a future development study.

Adult↗

PubMed2002

Arguing for the need of triangulation and iteration when designing medical equipment.

OBJECTIVE: 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. METHOD: The user requirements derived from the Human Factors approach were compared with the user requirements derived from the usability tests. RESULTS: The results show that the requirements derived from the Human Factors approach adequately covered contextual aspects of use. However, to derive requirements for a specific and operational level, usability tests must be conducted on existing equipment and prototypes. This study indicates that usability tests on existing medical equipment as a basis for redesign give a better understanding of problems with existing equipment. Moreover it is important to carry out usability tests to evaluate a redesign and find a satisfying solution. Expert users of the equipment had the experience, competence and confidence to be critical and suggest improvements based on their practical knowledge. The novice users on the other hand were important test users as they uncovered most of the serious handling problems and also committed most errors. CONCLUSION: 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.

Equipment Design↗