Biomedical subjects

Todd R Johnson

Publications and source records attributed to Todd R Johnson.

16 recordsLinked to original sources

PubMed2006

Operating manual-based usability evaluation of medical devices: an effective patient safety screening method.

BACKGROUND: Use of medical devices often directly contributes to medical errors. Because it is difficult or impossible to change the design of existing devices, the best opportunity for improving medical device safety is during the purchasing process. However, most hospital personnel are not familiar with the usability evaluation methods designed to identify aspects of a user interface that do not support intuitive and safe use. A review of medical device operating manuals is proposed as a more practical method of usability evaluation. METHOD: Operating manuals for five volumetric infusion pumps from three manufacturers were selected for this study (January-April 2003). Each manual's safety message content was evaluated to determine whether the message indicated a device design characteristic that violated known usability principles (heuristics) or indicated a violation of an affordance of the device. RESULTS: "Minimize memory load," with 65 violations, was the heuristic violated most frequently across pumps. Variations between pumps, including the frequency and severity of violations for each, were noted. DISCUSSION: Results suggest that manual review can provide a proxy for heuristic evaluation of the actual medical device. This method, intended to be a component of prepurchasing evaluation, can complement more formal usability evaluation methods and be used to select a subset of devices for more extensive and formal testing.

Equipment and Supplies↗

PubMed2006

Applying heuristic evaluation to improve the usability of a telemedicine system.

The development of a telemedicine system should not only take advantage of technological advances but also pay close attention to users and the human issues involved. In this paper we examine the utility of heuristic evaluation in improving the usability of a digital emergency medical services (EMS) system equipped on an ambulance. The digital EMS system used advanced communication technologies to help remotely located trauma specialists gain access to patient data in real-time and direct life-saving measures in a timely fashion. To improve its usability, three experts inspected prototypes of the system according to 14 software usability heuristics. The analyses revealed information on the prevalence, severity, and nature of heuristic violations in the user interface design. The results were subsequently utilized to guide the iterative software design process. A comparison between two consecutive prototypes showed that the second design had only half as many usability violations as the first prototype and had considerable improvement in a number of usability heuristic categories. The validity of heuristic evaluation was examined in an ethnographic study of paramedics using a prototype of the system in their work environment. Users' task performances partially verified heuristic evaluation results. However, they also revealed problems that were not identified in heuristic evaluation but only became prominent during field observation. In conclusion, we argue that usability should be given high priority in the development of a telemedicine system, and that heuristic evaluation can be an effective and efficient way to identify usability problems in the early stage of software development.

Ambulances↗

PubMed2005

A user-centered framework for redesigning health care interfaces.

Numerous health care systems are designed without consideration of user-centered design guidelines. Consequently, systems are created ad hoc, users are dissatisfied and often systems are abandoned. This is not only a waste of human resources, but economic resources as well. In order to salvage such systems, we have combined different methods from the area of computer science, cognitive science, psychology, and human-computer interaction to formulate a framework for guiding the redesign process. The paper provides a review of the different methods involved in this process and presents a life cycle of our redesign approach. Following the description of the methods, we present a case study, which shows a successfully applied example of the use of this framework. A comparison between the original and redesigned interfaces showed improvements in system usefulness, information quality, and interface quality.

Artificial Intelligence↗

PubMed2005

Object location memory: the interplay of multiple representations.

This article reports three experiments in which the representational nature of human object location memory was studied. The results show that multiple frames of reference can be used to encode the spatial relationships among objects. Depending on their dominancy, availability, and validity, these multiple representations interact to determine memory performance. Specifically, representations that are automatically encoded and extensively practiced are more dominant, and their availability improves performance when they are valid. On the other hand, when the dominant representations are available but invalid, people may have to resort to the less dominant representations. As a result, the availability of these dominant but invalid representations can actually hurt performance, due to interference. If these interfering representations are eliminated, the performance is again improved. The implications of these findings for general human spatial cognition are discussed.

Adult↗

PubMed2005

Interruptions in workflow for RNs in a Level One Trauma Center.

An understanding of interruptions in healthcare is important for the design, implementation, and evaluation of health information systems and for the management of clinical workflow and medical errors. The purpose of this study is to identify and classify the types of interruptions experienced by ED nurses working in a Level One Trauma Center. This was an observational field study of Registered Nurses employed in a Level One Trauma Center using the shadowing method. Results of the study indicate that nurses were both recipients and initiators of interruptions. Telephone, pagers, and face-to-face conversations were the most common sources of interruptions. Unlike other industries, the outcomes caused by interruptions resulting in medical errors, decreased efficiency and increased cost have not been systematically studied in healthcare. Our study presented here is an initial step to understand the nature, causes, and effects of interruptions, and to develop interventions to manage interruptions to improve healthcare quality and patient safety. We developed an ethnographic data collection technique and a data coding method for the capturing and analysis of interruptions. The interruption data we collected are systematic, comprehensive, and close to exhaustive. They confirmed the findings from early studies by other researchers that interruptions are frequent events in critical care and other healthcare settings. We are currently using these data to analyze the workflow dynamics of ED clinicians, identify the bottlenecks of information flow, and develop interventions to improve the efficiency of emergency care through the management of interruptions.

Communication↗

PubMed2004

Decisions about critical events in device-related scenarios as a function of expertise.

This paper presents the perspectives of personnel involved in decision-making about devices in critical care. We use the concept of "sharp and blunt ends" of practice to describe the performance of health care professionals. The "sharp end" is physically and temporally close to the system; the "blunt end" is removed from the system in time and space and yet affects the system through indirect influence on the sharp end. In this study, the sharp end is represented by the clinicians (nurses and doctors) and the blunt end by the administrators and biomedical engineers. These subjects represent the professionals involved in the decision-making process for purchasing biomedical equipment for the hospital. They were asked to "think aloud" while evaluating three error scenarios based on real events. The responses were recorded and transcribed for analysis. The results show differences in interpretation of critical events as a function of professional expertise. The clinicians (sharp-end practitioners) focused on clinical and human aspect of errors while the biomedical engineers focused on device-related errors. The administrators focused on documentation and training. These different interpretations mean that the problems are represented differently by these groups of subjects, and these representations result in variable decisions about devices. These results are discussed within a systems approach framework to help us assess the completeness of the problem representations of the subjects, their awareness of critical events, and how these events would collectively contribute to the occurrence of error.

Decision Making↗

PubMed2004

Assessing informatics students' satisfaction with a web-based courseware system.

This study assessed health informatics student satisfaction with two subsequent versions of Prometheus, a web-based courseware system. Prometheus versions 4 and 5 were assessed to gauge the effect of modifications to improve the usability of the system. The Questionnaire for User Interaction Satisfaction (QUIS, version 7.0) was administered at the end of fall semester 2001 (in which Prometheus version 4 was used) and again at the end of Spring 2002 (in which Prometheus version 5 was used). QUIS contains measures of user satisfaction of the overall system and 11 specific dimensions, including screen, terminology and system information, learning, system capabilities, manuals and online help, multimedia, and teleconferencing. In general, students had favorable judgments of Prometheus, and their satisfaction level remained relatively stable across the two versions. However, usability enhancements incorporated into version 5 produced no significant differences in student satisfaction ratings. The results of this study provide a benchmark for comparing the relative usability of alternative courseware systems and demonstrate the utility of user satisfaction surveys for assessing and improving courseware systems. With increases in the need for compliance education and the education of clinicians with 'just in time knowledge', courseware systems will become an integral part of the clinical information systems, increasing the importance of usability studies such as this one.

Adult↗

PubMed2004

Heuristic evaluation of infusion pumps: implications for patient safety in Intensive Care Units.

OBJECTIVE: The goal of this research was to use a heuristic evaluation methodology to uncover design and interface deficiencies of infusion pumps that are currently in use in Intensive Care Units (ICUs). Because these infusion systems cannot be readily replaced due to lease agreements and large-scale institutional purchasing procedures, we argue that it is essential to systematically identify the existing usability problems so that the possible causes of errors can be better understood, passed on to the end-users (e.g., critical care nurses), and used to make policy recommendations. DESIGN: Four raters conducted the heuristic evaluation of the three-channel infusion pump interface. Three raters had a cognitive science background as well as experience with the heuristic evaluation methodology. The fourth rater was a veteran critical care nurse who had extensive experience operating the pumps. The usability experts and the domain expert independently evaluated the user interface and physical design of the infusion pump and generated a list of heuristic violations based upon a set of 14 heuristics developed in previous research. The lists were compiled and then rated on the severity of the violation. RESULTS: From 14 usability heuristics considered in this evaluation of the Infusion Pump, there were 231 violations. Two heuristics, "Consistency" and "Language", were found to have the most violations. The one with fewest violations was "Document". While some heuristic evaluation categories had more violations than others, the most severe ones were not confined to one type. The Primary interface location (e.g., where loading the pump, changing doses, and confirming drug settings takes place) had the most occurrences of heuristic violations. CONCLUSION: We believe that the Heuristic Evaluation methodology provides a simple and cost-effective approach to discovering medical device deficiencies that affect a patient's general well being. While this methodology provides information for the infusion pump designs of the future, it also identifies important insights concerning equipment that is currently in use in critical care environments.

Humans↗

PubMed2004

A cognitive taxonomy of medical errors.

OBJECTIVE: Propose a cognitive taxonomy of medical errors at the level of individuals and their interactions with technology. DESIGN: Use cognitive theories of human error and human action to develop the theoretical foundations of the taxonomy, develop the structure of the taxonomy, populate the taxonomy with examples of medical error cases, identify cognitive mechanisms for each category of medical error under the taxonomy, and apply the taxonomy to practical problems. MEASUREMENTS: Four criteria were used to evaluate the cognitive taxonomy. The taxonomy should be able (1) to categorize major types of errors at the individual level along cognitive dimensions, (2) to associate each type of error with a specific underlying cognitive mechanism, (3) to describe how and explain why a specific error occurs, and (4) to generate intervention strategies for each type of error. RESULTS: The proposed cognitive taxonomy largely satisfies the four criteria at a theoretical and conceptual level. CONCLUSION: Theoretically, the proposed cognitive taxonomy provides a method to systematically categorize medical errors at the individual level along cognitive dimensions, leads to a better understanding of the underlying cognitive mechanisms of medical errors, and provides a framework that can guide future studies on medical errors. Practically, it provides guidelines for the development of cognitive interventions to decrease medical errors and foundation for the development of medical error reporting system that not only categorizes errors but also identifies problems and helps to generate solutions. To validate this model empirically, we will next be performing systematic experimental studies.

Cognition↗

PubMed2004

Institutional decision-making for medical device purchasing: evaluating patient safety.

Many medical devices that are currently on the market are sub-optimal for human use, thus contributing to medical errors. This places significant responsibility for device selection on purchasers. This paper describes a retrospective analysis of decision making processes for infusion pump selection in three large hospitals and focuses on patient safety. Through a series of detailed interviews and a study of relevant documentation we characterized the nature of the decision-making, patterns of communication, and the roles of different participants. Findings suggest that success of the process is related to effective communication among participants with different expertise and adequate device usability assessment during the process. The paper discusses how information technology could provide support to distributed institutional decision making.

Communication↗

PubMed2003

An extended hierarchical task analysis for error prediction in medical devices.

This paper introduces an extended hierarchical task analysis (HTA) methodology devised to evaluate and compare user interfaces on volumetric infusion pumps. The pumps were studied along the dimensions of overall usability and propensity for generating human error. With HTA as our framework, we analyzed six pumps on a variety of common tasks using Norman's Action theory. The introduced method of evaluation divides the problem space between the external world of the device interface and the user's internal cognitive world, allowing for predictions of potential user errors at the human-device level. In this paper, one detailed analysis is provided as an example, comparing two different pumps on two separate tasks. The results demonstrate the inherent variation, often the cause of usage errors, found with infusion pumps being used in hospitals today. The reported methodology is a useful tool for evaluating human performance and predicting potential user errors with infusion pumps and other simple medical devices.

Ergonomics↗

PubMed2002

Evaluating a medical error taxonomy.

Healthcare has been slow in using human factors principles to reduce medical errors. The Center for Devices and Radiological Health (CDRH) recognizes that a lack of attention to human factors during product development may lead to errors that have the potential for patient injury, or even death. In response to the need for reducing medication errors, the National Coordinating Council for Medication Errors Reporting and Prevention (NCC MERP) released the NCC MERP taxonomy that provides a standard language for reporting medication errors. This project maps the NCC MERP taxonomy of medication error to MedWatch medical errors involving infusion pumps. Of particular interest are human factors associated with medical device errors. The NCC MERP taxonomy of medication errors is limited in mapping information from MEDWATCH because of the focus on the medical device and the format of reporting.

Classification↗

PubMed2002

Toward a cognitive taxonomy of medical errors.

One critical step in addressing and resolving the problems associated with human errors is the development of a cognitive taxonomy of such errors. In the case of errors, such a taxonomy may be developed (1) to categorize all types of errors along cognitive dimensions, (2) to associate each type of error with a specific underlying cognitive mechanism, (3) to explain why, and even predict when and where, a specific error will occur, and (4) to generate intervention strategies for each type of error. Based on Reason's (1992) definition of human errors and Norman's (1986) cognitive theory of human action, we have developed a preliminary action-based cognitive taxonomy of errors that largely satisfies these four criteria in the domain of medicine. We discuss initial steps for applying this taxonomy to develop an online medical error reporting system that not only categorizes errors but also identifies problems and generates solutions.

Cognition↗

PubMedDate not supplied

Institutional decision-making to select patient care devices: identifying venues to promote patient safety.

Many medical errors that involve drug infusion devices are related to classic interface problems. Although manufacturers are becoming increasingly aware of human factors design considerations, many devices that are currently on the market are still sub-optimal for human use. This places significant responsibility for device selection on institutional purchasing groups. Theories of naturalistic decision-making point to many potential strengths and pitfalls of group decision-making processes that may affect the final outcome. This paper describes a retrospective analysis of decision-making process for infusion pump selection in a large hospital and focuses on factors related to patient safety. Through a series of detailed interviews and a study of relevant documentation we characterized the nature of the decision-making, patterns of communication, and the roles of different participants. Findings show that although the process involves a number of different professional groups and committees, the information flow among them is restricted. This results in inadequate representation of critical device usability considerations in the decision-making process. While all participants view device safety as an important consideration in the selection process, administrators (who are the final decision-makers) tend to equate safety with technical accuracy and reliability, paying less attention to the role of human factors in safe device use. Findings suggest that collaborative communication technology and automated evidence-based guidelines could provide support to institutional decision-making, ensuring that the process is efficient, effective, and ultimately safe for the patients.

Decision Making, Organizational↗

PubMedDate not supplied

Using usability heuristics to evaluate patient safety of medical devices.

OBJECTIVE: To modify the traditional heuristic evaluation method of assessing software usability so that it can be applied to medical devices and used to evaluate the patient safety of those devices through the identification and assessment of usability problems. DESIGN: Heuristic evaluation, a usability inspection method commonly used for software usability evaluation, was modified and extended for medical devices. The modified method was used to evaluate and compare the patient safety of two 1-channel volumetric infusion pumps. RESULTS: The modified heuristic evaluation method was successfully applied to medical devices. One hundred and ninety-two heuristic violations were categorized for 89 usability problems identified for Pump 1, and 121 heuristic violations were categorized for the 52 usability problems identified for Pump 2. Pump 1 had more usability problems with high severity ratings than Pump 2. In general, Pump 1 was found to have more usability issues that are likely to induce more medical errors. CONCLUSIONS: Heuristic evaluation, when modified for medical devices, is a useful, efficient, and low cost method for evaluating patient safety features of medical devices through the identification of usability problems and their severities.

Algorithms↗

PubMedDate not supplied

Medical error: is the solution medical or cognitive?

Is the solution for medical errors medical or cognitive? In this AMIA2001 panel on medical error, we argued that medical error is primarily an issue for cognitive science and engineering, not for medicine, although the knowledge of the practice of medicine is essential for the research and prevention of medical errors. The three panelists presented studies that demonstrate that cognitive research is the foundation for theories of medical errors and interventions of error reductions.

Cognition↗