Abstract:

There are several medical devices used for patient care in Intensive Care Unit (ICU). These devices include Ventilator System, Patient Monitoring System, Arterial Blood Gas (ABG) Machine, Syringe Pump, Mobile X-ray Machine and others. The onscreen User Interface (UI) of these devices helps medical users to input parameter values and control diversified system parameters during patient care. There are various commonly observed usability problems with medical user interfaces such as poor legibility, right-handed design, poorly distinguished alarms or alerts, poor feedback about device behavior and other problems. These usability problems may contribute to medical errors, causing injuries or death of patients. Therefore, the usability evaluation of medical devices and related user interfaces is extremely important for designing medical user interfaces and improving patient safety. The study of usability evaluation tools such as evaluation models and checklists in medical and other critical domains has revealed that there is a need of domain-specific usability evaluation tool for effective usability evaluation of medical user interfaces, focusing on medical context; especially critical aspects in an ICU. Most of the evaluation tools such as models and checklists in critical domains are error-oriented models supporting identification and categorization of usability problems providing remedial measures.

The usability evaluation tools for evaluation of medical user interfaces are employed for identification and categorization of usability problems. The proposed usability evaluation tools include UI Component Model, Usability Reckoner and Usability Checklist. The identified usability problems are categorized as catastrophic, critical and serious problems. The UI components in medical user interfaces are of two types – Physical and Onscreen components. These categorizations are a vital consideration in design of proposed usability evaluation tools. The design of UI Component Model is based on selected reference model by Winter et al. It is designed for expert evaluators such as device designers and usability professionals. First, this model is proposed for Ventilator System and then extended for other two devices - patient monitoring system and ABG machine. This model is also generalized with due consideration to these three medical devices. A Usability Reckoner is a concise reference table or book to facilitate the evaluation of medical user interfaces. It is simplified usability evaluation tool designed for medical users such as physicians, nurses and hospital administrators. Once usability problems are identified by using a model or reckoner, a usability checklist helps the evaluators to analyze the problem in details and initiate a corrective action, if possible.

A usability checklist is designed for a detailed analysis of identified usability problems and also, for a detection of extent of usability problems. This checklist has more than 50 checklist items or points with weightages provided. It can be used by experts as well as medical users. All the components of usability evaluation tools are dynamic, editable and extensible. One can modify UI components, usability problems or checklist items due to changes in medical technology or domain, if required. The proposed usability evaluation tools are validated by expert evaluators including representatives of vendors, usability professionals as well as physicians using latest medical user interfaces of ventilator system and other devices. This evaluation has three stages viz. evaluation using preferred Usability Evaluation Method (UEM), evaluation using prepared problem list and evaluation using proposed Usability Evaluation Tools involving UI Component Model, Usability
Reckoner and Usability Checklist. These usability evaluation tools are able to identify more number of usability problems. The UI Component Model identifies more number of critical problems compared to usability reckoner. The identified usability problems mainly consist of several critical problems such as preferred measuring units, long-distance visibility, absence of onscreen help and high execution time.

In future, usability evaluation tools can be extended to other medical devices in ICU such as electrocardiogram (ECG) machine, syringe pump and defibrillator. These evaluation tools can be generalized even further to accommodate more medical devices. Such tools can also be designed for other working environments such as Operating Theatres, Ambulances, Hospitals and Patient Homes in medical domain.