Clinicians often work under high-pressure, because of emergency situations, high volume, or speed required.  Their cognitive state is constant flux and while using digital interfaces, their experience and judgement is likely influenced by their mental state.

Experience in aviation using the NASA-TLX (Task Load Index) tool for assessing Human Mental Workload (HMW) can be usefully applied along with Nielsen usability heuristics for evaluating an Electronic Health Records (EHR).

A pilot study was conducted to assess clinicians’ cognitive state and investigate how HMW imposed by the EHR influences its usability.  Two wards demanding different levels of physical/mental stress for staff, both using the same EHR to document patients’ daily progress, were compared.

Ward-1: 18 long-stay elderly patients with high dependency scores;

Ward-2: 10 short-stay elderly patients with low dependency score

Method: Questionnaires incorporating the NASA-TLX model and Neilsen’s design/usability principles were completed by a clinician in each scenario, following each use of the EHR.  The NASA-TLX model measures mental, physical and temporal demands, effort, performance and frustration levels. 

Results:  HMW influences usability for the same EHR interface.  Towards the end of day, clinician performance in using the EHR drastically decreases.  They need to work harder mentally to reach the same level of performance (high HMW).  Pearson correlation for Nielsen/NASA-TLX is significant (Ward-1: r = -0.86;  Ward-2:  r = -0.930).  Increments of HMWs correspond to moderate decrements in usability.  This evidence suggests that an EHR design process should consider more the context of use and the cognitive workload of its clinicians.