Human Factors in Medical Simulation

Article Author:
Carla Pruden
Article Author:
Gabriel Beecham
Article Editor:
Muhammad Waseem
9/17/2020 3:31:00 PM
PubMed Link:
Human Factors in Medical Simulation


Macroergonomics is the formal study of work systems.[1] As applied to healthcare, the human-task/tool interface represents the "microsystem." Individuals interacting as teams or organizations represent "mesosystems," while more complex sociotechnical interactions create the "macrosystem."  Regardless of which sub-system is under evaluation, the "systems approach" to HFE will always clearly map the interventions to the macrosystem.[2] A central tenet to the discipline of human factors and ergonomics (HFE) is the balance of work-systems to the active and adaptive roles of those who work within them.[3]

Quality improvement initiatives frequently employ training as a means to reach error reduction. This approach is appropriately applicable when developing/testing new techniques, practicing new techniques in a safe/low-risk environment, gaining individual experience with sensorimotor dependent techniques, or improving team processes/interactions, while practicing or testing emergency responses. It is a common misconception, however, that HFE strives to eliminate human error.  The paradigms more accurately align with creating systems that are resilient to unanticipated events by utilizing a thoughtful design process. To this end, the modification of tools and techniques creates more sustainable improvements in safety than behavior modification through training alone.[4]


From a healthcare perspective, the primary goal of HFE becomes the optimization of technology design and care systems to achieve productivity, safety, efficiency, and quality in the care delivery process.[4] Secondarily, the science works to enhance the wellbeing (experience, joy, satisfaction, health, and safety) of anyone (patient, staff, or visitor) who interacts with the system.[5] Healthcare simulation methodologies can be applied to HFE foci (cognitive engineering, heuristics and decision making; communication; perception and performance; safety; training; and usability) to create the synergism necessary to effectively “fit the system to the human.”[1]

Issues of Concern

A recent addition to HFE research methodology is the concept of “human-centered design.  While human factors professionals amass years of expertise, the discipline incorporates multiple investigatory skill sets, and there exists no “standard” set of training criteria.[4] As such, there is minimal literature describing the comprehensive application of “human-centered design” to healthcare system quality and improvement. Ideally, the following six elements are demonstrated: explicit understanding of each system component (users, tasks, and environments); end-user involvement throughout the process; iterative refinement reflecting user-centered evaluation; inclusion of the entire user experience, incorporation of multidisciplinary perspectives.[1] Through the use of mixed-methods research, healthcare simulation can provide a platform on which to evaluate the impact of organizational design/policies/procedures on an individual or team performance and safety through the human-centered design approach.[4]

Curriculum Development

From a "countermeasure" perspective, the avoidance, capture, and mitigation of error represent three patient safety lines of defense.  Simulation is most effective when there is adequate task alignment - the reproduction of required skills allows for the successful completion of the tasks.[6]  With this in mind, one group created a low-cost, low-tech reproduction of psychological fidelity by creating an Escape Room to teach patient safety skills to medical students. This suitcase-sized, portable platform incorporated the clinical tasks of diagnosis, treatment, medication prescription, and calculation of an early warning score. Successful task completion was rewarded with the "codes" necessary to open additional padlocks within the suitcase, thus allowing progression through the simulated scenario.  Students successfully "escaped" the room by avoiding preventable harm to the patient.[7]

From an adverse event perspective, multiple different applications of simulation have been suggested to aid in the investigation and mitigation process, including:

  1. Using the high-fidelity simulation of key activities, like an end-to-end major incident investigation, for emergency investigator training
  2. Bringing relevant participants together from multiple organizations for testing, reversing, and improving coordinated investigation to improve investigative infrastructure
  3. Exploring contributory factors, developing, and testing solutions through the simulated recreation of conditions/events underlying serious safety incidents.
  4. Probing systems vicariously to uncover latent safety issues while applying safety 1 and/or safety 2 principles[8]

Clinical Clerkships

Within healthcare education, human factors skills are often described as either technical or non-technical. Technical skills generally refer to the medical and procedural knowledge necessary for delivering competent patient care.[9] Central line placement and management strategies incorporating HFE principles through simulated training have yielded reductions in the frequency of central line-associated bloodstream infections.[10] Such collaborative efforts between infection prevention/control (IPC), HPE, and in-situ simulation have also been identified as prime foci for preparedness improvement initiatives. Recognizing this, the Alberta Health Services group demonstrated a more global evaluation of the "IPC – system" interface. After initiating practical/virtual workshops, investigators evaluated patient care simulations to target latent safety issues surrounding the use of personal protective equipment. Instead of relying solely on an individuals' process recall, the human limitations and individual differences identified through this process were subsequently incorporated into design modifications (logistically matching the supply cart to the "donning and doffing" guide) to improve the likelihood of safe and appropriate the PPE use.[11]

Medication prescribing is another healthcare delivery skill that is inherently error-prone, regardless of the clinical setting.  To assess the "communication- human information processing" model of HFE of medication prescribing, scenario-based simulations were integrated into a counterbalanced, crossover design study. Researchers assessed usability, perceived workload, and error frequency concerning system alerts triggered during this process.  After combining participant feedback with the efficiency linked to intrusive alerts,  the process was redesigned, and a modestly significant reduction in workload was attained.[12]

The ability to recognize and integrate information regarding life-threatening conditions is paramount in the critical care setting.  Mixed methods studies have highlighted the benefit of utilizing simulation to evaluate clinical pattern recognition and intervention in these circumstances as well.[13] The prospective use of in-situ simulation in the emergency department helped to identify limitations to a telemetry system. Insights gained regarding the physical/human–machine interactions, as well as the organizational/human–organization interactions, elucidated the process improvements necessary to address both telemetry-based detection and appropriate dispositioning of patients with life-threatening arrhythmias.[14] Simulated scenarios delivered in the pediatric ICU allowed researchers to evaluate 20 types of tasks surrounding the institution of multimodal monitoring. In addition to providing insight into participant thought processes, the "think aloud" simulation method allowed investigators to provide insight for participants regarding the information available on the platform.  This highlights the dichotomous ability of technology to either support or hinders technical tasks, as well as the utility of simulation methodology to support the HFE evaluation process.[13] 

Recently, the following consensus definition of non-technical skills was published: "A set of social (communication and teamwork) and cognitive (analytical and personal behavior) skills that support high-quality, safe, effective, and efficient inter-professional care within the complex healthcare system."[15] Such non-technical skills have also been addressed in the HFE and simulation literature. After completing simulation-based, inter-professional training sessions within the Training In Non-technical Skills to Enhance Levels of Medicines Safety (TINSELS) program, study participants attended focus groups to capture the "richness of the human experience" and explore the concepts of non-technical skill acquisition and "safety" development.  For effective intergroup communication to develop, "intergroup anxiety" needed to be managed – a task not adequately addressed within homogenous professional groups.  This goal was accomplished through the development of cooperative goal structure, institutional/normative support for these interactions, and the complexity of "scripts."  Researchers highlight the simulated environment as a means to support the pedagogical approach of "exposure-based" inter-professional team training.[16]

Assessment of Procedural Skills

From an educational perspective, transfer-appropriate processing occurs when the cues available during information encoding/memorization are the same as those expected to be available at the time of memory recall. This approach requires a priori team task analysis to determine appropriate fidelity for task alignment for the taskwork skills related to individual performance, and the teamwork skills (cognitive, behavioral, and attitudinal) representing the performance of the team as a whole.[6] For an assessment tool to be useful, its application to the taskwork or teamwork skills must be valid, reliable, sensitive, and feasible. Multiple studies have focused on developing, evaluating, and refining assessment tools for teaching human factors in different environments. A selection of these tools will be reviewed below.

In the peri-surgical arena, the Oxford Non-technical skills (NOTECHS), which have both been used to assess team and behavior skills, and subsequently adapted for use in other environments.[17] For assessment of non-technical skills in trauma teams, the T-NOTECHS was developed.  Score improvement was noted in both simulated and actual trauma resuscitations after team training sessions. These higher scores were correlated with better performance in both simulated and actual team resuscitations, as evidenced by higher task completion rates and faster time to completion.  Notably, there was a higher intraclass correlation for video review situations than real-time assessments of either simulated and actual resuscitations (0.71 vs. 0.44 to 04.8, respectively).[18] This tool has subsequently been translated and validated with use in international multi-professional trauma simulations.[19]

In the surgical environment, the observational teamwork assessment for surgery (OTAS) was used for the evaluation of non-technical skills. This was subsequently adapted to the medical resuscitation process through the development of the Observational Skill-based Clinical Assessment Tool for Resuscitation (OSCAR). With a Cronbach's alpha > 0.8: (0.736 to 0.96), the tool demonstrated high internal consistency in its ability to assess six behavioral domains of 3 separate rapid response team members (airway, team leader, and nurse). Investigators suggest this tool could be used in simulation centers, as well as simulated and authentic ward environments.[20] 

The simulation team assessment tool (STAT) also evaluates domains of medical resuscitation: basic skills, circulation, human factors, and overall performance. Investigators were able to show excellent inter-rater reliability (ICC for overall performance equals 0.81), as well as the ability to discriminate between expert and resident teams (P < 0.01 for basic skills; p = 0.02 in circulation, human factors, and overall performance).[21] Recently, the NRP steering committee approved the use of a performance tool developed through simulated resuscitations.  The tool demonstrated excellent agreement, with an intra-class coefficient of 0.86and was generalizable between academic and non-academic hospitals (p = 0.98).[22]

The human factor skills for healthcare instrument represents an international, multidisciplinary collaboration to improve the assessment of human factors in the clinical setting. After undergoing an iterative approach to tool refinement, the final instrument was evaluated with 711 trainees. It was found to be valid and reliable in its ability to assess self-efficacy in non-technical skills across multiple clinical professions.[23]  When this tool was later adapted to the non-clinical setting, it retained these features, with a Cronbach's alpha of 0.93. The final 12-item instrument was also found to be sensitive to change after simulated training with a large effect size (p<0.0001, and d > 0.7, respectively).[24]

Medical Decision Making and Leadership Development

Leaders of high-performance teams rely on the critical skill of Situational awareness (SA). Three cognitive levels of SA include the perception of available information, the comprehension/interpretation of the perceived information, and anticipation of future events based on this comprehension/interpretation. When used in the simulated setting, the Situation Present Assessment Method (SPAM) process is a validated and reliable method used to assess SA through the evaluation of latency periods. After warning the participant of a pending "query," the latency between this warning and its acknowledgment is considered a measure of cognitive workload. The latency between the query and the answer, however, is considered a proxy measure of SA.  By carefully crafting the timing and the content of the queries, each level of SA can undergo assessment.[25] 

The ability to facilitate effective communication is another crucial leadership skill.  Of ten human factor foci considered most relevant for patient safety, the WHO identified "communication failure" as a significant and recurrent contributor to adverse events. They assert that there is a clear relationship between communication skills, teamwork, and simulation-based medical education.[26] In high acuity situations, increasing illness severity has correlated with an increase in directive-style leadership, but there remains ample opportunity to inform HFE and simulation literature regarding ideal leadership communication styles. 

Additional communication-related topics ripe for clarification include "outer-loop" communications. This includes how team members decide what items are "relevant" to the team leader, or when the appropriate timing for team leader updates would be.[27] In one study utilizing inter-professional simulation to evaluate the response to neurologic emergencies, investigators identify concepts of clear communication. Approaches such as "stating the obvious," "announcing what you are doing," and "repeating information back" to ensure its accuracy were highlighted.  Further, while the development of a "flat-hierarchy" was considered conducive to all team members being "heard," assertive communication was a requisite expectation of each team member's role to best support error prevention and other patient safety principles.[28]

Clinical Significance

Simulation-based CRM can provide results translatable to patient outcomes.  This fact is exemplified in the results of the prospective evaluation of the Medical Team Training program utilized by the Veterans Administration.  Investigators identified a dose-response relationship between training and mortalityFor every three months of training, there was a commensurate reduction of 0.5 deaths per thousand operations.[17]

In an observational study of the impact of ward culture on the escalation of care, debriefing sessions revealed that explicit"permission to act" empowered staff to facilitate this process. By protecting training time, participant attendance at these sessions was greater than 95%.  The cost-benefit analysis revealed a reduction in PICU bed associated costs by £801,600 per year (£2400 per day x 334 PICU bed days).  Furthermore, these savings substantially exceeded the costs of regular team training. Investigators suggested that future research should include the financial impact on providers of "failure to rescue."[29]  

In a multicenter study evaluating training for IHCA response, survival rates were significantly higher for patients in hospitals with more active participation in simulation training (42.8% versus 31.8%; P less than 0.0001). This effect was true for large and medium-sized hospitals and did not significantly change after adjusting hospital expected mortality through logistic regression. The adjusted OR of 0.62 (CI 0.54- 0.71; P less than 0.001), represented an additional 151 potential lives saved - a substantial benefit given a cost of only 1.1 additional simulation/100 beds/year/life saved.[30]

Pearls and Other Issues

The human factors have demonstrated  important role in the development of simulation to optimize performance. Therefore, the principles of human factors and ergonomics can be applied to improve human and system performance.

The human factors should be integrated into simulation-based education to make it more relevant to clinical practice.

Human factors are more relevant in emergency medicine simulation particularly when there is limited time to think and therefore can significantly influence outcome.

Enhancing Healthcare Team Outcomes

Leadership can support the establishment of "a culture of habitual excellence" through the use of briefings and debriefings to demonstrate transparency and sharing of problems. Thoughtful crafting and/or facilitation of the debriefing process is demonstrated by the ability to establish the following essential elements: psychological safety, debriefing stance/basic assumption, debriefing rules, and a shared mental model. In a meta-analysis of factors moderating the efficiency and effectiveness of debriefing, researchers revealed that a general discussion of overall performance is enhanced when reflecting on specific past events couples with cue-strategy associations. This allows participants to examine actions and their underlying cognitions more deeply. Periods of silence allow for active listening and support transitions between difficult topics. This approach also provides an opportunity for facilitators to evaluate non-verbal communication and determine if participants are "ready to learn." [31]

Through the simulation design process, contextual factors are augmented to optimize workflow representation, thus promoting the natural execution of tasks.[32] Participant motivation and engagement are fueled by the "gamification" inherent in the simulation delivery process, thus promoting teamwork and communication skills development.[7] Functional task alignment can be confirmed by measuring participants' immersion in the simulation session.[33] The collection of performance metrics at the team level helps to support methodological alignment when evaluating critical teamwork processes.[34] As previously noted, the incorporation of global rating or behavioral assessment tools into the debriefing session allows for discussion of roles and expectations of the team as a whole.[20] Finally, by asking open-ended questions, and confirming that learning objectives have been addressed, this critical component of successful healthcare simulation delivery optimizes the reflective experience of the participants.[35] By enabling teams and individuals to experience the appropriate conceptual, emotional, and physical fidelity of high-risk situations without the potential for patient injury, high fidelity simulation is well suited to HFE through CRM.[17]


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