It’s 19:20. The waiting room is full.
A 2-year-old girl is called into triage with fever and lethargy. Vital signs show a heart rate of 160 and a temperature of 38.5 °C, but she is alert, clinging to her mother. You give some paracetamol. It’s your twelfth hour on shift. Triage times exceed 15 minutes, and the phone will not stop ringing!
You assign a lower acuity based on your clinical gestalt; the HR is high due to fever, and parents have not given any paracetamol at home. You triage to “fit-to-sit”, allowing the child to wait in the children’s playroom, to help her relax.
Two hours later, she deteriorates rapidly and is rushed to resus.
Was this a knowledge gap or a human factors failure?
This scenario highlights a critical question: how do cognitive load and decision fatigue influence early clinical decisions?
Triage comes from the French verb trier, meaning “to sort,” and refers to the rapid clinical assessment by which clinicians make high-stakes decisions about how urgently a patient needs to be seen.
Triage is not simply about categorising urgency; it is a cognitive task under pressure that encompasses staffing systems, processes, and communication. Triage should be performed by a clinician who is trained and competent in using the specific triage system being applied. Its correct use ensures a useful, valid and reproducible assessment. Several validated symptom-based triage systems are in use, such as the Manchester Triage System, Canadian Triage and Acuity Scale and the Emergency Severity Index.
While designed to improve safety, the 15-minute triage target can intensify pressure at the front door when demand exceeds capacity. Early decisions shape patient flow, risk and downstream outcomes. A large Canadian cross-sectional study of 587,419 attendances across 14 facilities found that length of stay was strongly associated with system-level, modifiable factors—particularly hospital occupancy, the number of emergency inpatients, and staffing (continuity of care). These findings suggest that crowding is less a frontline performance issue and more a reflection of whole-system constraints.
At the same time, evidence indicates that clinician fatigue, cognitive overload and bias influence triage judgement. The tension is clear: individual performance is scrutinised, yet structural capacity often drives delay. Improving occupancy management, staffing resilience and cross-pathway coordination may therefore yield greater gains than focusing solely on speed metrics.
Why Triage is a Cognitively Extreme Task: Cognitive overload and decision fatigue
Working memory is limited.
Cognitive load theory, developed by John Sweller, proposes that performance deteriorates when task demands exceed cognitive capacity.
When clinicians are under pressure, thinking becomes more effortful and step-by-step. This uses up cognitive capacity, leaving less room for pattern recognition, anticipation and early identification of risk.
As workload, interruptions and time pressure increase, clinicians are more likely to rely on shortcuts in decision-making. These are often necessary—but they also make judgment more vulnerable to error, particularly in subtle or evolving presentations.
Decision-making in triage is not purely individual. Lev Vygotsky argues that cognition is shaped socially and supported through interaction, language and shared tools.
Clinical judgement, then, is shaped by interaction, communication and shared understanding within teams. Informal discussion, second opinions and shared mental models can all support safer decisions, particularly in uncertain cases.
A double-blind, randomised framing study explored whether triage decisions were influenced by the way information was presented. 120 nurses were invited to complete a questionnaire for payment; 78 completed it. The primary outcome was the accuracy of triage categorisation. While no significant effect on accuracy was found, common cognitive biases were still observed. Initial impressions often shaped decisions (anchoring), recent experiences influenced judgement (availability), and clinicians sometimes stopped analysing too early (premature closure). Importantly, this study was conducted using written scenarios and did not replicate real clinical pressures such as interruptions, fatigue or parental anxiety—factors that are central to triage practice.
A broader scoping review of 22 studies found that accurate triage was more strongly associated with clinical reasoning, situational awareness and critical thinking than with patient or environmental factors. In practice, clinicians combine verbal cues, visual assessment and contextual information while coordinating with colleagues to reach decisions.
Cognitive strain is also cumulative. Repeated high-stakes decisions over the course of a shift can lead to decision fatigue, in which the quality of judgment declines over time. This is particularly relevant in triage, where uncertainty, time pressure and frequent interruptions are constant.
Emerging paediatric evidence suggests that fatigue is not only theoretical but measurable. A recent quality improvement project found that moving from 12-hour to 6-hour triage shifts significantly reduced self-reported fatigue. While patient outcomes were not assessed, the finding is important because fatigue directly affects attention, working memory, and prioritisation, all of which are essential for safe triage decisions.
Taken together, this evidence suggests that triage performance is not simply a reflection of individual knowledge or experience. It depends on how much cognitive capacity is available in the moment—and how well the surrounding system supports clinicians to make decisions under pressure.
Teamwork (makes the dream work)
Emergency assessment involves uncertainty, emotion and social dynamics that extend far beyond the triage clinician. The response is not to demand greater individual resilience, but to design systems that minimise unnecessary cognitive burden—through clear processes, supportive environments and shared team cognition—so clinicians can focus on meaningful judgement rather than simply surviving overload.
A quasi-interventional study of 200 patients compared team triage with traditional single-nurse triage. In the team model, physicians and advanced practitioners worked alongside nurses and healthcare assistants at the front door. Triage was reported to be over 50% faster, with shorter waits to both assessment and treatment. Patient satisfaction was also higher.
However, these findings should be interpreted cautiously. Satisfaction was self-reported, introducing potential bias. The study was conducted in a single centre in Iran, limiting applicability to UK settings, where senior decision-makers are often already present in triage. Staffing levels were modest, and shifting clinicians to triage may have affected performance elsewhere in the department. The exclusion of patients with COVID-19 further reduces the extent to which this reflects real-world practice.
Wider evidence supports some of these findings. Systematic review and meta-analytic data associate team triage with lower rates of patients leaving without being seen, consistent with earlier reviews. However, these outcomes are largely operational. They do not fully address diagnostic accuracy, patient safety, or downstream system impact.
UK standards do not prescribe a single triage model. Instead, they emphasise adequate staffing, appropriate space, and systems that can respond to surges in demand. Importantly, escalation processes should be triggered when triage times exceed 15 minutes.
What to include in a triage
Structured Tools: Support, Not Replace
Effective communication underpins safe and effective patient care. UK professional regulators, including the Nursing and Midwifery Council, General Medical Council and Health and Care Professions Council, emphasise clear, structured and patient-centred communication, particularly during handover, escalation and consultation.
Similarly, NHS England advises that triage should incorporate a brief medication history, basic observations, simple analgesia, chief complaint, and an assessment of acuity, severity and urgency Facing the Future standards for paediatric care, published by the Royal College of Paediatrics and Child Health, suggest a standardised triage system with structured processes and appropriate training, including full vital sign assessment (temperature, oxygen saturation, respiratory rate, heart rate, capillary refill time, blood pressure, level of consciousness and pain score).
Recording Paediatric Early Warning Scores (PEWS) can provide objective physiological cues to support recognition of deterioration. A multilayered triage system, including structured tools such as the Manchester Triage or the Emergency Severity Index, is well validated and widely used in emergency departments. However, a gap appears to exist in robust auditing of under- and overtriages. A multi-layer triage can increase accuracy, although this approach was tested in a single centre among adults and included adult-targeted scoring systems, which may not be transferable to paediatric presentations.
Structured communication tools may reduce cognitive load by providing a consistent framework, decreasing variation in documentation and improving clarity and transferability across teams. SBAR (Situation, Background, Assessment, Recommendation) was initially adopted to structure urgent nurse–physician communication and is now widely used across healthcare.
A 2018 systematic review found SBAR to be transferable across settings, but patient outcomes were heterogeneous, spanning 26 measures. Of 1053 articles screened, only 11 met the inclusion criteria, including 1 RCT and 2 controlled trials, underscoring the limited availability of high-quality evidence. While some studies demonstrated improvements in communication and selected patient outcomes, others showed no significant effect, making direct attribution challenging.
A subsequent review reported variable impact, with high fidelity in classroom settings but reduced adherence in clinical practice. Improvements in teamwork and safety culture were more likely within multifaceted interventions, and consistent patient outcome benefits were uncommon. This suggests SBAR is a useful educational and structuring tool, yet its real-world effectiveness depends on robust implementation and monitoring.
Evans and Da’Costa describe structured tools such as MIST (Mechanism, Illness/injury history, Signs, Treatments), originally used in military settings, as a means of promoting concise, factual handover and reducing bias during transfer of care.
More targeted paediatric tools, such as CWILTED, are associated with improved documentation. This single-centre quality improvement project, reviewing 207 triage records over three months, found that documentation improved after introducing a structured approach: recording of who witnessed the incident increased from 15.7% to 76.8%, location from 21.1% to 78.2%, and demeanour from 44.2% to 79.2%. However, generalisability is limited. Only one record per shift was sampled, the study was conducted in a single centre, and potential confounders—such as clinician experience, crowding, patient flow and fatigue—were not controlled for, although a pre-intervention audit was undertaken.
The Future is AI
AI-based solutions have targeted emergency triage and may take some of the burden off. A systematic review of 26 studies suggests AI-driven triage models frequently outperform traditional triage tools, especially in predicting admission and critical illness.
Integration of vital signs, demographics, and free-text data appears to enhance discrimination and may reduce under- and overtriage. However, most evidence is retrospective and single-centre, with moderate risk of bias, limited external validation, and no reporting of positive predictive value. Cost-effectiveness and real-world workflow impact remain unclear. From a human factor’s perspective, successful adoption will depend on explainability, clinician trust, and data quality. AI shows promise, but implementation must prioritise safety, usability, and system resilience.
The deteriorating child in the opening scenario highlights the interplay of cognition, context, and system design in emergency care. While tools like the Manchester Triage System and Emergency Severity Index provide structure, triage remains a high-pressure human task. Early warning scores offer support but cannot overcome excessive workload or flawed systems. Evidence suggests safety depends less on vigilance and more on designing environments that respect cognitive limits. In paediatric care, where deterioration is rapid and subtle, acknowledging these limits is essential. Reliable triage comes not from superhuman effort, but from systems that let clinicians think clearly when it matters most.
Key Take-Home Points
Paediatric ED triage is a cognitively demanding task where human factors matter.
Decision fatigue is real but undermeasured
Cognitive biases are prevalent and increase under load, but may be mitigated by expertise and structured processes.
Overcrowding is a human factors hazard
System design — including shift patterns — can reduce clinician fatigue.
Psychological safety and shared decision-making distribute cognitive burden.
Tools like PEWS, SBAR and CWILTED support documentation but require integration into the workflow.
Robust AI research is still needed to quantify direct relationships between improved patient outcomes.
A whole system approach, measuring length of stay, time to be seen, time to discharge, left without being seen, self-discharge, family and friends feedback, complaints, deaths within 30 days, hospital occupancy, staffing levels and sickness, escalation areas open, and displaying these metrics rather than triage times within 15 minutes will give a more truthful account.
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