Recognise shock from the whole child — physiology and classification

Station status

This is one MedVellum formative structured clinical encounter. The scoring, prompts and performance descriptions are educational feedback tools. They are not an official college station, timing, mark allocation, pass score or reproduced examination format. The encounter assesses recognition of compensated shock from the whole child, grading severity, classifying phenotype, the fluid-as-a-ceiling principle, warm versus cold shock, early escalation to vasoactive support and retrieval, communication, safeguarding in parallel, handover and disposition. [1] [6]

Candidate instructions

You are the paediatric registrar called to the acute assessment room. Assess the child from the doorway and say aloud what you see. Make the whole-circulation assessment, grade the severity and name the phenotype. Treat shock with fluid in aliquots, stating the expected response and reassessing after each. Call senior, critical-care or retrieval support early. Run safeguarding alongside urgent care. Finish with a structured handover and disposition plan. Say what you would assess or do; do not perform painful or distressing manoeuvres on the actor. [9]

Room setup and observable starting state

The encounter. Mia is two and is supported on the assessment trolley by a parent. The parent says simply, "She's not herself." Mia is lethargic, opens her eyes briefly to voice, has cool mottled limbs, and a weak cry. These are abnormalities in appearance, work of breathing and circulation to skin. The candidate should describe these signs objectively, declare concern, call for help and begin the whole-circulation assessment immediately, recognising compensated shock despite a blood pressure that is still normal. [1] [6]

Simulation safety. Mia remains on the trolley and is never forcibly positioned. Cards or the assessor supply the monitor readings and examination findings. The parent does not obstruct urgent care. [6]

Actor cues

Parent actor

• Begin with "She's not herself." If asked what has changed, answer: "Mia is usually into everything. For three days she's had a fever and hardly drunk anything, and today she's floppy and her hands are cold and blotchy."
• If the candidate explains shock and the plan, answer: "I'm scared. What can I do to help?"
• If safeguarding is raised, answer factual questions about the history without coaching.

Child actor

• Respond briefly to voice early in the encounter; become harder to rouse as the scenario progresses, following the assessor's cue card.

Assessor cues and clinical data

Release findings as the candidate reaches each step. Reward whole-child recognition and the fluid-as-a-ceiling principle; penalise waiting for hypotension or targeting a fixed volume. [1]

Doorway and circulation assessment

Heart rate 168, central pulses felt but peripheral pulses weak, skin cool and mottled, capillary refill 4 seconds on the sternum, blood pressure low-normal for age, oxygen saturation 94% on air, respiratory rate 42 with mild recession, reduced urine output, responds to voice but cannot sustain interaction. Expected strong behaviour: diagnose compensated shock from the whole picture despite the non-hypotensive blood pressure; state that waiting for hypotension is a classic error; declare concern and call for help. [2] [3]

Phenotype and severity

The candidate must grade the severity as compensated shock (blood pressure still normal) and name the leading phenotype. Initially Mia is warm then cold, with a narrow pulse pressure and weak pulses. Expected strong behaviour: name septic shock as a distributive phenotype that has become cold and low-output, with myocardial depression and relative hypovolaemia giving a mixed picture; state that mixed physiology is expected in sepsis and the phenotype must be revised after each reassessment. [1] [5]

Fluid-as-a-ceiling event

The candidate gains access and prepares fluid. Expected strong behaviour: give an isotonic crystalloid aliquot of 10 to 20 mL per kilogram, state the response expected before it goes in, and reassess the whole child immediately afterwards; state that the first-hour total is a ceiling, not a target, and that fluid is repeated only while the child remains in shock and is not overloaded. [4] [5]

Warm-versus-cold question

The assessor asks which vasoactive agent the candidate would choose if fluid is exhausted. Expected strong behaviour: match the agent to the phenotype; a cold, low-output state leans toward an inotrope such as adrenaline, while a warm, vasodilated state leans toward a vasoconstrictor such as noradrenaline; state that the exact dose belongs to local protocol and the dedicated critical-care pages. [1] [5]

Escalation event — the cliff edge

On reassessment after aliquots, Mia becomes harder to rouse, the central pulses weaken, and the blood pressure falls below the threshold for age. Expected strong behaviour: recognise decompensated shock at the cliff edge, start vasoactive support early rather than pushing more fluid, and call critical care and retrieval in parallel, before local options are exhausted. [6] [9]

Weight and escalation

The candidate must obtain a working weight for drug and device sizing. Expected strong behaviour: use a measured weight if available immediately; otherwise document a working weight from a recent reliable value, a credible parent estimate, or the trained length-and-habitus tool, and use the local paediatric cognitive aid, re-weighing at the first safe opportunity. [6]

Marking domains

Debrief prompts

• What made this compensated shock rather than a well child, and why was the blood pressure misleading?
• How did the compensation-to-collapse trajectory explain the change you saw during the encounter?
• Why was the first-hour fluid total a ceiling rather than a target, and how did FEAST inform your caution?
• When did fluid stop being the answer, and what governed your choice of vasoactive agent?
• What was the single most important early sign, and what change told you the cliff edge had arrived?