Branching cross-examination

This is a MedVellum formative viva. It is not an official RACP, MRCPCH, ABP, ACGME or RCPSC station, mark scheme, duration or pass standard. Release each update only after the candidate states the failing system, the immediate action and the reassessment endpoint. [1]

Candidate brief

You are the senior paediatric clinician in a rural district emergency department. Speak as you would during resuscitation. Recognise shock from the whole circulation, state the change you expect from each action, and say what you will reassess. This is one continuous case. Each escalation branch leads to the next update. [1]

Question 1 — Recognition and the first 60 seconds

Stimulus update. A parent carries a five-year-old who has been unwell for two days with fever and reduced intake. Before you touch the child you see poor tone, little eye contact, marked recession, and cold mottled limbs. Question: What do you say and do now? [1]

Consultant-level model answer. "I am immediately concerned. The first impression is abnormal: reduced appearance and tone, increased work of breathing, and poor circulation to skin. I call the senior paediatric and resuscitation teams now, name a leader, allocate roles, and bring age- and weight-appropriate equipment and monitoring. I begin the hands-on primary survey immediately. This child is in decompensated septic shock in evolution, and I will not wait for hypotension." [1] [5]

Probing follow-up. "Why do you not wait for the blood pressure to fall?" A strong answer is: "Because children compensate by raising heart rate and vascular tone, so blood pressure is maintained until relatively late. This child already shows poor perfusion in the skin, pulses and consciousness. Shock is a circulation diagnosis, never a blood pressure number." [5]

Common weak answer. "I will take a full history and order bloods and a chest X-ray first." This delays resuscitation in a visibly critical child and inverts the order: first impression, then primary survey, then secondary assessment. [1]

Escalation branch. If the candidate declares concern and starts the bundle, release the survey data in Question 2. If they anchor on a diagnosis, ask which failing system they will treat first. [1]

Question 2 — The first-hour bundle and response endpoints

Stimulus update. Airway is patent. Respiratory rate is 48 with recession and reduced air entry; oxygen saturation is 91% on air with a reliable waveform. Heart rate is 160, central pulses are weak, capillary refill is 4 seconds, blood pressure is low-normal, and the child responds to voice but cannot sustain interaction. Bedside glucose is 2.3 mmol per litre. Question: Lead the first hour. What improvement do you expect from each action? [1]

Consultant-level model answer. "I give high-flow oxygen because the child is in failure and I judge effectiveness by air entry and interaction, targeting 94 to 98%. I establish intravenous or intraosseous access and send gas, lactate, glucose, culture and core bloods. I restore the circulation with crystalloid aliquots of 10 to 20 mL per kilogram, expecting stronger pulses, warmer skin, shorter refill, better interaction and rising urine; I reassess after each and stop for overload or no benefit, because the first-hour total is a ceiling. I give broad-spectrum antibiotics within the first hour, and I correct the dangerously low glucose immediately through the local pathway." [1] [5]

Probing follow-up. "Why is the ceiling a ceiling and not a target?" A strong answer is: "Because the septic circulation leaks. Driving fluid toward a fixed volume risks fluid accumulation injury with crackles, hepatomegaly and a rising oxygen requirement. I reassess after each aliquot and escalate to a vasoactive agent if shock persists." [9]

Common weak answer. "Give a 60 mL per kilogram bolus then reassess in an hour." This treats a ceiling as a target and delays reassessment. [9]

Escalation branch. If the candidate gives several endpoints and respects the ceiling, reveal in Question 3 that shock persists. If they push toward a fixed volume, ask how they would recognise overload. [1]

Question 3 — Fluid-refractory cold shock and the vasoactive choice

Stimulus update. After two reassessed boluses totalling 40 mL per kilogram, the child remains cold and mottled with weak thready pulses and a narrow pulse pressure. Question: What is the diagnosis, and which vasoactive agent do you start and why? [1] [6]

Consultant-level model answer. "This is fluid-refractory septic shock. The phenotype is cold shock, so I start an adrenaline infusion at 0.05 to 0.1 microgram per kilogram per minute and titrate to perfusion. Adrenaline restores inotropy and therefore cardiac output, and adds an alpha effect at higher doses. I arrange central access and intensive care, and I call retrieval in parallel." [1] [6]

Probing follow-up. "Why not dopamine?" A strong answer is: "Dopamine is no longer the preferred first-line agent. The Surviving Sepsis Campaign recommends adrenaline or noradrenaline over dopamine, and a meta-analysis found no survival advantage for dopamine over adrenaline in paediatric and neonatal septic shock, with a higher dysrhythmia burden. Noradrenaline would be first line for warm, vasodilated shock, but this is cold shock." [1] [6]

Common weak answer. "I will give dopamine at 10 micrograms per kilogram per minute." This defaults to a demoted agent and ignores the phenotype. [6]

Escalation branch. If the candidate starts adrenaline correctly, reveal in Question 4 that the child develops signs of overload despite the agent. If they choose dopamine, ask what the evidence shows. [1]

Question 4 — Fluid accumulation injury and catecholamine resistance

Stimulus update. On the adrenaline infusion the child develops bilateral crackles, hepatomegaly and a rising oxygen requirement, while perfusion remains poor despite an adequate dose. Question: Interpret this and act. [1] [9]

Consultant-level model answer. "Two things are happening. The crackles, hepatomegaly and rising oxygen requirement are fluid accumulation injury: I stop driving fluid immediately. The poor perfusion despite adequate fluid and a titrated vasoactive infusion is catecholamine-resistant shock. I reconsider reversible causes: a missed tamponade or pneumothorax, ongoing loss, an undrained source, electrolyte or metabolic derangement, or hypoadrenalism. I arrange echocardiography, and I add stress-dose hydrocortisone, which the Surviving Sepsis Campaign suggests for shock unresponsive to adequate fluid and vasoactive therapy." [1] [9]

Probing follow-up. "Could this simply be that the child needs more fluid?" A strong answer is: "No. The pulmonary and hepatic signs prove the circulation cannot hold more volume. The problem now is a failing, leaking circuit and possibly unresponsive vasculature, not a deficit of preload. More fluid would worsen the oedema and hypoxaemia." [9]

Common weak answer. "I will give another 20 mL per kilogram bolus." This ignores the signs of overload and worsens the injury. [9]

Escalation branch. If the candidate recognises overload and adds hydrocortisone, move to Question 5 on retrieval and handover. [1]

Question 5 — Retrieval, the FEAST lesson and handover

Stimulus update. The child stabilises on adrenaline, hydrocortisone and ventilation. The rural hospital has no paediatric intensive care. Question: Describe your escalation and handover, and explain the FEAST lesson. [4]

Consultant-level model answer. "I called retrieval in parallel with resuscitation, before local support was exceeded. I agree the destination, the treatment to continue, the escort and equipment, the expected deterioration, the plan if transfer is delayed, and the monitoring en route. FEAST found that saline or albumin bolus increased early mortality compared with no bolus in African children with severe febrile illness; its correct lesson is that a fluid algorithm cannot be transplanted across populations, shock types and rescue resources. Here I gave reassessed aliquots, watched the response, respected the ceiling and escalated rather than forcing a fixed volume. My structured handover transfers identity and working weight, current physiology and trend, timed actions and response, the prioritised differential and pending tests, local limits, family and safeguarding information, and the next contingency and its named owner." [4] [9]

Probing follow-up. "What is the one principle you most want the team to carry forward?" A strong answer is: "Recognise shock from the whole circulation, restore perfusion with reassessed aliquots, treat the ceiling as a ceiling, choose the vasoactive agent for the phenotype, and escalate before local support is exceeded." [1]

Common weak answer. "I will wait for the retrieval team to arrive before doing anything else." The child needs ongoing reassessment and stabilisation during the wait, with a contingency for deterioration. [1]