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 problem, the immediate action and the stabilisation endpoint. [1] [4]

Candidate brief

You are the senior paediatric clinician in a rural hospital. Speak as you would during a real retrieval. Call retrieval in parallel with resuscitation, complete pre-transport stabilisation before departure, manage the physics of the flight, choose the mode and escort, rehearse the contingency, and hand over safely. This is one continuous case. Each escalation branch leads to the next update. [12] [1]

Question 1 — The referral and the principle

Stimulus update. A six-year-old is admitted with pneumonia and is deteriorating: respiratory rate 50, oxygen saturation 88 per cent on high-flow oxygen, heart rate 160, capillary refill 4 seconds, and a venous lactate of 4. The hospital is three hours by road from the paediatric intensive care unit. Question: What do you do in the first 15 minutes? [1] [4]

Consultant-level model answer. "This child is in septic shock with respiratory failure and is on the ascending limb of resuscitation. I call the retrieval service and the paediatric intensive care unit in parallel with resuscitation, before local resources are exceeded, and I agree the destination and the bed. I apply the stay-and-stabilise principle: I bring intensive care to the child here, complete the airway, breathing and circulation work, and only then move the child through it. I keep telehealth support open with the retrieval service while I resuscitate." [1] [12]

Probing follow-up. "Why not send the child by road now to save time?" A strong answer is: "A child who departs unstable arrives worse. The journey is the most dangerous part, because the cabin is cramped, noisy, vibrating and cold, and reassessment in flight is far less reliable than at the bedside. I stabilise in full first; speed of departure is never a substitute for completeness of resuscitation." [2] [4]

Common weak answer. "I will wait for the retrieval team to arrive before doing anything." The child needs active resuscitation and stabilisation during the wait, with a contingency for deterioration, not passive observation. [4]

Escalation branch. If the candidate activates retrieval and starts resuscitation, release the survey data in Question 2. If they want to send the child immediately, ask which threat they will treat first. [1]

Question 2 — Pre-transport stabilisation

Stimulus update. The child remains tachypnoeic and hypoxic on high-flow oxygen; the blood pressure is now low; the lactate is rising; the conscious level is falling. Question: What must be true of this child before the trolley moves? [4] [2]

Consultant-level model answer. "The airway must be secure and verified. With respiratory failure, shock and a falling conscious level I intubate by rapid sequence, confirm the tube with capnography, fix it firmly, and check the cuff pressure because cuff gas expands at altitude. Breathing must be effective with oxygen reserve for the whole journey plus a margin; I set the ventilator and drain any pneumothorax before flight. The circulation must be treated to a sustained perfusion trend with reliable access, vasoactive drugs on a dedicated line, and crossmatched blood. Glucose must be checked, seizures controlled, and the child warm. Every line and tube must be secured and the monitoring continuous." [4] [8]

Probing follow-up. "What single question decides whether the child is stable to move?" A strong answer is: "If this child deteriorated right now, could I manage it here better than in the cabin? If yes, I keep resuscitating. The journey should be the calmest part of the child's course." [1] [2]

Common weak answer. "The blood pressure is acceptable, so we can move." Shock is a whole-circulation diagnosis, never a single blood pressure, and a rising lactate with poor perfusion is compensated shock in evolution. [4]

Escalation branch. If the candidate completes stabilisation, reveal in Question 3 that the retrieval is by rotary-wing. [8]

Question 3 — The physics of the flight

Stimulus update. The retrieval team arrives; the child is intubated and ventilated, on a noradrenaline infusion, warm and packaged. The plan is a 60-minute rotary-wing flight; the cabin altitude will be around 7000 feet. Question: How does altitude, vibration and cold threaten this child, and what do you do? [4] [8]

Consultant-level model answer. "Gas expands by Boyle's law as ambient pressure falls, so at a cabin altitude of around 7000 feet a trapped gas volume expands by up to about a third. I drain any pneumothorax before flight, decompress the bowel and stomach, and check the endotracheal tube cuff pressure, with a plan to recheck it in flight, because cuff gas expands and can injure the trachea. Vibration and noise jitter the waveforms and mask alarms, so I trust continuous monitored data — capnography, pulse oximetry, blood pressure — and I secure the child and every line before departure. Cold steals heat fast from a small body and worsens shock and coagulopathy, so I pre-warm the cabin, wrap the child, and monitor temperature throughout." [4] [2]

Probing follow-up. "Why does cuff pressure matter specifically?" A strong answer is: "The cuff is a sealed gas pocket. At altitude the gas expands, the cuff pressure rises, and the tracheal mucosa can be injured. I measure and adjust the cuff to a safe pressure before and during the flight." [8] [4]

Common weak answer. "I will just watch the child in flight." Reassessment in a moving, noisy, poorly lit cabin is unreliable, so I trust monitored data and secure everything before departure. [2]

Escalation branch. If the candidate manages the physics correctly, move to Question 4 on the contingency and handover. [4]

Question 4 — Contingency, escort and handover

Stimulus update. The team is ready to depart. The child is stable but at risk of further deterioration. Question: Describe your contingency, your escort rationale, and the handover you will give. [6] [2]

Consultant-level model answer. "I rehearse, with the escort, who does what if the child obstructs, desaturates, becomes hypotensive, seizes or loses a line, and I carry the drugs, airway equipment and fluid and blood to manage each. I escort with a specialist paediatric retrieval team that can manage the foreseeable deterioration, because matching the escort's skills to the child is the key safety factor. At the receiving door I give a structured ISBAR handover: identity and working weight, diagnosis and current physiology, actions and response including the fluid and blood given, current ventilator and vasoactive settings, timed events and unresolved threats, family and safeguarding context, and the next contingency with a named owner. I confirm acceptance of care and close the loop." [6] [1]

Probing follow-up. "What is the one principle you most want the team to carry forward?" A strong answer is: "Bring intensive care to the child and then move the child through it; stabilise in full before departure; respect the physics of altitude, vibration and cold; and rehearse the contingency. The journey should be the calmest part of the child's course." [1] [4]

Common weak answer. "I will hand over when we arrive." The handover must be structured and rehearsed, transferring the trend and the contingency, not improvised at the door. [6]

Closing. The case ends when the candidate hands over safely and closes the loop. [1] [6]