Hypothermic submersion cardiac arrest — OSCE

Station brief (8–10 minutes)

An 8-year-old is brought to the emergency department by ambulance after falling through ice into a lake. Submersion was approximately thirty minutes. The child is cold, pale, and pulseless. Cardiopulmonary resuscitation is in progress by paramedics. Intraosseous access is in place. The core temperature reads 25 degrees Celsius, and the monitor shows ventricular fibrillation. You are the registrar leading the resuscitation, with a skilled nurse and a junior doctor present. Apply the hypothermic defibrillation and drug rules, choose the rewarming strategy, and state when resuscitation may be terminated. Name the source for each threshold. [5] [6]

Tasks for the candidate

1. Confirm the rhythm and the hypothermia stage, and deliver the correct first shock by the hypothermic rules. [5]
2. State the adrenaline and antiarrhythmic strategy below and above thirty degrees Celsius. [5]
3. Choose the rewarming strategy by Swiss stage and state the indication for extracorporeal rewarming. [6]
4. State the core temperature at which resuscitation may be terminated, and justify continued resuscitation in cold-water submersion. [9]
5. Outline the post-arrest neuroprotective bundle and disposition after return of spontaneous circulation. [6]

Expected performance

Must hit. Identifies ventricular fibrillation in a Swiss stage four (profound, core 25 degrees) hypothermic arrest. Continues high-quality cardiopulmonary resuscitation, handles the child gently to avoid precipitating fibrillation, removes wet clothes, dries and insulates. Delivers a single shock at four joules per kilogram, and states that further shocks and adrenaline are withheld until the core rises above thirty degrees, because the cold myocardium is refractory and drug clearance is slowed; once above thirty degrees, resumes standard shocks and adrenaline with a lengthened adrenaline interval. Chooses extracorporeal rewarming with ECMO or cardiopulmonary bypass as the treatment of stage four cardiac arrest, with active internal rewarming (warmed humidified oxygen forty-two to forty-six degrees, warmed crystalloid at approximately forty degrees) as a bridge. States that resuscitation continues until the core reaches at least thirty-two degrees, because nobody is dead until warm and dead, and cold-water submersion can recover with good neurological outcome. [5] [6]

Merit. Names the van Beeck definition and the obsolete terms it retires; cites the Saczkowski meta-analysis on survival after extracorporeal rewarming; explains the diving response and cerebral protection that justify prolonged resuscitation in cold water; anticipates the afterdrop and rewarming shock with warmed fluids; and describes the post-arrest neuroprotective bundle of normothermia with avoidance of fever, normoxia (saturations 94 to 99 per cent), normocapnia, glucose control, and seizure surveillance in the paediatric intensive care unit. [8] [9]

Fail. Delivers repeated escalating shocks or adrenaline doses below thirty degrees; chooses passive or active external rewarming alone for an arrested stage four patient; declares the child dead at the scene or before rewarming; fails to arrange extracorporeal rewarming; handles the child roughly; or cannot state the termination temperature. [5] [9]

Sample candidate structure

"This is a profound hypothermic submersion cardiac arrest — Swiss stage four, core 25 degrees, in ventricular fibrillation. I continue high-quality CPR and handle him gently. I deliver a single shock at four joules per kilogram, and because the core is below thirty degrees I withhold further shocks and adrenaline until the core rises above thirty, then resume standard care with a lengthened adrenaline interval. I remove the wet clothes, dry and insulate, and I start active internal rewarming with warmed humidified oxygen and warmed crystalloid. The definitive treatment is extracorporeal rewarming, which I arrange immediately with ECMO or cardiopulmonary bypass, because the Saczkowski meta-analysis shows meaningful survival. I continue resuscitation until the core reaches at least thirty-two degrees — nobody is dead until warm and dead — and if he regains a pulse I hold normothermia, normoxia, and normocapnia and admit him to the PICU." [5] [9]