Propofol infusion syndrome — FFICM MCQ

Correct answer: C — Propofol infusion syndrome

The correct answer is C, propofol infusion syndrome (PRIS). This patient has had prolonged, high-dose propofol (over 48 hours, a recognised threshold) for sedation in severe traumatic brain injury, and has developed the classic pentad of refractory metabolic acidosis, rhabdomyolysis, hyperkalaemia, new bradyarrhythmia and hypertriglyceridaemia, with sepsis excluded as an alternative cause. PRIS results from propofol-induced impairment of mitochondrial fatty acid oxidation and the electron transport chain, causing failure of cellular energy metabolism, lipaemia, and myocardial and skeletal muscle injury. Cardiac involvement (bradyarrhythmia, Brugada-like ECG changes, cardiac failure) in combination with lactic acidosis and rhabdomyolysis in a patient on high-dose propofol is essentially diagnostic and mandates immediate cessation of the infusion. Neurocritical care patients are at particular risk because high sedation requirements for raised intracranial pressure often necessitate the very high doses and durations that predispose to PRIS. Why the other options are wrong: B. Malignant hyperthermia: this is triggered by volatile anaesthetics or suxamethonium, not propofol, and classically presents intraoperatively with hypercarbia, masseter rigidity and rapidly rising temperature, none of which fit a 72 hour propofol infusion in ICU. D. Neuroleptic malignant syndrome: occurs with antipsychotic or dopamine antagonist exposure and features rigidity, hyperthermia and altered consciousness; there is no antipsychotic history here and triglycerides are not typically deranged. E. Alcohol withdrawal: causes autonomic hyperactivity, tremor and seizures rather than rhabdomyolysis, hypertriglyceridaemia and bradyarrhythmia, and would not explain the temporal link to propofol dosing. A. Local anaesthetic systemic toxicity: requires recent local anaesthetic administration, causes CNS excitation and cardiovascular collapse via sodium channel blockade, and has no mechanistic link to lipaemia or rhabdomyolysis in this scenario. Key point: prolonged high-dose propofol plus lactic acidosis, rhabdomyolysis, hyperkalaemia, hypertriglyceridaemia and new bradyarrhythmia, with sepsis excluded, equals propofol infusion syndrome, and the infusion must be stopped immediately.

Reference: electronic Medicines Compendium (emc), Propofol SmPC, Section 4.4 Special warnings and precautions for use, Propofol Infusion Syndrome, https://www.medicines.org.uk/emc/product/1365/smpc