Propofol Infusion Syndrome & Drug Toxicities

ABPN Neurocritical Care Study Guide Exam

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1 Chapter 1: Neurologic Examination & Coma Assessment in the ICU

Current Examination, Blueprint & Preparation Neurologic Examination in Critically Ill Patients Coma Evaluation & Consciousness Alterations Delirium & Toxic-Metabolic Encephalopathy in the ICU

2 Chapter 2: Cerebral Physiology & Intracranial Dynamics

Cerebral Blood Flow, Metabolism & Autoregulation Intracranial Pressure & Compliance Cerebral Edema & Herniation Syndromes

3 Chapter 3: Intracranial Hypertension & Cerebral Perfusion Management

Tiered ICP Management Protocols Hyperosmolar Therapy & Fluid Management Advanced & Refractory ICP Interventions

4 Chapter 4: Airway, Mechanical Ventilation & Pulmonary ICU Management

Emergency Airway Management & Neuro-Intubation Mechanical Ventilation Strategies in Acute Brain Injury Tracheostomy & Ventilator Weaning in Neurocritical Care Pulmonary Complications in the Neuro-ICU Obstructive Lung Disease, Pulmonary Hypertension & Bronchoscopy

5 Chapter 5: Hemodynamics, Shock & Cardiovascular Management

Hemodynamic Monitoring & Blood Pressure Targets Vasoactive Agents: Inotropes, Vasopressors & Antihypertensives Cardiac Complications of Brain Injury

6 Chapter 6: Neuropharmacology, Analgesia & Sedation

ICU Sedation & Analgesia Neuromuscular Blockade & Monitoring Propofol Infusion Syndrome & Drug Toxicities Antiseizure Drug Pharmacology in the ICU

7 Bleeding, Thrombosis & Hematologic Emergencies

Warfarin & Heparin Reversal Direct Oral Anticoagulant (DOAC) Reversal Antiplatelet Management & Platelet Dysfunction Venous Thromboembolism Prophylaxis & Management Transfusion, Coagulopathy, TMA & Cellular-Therapy Neurotoxicity

8 Chapter 8: Systemic ICU Care, Fluids, Electrolytes & Endocrine

Hyponatremia & Osmoregulation: SIADH vs Cerebral Salt Wasting Diabetes Insipidus, Hypernatremia & Endocrine Crises Critical Care Prophylaxis, Nutrition & Infection Prevention

9 Systemic Trauma & Environmental Injury

Polytrauma, Chest Injury & Abdominal Hemorrhage Burns, Electrical Injury & Hanging

10 Cardiac Emergencies & Mechanical Support

IABP, Ventricular Devices & ECMO Acute Coronary, Valvular, Rhythm & Aortic Emergencies

11 Kidney Injury, Acid–Base & Renal Replacement

Acute Kidney Injury & Renal Drug Clearance Acid–Base Disorders, Electrolytes & Renal Replacement

12 Systemic Infection & Endocrine Emergencies

Sepsis, Endocarditis & Antimicrobial Principles Thyroid, Adrenal & Dysglycemic Emergencies

13 Gastrointestinal & Hepatic Emergencies

Acute Abdomen, GI Bleeding & Abdominal Compartment Syndrome Acute Liver Failure, Cirrhosis & Hepatic Drug Effects

14 Chapter 9: Neuroimaging in the Neuro-ICU

Non-Contrast CT & CT Angiography CT Perfusion & Advanced Perfusion Imaging Magnetic Resonance Imaging in Critical Illness

15 Chapter 10: Electrophysiology & Neuromonitoring

Continuous EEG & ACNS Standardized Critical Care Terminology Invasive Neuromonitoring: ICP & External Ventricular Drains Multimodal Monitoring: PbtO2, Microdialysis & Transcranial Doppler

16 Angiography, Electrodiagnosis & CSF Analysis

Conventional Angiography & Cranial–Spinal Shunts EMG, Nerve Conduction & Acute Muscle Disease CSF Analysis: Infection, Inflammation & Hemorrhage

17 Chapter 11: Bedside Procedures, Ultrasound & Death by Neurologic Criteria

Critical Care Procedural Skills Critical Care Ultrasound & Echocardiography Determination of Death by Neurologic Criteria

18 Chapter 12: Acute Ischemic Stroke & Reperfusion Therapies

Acute Ischemic Stroke Management & Thrombolysis Endovascular Thrombectomy & Large Vessel Occlusion Malignant Hemispheric & Cerebellar Infarction

19 Chapter 13: Spontaneous Intracerebral Hemorrhage & Intraventricular Hemorrhage

Acute Intraparenchymal Hemorrhage Management Intraventricular Hemorrhage & Hydrocephalus Surgical Evacuation & Minimally Invasive Surgery in ICH

20 Chapter 14: Aneurysmal Subarachnoid Hemorrhage & Delayed Cerebral Ischemia

Aneurysmal Subarachnoid Hemorrhage: Acute Resuscitation & Securing Delayed Cerebral Ischemia & Cerebral Vasospasm Non-Aneurysmal Subarachnoid Hemorrhage & Vascular Malformations

21 Venous, Spinal & Traumatic Vascular Disease

Cerebral Venous Thrombosis & Spinal Cord Infarction Traumatic Dissection, Carotid–Cavernous Fistula & Penetrating Injury

22 Chapter 15: Traumatic Brain & Spinal Cord Injury

Severe Traumatic Brain Injury & Contusions Acute Traumatic Spinal Cord Injury & Neurogenic Shock Spine Trauma, Fractures & Cord Syndromes

23 Chapter 16: Status Epilepticus, Seizures & Neuromuscular Emergencies

Status Epilepticus: Convulsive & Non-Convulsive Refractory & Super-Refractory Status Epilepticus Acute Neuromuscular Respiratory Failure

24 Chapter 17: Post-Cardiac Arrest Care, CNS Infections & Encephalitis

Targeted Temperature Management & Post-Cardiac Arrest Care Post-Cardiac Arrest Neuroprognostication Acute CNS Infections, Encephalitis & Inflammatory Emergencies

25 Neuroinflammation & Neurooncology

Fulminant Demyelination & Autoimmune Encephalitis Brain, Spinal & Leptomeningeal Cancer Emergencies

26 Pregnancy, Transplantation & Pediatric Care

Pregnancy, Postpartum & Post-Transplant Neurologic Care Pediatric Neurocritical Care

27 Chapter 18: Neurosurgical & Perioperative Emergencies

Postoperative Neurosurgical Complications Device Complications: EVDs, Shunts & ICP Monitors Cerebral Hyperperfusion Syndrome & Post-Interventional Emergencies

28 Chapter 19: Ethics, Palliative Care & Organ Donation in the Neuro-ICU

Communication, Surrogate Decision-Making & Conflict Resolution Neuroprognostication Ethics, Withdrawal of Life Support & Palliative Care Organ Donation & Management of the Deceased Donor

Propofol Infusion Syndrome & Drug Toxicities

Key Takeaways Explain This Topic AI

Propofol Infusion Syndrome (PRIS) is a lethal mitochondrial toxicity characterized by refractory high-anion-gap lactic acidosis, rhabdomyolysis, hypertriglyceridemia, acute renal failure, and cardiogenic shock.

PRIS results from propofol-mediated inhibition of carnitine palmitoyltransferase-1 (CPT-1) and uncoupling of electron transport chain complexes I, II, and IV, leading to myocyte energy failure.

Major PRIS risk factors include infusion rates exceeding 4 to 5 mg/kg/h (> 67 to 83 µg/kg/min), infusion durations exceeding 48 hours, young age, and concurrent exogenous catecholamines or systemic corticosteroids.

Electrocardiographic hallmarks of PRIS include a Brugada-like coved ST-segment elevation in precordial leads V1-V3, right bundle branch block, progressive bradyarrhythmias, and asystole.

Cefepime neurotoxicity results from concentration-dependent GABA-A receptor antagonism in patients with unadjusted renal impairment, causing non-convulsive status epilepticus with generalized periodic discharges that resolves rapidly with hemodialysis.

Last updated: October 2026

Propofol Infusion Syndrome & Drug Toxicities

Pharmacotherapy in the neuro-ICU carries narrow therapeutic indices. Critically ill neurological patients frequently suffer from disrupted blood-brain barriers, fluctuating organ perfusion, altered protein binding, and multi-organ failure. Among pharmacologic emergencies, Propofol Infusion Syndrome ( P R I S PRIS PR I S ) represents the most notorious and lethal iatrogenic disaster. Rapid identification of PRIS, cefepime neurotoxicity, and hyperthermic toxidromes is vital to prevent fatal multi-organ collapse.

• Propofol Infusion Syndrome (PRIS)
• Mitochondrial Pathophysiology

PRIS is a toxic mitochondrial myopathy affecting cardiac and skeletal muscle. Propofol impairs cellular energy generation through two distinct mechanisms:

Inhibition of Fatty Acid Transport: Propofol inhibits carnitine palmitoyltransferase-1 ( C P T − 1 CPT-1 CPT − 1 ) , the rate-limiting outer mitochondrial membrane enzyme responsible for converting long-chain fatty acyl-CoA into acylcarnitine for transport into the mitochondrial matrix. This blocks long-chain fatty acid β \beta β -oxidation, creating an intracellular deficit of acetyl-CoA and causing cellular accumulation of free fatty acids and toxic acylcarnitines.

Disruption of the Electron Transport Chain: Propofol directly uncouples oxidative phosphorylation and inhibits Complex I (NADH dehydrogenase), Complex II (succinate dehydrogenase), and Complex IV (cytochrome c oxidase) of the inner mitochondrial electron transport chain ( E T C ETC ETC ). Mitochondrial Mechanisms of Propofol Infusion Syndrome (PRIS)

• [ Cytosol ]
• Long-Chain Fatty Acyl-CoA ──(X CPT-1 Inhibited by Propofol)──X Matrix Entry Blocked
• Accumulation of Toxic Free Fatty Acids & Acylcarnitines
• │
• [ Inner Mitochondrial Membrane ]

NADH ──[ Complex I (Inhibited) ]──> CoQ ──[ Complex II (Inhibited) ]──> Cyt C ──[ Complex IV (Inhibited) ]──> O2

• Uncoupling of Oxidative Phosphorylation ──> Zero ATP Generation ──> Severe Cellular Energy Failure
• │
• [ Cellular Necrosis & Systemic Collapse ]
• ├── Skeletal Muscle: Severe Rhabdomyolysis, CPK > 50,000 U/L, Hyperkalemia, Myoglobinuria, AKI
• ├── Liver: Hepatic Steatosis, Severe Hepatomegaly, Impaired Lactate Clearance
• └── Myocardium: Brugada-like ECG (Coved ST V1-V3), Heart Block, Ventricular Arrhythmias, Cardiogenic Shock

Deprived of fatty acid oxidation—the primary energy source of resting myocardium and skeletal muscle—cells suffer acute bioenergetic failure, loss of membrane potential, intracellular calcium overload, and cellular necrosis.

Major Risk Factors & Priming Triggers

Dose & Duration: Infusion rates > 4 to 5 mg/kg/h > 4\text{ to }5\text{ mg/kg/h} > 4 to 5 mg/kg/h ( > 67 to 83 μ g/kg/min > 67\text{ to }83\text{ }\mu\text{g/kg/min} > 67 to 83 μ g/kg/min ) and duration > 48 hours > 48\text{ hours} > 48 hours .

Exogenous Catecholamines & Glucocorticoids: High levels of epinephrine, norepinephrine, and corticosteroids act as priming triggers. Catecholamines stimulate hormone-sensitive lipase, flooding the circulation with free fatty acids that cannot be oxidized, while glucocorticoids exacerbate muscle catabolism.

Low Carbohydrate Intake: Depletion of glycogen stores forces tissues to rely exclusively on fatty acid oxidation, accelerating bioenergetic collapse.

Demographics: Young age (pediatric patients have lower glycogen stores and higher fatty acid dependence) and acute neurologic trauma ( T B I TBI TB I , S A H SAH S A H , status epilepticus).

Clinical Presentation & Hallmarks

PRIS typically presents as an unexpected, explosive multi-system deterioration:

Refractory High-Anion-Gap Metabolic Acidosis: Severe, progressive lactic acidosis refractory to bicarbonate administration, resulting from mitochondrial inhibition and hepatic clearance failure.

Severe Rhabdomyolysis: Marked elevation of creatine kinase ( C K > 10,000 to > 100,000 U/L CK > 10{,}000\text{ to }> 100{,}000\text{ U/L} C K > 10 , 000 to > 100 , 000 U/L ), myoglobinuria ("tea-colored" urine), hyperkalemia, and acute tubular necrosis ( A T N ATN A TN ).

Hypertriglyceridemia: Plasma triglycerides frequently exceed 400 to 1000 mg/dL 400\text{ to }1000\text{ mg/dL} 400 to 1000 mg/dL due to impaired lipid clearance and continuous lipid emulsion infusion.

Hepatomegaly & Hepatic Failure: Fatty infiltration of hepatocytes causes rapid liver enlargement and transaminitis.

Refractory Cardiovascular Collapse: Progressive myocardial failure, profound cardiogenic shock refractory to high-dose inotropes, and electrical instability:

Brugada-like ECG Pattern: Coved ST-segment elevation with T-wave inversion in precordial leads V 1 to V 3 V_1\text{ to }V_3 V 1 ​ to V 3 ​ .

Progressive conduction blocks: widening QRS, right bundle branch block ( R B B B RBBB RBBB ), sinus bradycardia, ventricular tachycardia/fibrillation, and asystole.

• Prevention, Surveillance, and Emergency Management PRIS Surveillance & Emergency Protocol
• ├── Prevention: Cap infusion at <= 4 mg/kg/h (<= 67 µg/kg/min), avoid infusions > 48 hours
• ├── Monitoring: Baseline & daily triglycerides, CK, arterial blood gas (lactate), electrolytes (K+)

└── Immediate Emergency Management upon Suspicion:

• ├── 1. INSTANTLY HALT PROPOFOL (switch to ketamine, dexmedetomidine, midazolam)
• ├── 2. Hemodynamic Resuscitation: Milrinone/glucagon, pacing, VA-ECMO cannulation
• └── 3. Extracorporeal Elimination: High-flux CRRT/hemodialysis for K+, lactate, and myoglobin

Important

Because propofol has a massive volume of distribution and binds strongly to plasma proteins and lipid membranes, hemodialysis does not remove propofol itself . Continuous renal replacement therapy ( C R R T CRRT CRRT ) is lifesaving because it eliminates circulating toxic acylcarnitines, corrects profound lactic acidosis, treats lethal hyperkalemia, and clears myoglobin.

• Other ICU Drug Toxicities
• Cefepime Neurotoxicity

Cefepime is a widely prescribed fourth-generation cephalosporin that crosses the blood-brain barrier ( B B B BBB BBB ). It acts as a concentration-dependent competitive antagonist of G A B A A GABA_A G A B A A ​ receptors, disinhibiting cortical excitatory pathways.

Risk Factor: Failure to adjust cefepime doses for reduced glomerular filtration rate in acute kidney injury ( A K I AKI A K I ) or chronic renal failure.

Clinical Manifestations: Onset typically occurs 2 to 5 days after therapy initiation, presenting with altered mental status, fluctuating encephalopathy, confusion, multifocal myoclonus, asterixis, and non-convulsive status epilepticus ( N C S E NCSE NCSE ).

EEG Hallmarks: Characteristic generalized periodic discharges ( G P D s GPDs GP Ds ) with triphasic morphology at 1 to 2 Hz 1\text{ to }2\text{ Hz} 1 to 2 Hz , rhythmic delta activity, or continuous sharp-and-slow complexes.

Treatment: Immediate discontinuation of cefepime. Because cefepime exhibits low plasma protein binding ( 20 % 20\% 20% ) and renal excretion, emergent hemodialysis rapidly eliminates up to 70 % 70\% 70% of circulating drug within a single 3-hour session, leading to clinical and electrographic recovery within 24 to 48 hours.

Serotonin Syndrome vs. Neuroleptic Malignant Syndrome (NMS)

Both conditions present as life-threatening hyperthermic syndromes in the neuro-ICU but stem from opposing neurochemical pathways requiring distinct management:

Diagnostic Feature Serotonin Syndrome Neuroleptic Malignant Syndrome (NMS)

Mechanism Excessive central & peripheral 5 -HT 5\text{-HT} 5 -HT agonism ( 5 -HT 1 A , 5 -HT 2 A 5\text{-HT}_{1A}, 5\text{-HT}_{2A} 5 -HT 1 A ​ , 5 -HT 2 A ​ ) Severe central dopamine ( D 2 D_2 D 2 ​ ) receptor blockade or sudden withdrawal of dopamine agonists

Causative Agents SSRIs, SNRIs, tramadol, fentanyl, linezolid, methylene blue, triptans Antipsychotics (haloperidol, fluphenazine), antiemetics (metoclopramide), abrupt levodopa cessation

Onset & Course Rapid onset ( < 24 hours < 24\text{ hours} < 24 hours ) ; resolves rapidly ( 24 – 48 hours 24\text{--}48\text{ hours} 24 – 48 hours ) with treatment Subacute onset ( 1 – 3 days 1\text{--}3\text{ days} 1 – 3 days to weeks) ; prolonged resolution ( 1 – 2 weeks 1\text{--}2\text{ weeks} 1 – 2 weeks )

Neuromuscular Tone Hyperkinesia, tremor, spontaneous / ocular / inducible clonus, hyperreflexia Extreme generalized "lead-pipe" rigidity, akinesia, hyporeflexia

Neuromuscular Distribution Lower extremities markedly more affected than upper Generalized, symmetric across axial and appendicular muscles

Pupils & Bowel Mydriasis , hyperactive bowel sounds, diarrhea Normal pupils, normal or decreased bowel sounds

Diagnostic Standard Hunter Toxicity Criteria (Clonus is the essential sign) DSM-5 Criteria (Rigidity + Hyperthermia + D 2 D_2 D 2 ​ agent)

Specific Antidote Cyproheptadine ( 5 -HT 2 A 5\text{-HT}_{2A} 5 -HT 2 A ​ antagonist, 12 mg 12\text{ mg} 12 mg PO/NG load) Dantrolene (ryanodine antagonist) and Bromocriptine ( D 2 D_2 D 2 ​ agonist)

Warning

In Serotonin Syndrome, avoid succinylcholine for intubation due to hyperkalemia risks. In NMS, antipyretics (acetaminophen, NSAIDs) are completely ineffective because the hyperthermia is driven by intense peripheral muscular thermogenesis and hypothalamic set-point derangement rather than prostaglandin-mediated pyrexia.