Study guide
18.2 Alcohol & Sedative Withdrawal, Wernicke Encephalopathy & Drug-Induced Encephalopathy
ABIM Critical Care Medicine Study Guide Exam
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1 Chapter 1: Exam Orientation: Format, Blueprint & Study Strategy
1.1 ABIM Critical Care Medicine Exam: Format, Blueprint & Study Strategy
2 Chapter 2: Acute Respiratory Failure & ARDS
2.1 ARDS Definition, Pathophysiology & Phenotypes 2.2 Lung-Protective Mechanical Ventilation 2.3 Refractory ARDS: Prone Positioning, Neuromuscular Blockade & VV-ECMO
3 Chapter 3: Obstructive Airways, Pulmonary Vascular & Pleural Emergencies
3.1 Severe Asthma & COPD Exacerbations in the ICU 3.2 Massive & Submassive Pulmonary Embolism 3.3 Pulmonary Hypertension & Right Ventricular Failure in the ICU 3.4 Massive Hemoptysis, Complex Pleural Effusions & Thoracic Drainage
4 Chapter 4: Airway, Parenchymal & Nonthrombotic Pulmonary Emergencies
4.1 Airway Management, Upper-Airway Obstruction & Artificial-Airway Complications 4.2 Diffuse Alveolar Hemorrhage, Interstitial Lung Disease, Pulmonary Vasculitis & Noncardiogenic Edema 4.3 Severe Community-Acquired & Viral Pneumonia 4.4 Nonthrombotic Embolism (Air, Fat, Amniotic Fluid, Tumor, Septic) & Acute Chest Syndrome
5 Chapter 5: Mechanical Ventilation Modes, Dyssynchrony & Liberation
5.1 Mechanical Ventilator Modes & Advanced Breath Delivery 5.2 Patient-Ventilator Dyssynchrony & Waveform Analysis 5.3 Ventilator Liberation, Spontaneous Breathing Trials & Post-Extubation Support
6 Chapter 6: Shock Syndromes & Hemodynamic Principles
6.1 Shock Classification, Cellular Pathophysiology & Biomarkers 6.2 Hemodynamic Monitoring: Arterial Lines, CVP & Pulmonary Artery Catheter 6.3 Dynamic Assessment of Fluid Responsiveness & Resuscitation Targets
7 Chapter 7: Vasoactive Therapies & Mechanical Circulatory Support
7.1 Vasopressors & Inotropes: Pharmacology & Clinical Titration 7.2 Temporary Mechanical Circulatory Support: IABP, Impella & TandemHeart 7.3 Venoarterial ECMO (VA-ECMO) & Differential Hypoxemia 7.4 Post-Cardiac Arrest Care, Targeted Temperature Management & Neuroprognostication
8 Chapter 8: Acute Kidney Injury & Renal Replacement Therapy
8.1 KDIGO AKI Classification, Etiologies & Diagnostic Evaluation 8.2 Continuous Renal Replacement Therapy (CRRT) vs Intermittent Hemodialysis 8.3 Indications & Timing for RRT in Critical Illness: AKIKI & STARRT-AKI
9 Chapter 9: Electrolyte, Acid-Base & Endocrine Emergencies
9.1 Severe Dysnatremias: Hyponatremia, Hypernatremia & Osmotic Demyelination 9.2 Potassium, Calcium, Magnesium & Phosphate Disorders 9.3 Complex & Mixed Acid-Base Disorders: Boston vs Copenhagen vs Stewart 9.4 Endocrine Crises: DKA, HHS, Thyroid Storm, Myxedema Coma & Adrenal Crisis
10 Chapter 10: Glycemic Control, Hyperammonemia, Pituitary & Adrenal Disorders
10.1 ICU Glycemic Control & Severe Hypoglycemia 10.2 Non-Hepatic Hyperammonemia & Metabolic Encephalopathy 10.3 Pituitary Emergencies, Adrenal Excess & Critical Illness-Related Corticosteroid Insufficiency
11 Chapter 11: Acute Coronary Syndromes & Cardiac Arrhythmias
11.1 Acute Coronary Syndromes & Mechanical Complications of Myocardial Infarction 11.2 Critical Tachyarrhythmias: Atrial Fibrillation with RVR, VT & VF 11.3 Critical Bradyarrhythmias, Conduction Blocks & Temporary Cardiac Pacing
12 Chapter 12: Acute Heart Failure, Valvular & Pericardial Emergencies
12.1 Acute Decompensated Heart Failure & Cardiogenic Pulmonary Edema 12.2 Acute Valvular Regurgitation & Prosthetic Valve Emergencies 12.3 Pericardial Tamponade & Acute Aortic Syndromes
13 Chapter 13: Myocardial Disease, Hypertensive & Cardiac Device Emergencies
13.1 Fulminant Myocarditis, Stress & Peripartum Cardiomyopathy, and Hypertrophic Cardiomyopathy 13.2 Hypertensive Emergencies & Ruptured Abdominal Aortic Aneurysm 13.3 Implanted Cardiac Devices, LVAD Emergencies & Electrical Storm
14 Chapter 14: Sepsis & Systemic Infectious Diseases
14.1 Sepsis-3 Definitions & Surviving Sepsis Campaign 2026 Guidelines 14.2 Refractory Septic Shock & Adjunctive Therapies 14.3 Multidrug-Resistant Pathogens & Antimicrobial Stewardship in the ICU
15 Chapter 15: ICU-Acquired & Severe Focal Infections
15.1 Hospital-Acquired & Ventilator-Associated Pneumonia 15.2 Central Line-Associated Bloodstream Infections & Catheter-Associated UTIs 15.3 Intra-Abdominal Sepsis, Necrotizing Soft Tissue Infections & CNS Infections
16 Chapter 16: Focal, Special-Host & Systemic Infections
16.1 CNS Infections Beyond Bacterial Meningitis: Encephalitis, Brain Abscess & Epidural Abscess 16.2 Infections in the Immunocompromised Host, Tropical & Bioterror Infections 16.3 Infective Endocarditis, Device Infections & Other Focal Cardiovascular Infections 16.4 Antimicrobial Pharmacokinetics, Allergy, Toxicity & Infection Prevention 16.5 Gastrointestinal & Hepatobiliary Infections: Fulminant C. difficile, Typhlitis, CMV Colitis & Abscesses
17 Chapter 17: Neurocritical Care & Coma
17.1 Coma, Altered Mental Status & Acute Delirium in the ICU 17.2 Status Epilepticus & Non-Convulsive Status Epilepticus 17.3 Acute Ischemic Stroke & Intracranial Hemorrhage
18 Chapter 18: Cerebrovascular Syndromes, Encephalopathy & Withdrawal States
18.1 Cerebral Venous Sinus Thrombosis, PRES & Reversible Cerebral Vasoconstriction Syndrome 18.2 Alcohol & Sedative Withdrawal, Wernicke Encephalopathy & Drug-Induced Encephalopathy
19 Chapter 19: Intracranial Hypertension & Neuromuscular Weakness
19.1 Intracranial Pressure Monitoring, Cerebral Perfusion & Tiered ICP Management 19.2 Acute Neuromuscular Respiratory Failure, ICU-Acquired Weakness & Brain Death Determination
20 Chapter 20: Traumatic Brain Injury, Spinal Cord Injury & Toxin-Mediated Paralysis
20.1 Traumatic Brain Injury Management & Paroxysmal Sympathetic Hyperactivity 20.2 Acute Spinal Cord Injury, Neurogenic Shock & Autonomic Dysreflexia 20.3 Toxin-Mediated Paralysis & Neuromuscular Crises: Botulism, Tetanus, Tick Paralysis & Myasthenic Crisis
21 Chapter 21: Gastrointestinal, Hepatic & Abdominal Emergencies
21.1 Acute Upper & Lower Gastrointestinal Bleeding in the ICU 21.2 Acute Liver Failure & Severe Acute Pancreatitis 21.3 Abdominal Compartment Syndrome & Acute Mesenteric Ischemia
22 Chapter 22: Luminal GI Emergencies & Complications of Cirrhosis
22.1 Esophageal, Gastric & Bowel Emergencies: Perforation, Obstruction, Ogilvie Syndrome & Colonic Ischemia 22.2 Complications of Cirrhosis: Alcohol-Associated Hepatitis, Hepatorenal Syndrome & Pulmonary Vascular Syndromes
23 Chapter 23: Trauma, Burns & Perioperative Critical Care
23.1 Polytrauma Resuscitation, Damage Control & Massive Transfusion 23.2 Severe Burn Injury, Inhalation Injury & Environmental Emergencies 23.3 Perioperative Critical Care for High-Risk Surgical Patients
24 Chapter 24: Thoracic Trauma, Environmental Injury & Obstetric Critical Care
24.1 Thoracic Trauma: Flail Chest, Pulmonary Contusion, Great Vessel & Tracheobronchial Injury 24.2 Environmental Injury: Drowning, Diving, Altitude, Heat, Cold, Electrical & Radiation 24.3 Obstetric & Genitourinary Emergencies and the Physiology of Pregnancy
25 Chapter 25: Transplantation, Donor Management & Post-Cardiac Surgery Care
25.1 Solid Organ Transplant Recipients & Deceased Donor Management 25.2 Post-Cardiac Surgery Critical Care: Bleeding, Tamponade, Low Output & Vasoplegia
26 Chapter 26: Hematologic Emergencies, Toxicology, Critical Ultrasound & ICU Liberation
26.1 Hematologic Emergencies in the ICU: HIT, DIC, TMA & Anticoagulant Reversal 26.2 Critical Care Toxicology, Toxidromes & Specific Antidotes 26.3 Critical Care Point-of-Care Ultrasound (POCUS) 26.4 ICU Liberation, Analgosedation, Goals of Care & Critical Care Ethics
27 Chapter 27: Transfusion Medicine, Hematologic & Oncologic Disorders
27.1 Transfusion Medicine: Products, Thresholds, Reactions & Apheresis 27.2 Red and White Cell Disorders, Hemoglobinopathies, Factor Deficiencies & Hypercoagulable States 27.3 Oncologic Emergencies, Hematopoietic Cell Transplant Complications & Cellular Therapy Toxicity
28 Chapter 28: Clinical Pharmacology, Adverse Drug Reactions & Specific Poisonings
28.1 Pharmacokinetic Principles, Dose Adjustment & Drug Interactions in Critical Illness 28.2 Adverse Drug Reactions: Anaphylaxis, Severe Cutaneous Reactions & Hyperthermic Syndromes 28.3 Specific Poisonings: Sodium-Channel Blockers, Lithium, Valproate, Theophylline, Iron, Sulfonylureas & Methemoglobinemia
29 Chapter 29: Ethics, Research Methods, Administration & Abdominal Ultrasound
29.1 Advance Care Planning, Nonbeneficial Treatment, Informed Consent & Confidentiality 29.2 Critical Care Research Methods, Statistics, IRB Oversight & Quality Improvement 29.3 Abdominal, Vascular & Procedural Point-of-Care Ultrasound
18.2 Alcohol & Sedative Withdrawal, Wernicke Encephalopathy & Drug-Induced Encephalopathy
Key Takeaways Explain This Topic AI
Symptom-triggered benzodiazepine dosing using a validated scale shortens treatment and lowers total dose compared with fixed-schedule dosing in alcohol withdrawal.
Phenobarbital and propofol act at the GABA-A receptor independent of benzodiazepine binding and are the escalation options for benzodiazepine-refractory delirium tremens.
Dexmedetomidine controls autonomic hyperactivity in alcohol withdrawal but does not prevent seizures, so it is an adjunct rather than a substitute for GABAergic therapy.
Wernicke encephalopathy is treated with thiamine 500 mg intravenously three times daily for 2 to 3 days, given before any glucose load.
ICANS from CAR-T therapy is graded by the ICE score and treated with corticosteroids, with tocilizumab reserved for concurrent cytokine release syndrome because it does not penetrate the central nervous system well.
Last updated: October 2026
Alcohol Withdrawal: Timeline and Severity
- Time after the last drink Syndrome
- 6 to 24 hours Minor withdrawal: tremor, anxiety, sweating, tachycardia, hypertension, nausea; sensorium intact
- 12 to 48 hours Withdrawal seizures , usually generalized tonic-clonic, often in a brief flurry
- 12 to 48 hours Alcoholic hallucinosis: visual or tactile hallucinations with a clear sensorium
48 to 96 hours Delirium tremens : delirium with disorientation, severe autonomic hyperactivity, hyperthermia, and hallucinations; untreated mortality is substantial
Risk factors for severe withdrawal : prior delirium tremens or withdrawal seizures, a high blood alcohol level despite being alert, a long heavy-drinking history, concurrent illness or surgery, older age, and electrolyte derangement. The PAWSS score screens for risk at admission.
Treatment
Benzodiazepines are first-line because they are the only class shown to reduce seizures and delirium.
Symptom-triggered dosing using a validated scale (CIWA-Ar, or a sedation-agitation-based protocol in intubated patients) shortens duration and lowers total dose compared with fixed schedules. Fixed schedules remain useful where monitoring is limited or the patient cannot be assessed.
Diazepam and chlordiazepoxide have long-acting active metabolites that self-taper; lorazepam is preferred with significant liver disease because it is glucuronidated without active metabolites.
Escalate quickly in severe withdrawal: repeated intravenous diazepam 10 mg doses, doubling as needed.
Benzodiazepine-refractory delirium tremens : patients requiring very large cumulative doses need an agent acting at a different site on the GABA-A receptor.
Phenobarbital : long half-life, predictable, effective; watch for respiratory depression and hypotension.
Propofol : requires intubation; it also acts at GABA-A independent of the benzodiazepine site.
Ketamine is used as an adjunct to reduce benzodiazepine requirements.
Dexmedetomidine controls autonomic hyperactivity and agitation but does not prevent seizures or treat the underlying GABA deficit , so it is an adjunct only.
Avoid beta-blockers or clonidine as monotherapy : they blunt the vital-sign markers while the patient remains at risk of seizures and delirium.
Antipsychotics are adjuncts for hallucinations and agitation and lower the seizure threshold; they never replace GABAergic therapy.
Supportive care : thiamine before glucose, folate, multivitamins, and aggressive replacement of magnesium, potassium, and phosphate (watch for refeeding syndrome). Treat concurrent illness, which commonly precipitates severe withdrawal, and screen for occult infection, trauma, pancreatitis, and subdural hematoma.
Sedative-hypnotic withdrawal (benzodiazepines, barbiturates, baclofen, gamma-hydroxybutyrate) looks similar and is treated by substituting and tapering a long-acting agent of the same class. Baclofen withdrawal after pump failure causes severe rigidity, fever, and rhabdomyolysis that mimics neuroleptic malignant syndrome; restore baclofen urgently.
Wernicke Encephalopathy and Korsakoff Syndrome
Classic triad : encephalopathy, oculomotor abnormalities (nystagmus, bilateral abducens palsy, conjugate gaze palsy), and gait ataxia . All three are present in only a minority, so treat on suspicion.
At-risk patients : alcohol use disorder, hyperemesis gravidarum, bariatric surgery, prolonged parenteral nutrition without vitamins, malignancy and chemotherapy, dialysis, and refeeding after starvation.
MRI : symmetric signal change in the mammillary bodies, medial thalami, periaqueductal gray, and tectal plate.
Treatment : thiamine 500 mg IV three times daily for 2 to 3 days , then 250 mg daily for several days, then oral supplementation. Give thiamine before glucose , because a carbohydrate load consumes the remaining thiamine and can precipitate or worsen the syndrome. Replace magnesium , which is a cofactor for thiamine-dependent enzymes; untreated hypomagnesemia causes thiamine refractoriness.
Untreated Wernicke encephalopathy progresses to Korsakoff syndrome : irreversible anterograde and retrograde amnesia with confabulation.
Drug-Induced and Metabolic Encephalopathy
Agent or cause Signature Management
Cefepime (and other beta-lactams) Myoclonus, encephalopathy, nonconvulsive status; kidney impairment with unadjusted dosing Stop or dose-adjust; dialysis if severe
Ifosfamide Encephalopathy within 1 to 2 days of infusion, sometimes with seizures Stop the infusion; methylene blue is used, with thiamine as an adjunct
Calcineurin inhibitors (tacrolimus, cyclosporine) Tremor, seizures, PRES Reduce the level or switch agents
Chemotherapy-related Methotrexate (stroke-like syndrome, treated with leucovorin and aminophylline), cytarabine (cerebellar toxicity), 5-fluorouracil (with DPD deficiency), cisplatin Stop the drug; agent-specific measures
Serotonin syndrome and neuroleptic malignant syndrome Hyperthermia with clonus and hyperreflexia, or with lead-pipe rigidity See the adverse drug reaction section
Opioid and sedative accumulation Reduced level of arousal with miosis; prolonged with kidney or liver failure and obesity Dose interruption, naloxone when appropriate
Lithium, valproate, and antiepileptic toxicity Tremor, ataxia, encephalopathy, hyperammonemia with valproate Levels, drug withdrawal, dialysis for lithium
Serotonergic antibiotics Linezolid with SSRIs Stop and support
Uremia, hepatic failure, hyponatremia, hypercapnia, hypoglycemia, hypothyroidism, hypercalcemia Metabolic patterns Correct the derangement
Important
Any ICU patient with unexplained encephalopathy needs an EEG : nonconvulsive status epilepticus accounts for a meaningful share of unexplained coma and is otherwise invisible.
Neurotoxicity of Immune Effector Cell Therapy (ICANS)
Setting : CAR-T cell therapy and bispecific T-cell engagers, usually within 1 to 3 weeks and typically after cytokine release syndrome begins.
Presentation : expressive aphasia and dysgraphia first, then confusion, tremor, somnolence, seizures, and in severe cases cerebral edema.
Grading : the ICE score (immune effector cell-associated encephalopathy) tests orientation, naming, following commands, writing, and attention out of 10 points; grading also uses level of consciousness, seizures, motor findings, and raised intracranial pressure or edema.
Management :
Corticosteroids (dexamethasone, escalating to high-dose methylprednisolone for grade 3 or 4) are the mainstay.
Tocilizumab treats concurrent cytokine release syndrome but penetrates the central nervous system poorly and does not treat ICANS itself; it may even raise CSF IL-6.
Antiseizure prophylaxis (commonly levetiracetam), EEG monitoring, aspiration precautions, and treatment of cerebral edema.
Hold oral intake in patients with aphasia or reduced consciousness; many require intubation for airway protection.
Related entities: immune checkpoint inhibitor encephalitis (treated with steroids and drug discontinuation), and hemophagocytic lymphohistiocytosis with neurologic involvement.