Study guide
20.1 Traumatic Brain Injury Management & Paroxysmal Sympathetic Hyperactivity
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
20.1 Traumatic Brain Injury Management & Paroxysmal Sympathetic Hyperactivity
Key Takeaways Explain This Topic AI
Brain Trauma Foundation guidance treats intracranial pressure above 22 mmHg and targets cerebral perfusion pressure between 60 and 70 mmHg in severe traumatic brain injury.
In CRASH-3, tranexamic acid given within 3 hours of injury reduced head injury-related death in mild-to-moderate traumatic brain injury without increasing vascular occlusive events.
Hypotension and hypoxemia are the two prehospital variables most strongly associated with death after severe traumatic brain injury; a single systolic pressure below 90 mmHg roughly doubles mortality.
Paroxysmal sympathetic hyperactivity presents with episodic hypertension, tachycardia, tachypnea, hyperthermia, sweating, and dystonic posturing, treated with propranolol, gabapentin, and clonidine.
Blunt cerebrovascular injury is screened with CT angiography using the expanded Denver criteria, and most low-grade injuries are treated with aspirin or heparin to prevent stroke.
Last updated: October 2026
Primary and Secondary Injury
Primary injury happens at impact: contusion, axonal shearing (diffuse axonal injury), epidural and subdural hematoma, traumatic subarachnoid hemorrhage, and skull fracture. Nothing in the ICU reverses it.
Secondary injury develops over hours to days and is what critical care prevents:
Hypotension and hypoxemia : a single episode of systolic pressure below 90 mmHg roughly doubles mortality, and hypoxemia compounds it. These are the two prehospital variables most strongly linked to death.
Intracranial hypertension and reduced cerebral perfusion pressure.
Fever, seizures, hyperglycemia and hypoglycemia, hyponatremia, and anemia.
Excitotoxicity, mitochondrial failure, and inflammation.
Early Management
- Priority Target
- Oxygenation SpO2 above 90%; avoid hypoxemia and extreme hyperoxia
- Ventilation PaCO2 35 to 45 mmHg; hyperventilation only as a brief bridge for herniation
Blood pressure Systolic at least 110 mmHg (ages 15 to 49 and over 70) or at least 100 mmHg (ages 50 to 69); avoid any hypotension
- Cerebral perfusion pressure 60 to 70 mmHg
- Intracranial pressure Treat above 22 mmHg
- Glucose 140 to 180 mg/dL; avoid hypoglycemia
- Temperature Normothermia; treat fever aggressively
- Sodium Avoid hypotonic fluids; use isotonic saline. Hyponatremia worsens edema
- Coagulopathy Reverse anticoagulants urgently; tranexamic acid within 3 hours (CRASH-3)
Seizures Prophylaxis for 7 days after severe injury with phenytoin (the agent in the supporting trial) or levetiracetam
Nutrition Early enteral feeding, with transpyloric feeding when gastroparesis prevents gastric feeding
Venous thromboembolism Mechanical prophylaxis immediately; add pharmacologic prophylaxis once the hematoma is stable, typically within 24 to 72 hours
CRASH-3 randomized more than 12,000 patients with traumatic brain injury to tranexamic acid or placebo. Treatment within 3 hours reduced head injury-related death in mild-to-moderate injury (GCS 9 to 15) without an excess of vascular occlusive events; benefit was not seen in patients with a GCS of 3 or bilateral unreactive pupils. Note the contrast with CRASH-2 , where tranexamic acid reduced death from bleeding in general trauma within 3 hours.
Surgical indications include an epidural hematoma larger than 30 mL regardless of GCS, an acute subdural hematoma with a thickness above 10 mm or midline shift above 5 mm, a contusion with mass effect and deterioration, posterior fossa lesions with compression, and depressed open skull fractures. Decompressive craniectomy decisions follow the DECRA and RESCUEicp evidence discussed in the intracranial hypertension section.
Monitoring : place an intracranial pressure monitor for severe injury (GCS 3 to 8) with an abnormal CT, or a normal CT with two of age over 40, motor posturing, or systolic pressure below 90 mmHg. An external ventricular drain also allows CSF drainage. Multimodality options include brain tissue oxygen tension (the BOOST-3 trial compared management strategies), jugular venous oximetry, and continuous EEG.
Specific Problems After Head Injury
Cerebral contusion blossoming : lesions expand over 24 to 72 hours, so repeat imaging and deterioration thresholds matter.
Traumatic subarachnoid hemorrhage : vasospasm occurs but is less common than after aneurysmal bleeding.
Post-traumatic hydrocephalus : consider it with failure to improve or late deterioration.
Pituitary dysfunction : diabetes insipidus and anterior pituitary failure occur acutely and chronically; screen for cortisol deficiency in refractory hypotension.
Neurogenic pulmonary edema and cardiac stunning from the catecholamine surge.
Coagulopathy : tissue factor release can cause disseminated intravascular coagulation; follow fibrinogen and platelets.
Hyponatremia : distinguish SIADH (euvolemic, concentrated urine, treated with fluid restriction) from cerebral salt wasting (hypovolemic, high urine sodium with volume depletion, treated with salt and volume). Treating one as the other worsens the patient.
Blunt Cerebrovascular Injury
Mechanism : carotid or vertebral artery dissection from hyperextension and rotation, direct blow, or fracture through the foramen transversarium or carotid canal.
Screen with CT angiography (expanded Denver criteria): cervical spine fracture (especially C1 to C3, subluxation, or transverse foramen involvement), basilar skull fracture involving the carotid canal, Le Fort II or III fracture, a seat-belt sign or neck hematoma, severe traumatic brain injury (GCS below 6), near-hanging with anoxia, or an unexplained focal neurologic deficit.
Grading (Biffl) runs from intimal irregularity (grade I) to occlusion (grade IV) and transection (grade V).
Treatment : antithrombotic therapy (aspirin or systemic heparin) reduces stroke in grades I to III; endovascular treatment is used for pseudoaneurysms and selected high-grade lesions. Weigh bleeding risk from other injuries, and repeat imaging in 7 to 10 days for low-grade lesions.
Paroxysmal Sympathetic Hyperactivity (PSH)
Setting : usually 1 to 2 weeks after severe traumatic brain injury (also after hypoxic injury, stroke, and hemorrhage), in patients with diffuse axonal injury.
Presentation : paroxysms lasting minutes to hours, often several times a day, with hypertension, tachycardia, tachypnea, hyperthermia , profuse sweating, and dystonic posturing or rigidity . Episodes are triggered by pain, suctioning, turning, bladder distension, or constipation.
Diagnosis uses the PSH Assessment Measure, which combines a clinical feature scale with a diagnostic likelihood score. It is a diagnosis of exclusion : rule out sepsis, pulmonary embolism, seizures, withdrawal syndromes, pain, serotonin syndrome, neuroleptic malignant syndrome, malignant hyperthermia, thyroid storm, and raised intracranial pressure.
Consequences : high energy expenditure with weight loss, muscle contractures and heterotopic ossification, secondary brain injury from hyperthermia, and prolonged ICU stay.
Treatment :
Reduce triggers : analgesia, bowel and bladder care, cluster care, and a quiet environment.
Propranolol : a nonselective beta-blocker with central penetration, which also reduces energy expenditure.
Gabapentin : targets the paroxysmal allodynic component and is often the most effective long-term agent.
Clonidine or dexmedetomidine : central alpha-2 agonists for sympathetic outflow.
Opioids , particularly morphine, abort acute episodes.
Bromocriptine for hyperthermia and dystonia, baclofen or intrathecal baclofen and benzodiazepines for severe posturing.
Avoid chasing each episode with antibiotics and cultures once the pattern is established, and avoid antipyretics alone, which do not control the syndrome.