Study guide
24.2 Environmental Injury: Drowning, Diving, Altitude, Heat, Cold, Electrical & Radiation
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
24.2 Environmental Injury: Drowning, Diving, Altitude, Heat, Cold, Electrical & Radiation
Key Takeaways Explain This Topic AI
In drowning, hypoxemia from surfactant washout and atelectasis is the central problem; management is oxygenation with PEEP, and prophylactic antibiotics and corticosteroids are not indicated.
Hypothermic cardiac arrest is resuscitated with rewarming, because a patient is not dead until warm and dead; serum potassium above about 12 mEq/L suggests death before cooling.
Heat stroke outcomes depend on cooling within 30 minutes; cold-water immersion is the fastest method, and antipyretics and dantrolene are ineffective.
Arterial gas embolism and severe decompression sickness are treated with 100% oxygen, supine positioning, fluids, and urgent hyperbaric oxygen therapy.
The rate of absolute lymphocyte count decline in the first 48 hours is the best early predictor of radiation dose and prognosis in acute radiation syndrome.
Last updated: October 2026
Drowning
Pathophysiology : the fundamental insult is hypoxemia . Aspirated water washes out surfactant, causing alveolar collapse, shunt, and noncardiogenic pulmonary edema. Fresh and salt water differ little clinically; electrolyte shifts are rarely significant.
Resuscitation : begin with ventilation and oxygenation , because the arrest is hypoxic (this is the one adult arrest where rescue breathing matters most). Cervical spine precautions apply only with a plausible mechanism, such as a dive.
Hospital care :
Oxygen with PEEP (noninvasive ventilation or intubation with lung-protective settings), since the problem is shunt and atelectasis.
No prophylactic antibiotics and no corticosteroids ; treat pneumonia if it develops (watch for Aeromonas and Pseudomonas in fresh water, and fungi in contaminated water).
Rewarming for hypothermia, which frequently coexists.
Observation for 4 to 8 hours in asymptomatic patients with normal oxygenation; symptoms of significance develop within that window, and "delayed drowning" days later is a myth.
Prognosis : depends on submersion duration and the initial neurologic examination. Cold-water submersion with rapid cooling occasionally permits survival after prolonged arrest, so rewarm before prognosticating .
Diving Injuries
Syndrome Mechanism Treatment
Pulmonary barotrauma and arterial gas embolism Breath-holding during ascent causes alveolar rupture; gas enters pulmonary veins and embolizes to brain and coronaries. Symptoms begin within minutes of surfacing 100% oxygen, supine position, fluids, and urgent hyperbaric oxygen ; treat a pneumothorax with a chest tube before compression
Decompression sickness, type I Nitrogen bubbles in joints and skin: "the bends," cutis marmorata; onset usually within hours Oxygen, fluids, hyperbaric oxygen for significant symptoms
Decompression sickness, type II Neurologic (spinal cord more than brain), vestibular, or cardiopulmonary ("the chokes") 100% oxygen, fluids, and hyperbaric oxygen ; avoid air travel until treated
Nitrogen narcosis Inert gas narcosis at depth Resolves with ascent
Middle ear and sinus barotrauma Failure to equalize Decongestants, analgesia; avoid further diving until healed
Oxygen toxicity High partial pressures: seizures (central) or pulmonary injury Reduce the oxygen partial pressure
Air travel after diving, and transport in an unpressurized aircraft, worsens bubble disease. For transport, fly low (below about 1,000 feet of cabin altitude change) or in a pressurized aircraft at sea-level cabin pressure.
High-Altitude Illness
Condition Features Treatment
Acute mountain sickness Headache with nausea, fatigue, dizziness after ascent Stop ascending, descend if worsening; acetazolamide, analgesia; dexamethasone for moderate-to-severe illness
High-altitude cerebral edema Ataxia, confusion, coma Immediate descent , dexamethasone, oxygen, hyperbaric bag
High-altitude pulmonary edema Dyspnea at rest, cough, pink frothy sputum, 2 to 4 days after ascent; from uneven hypoxic pulmonary vasoconstriction Descent and oxygen ; nifedipine (and phosphodiesterase-5 inhibitors) as adjuncts; a hyperbaric bag when descent is delayed
Acetazolamide (125 mg twice daily) prevents acute mountain sickness by inducing a metabolic acidosis that drives ventilation; it is a sulfonamide derivative.
Heat Illness
Heat exhaustion : volume and salt depletion with a core temperature usually below 40 °C and preserved mental status. Treat with rest, cooling, and oral or intravenous salt-containing fluids.
Heat stroke : core temperature above 40 °C with central nervous system dysfunction .
Classic (non-exertional) : older adults in heat waves, often anhidrotic, with chronic illness and drugs (anticholinergics, diuretics, antipsychotics).
Exertional : athletes, military recruits, and laborers; often still sweating, with rhabdomyolysis, acute kidney injury, disseminated intravascular coagulation, and hepatic injury.
Treatment : cool fast . The target is a core temperature below about 39 °C within 30 minutes. Cold-water immersion is the fastest method for exertional heat stroke; evaporative cooling with mist and fans suits older classic cases. Use ice packs to the groin, axillae, and neck and cold intravenous fluids as adjuncts; stop active cooling at about 38.5 °C to avoid overshoot.
Antipyretics do not work (the hypothalamic set point is normal), and dantrolene is ineffective in heat stroke. Treat shivering with benzodiazepines.
Manage complications: rhabdomyolysis with fluids, hepatic failure (which can be fulminant), coagulopathy, seizures, and ARDS.
Accidental Hypothermia
- Stage Core temperature Findings
- Mild 32 to 35 °C Shivering, tachycardia, ataxia, cold diuresis
- Moderate 28 to 32 °C Shivering stops, bradycardia, atrial fibrillation, J waves (Osborn waves), stupor
- Severe Below 28 °C Coma, hypotension, ventricular fibrillation risk, apparent rigor
Rewarming :
Passive external (dry blankets, warm environment) for mild cases.
Active external (forced-air warming, heating pads) and minimally invasive (warm intravenous fluids, warm humidified oxygen).
Active internal : bladder, gastric, or thoracic lavage; and extracorporeal rewarming (ECMO or cardiopulmonary bypass) for hypothermic cardiac arrest or severe instability, which is the treatment of choice when available.
Handling : move the patient gently, because rough handling can precipitate ventricular fibrillation.
Arrest management : continue CPR during rewarming. Defibrillation and drugs often fail below about 30 °C, so warm the patient while resuscitating. A patient is not dead until warm and dead ; neurologically intact survival has been reported after hours of arrest. A serum potassium above about 12 mEq/L suggests death preceded cooling (for example, avalanche asphyxia), and other markers of non-survivability include a frozen chest and severe hyperkalemia with asystole.
Frostbite : rapid rewarming in 37 to 39 °C water, analgesia, no rubbing, delayed debridement, and iloprost or thrombolysis in severe, early presentations at experienced centers.
Electrical Injury and Lightning Strike
Alternating current causes tetanic muscle contraction (the victim cannot let go), with a risk of ventricular fibrillation; direct current causes a single large contraction and throws the victim.
Deep tissue injury far exceeds skin findings. Watch for compartment syndrome, rhabdomyolysis with pigmented urine, and long bone and spine fractures from falls.
Cardiac : arrhythmias, including asystole and ventricular fibrillation; monitor patients with loss of consciousness, abnormal ECG, or high-voltage exposure.
Lightning is a massive direct-current-like exposure causing immediate asystole (which often resolves spontaneously while respiratory arrest persists, so prolonged ventilation can be life-saving), keraunoparalysis (transient limb paralysis with cool mottled extremities), Lichtenberg figures, and tympanic membrane rupture. Reverse triage applies in a mass lightning event: resuscitate the apparently dead first, because they may only be in respiratory arrest.
Fluid resuscitation is guided by myoglobinuria and measured injury; burn formulas underestimate requirements in deep electrical injury.
Radiation Injury and Chemical Agents
Acute radiation syndrome : a prodrome of nausea and vomiting whose latency predicts dose (vomiting within an hour suggests a high dose), then hematopoietic (cytopenias at 2 to 4 weeks), gastrointestinal (mucosal failure at higher doses), and neurovascular syndromes.
The rate of absolute lymphocyte count decline over the first 48 hours is the best early dose estimate (the Andrews nomogram).
Management : decontaminate (remove clothing, wash), treat trauma first, give G-CSF or GM-CSF early, transfuse irradiated products, use antimicrobial prophylaxis for neutropenia, and consider specific internal contamination therapy: potassium iodide for radioiodine, Prussian blue for cesium and thallium, and DTPA for transuranics.
Chemical agents :
Nerve agents and organophosphates : cholinergic crisis treated with large, escalating doses of atropine titrated to secretions, pralidoxime , and benzodiazepines for seizures.
Vesicants (mustard, lewisite) : decontaminate, supportive airway and skin care; dimercaprol for lewisite.
Cyanide : hydroxocobalamin, or sodium nitrite plus thiosulfate.
Phosgene and chlorine : delayed pulmonary edema with observation and supportive care.
Protect staff: decontamination before entry into the department, with appropriate personal protective equipment.