Study guide
4.1 Airway Management, Upper-Airway Obstruction & Artificial-Airway Complications
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
4.1 Airway Management, Upper-Airway Obstruction & Artificial-Airway Complications
Key Takeaways Explain This Topic AI
Bradykinin-mediated angioedema from ACE inhibitors or C1-inhibitor deficiency causes swelling without urticaria and responds poorly to epinephrine, antihistamines, and corticosteroids.
In the DEVICE trial (2023), video laryngoscopy achieved first-attempt intubation success in 85.1% of critically ill adults versus 70.8% with direct laryngoscopy.
In the PREOXI trial (2024), noninvasive ventilation for preoxygenation halved hypoxemia during ICU intubation compared with an oxygen mask (9.1% vs 18.5%).
A tracheoinnominate artery fistula typically bleeds within the first few weeks after tracheostomy; massive bleeding is controlled first by cuff hyperinflation, then by digital compression through the stoma.
A post-extubation stridor risk is screened with the cuff leak test; guidelines suggest systemic corticosteroids at least 4 hours before extubation for high-risk patients who fail it.
Last updated: October 2026
Recognizing Upper-Airway Obstruction
Obstruction above the carina presents with inspiratory stridor , a muffled or hoarse voice, drooling, inability to handle secretions, and a tripod posture. Silent chest movement with paradoxical breathing signals near-complete obstruction. On flow-volume loops:
A variable extrathoracic lesion flattens the inspiratory limb.
A variable intrathoracic lesion flattens the expiratory limb.
A fixed lesion, such as tracheal stenosis, flattens both.
Cause Key clues First priority
Post-thyroidectomy or carotid endarterectomy hematoma Neck swelling and stridor within hours of surgery Open the wound at the bedside to decompress, then secure the airway
Epiglottitis or supraglottitis Fever, odynophagia, drooling, "hot potato" voice Controlled intubation in the operating room with surgical airway backup; ceftriaxone plus anti-staphylococcal coverage
Ludwig angina or deep neck abscess Floor-of-mouth swelling, trismus, dental source Awake fiberoptic intubation or tracheostomy, broad-spectrum antibiotics, surgical drainage
Post-extubation laryngeal edema Stridor within minutes to hours of extubation Nebulized epinephrine, IV steroids, heliox as a bridge; reintubate early if failing
- Foreign body Sudden choking, unilateral wheeze Rigid bronchoscopy for central objects
- Inhalation injury Facial burns, carbonaceous sputum, hoarseness Early intubation before edema progresses
Heliox (helium-oxygen, typically 70:30 or 80:20) lowers the density of the inhaled gas and reduces turbulent resistance across a narrowed airway. It buys time but limits the FiO2, so it is a bridge, not a definitive fix.
Angioedema: Histamine Versus Bradykinin
Feature Histamine (allergic, mast cell) Bradykinin (ACE inhibitor, hereditary or acquired C1-inhibitor deficiency)
- Urticaria and pruritus Usually present Absent
- Onset Minutes after exposure Hours; ACE inhibitor angioedema can appear years after the drug is started
- Response to epinephrine, antihistamines, steroids Good Poor
Specific therapy IM epinephrine 0.5 mg (repeat every 5–15 min), H1/H2 blockers, steroids Hereditary angioedema: C1-inhibitor concentrate, icatibant, or ecallantide (fresh frozen plasma if unavailable). ACE inhibitor angioedema: stop the drug permanently; targeted agents have not shown consistent benefit in trials
When the tongue or floor of the mouth is involved, plan an awake fiberoptic (often nasal) intubation in a "double setup," with the team ready for cricothyrotomy. Do not paralyze a patient whose airway you may not be able to see.
Intubating the Critically Ill Patient
ICU intubation is physiologically difficult even when the anatomy is easy. Hypoxemia, hypotension, severe metabolic acidosis, and right ventricular failure turn a 60-second apnea into cardiac arrest.
Preoxygenation : use noninvasive ventilation or high-flow nasal oxygen in hypoxemic patients. In PREOXI (NEJM 2024), noninvasive ventilation reduced hypoxemia (SpO2 below 85%) during intubation to 9.1% versus 18.5% with an oxygen mask.
Device : video laryngoscopy is the default. In DEVICE (NEJM 2023), first-attempt success was 85.1% with video versus 70.8% with direct laryngoscopy. A bougie did not improve first-pass success over a stylet in the BOUGIE trial.
Hemodynamics : anticipate post-intubation hypotension from loss of sympathetic tone, sedative vasodilation, and positive pressure reducing venous return. Have a vasopressor running or drawn up. A routine fluid bolus did not prevent cardiovascular collapse in PREPARE II.
Induction : ketamine and etomidate are both used; trials have not shown a clear mortality difference. Reduce doses in shock.
Paralysis : use rocuronium (1.2 mg/kg) or succinylcholine (1.5 mg/kg). Avoid succinylcholine in the following settings:
Hyperkalemia.
Burns or crush injury beyond about 24 to 48 hours.
Denervation, stroke, or spinal cord injury after the first days.
Prolonged immobilization.
Myopathies.
A personal or family history of malignant hyperthermia.
Confirmation : continuous waveform capnography is the standard. The tube tip should sit about 3 to 5 cm above the carina.
Tracheostomy and Its Emergencies
Early tracheostomy (within 4 days) did not lower 30-day mortality compared with tracheostomy after day 10 in TracMan . Its benefits are comfort, less sedation, easier oral care, and earlier mobility. Percutaneous and surgical techniques have similar outcomes in suitable necks.
Accidental decannulation : if the tract is fresh (under about 7 days), do not blindly reinsert, because you can create a false passage in the pretracheal tissues. Oxygenate from above and intubate orally if the upper airway is patent. A mature tract can usually be recannulated with an obturator.
Obstruction : remove the inner cannula, pass a suction catheter, and deflate the cuff. If the patient is still failing, remove the tube and ventilate from above or through the stoma.
Tracheoinnominate artery fistula : the cuff or tube tip erodes into the innominate artery, usually within the first few weeks after placement. A small sentinel bleed often precedes exsanguination. For massive bleeding:
Hyperinflate the cuff.
If that fails, insert a finger through the stoma and compress the artery anteriorly against the sternum (the Utley maneuver), while an oral tube is passed beyond the bleeding site.
Arrange emergent surgery.
A stable sentinel bleed calls for urgent evaluation in a setting where surgery is immediately available.
Tracheoesophageal fistula (TEF) : caused by pressure necrosis between the cuff and a nasogastric tube. Clues include:
Copious secretions containing tube feeds.
Recurrent aspiration.
Abdominal distension with a ventilator air leak.
Confirm by bronchoscopy and esophagoscopy. Position the cuff below the fistula, remove the nasogastric tube in favor of a gastrostomy, and repair surgically once the patient is off the ventilator. Malignant fistulas are usually treated with airway and esophageal stents.
Endotracheal Tube and Positive-Pressure Complications
Cuff pressure : keep it at 20 to 30 cmH2O . Higher pressures impair tracheal mucosal perfusion and lead to stenosis or tracheomalacia, while lower pressures permit microaspiration.
Cuff leak test : an absent leak identifies patients at higher risk of post-extubation stridor. For high-risk patients who fail it, ATS/CHEST guidance suggests systemic corticosteroids at least 4 hours before extubation. Treat established stridor with nebulized epinephrine and steroids; noninvasive ventilation should not delay reintubation.
Bronchopleural fistula : a persistent air leak after pneumonectomy, necrotizing pneumonia, or barotrauma. The leak equals inspired minus exhaled tidal volume. Management:
Minimize airway pressures with lower tidal volume and PEEP, a shorter inspiratory time, and permissive hypercapnia.
Use the least chest tube suction that keeps the lung expanded.
Favor spontaneous modes.
Consider endobronchial valves, independent lung ventilation, surgery, or ECMO for refractory leaks.
Intracardiac shunt : a patent foramen ovale is present in about a quarter of adults. High PEEP or acute pulmonary hypertension can raise right atrial pressure enough to open it, causing right-to-left shunting and refractory hypoxemia that worsens with more PEEP. A bubble study confirms it. Lower PEEP if possible, unload the right ventricle (prone positioning, inhaled pulmonary vasodilators), and avoid fluid loading.