Study guide
29.3 Abdominal, Vascular & Procedural Point-of-Care Ultrasound
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
29.3 Abdominal, Vascular & Procedural Point-of-Care Ultrasound
Key Takeaways Explain This Topic AI
The FAST examination images the hepatorenal (Morison) pouch, splenorenal recess, pelvis, and pericardium; it detects free fluid but cannot exclude retroperitoneal or solid organ injury.
An abdominal aorta measured outer wall to outer wall above 3 cm defines an aneurysm, and ultrasound cannot reliably exclude rupture.
Real-time ultrasound guidance reduces mechanical complications and failed attempts for central venous catheterization and is recommended for internal jugular access.
A diaphragm thickening fraction below about 20% to 30% during a spontaneous breathing trial is associated with weaning failure.
An optic nerve sheath diameter above about 5 mm measured 3 mm behind the globe suggests raised intracranial pressure but does not replace invasive monitoring.
Last updated: October 2026
Abdominal Free Fluid: The FAST Examination
The Focused Assessment with Sonography for Trauma answers one question: is there free fluid?
View Probe position Looking for
Right upper quadrant Mid-axillary line, 8th to 11th ribs, probe marker cephalad Fluid in the hepatorenal (Morison) pouch , the most dependent space in the supine patient; also the right pleural space above the diaphragm
Left upper quadrant Posterior axillary line, 6th to 9th ribs ("knuckles to the bed") Splenorenal recess and the subphrenic space, where fluid collects first on the left; left pleural space
Pelvis Suprapubic, transverse and sagittal Fluid in the rectovesical or rectouterine (Douglas) pouch ; a full bladder provides the acoustic window
- Subxiphoid Subcostal Pericardial effusion
- Extended FAST (eFAST) Anterior chest, bilateral Pneumothorax (absent lung sliding) and hemothorax
Limitations : FAST detects about 200 mL or more of free fluid, is insensitive for retroperitoneal injury, bowel injury, and solid organ laceration without free fluid , cannot distinguish blood from ascites or urine, and does not exclude ongoing bleeding. A negative FAST in an unstable patient does not exclude abdominal hemorrhage, and a positive FAST in a stable patient prompts CT rather than automatic laparotomy. Serial examinations add sensitivity.
Renal, Bladder and Ascites Applications
Hydronephrosis : look for anechoic dilation of the renal pelvis and calyces. Grading from mild to severe guides urgency, and bilateral hydronephrosis or hydronephrosis in a single functioning kidney with acute kidney injury calls for urgent decompression. Caveat : hydronephrosis can be absent early, with volume depletion, or in retroperitoneal fibrosis, and a prominent extrarenal pelvis or parapelvic cysts can mimic it.
Bladder volume : a simple estimate is height × width × depth × 0.7 \text{height} \times \text{width} \times \text{depth} \times 0.7 height × width × depth × 0.7 in centimeters, giving milliliters. This distinguishes anuria from retention and avoids unnecessary catheterization.
Ascites and paracentesis : identify a pocket free of bowel, mark the site in the left or right lower quadrant lateral to the rectus sheath (avoiding the inferior epigastric vessels), and use color Doppler to check for vessels in the path. Ultrasound reduces bleeding and bowel injury.
Pleural effusion and thoracentesis : confirm the fluid, identify the diaphragm and liver or spleen, choose a site above the diaphragm with the patient positioned consistently, and avoid draining more than about 1 to 1.5 liters at a session or stopping with chest discomfort, to limit re-expansion edema.
Aorta and Vascular Applications
Abdominal aortic aneurysm : scan from the epigastrium to the bifurcation in transverse and longitudinal planes, measuring outer wall to outer wall . Above 3 cm defines an aneurysm ; rupture risk rises sharply above 5.5 cm. In a hypotensive older patient with abdominal or back pain, finding an aneurysm is actionable even though ultrasound cannot confirm rupture, which usually requires CT in the stable patient or immediate operation in the unstable one.
Aortic dissection clues : an intimal flap in the aortic root or abdominal aorta, a pericardial effusion, or a new aortic regurgitation jet; the definitive test remains CT angiography or transesophageal echocardiography.
Deep vein thrombosis : compression ultrasound of the common femoral and popliteal veins (see the core POCUS section).
Volume and flow adjuncts : inferior vena cava measurement, carotid or femoral artery Doppler velocity time integral change with a passive leg raise, and left ventricular outflow tract velocity time integral for stroke volume. Each has limits and should be combined with other data rather than used alone.
Hepatobiliary Applications
Acalculous cholecystitis in the critically ill: a thickened gallbladder wall (above about 3.5 mm), pericholecystic fluid, sludge, and distension without stones, with a sonographic Murphy sign if the patient can report pain. This is an important cause of unexplained sepsis in ventilated patients on parenteral nutrition.
Cholelithiasis and biliary dilation : hyperechoic stones with shadowing and a common bile duct above about 6 mm (rising with age and after cholecystectomy).
Portal hypertension signs : a nodular liver, splenomegaly, ascites, recanalized umbilical vein, and portal flow reversal.
Pneumoperitoneum and bowel : enhanced peritoneal stripe sign for free air, dilated loops with to-and-fro content in obstruction, and a thickened aperistaltic segment in ischemia. These are supportive rather than definitive findings.
Procedural Guidance
Procedure Ultrasound contribution
Central venous access Real-time guidance improves first-pass success and reduces arterial puncture, pneumothorax, and hematoma; it is recommended for internal jugular access and beneficial for subclavian (infraclavicular axillary) and femoral sites. Confirm the guidewire in the vein in a long-axis or biplane view and screen for pneumothorax afterward
- Arterial line Higher first-pass success, especially in shock or obesity
- Peripheral access and midlines Enables access when landmarks fail
Thoracentesis and chest tube Site selection, confirmation of fluid, avoidance of the liver and spleen; it lowers the pneumothorax rate
- Paracentesis Pocket selection and vessel avoidance
- Lumbar puncture Midline and interspace identification in obese patients
Pericardiocentesis Identifies the shortest safe route (often apical rather than classic subxiphoid) and confirms needle and wire position with agitated saline
Airway Confirms tracheal versus esophageal intubation, identifies the cricothyroid membrane before a surgical airway, and assesses diaphragm motion
- Nasogastric tube Confirms gastric placement when radiography is delayed
- Adjunct ICU Applications
Diaphragm assessment : measure thickness in the zone of apposition. A thickening fraction below about 20% to 30% during a spontaneous breathing trial predicts weaning failure, and excursion below about 10 to 15 mm suggests dysfunction. Unilateral paralysis shows paradoxical motion.
Optic nerve sheath diameter : measured 3 mm behind the globe , a diameter above about 5 mm suggests raised intracranial pressure. It is a screening adjunct, not a substitute for invasive monitoring, and is operator-dependent.
Gastric ultrasound : antral cross-sectional area estimates volume and aspiration risk before sedation or extubation, which is useful when fasting status is unknown.
Soft tissue : differentiates cellulitis (cobblestoning) from abscess (a drainable fluid collection) and detects subcutaneous gas in necrotizing infection.
Transcranial Doppler : assesses vasospasm after subarachnoid hemorrhage and cerebral blood flow patterns in brain death evaluation (where it is an ancillary test).
Governance and Pitfalls
Image acquisition, interpretation, and documentation should be archived with a written report, because POCUS findings drive decisions and have medicolegal weight.
Know the limits of the question asked : POCUS is a focused examination, not a comprehensive study, and a negative focused scan does not exclude disease.
Common errors : mistaking a seminal vesicle or ovarian cyst for free fluid, calling perinephric fat free fluid, measuring the aorta inner wall to inner wall (which underestimates), missing posterior effusions by scanning too anteriorly, mistaking the gastric antrum for the aorta, and failing to repeat the scan when the clinical picture changes.
Credentialing and quality assurance : training, image review, and documented competence support safe use, and findings that contradict the clinical picture should prompt a confirmatory study.