Study guide
22.1 Esophageal, Gastric & Bowel Emergencies: Perforation, Obstruction, Ogilvie Syndrome & Colonic Ischemia
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
22.1 Esophageal, Gastric & Bowel Emergencies: Perforation, Obstruction, Ogilvie Syndrome & Colonic Ischemia
Key Takeaways Explain This Topic AI
Esophageal perforation is confirmed by CT with water-soluble oral contrast; management combines drainage, broad-spectrum antibiotics with antifungal coverage, and either surgical repair or endoscopic stenting.
Neostigmine 2 mg intravenously resolves acute colonic pseudo-obstruction in most patients, and requires continuous cardiac monitoring with atropine available for bradycardia.
Mechanical obstruction, ischemia, and perforation must be excluded before neostigmine, which is contraindicated in those settings.
Toxic megacolon is defined by colonic dilation above 6 cm with systemic toxicity; colectomy is indicated if there is no improvement within 48 to 72 hours of maximal medical therapy, or sooner for perforation.
Gastric volvulus presents with the Borchardt triad of severe epigastric pain, retching without vomiting, and inability to pass a nasogastric tube.
Last updated: October 2026
- Esophageal Emergencies
- Perforation and Rupture
Type Setting
Iatrogenic (most common) Endoscopy, dilation, transesophageal echocardiography, nasogastric tube placement, intubation
- Boerhaave syndrome Barogenic rupture after forceful vomiting; typically a left posterolateral distal tear
- Foreign body or caustic Button batteries, impacted food, caustic ingestion
- Malignant Tumor erosion, with or without a fistula
- Traumatic Penetrating injury, rarely blunt
Presentation : severe chest, epigastric, or back pain, subcutaneous emphysema, odynophagia, fever, and rapid progression to septic shock from mediastinitis . The Mackler triad (vomiting, chest pain, subcutaneous emphysema) is often incomplete. A left pleural effusion with high amylase and low pH is suggestive.
Imaging : CT of the chest with water-soluble oral contrast is the test of choice, showing extraluminal air and contrast, mediastinal fluid, and effusions. Avoid barium first, because it causes mediastinal inflammation, though it is more sensitive for small leaks.
Management :
Nil by mouth, large-bore intravenous access, resuscitation.
Broad-spectrum antibiotics plus antifungal coverage (oral flora and Candida ).
Drainage of the mediastinum and pleural space.
Definitive control : primary surgical repair with buttressing for early, large thoracic perforations; endoscopic stenting or clipping with drainage for contained leaks, iatrogenic injuries, and poor surgical candidates; esophageal diversion or resection for destroyed tissue.
Nutrition by jejunal feeding or parenteral support.
Caustic ingestion : assess the airway first; do not induce vomiting, do not neutralize, and do not place a blind nasogastric tube . Early endoscopy grades injury; steroids are not recommended, and strictures develop later.
Variceal bleeding, food impaction, and Mallory-Weiss tears are covered in the gastrointestinal bleeding section.
Gastric Emergencies
Perforated peptic ulcer : sudden severe epigastric pain with peritonitis; free air on upright chest radiograph or CT. Resuscitate, give antibiotics, and arrange surgical repair (often an omental patch); treat Helicobacter pylori afterward.
Gastric outlet obstruction : vomiting with hypokalemic, hypochloremic metabolic alkalosis and paradoxical aciduria. Decompress, replace sodium chloride and potassium, and treat the cause (ulcer disease or malignancy).
Gastric volvulus : organoaxial rotation, typically with a paraesophageal hernia. The Borchardt triad is severe epigastric pain, retching without vomiting , and inability to pass a nasogastric tube . It can strangulate and perforate: obtain urgent CT and surgical consultation, and attempt careful endoscopic or operative reduction.
Stress-related mucosal bleeding : prophylaxis with a proton pump inhibitor is indicated for ventilated patients and those with coagulopathy; the REVISE trial showed less clinically important upper gastrointestinal bleeding with pantoprazole without a mortality difference.
Gastroparesis in critical illness : manage with prokinetics (metoclopramide, erythromycin) and post-pyloric feeding.
Small and Large Bowel Obstruction
Feature Small bowel obstruction Large bowel obstruction
Common causes Adhesions, hernia, Crohn disease, malignancy, gallstone ileus, intussusception Colorectal cancer, volvulus, diverticular stricture
Vomiting Early and bilious Late, feculent
Imaging Dilated small bowel with air-fluid levels, a transition point, a collapsed distal colon Dilated colon to a transition point; a competent ileocecal valve raises perforation risk
Management of uncomplicated adhesive small bowel obstruction : nasogastric decompression, fluid and electrolyte repletion, and serial examination. Water-soluble contrast (gastrografin) is both diagnostic and therapeutic; contrast reaching the colon within 24 hours predicts resolution.
Signs demanding surgery : peritonitis, a closed-loop or strangulated obstruction, pneumatosis, portal venous gas, free air, or failure to resolve. A rising lactate, fever, and localized tenderness in a patient who was improving indicate ischemia.
Sigmoid volvulus : a "coffee bean" loop; endoscopic detorsion with rectal tube placement is first-line, followed by elective sigmoidectomy because recurrence is common. Peritonitis or gangrene requires immediate surgery.
Cecal volvulus : usually operative (right colectomy), because endoscopic reduction fails more often.
Malignant obstruction : a self-expanding metal stent can decompress as a bridge to surgery or as palliation.
Acute Colonic Pseudo-Obstruction (Ogilvie Syndrome)
Setting : critically ill, postoperative (especially orthopedic, cardiac, and obstetric), neurologic injury, electrolyte disturbance, and opioids and anticholinergics .
Presentation : massive abdominal distension with little pain, usually with passage of some flatus, and imaging that shows colonic dilation without a mechanical transition point .
Risk : cecal diameter above about 10 to 12 cm, or distension lasting beyond about 6 days, raises the risk of ischemia and perforation.
Stepwise management :
Conservative measures for 24 to 48 hours : nil by mouth, nasogastric decompression, a rectal tube, correction of potassium, magnesium, and calcium, stopping opioids and anticholinergics, treating infection, and mobilizing and repositioning the patient.
Neostigmine 2 mg IV over 3 to 5 minutes if conservative measures fail and there is no contraindication. Most patients respond within minutes with a dramatic passage of flatus and stool.
Requires continuous cardiac monitoring with atropine at the bedside , because bradycardia is common.
Contraindications : mechanical obstruction, suspected ischemia or perforation, significant bradycardia, active bronchospasm, pregnancy, and severe kidney failure (relative).
Oral or subcutaneous regimens and polyethylene glycol afterward reduce recurrence.
Colonoscopic decompression with tube placement for failure of or contraindication to neostigmine.
Surgery (cecostomy or colectomy) for perforation, ischemia, or refractory distension.
Methylnaltrexone is an option when opioids are the dominant driver.
Toxic Megacolon
Causes : C. difficile colitis, inflammatory bowel disease (ulcerative colitis more than Crohn disease), other infectious colitis ( Salmonella , Shigella , Campylobacter , CMV in immunocompromised patients), and ischemic colitis.
Definition : radiographic colonic dilation above 6 cm (transverse colon) plus systemic toxicity : fever, tachycardia, leukocytosis or leukopenia, anemia, and one of dehydration, altered mental status, electrolyte disturbance, or hypotension.
Management :
Bowel rest, nasogastric decompression, aggressive fluid and electrolyte repletion, and transfusion as needed.
Stop antimotility agents, opioids, and anticholinergics .
Treat the cause: intravenous corticosteroids for inflammatory bowel disease (with infliximab or cyclosporine as rescue), or maximal C. difficile therapy.
Broad-spectrum antibiotics for suspected perforation or bacteremia.
Serial examinations and radiographs , often every 12 to 24 hours; avoid colonoscopy, which risks perforation.
Colectomy if there is no improvement within 48 to 72 hours of maximal medical therapy, or immediately for perforation, uncontrolled bleeding, or clinical deterioration. Perforation raises mortality several-fold, so operating before it occurs is the goal.
Colonic Ischemia
Distinct from acute mesenteric ischemia : colonic ischemia is usually a nonocclusive, mucosal and submucosal injury in watershed areas (the splenic flexure and rectosigmoid), in older patients after hypotension, cardiac surgery, aortic repair, dialysis, or vasopressor use, and sometimes with vasoconstrictors such as cocaine.
Presentation : crampy left-sided abdominal pain followed by bloody diarrhea , usually with less pain than the degree of concern raised by mesenteric ischemia.
Diagnosis : CT with contrast shows segmental wall thickening; colonoscopy confirms mucosal changes and a sharply demarcated segment, with biopsy.
Management : most cases resolve with supportive care: fluids, bowel rest, optimizing perfusion, stopping vasoconstrictors, and antibiotics for moderate or severe disease. Surgery is needed for gangrene, perforation, fulminant colitis, or a persistent protein-losing colopathy or stricture.
After aortic surgery , bloody diarrhea with acidosis should prompt immediate sigmoidoscopy to evaluate for left colon ischemia from a sacrificed inferior mesenteric artery.