Study guide
Acute Abdomen, GI Bleeding & Abdominal Compartment Syndrome
ABPN Neurocritical Care Study Guide Exam
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1 Chapter 1: Neurologic Examination & Coma Assessment in the ICU
Current Examination, Blueprint & Preparation Neurologic Examination in Critically Ill Patients Coma Evaluation & Consciousness Alterations Delirium & Toxic-Metabolic Encephalopathy in the ICU
2 Chapter 2: Cerebral Physiology & Intracranial Dynamics
Cerebral Blood Flow, Metabolism & Autoregulation Intracranial Pressure & Compliance Cerebral Edema & Herniation Syndromes
3 Chapter 3: Intracranial Hypertension & Cerebral Perfusion Management
Tiered ICP Management Protocols Hyperosmolar Therapy & Fluid Management Advanced & Refractory ICP Interventions
4 Chapter 4: Airway, Mechanical Ventilation & Pulmonary ICU Management
Emergency Airway Management & Neuro-Intubation Mechanical Ventilation Strategies in Acute Brain Injury Tracheostomy & Ventilator Weaning in Neurocritical Care Pulmonary Complications in the Neuro-ICU Obstructive Lung Disease, Pulmonary Hypertension & Bronchoscopy
5 Chapter 5: Hemodynamics, Shock & Cardiovascular Management
Hemodynamic Monitoring & Blood Pressure Targets Vasoactive Agents: Inotropes, Vasopressors & Antihypertensives Cardiac Complications of Brain Injury
6 Chapter 6: Neuropharmacology, Analgesia & Sedation
ICU Sedation & Analgesia Neuromuscular Blockade & Monitoring Propofol Infusion Syndrome & Drug Toxicities Antiseizure Drug Pharmacology in the ICU
7 Bleeding, Thrombosis & Hematologic Emergencies
Warfarin & Heparin Reversal Direct Oral Anticoagulant (DOAC) Reversal Antiplatelet Management & Platelet Dysfunction Venous Thromboembolism Prophylaxis & Management Transfusion, Coagulopathy, TMA & Cellular-Therapy Neurotoxicity
8 Chapter 8: Systemic ICU Care, Fluids, Electrolytes & Endocrine
Hyponatremia & Osmoregulation: SIADH vs Cerebral Salt Wasting Diabetes Insipidus, Hypernatremia & Endocrine Crises Critical Care Prophylaxis, Nutrition & Infection Prevention
9 Systemic Trauma & Environmental Injury
Polytrauma, Chest Injury & Abdominal Hemorrhage Burns, Electrical Injury & Hanging
10 Cardiac Emergencies & Mechanical Support
IABP, Ventricular Devices & ECMO Acute Coronary, Valvular, Rhythm & Aortic Emergencies
11 Kidney Injury, Acid–Base & Renal Replacement
Acute Kidney Injury & Renal Drug Clearance Acid–Base Disorders, Electrolytes & Renal Replacement
12 Systemic Infection & Endocrine Emergencies
Sepsis, Endocarditis & Antimicrobial Principles Thyroid, Adrenal & Dysglycemic Emergencies
13 Gastrointestinal & Hepatic Emergencies
Acute Abdomen, GI Bleeding & Abdominal Compartment Syndrome Acute Liver Failure, Cirrhosis & Hepatic Drug Effects
14 Chapter 9: Neuroimaging in the Neuro-ICU
Non-Contrast CT & CT Angiography CT Perfusion & Advanced Perfusion Imaging Magnetic Resonance Imaging in Critical Illness
15 Chapter 10: Electrophysiology & Neuromonitoring
Continuous EEG & ACNS Standardized Critical Care Terminology Invasive Neuromonitoring: ICP & External Ventricular Drains Multimodal Monitoring: PbtO2, Microdialysis & Transcranial Doppler
16 Angiography, Electrodiagnosis & CSF Analysis
Conventional Angiography & Cranial–Spinal Shunts EMG, Nerve Conduction & Acute Muscle Disease CSF Analysis: Infection, Inflammation & Hemorrhage
17 Chapter 11: Bedside Procedures, Ultrasound & Death by Neurologic Criteria
Critical Care Procedural Skills Critical Care Ultrasound & Echocardiography Determination of Death by Neurologic Criteria
18 Chapter 12: Acute Ischemic Stroke & Reperfusion Therapies
Acute Ischemic Stroke Management & Thrombolysis Endovascular Thrombectomy & Large Vessel Occlusion Malignant Hemispheric & Cerebellar Infarction
19 Chapter 13: Spontaneous Intracerebral Hemorrhage & Intraventricular Hemorrhage
Acute Intraparenchymal Hemorrhage Management Intraventricular Hemorrhage & Hydrocephalus Surgical Evacuation & Minimally Invasive Surgery in ICH
20 Chapter 14: Aneurysmal Subarachnoid Hemorrhage & Delayed Cerebral Ischemia
Aneurysmal Subarachnoid Hemorrhage: Acute Resuscitation & Securing Delayed Cerebral Ischemia & Cerebral Vasospasm Non-Aneurysmal Subarachnoid Hemorrhage & Vascular Malformations
21 Venous, Spinal & Traumatic Vascular Disease
Cerebral Venous Thrombosis & Spinal Cord Infarction Traumatic Dissection, Carotid–Cavernous Fistula & Penetrating Injury
22 Chapter 15: Traumatic Brain & Spinal Cord Injury
Severe Traumatic Brain Injury & Contusions Acute Traumatic Spinal Cord Injury & Neurogenic Shock Spine Trauma, Fractures & Cord Syndromes
23 Chapter 16: Status Epilepticus, Seizures & Neuromuscular Emergencies
Status Epilepticus: Convulsive & Non-Convulsive Refractory & Super-Refractory Status Epilepticus Acute Neuromuscular Respiratory Failure
24 Chapter 17: Post-Cardiac Arrest Care, CNS Infections & Encephalitis
Targeted Temperature Management & Post-Cardiac Arrest Care Post-Cardiac Arrest Neuroprognostication Acute CNS Infections, Encephalitis & Inflammatory Emergencies
25 Neuroinflammation & Neurooncology
Fulminant Demyelination & Autoimmune Encephalitis Brain, Spinal & Leptomeningeal Cancer Emergencies
26 Pregnancy, Transplantation & Pediatric Care
Pregnancy, Postpartum & Post-Transplant Neurologic Care Pediatric Neurocritical Care
27 Chapter 18: Neurosurgical & Perioperative Emergencies
Postoperative Neurosurgical Complications Device Complications: EVDs, Shunts & ICP Monitors Cerebral Hyperperfusion Syndrome & Post-Interventional Emergencies
28 Chapter 19: Ethics, Palliative Care & Organ Donation in the Neuro-ICU
Communication, Surrogate Decision-Making & Conflict Resolution Neuroprognostication Ethics, Withdrawal of Life Support & Palliative Care Organ Donation & Management of the Deceased Donor
Acute Abdomen, GI Bleeding & Abdominal Compartment Syndrome
Key Takeaways Explain This Topic AI
A negative pain history in a sedated patient does not exclude perforation, obstruction, or mesenteric ischemia.
Normal early lactate does not exclude acute mesenteric ischemia.
Abdominal compartment syndrome combines sustained intra-abdominal pressure above 20 mm Hg with new organ dysfunction.
Resuscitation and timely source control or hemostasis take priority over routine feeding or prophylaxis decisions.
Last updated: October 2026
Gastrointestinal Physiology in Critical Illness
The gastrointestinal tract depends on adequate perfusion, coordinated motility, mucosal integrity, and functioning hepatic and pancreatic systems. Shock and vasoconstriction can reduce splanchnic perfusion; opioids, immobility, electrolyte disorders, and autonomic injury impair motility. These mechanisms explain common feeding intolerance, but they do not establish that a new distended abdomen is benign ileus.
The official outline includes acute abdomen, upper and lower bleeding, adynamic and obstructive ileus, perforation, mesenteric ischemia, and abdominal compartment syndrome. A patient unable to describe pain needs serial examination and attention to distension, stool and gastric output, blood loss, ventilation pressures, urine output, and systemic perfusion. New deterioration should trigger diagnostic reassessment rather than automatic escalation of prokinetics or laxatives.
Recognize and Stabilize Gastrointestinal Hemorrhage
Upper GI bleeding may present with hematemesis, coffee-ground material, melena, or shock. Lower GI bleeding often causes hematochezia, but brisk upper bleeding can also do so. Assess circulation, airway protection, hemoglobin trend, coagulation, platelets, medications, and the possibility of portal hypertension. A normal initial hemoglobin does not exclude acute major blood loss.
Resuscitate and obtain urgent gastroenterology assessment for endoscopic diagnosis and hemostasis. Antithrombotic interruption or reversal depends on bleeding severity, drug, timing, and competing thrombotic indications. A recent intracranial event or coronary stent changes the decision. Suspected variceal hemorrhage requires a portal-hypertension-specific pathway, including appropriate vasoactive therapy and antimicrobial coverage, rather than acid suppression alone.
A transfusion threshold is not a substitute for treating shock or active hemorrhage. General restrictive strategies may need modification in acute brain injury, ischemia, or substantial ongoing loss. Monitor calcium, temperature, and coagulation during major transfusion. Pharmacologic stress-ulcer prophylaxis prevents selected bleeding risk; it does not replace investigation and treatment of established bleeding.
Ileus Versus Mechanical Obstruction
Adynamic ileus is impaired propulsion without a fixed mechanical blockage. Common contributors include surgery, opioids, electrolyte abnormalities, systemic illness, and immobility. Mechanical obstruction can involve a transition point, closed loop, hernia, adhesion, mass, or volvulus. Bowel sounds alone do not distinguish them reliably, and the usual pain pattern may be absent under sedation.
- Feature Adynamic ileus Mechanical obstruction
- Mechanism Reduced motility Physical blockage
Imaging pattern Often diffuse dilation without a clear transition Transition point or obstructive configuration may be present
Initial approach Correct contributors; assess feeding and decompression needs Surgical assessment; decompression and cause-specific treatment
Danger Mislabeling another disease as routine ileus Ischemia, strangulation, perforation
Hold or modify enteral feeding when obstruction, bowel ischemia, or another acute surgical problem is suspected. Treat electrolyte problems and reduce contributory drugs when possible, but do not use empiric motility treatment to postpone assessment of a mechanical lesion. Persistent distension with fever, shock, peritoneal findings, or worsening metabolic abnormalities warrants urgent imaging and surgical involvement.
Perforation and Mesenteric Ischemia
GI perforation can cause contamination, peritonitis, sepsis, and rapid circulatory deterioration. Obtain appropriate imaging when the patient is stable enough and initiate resuscitation, antimicrobial treatment, and urgent source-control assessment. Free air is a major clue, but postoperative context and the clinical syndrome matter. A normal or initially nondiagnostic plain radiograph cannot reliably exclude perforation.
Acute mesenteric ischemia may be arterial embolic, arterial thrombotic, venous, or nonocclusive. Atrial fibrillation, atherosclerotic disease, hypercoagulability, shock, and high vasopressor requirements provide different mechanisms. Pain out of proportion is a classic clue in an awake patient; its absence in coma is meaningless. Lactate can rise late or for other reasons, so a normal early concentration does not rule out the diagnosis.
CT angiography is important when ischemia is suspected and should not be deferred reflexively because of kidney dysfunction when the diagnosis is life threatening. Treatment combines resuscitation, bowel-viability assessment, antimicrobial therapy, and revascularization or surgery as appropriate. Nonocclusive ischemia requires correcting the low-flow state and assessing the bowel, not assuming that escalating vasoconstriction alone will solve the problem.
Intra-Abdominal Hypertension and Compartment Syndrome
Increasing abdominal pressure can impair renal perfusion, venous return, and ventilation and can hinder cerebral venous drainage. Abdominal compartment syndrome is sustained pressure above 20 mm Hg with new organ dysfunction, with or without a low abdominal perfusion pressure. A tense abdomen alone is insufficient, and organ dysfunction can occur before all classic signs appear.
Measure pressure using a standardized technique, commonly through the bladder, when the syndrome is suspected. Reassess fluid accumulation, abdominal contents, positioning, muscle tone, and reversible causes. Gastric or colonic decompression, drainage of fluid collections, and carefully selected medical measures may help, while overt refractory syndrome can require surgical decompression. In a patient with rising airway pressures, oliguria, and falling CPP after major resuscitation, consider an abdominal mechanism alongside primary pulmonary and intracranial causes.
Sources checked October 17, 2026: WSES mesenteric ischemia guideline , IDSA intra-abdominal infection guidance , and WSACS consensus definitions .