Abdominal compartment syndrome

Pathophysiology - Belly Under Pressure

• Intra-abdominal Pressure (IAP): Baseline pressure in the abdomen (Normal: 5-7 mmHg).
• Intra-abdominal Hypertension (IAH): Sustained IAP ≥ 12 mmHg.
• Abdominal Compartment Syndrome (ACS): Sustained IAP > 20 mmHg with new organ dysfunction.
• Abdominal Perfusion Pressure (APP): Crucial for organ viability. Calculated as $APP = MAP - IAP$. Goal: >60 mmHg.

⭐ Systemic effects of increased IAP include decreased cardiac output, impaired ventilation (increased peak airway pressures), and reduced renal blood flow leading to oliguria.

Etiology & Risk Factors - The Pressure Cookers

• Primary ACS (Intra-abdominal): Conditions increasing pressure from within the abdomen.

  • Severe trauma (e.g., liver hematoma)
  • Acute pancreatitis
  • Large-volume ascites
  • Ileus or bowel obstruction

• Secondary ACS (Extra-abdominal): Systemic issues causing third-spacing and abdominal wall edema.

  • Massive fluid resuscitation (e.g., sepsis, burns)
  • Systemic inflammation and capillary leak

⭐ Aggressive fluid resuscitation in trauma or sepsis patients is a leading cause of secondary ACS, even without direct abdominal injury.

Diagnosis - Feeling the Squeeze

Clinical suspicion is key, marked by a tense, distended abdomen, oliguria, hypotension, and rising airway pressures. The gold standard for diagnosis is measuring intra-abdominal pressure (IAP) via a bladder catheter.

• Intra-Abdominal Hypertension (IAH): IAP > 12 mmHg.
• Abdominal Compartment Syndrome (ACS): IAP > 20 mmHg with new organ dysfunction (e.g., renal, cardiovascular, respiratory).

⭐ Oliguria that is refractory to fluid boluses is a classic early sign of developing ACS and should prompt immediate IAP measurement.

Management - Release the Pressure!

• Medical (Non-operative) Management: Aims to reduce intra-abdominal pressure (IAP) without surgery.
  • Improve Compliance: Sedation, analgesia, consider neuromuscular blockade (paralysis).
  • Evacuate Contents: Nasogastric (NG) and rectal tube decompression.
  • Remove Fluid: Diuretics for fluid overload; percutaneous catheter drainage for ascites.

⭐ Decompressive laparotomy is the definitive, life-saving intervention for established ACS and should not be delayed.

High-Yield Points - ⚡ Biggest Takeaways

• Abdominal Compartment Syndrome (ACS) is defined by sustained intra-abdominal pressure (IAP) > 20 mmHg with new organ dysfunction.
• Most common after massive fluid resuscitation in trauma, pancreatitis, or major abdominal surgery.
• Presents with a tense, distended abdomen, oliguria, hypotension, and ↑ airway pressures.
• Intra-bladder pressure measurement is the gold standard for diagnosis.
• End-organ damage includes renal failure, cardiovascular collapse (↓ preload), and respiratory failure.
• Definitive management is urgent decompressive laparotomy to open the abdomen.