5.4 Retroperitoneal Hemorrhage & Abdominal Compartment Syndrome (ACS)

Retroperitoneal Hemorrhage & Abdominal Compartment Syndrome (ACS)

Clinical Core: Retroperitoneal hemorrhage requires zone-based anatomical management, with pelvic Zone III bleeding prioritized for non-operative angioembolization. Intra-Abdominal Hypertension (IAH >12 mmHg) and Abdominal Compartment Syndrome (ACS >20 mmHg with new organ failure) represent life-threatening complications of fluid resuscitation and tissue injury. Accurate bladder pressure measurement and open abdomen management are core critical care nursing competencies.

The retroperitoneum and peritoneal cavity are closely linked spaces vulnerable to massive occult bleeding, visceral edema, and progressive pressure accumulation. Following major trauma and damage-control resuscitation, patients are at high risk for developing Intra-Abdominal Hypertension (IAH) and Abdominal Compartment Syndrome (ACS). Without prompt measurement and intervention, elevated intra-abdominal pressure causes multi-organ dysfunction and death.

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Retroperitoneal Hemorrhage: Anatomical Zones & Management

The retroperitoneal space extends from the posterior parietal peritoneum to the anterior vertebral column and transverse fascia. Retroperitoneal hematomas are classified into three distinct anatomical zones, each dictating a specific surgical and interventional approach:

Clinical Management of Zone III Pelvic Hemorrhage

Zone III bleeding can result in rapid loss of several liters of blood into the retroperitoneum.

• Pelvic Stabilization: A commercial pelvic binder or sheet must be applied immediately centered over the greater trochanters (not the iliac crests) to reduce pelvic volume and promote internal tamponade.
• Interventional Radiology: Transcatheter arterial embolization (TAE) is the treatment of choice for active arterial pelvic bleeding. Direct surgical opening of a Zone III hematoma destroys the natural tissue tamponade, leading to unmanageable venous bleeding and exsanguination.

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Intra-Abdominal Hypertension (IAH) & Abdominal Compartment Syndrome (ACS)

The World Society of the Abdominal Compartment Syndrome (WSACS) provides standardized definitions and grading for elevated intra-abdominal pressure (IAP):

Consensus Definitions & Grading

• Normal IAP: 5 to 7 mmHg in healthy supine adults; 9 to 12 mmHg in critically ill adults.
• Intra-Abdominal Hypertension (IAH): Sustained pathological elevation of IAP ≥12 mmHg.
  • Grade I: IAP 12–15 mmHg
  • Grade II: IAP 16–20 mmHg
  • Grade III: IAP 21–25 mmHg
  • Grade IV: IAP >25 mmHg
• Abdominal Compartment Syndrome (ACS): Sustained IAP >20 mmHg (with or without Abdominal Perfusion Pressure [APP = MAP – IAP] <60 mmHg) that is associated with NEW-ONSET organ dysfunction or failure.

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Systemic Consequences of Elevated IAP

As intra-abdominal pressure rises, it exerts compressive forces across every organ system:

1. Cardiovascular System: High IAP compresses the inferior vena cava and portal vein, reducing venous return (preload) to the heart. Cardiac output drops significantly. Systemic vascular resistance (SVR) increases compensatory. Critically, Central Venous Pressure (CVP) and Pulmonary Artery Wedge Pressure (PAWP) become falsely elevated due to transmitted intrathoracic pressure.
2. Pulmonary System: The elevated abdomen pushes the diaphragm cephalad, reducing thoracic volume, pulmonary compliance, and functional residual capacity. Peak airway pressures spike, leading to alveolar hypoventilation, severe hypoxemia, hypercapnia, and barotrauma.
3. Renal System: The kidneys are exquisitely sensitive to elevated IAP. Direct renal parenchymal compression and renal vein congestion reduce renal perfusion pressure (RPP = MAP – IAP). Glomerular filtration rate (GFR) drops, leading to oliguria (IAP >15–20 mmHg) and anuria (IAP >30 mmHg) that is refractory to fluid boluses and diuretics.
4. Gastrointestinal System: Splanchnic hypoperfusion occurs at IAP as low as 10 to 12 mmHg, causing intestinal mucosal ischemia, bacterial translocation, lactic acidosis, and feeding intolerance.
5. Neurological System: Increased IAP impairs venous drainage from the brain via the internal jugular veins, leading to increased Intracranial Pressure (ICP) and decreased Cerebral Perfusion Pressure (CPP).

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Bladder Pressure Measurement: Gold Standard Technique

Transvesical (bladder) pressure measurement is the gold standard indirect method for quantifying IAP. The urinary bladder acts as a passive reservoir that accurately reflects intra-abdominal pressure when filled with a small volume of fluid.

Step-by-Step Measurement Procedure

1. Position the patient completely flat and supine. (Head of bed elevation >30° artificially elevates IAP by 4 to 9 mmHg due to visceral weight).
2. Instill a maximum of 20 to 25 mL of sterile 0.9% normal saline into the empty Foley catheter bladder lumen. (Excess volumes >50 mL artificially inflate bladder wall tension and falsely elevate pressure).
3. Connect an inline pressure transducer or manometer setup to the catheter sampling port.
4. Zero Landmark: Zero the transducer at the mid-axillary line at the level of the iliac crest.
5. Ensure the patient's abdominal wall musculature is relaxed (devoid of active muscular contraction or coughing).
6. Measure the pressure in mmHg at end-expiration.

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Medical & Surgical Management of ACS

Management of IAH and ACS follows a stepwise approach aimed at reducing abdominal contents, improving abdominal wall compliance, optimizing fluid balance, and surgical decompression.

Non-Operative & Medical Interventions

• Evacuate Intraluminal Contents: Insert Salem Sump NGT and rectal tubes; administer prokinetic agents (metoclopramide, erythromycin) or enemas.
• Evacuate Intra-Abdominal Space-Occupying Lesions: Perform bedside ultrasound-guided paracentesis to drain ascites, blood, or fluid collections.
• Improve Abdominal Wall Compliance: Administer adequate analgesia and sedation; remove restrictive abdominal binders; consider temporary neuromuscular blockade in severe IAH.
• Optimize Fluid Balance: Avoid excessive crystalloid resuscitation; transition to hypertonic saline or colloids (albumin); utilize diuretics or continuous renal replacement therapy (CRRT) with ultrafiltration.

Decompressive Laparotomy & Open Abdomen Care

When medical management fails and ACS persists (IAP >20 mmHg with organ failure), emergency decompressive laparotomy must be performed to relieve pressure.

• Temporary Abdominal Closure (TAC): Following decompression, the abdominal fascia is left open to prevent recurrent ACS. The abdomen is managed using a negative pressure temporary closure system:
  • Barker Vacuum Pack: A fenestrated non-adherent polyethylene sheet placed over viscera, covered with moist surgical towels, suction drains, and an occlusive drape connected to continuous suction (100–150 mmHg).
  • Commercial ABThera Therapy: Customized polyurethane foam system providing active negative pressure and fluid clearance while protecting viscera.
• Nursing Priorities for Open Abdomen: Quantify fluid loss (can exceed 2–5 L/day of protein-rich fluid requiring volume replacement), maintain strict aseptic dressing technique, monitor for enterocutaneous fistulas (fecal drainage in foam), and monitor for visceral desiccation.