Abdominal Pressure Monitoring: Indications and Management
Intra-abdominal pressure (IAP) monitoring should be performed in all patients at risk of intra-abdominal hypertension, particularly those with severe abdominal trauma, massive fluid resuscitation, or burns >30% TBSA, to enable early detection of abdominal compartment syndrome (ACS) which carries a 90% mortality if untreated. 1
When to Monitor IAP
High-Risk Populations Requiring Monitoring
- Severe abdominal trauma patients (AIS ≥3) admitted to ICU, especially those undergoing non-operative management 1, 2
- Patients receiving massive fluid resuscitation following trauma or burns, particularly when projected volumes exceed predetermined thresholds 3, 4
- Burn patients with >30% total body surface area requiring significant volume resuscitation 3
- Post-damage control laparotomy patients, particularly those with abdominal/pelvic packing for hemorrhage control 5
Specific Risk Factors
The following clinical scenarios mandate IAP monitoring 2:
- BMI >27 kg/m²
- APACHE II score >18
- Abdominal distension
- PEEP >7 cmH₂O under mechanical ventilation
- Hemodynamic shock
- Massive transfusion and/or massive fluid expansion
How to Monitor
Measurement Technique
- Urinary bladder pressure measurement is the standard, simple, noninvasive, and inexpensive method for continuous IAP monitoring 5
- Use a priming volume of ≤75 mL for accurate bladder pressure measurement 4
- The World Society of the Abdominal Compartment Syndrome recommends protocolized IAP monitoring in at-risk patients 1
Monitoring Frequency
- Measure compartment pressures every 30 minutes to 1 hour during the first 24 hours in high-risk patients 2
- Continue continuous monitoring for at least the first 24 hours, followed by clinical and biological observation for a minimum of 3-5 days 1, 2
Critical Thresholds and Definitions
Diagnostic Criteria for ACS
Abdominal compartment syndrome is defined as IAP >25 mmHg associated with any organ dysfunction and requires emergent treatment 1, 2, 6
Alternative diagnostic criteria include:
- IAP >30 mmHg with clinical signs of ACS 7
- Differential pressure (diastolic BP - compartment pressure) <30 mmHg 7
Clinical Manifestations
Monitor for the following organ dysfunctions indicating ACS 1, 5:
- Respiratory: Elevated inspiratory pressure >35 mbar, decreased PaO₂/FiO₂ ratio (<150 torr)
- Renal: Urine output <30 mL/hr
- Cardiovascular: Hemodynamic instability requiring vasopressors, elevated CVP and PAOP
- Abdominal: Rigid or tense abdomen
- Neurologic: Increased intracranial pressure in patients with concomitant head trauma 5
Management Algorithm
Medical Management for IAH (Before ACS Develops)
The World Society of the Abdominal Compartment Syndrome suggests the following interventions 1:
- Avoid sustained intra-abdominal hypertension through protocolized management
- Limit positive fluid balance after initial patient resuscitation
- Consider percutaneous catheter drainage for fluid collections
- Optimize body positioning (semi-recumbent may reduce IAP)
- Use enhanced ratios of plasma to red blood cells during resuscitation
Surgical Management for Overt ACS
Decompressive laparotomy is the definitive treatment for fully developed ACS and should be performed emergently 1
Indications for Emergency Decompression 1, 5:
- IAP >25 mmHg with organ dysfunction
- Life-threatening physiologic derangements despite medical management
- Critical rise in intracranial pressure in patients with combined abdominal and head trauma
Expected Outcomes After Decompression
Emergency decompression produces immediate physiologic improvements 5:
- Cardiac index increases by 146%
- Tidal volume increases by 133%
- Urine output increases by 1557%
- Peak airway pressure decreases by 31%
- Central venous pressure decreases by 30%
Post-Decompression Management
After decompressive laparotomy 1:
- Apply negative pressure wound therapy to the open abdomen
- Make efforts to achieve same-hospital-stay fascial closure
- Avoid routine early biologic mesh use
Special Considerations
Timing of ACS Development
- ACS typically occurs within 12-13 hours after primary laparotomy in trauma patients 5
- 95% of delayed hemorrhagic complications occur within the first 72 hours, with maximum risk in the first 24 hours 1, 2
- Most complications (hemorrhagic or infectious) occur within the first 5 days following trauma 1, 2
Institutional Requirements
Patients with severe abdominal trauma undergoing non-operative management must be admitted to institutions with 24/7 capacity to perform emergency hemostatic laparotomy 1, 2, 6
Common Pitfall
Do not wait for pulselessness and pallor as these are late signs indicating irreversible damage; ACS must be diagnosed and treated based on IAP measurements and early organ dysfunction 7