Abdominal Compartment Syndrome

OVERVIEW

Definitions (from Kirkpatrick et al, 2013)

  • Intra-abdominal pressure (IAP) is the steady state pressure concealed within the abdominal cavity
  • Intra-abdominal Hypertension (IAH) is sustained intra-abdominal pressure (IAP) of > 12mmHg
  • Abdominal Compartment Syndrome (ACS) is sustained IAP > 20mmHg with new organ failure
  • Abdominal Perfusion Pressure (APP) = MAP – IAP
  • A polycompartment syndrome is a condition where two or more anatomical compartments have elevated compartmental pressures
  • Abdominal compliance is a measure of the ease of abdominal expansion, which is determined by the elasticity of the abdominal wall and diaphragm. It should be expressed as the change in intra-abdominal volume per change in IAP

Types of ACS

  • Primary ACS — injury or disease causing ACS (typically requires early surgical/radiological intervention)
  • Secondary ACS — ACS due not due to primary condition
  • Recurrent ACS — ACS develops after previous surgical or medical treatment of ACS

Grade of IAH (severity)

  • Normal = IAP 5-7 mmHg
  • Grade I = IAP 12–15 mmHg
  • Grade II = IAP 16–20 mmHg
  • Grade III = IAP 21–25 mmHg
  • Grade IV = IAP >25 mmHg

Differences in children

  • IAP in critically ill children is approximately 4–10 mmHg
  • IAH in children is defined by a sustained or repeated pathological elevation in IAP > 10 mmHg
  • ACS in children is defined as a sustained elevation in IAP of greater than 10 mmHg associated with new or worsening organ dysfunction that can be attributed to elevated IAP
  • The reference standard for intermittent IAP measurement in children is via the bladder using 1 mL/kg as an instillation volume, with a minimal instillation volume of 3 mL and a maximum installation volume of 25 mL of sterile saline

RISK FACTORS

Diminished Abdominal Wall Compliance

  • acute respiratory failure (especially with elevated intrathoracic pressure)
  • abdominal surgery with fascial closure
  • major trauma/burns
  • prone positioning
  • head > 30 degrees
  • high BMI
  • central obesity

Increased Intra-luminal Contents

  • gastroparesis
  • ileus
  • colonic pseudo-obstruction

Increased Abdominal Contents

  • haemo/pneumoperitoneum
  • ascites
  • liver dysfunction

Capillary Leak or Fluid Resuscitation

  • acidosis (pH < 7.2)
  • hypotension
  • hypothermia (T < 33 C)
  • massive transfusion (> 10 U in 24 hrs)
  • coagulopathy
  • massive fluid resuscitation
  • pancreatitis
  • sepsis
  • oliguria
  • damage control laparotomy

CONSEQUENCES

Gastrointestinal

  • direct compression
  • thrombosis
    -> bowel wall ischaemia + oedema
    -> translocation of bacterial products leading to additional accumulation

Renal

  • direct compression of renal parenchyma and ischaemia
    -> AKI

Respiratory

  • reduced compliance
  • elevated airway pressures
  • decreased TV

Neurological

  • increased ICP
  • decompressive laparotomy has been shown to reduced intractable intra-cranial hypertension in patients with intra-abdominal hypertension

Cardiovascular

  • elevated CVP and PCWP
  • however, decreased VR
    -> decreased cardiac output

INVESTIGATIONS

Imaging

  • AXR: useless!
  • CT: only subtle findings
    -> increased AP diameter, collapse of vena cava, bowel wall thickening, bilateral inguinal herniation
  • Ultrasound: AAA

Gold standard is measurement of intra-vesical pressure (see IAP monitor)

MEDICAL MANAGEMENT

Monitor

  • measure IAP when patient has 2 or more risk factors or in the presence of new or progressive organ failure

Improve Abdominal Wall Compliance

  • sedation & analgesia
  • avoid head elevation > 30 degrees
  • remove constrictive dressing
  • eschars
  • neuromuscular blockade

Evacuate Intra-Luminal Contents

  • nasogastric decompression
  • rectal decompression
  • prokinetics
  • minimise enteral nutrition
  • enemas

Evacuate Abdominal Fluid Collections

  • paracentesis
  • percutaneous drainage
  • surgical evacuation

Correct Positive Fluid Balance

  • avoid excessive fluid
  • aim for zero to negative balance
  • diuretics
  • colloids/hypertonic fluids
  • haemodialysis/filtration

Organ Support

  • maintain a APP > 60mmHg with vasopressors
  • optimise ventilation: use transmural airway pressure (Pplattm = Pplat – IAP)
  • if using CVP use transmural pressure (CVPtm = CVP – 0.5 x IAP)

SURGICAL MANAGEMENT

  • if IAP 25-35 and not responding to medical treatment
    -> decompression with delayed closure (laparostomy)
  • on release be aware of hypotension
    -> PEA arrest from reperfusion and a sudden decrease in SVR

References and Links

LITFL

Journal articles

  • Kirkpatrick AW, et al. Intra-abdominal hypertension and the abdominal compartment syndrome: updated consensus definitions and clinical practice guidelines from the World Society of the Abdominal Compartment Syndrome. Intensive Care Med (2013) 39:1190–1206 [Free Full Text]

FOAM and web resources


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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