Question 1

College answer

Not available.

Discussion

a)  Definitions

• Intra-abdominal hypertension is a sustained or repeated pathological elevation in IAP≥12 mmHg.
• Abdominal Compartment Syndrome is defined as a sustained IAP>20 mmHg that is associated with new organ dysfunction.
  (normal intraabdominal pressure ranges from subatmospheric to 0 mmHg in normal healthy adults, and around 5-7 mmHg in the prostrate ventilated critically ill patient)

b) Measurement

• Empty the bladder
• Clamp IDC
• Attach noncompressible tubing and transducer
• Inject 20ml of fluid into the bladder
• Wait for the detrusor to relax (60 seconds)
• Zero the transducer to atmosphere, at mid-axillary line and at the level of the iliac crest
• Measure the pressure at end-expiration
• The measurement is valid under the following conditions:
  • Patient is supine
  • Muscle contraction is eliminated (eg. NMJ blockers)

c) Management of abdominal compartment syndrome:

• Prevention:
  • Avoid overvigorous fluid resusictation
  • Patients at risk of ACS should perhaps remain open-abdomen after largescale abdominal surgery
  • monitor the compartment pressure
• Management
  • Staged closure of abdominal defect
  • Vasopressors to maintain MAP within a certain range (some aim for an abdominal perfsion pressure of >60mmHg)
  • Titrate PEEP to optimise V-Q matching, to maintain normoxia and normocapnea
  • If compartment pressure remains elevated, neuromuscular blockade can be considered
  • If pressure remains high in spire of NMJ blockade, may consider opening the abdomen (if it is closed)