Abdominal Compartment Syndrome

Question 1

Define intra-abdominal hypertension.

Answer 1

IAP > 12 mmHg: sustained/repeated.

Question 2

Describe the grading of intra-abdominal hypertension

Answer 2

Grade 1: 12 - 15
Grade 2: 16 - 20
Grade 3: 21 - 25
Grade 4: > 25

Question 3

What is the definition of critical intrabdoinal pressure

Answer 3

IAP > 20 mmHg

higher pressures will cause a reduction in micro-circulatory blood flow which will lead to organ dysfunction

Question 4

Define and classify Abdominal Compartment Syndrome (ACS)

Answer 4

IAP > 20 with new organ dysfunction/failure

Primary - Cause within abdominopelvis
Secondary - Cause outside abdominopelvis
Recurrent - ACS that redevelops after Rx of primary/ secondary ACS

Question 5

Define and write the equation for Abdominal Perfusion Pressure (APP)

Answer 5

APP = MAP - IAP

APP is a predictor of visceral perfusion
Considers both arterial inflow (MAP) and restrictors to venous outflow (IAP)

Question 6

What is the desired APP

Answer 6

APP > 60 mmHg to prevent organ failure

Question 7

Describe the concept of the Filtration Gradient (FG)

Answer 7

Filtration Gradient (FG)
Glomerular Filtration Pressure (GFP)
Proximal Tubule Pressure (PTP)
Intra-abdominal Pressure (IAP)

FG = GFP - PTP

GFP = MAP - IAP

PTP = IAP

SO

FG = MAP - 2(IAP)

Change in IAP will have a greater impact on renal function than a change in MAP

Question 8

How should the measurement of IAP be done

Answer 8

1. At end expiration
2. Transducer zeroed at Mid axillary line
3. Patient supine
4. Abdominal muscles relaxed
5. 25 ml Sterile saline into the bladder via 3 way tap.

Normal value is 5 - 7 mmHg

Question 9

Summarise the steps to treat rising IAP

Answer 9

1. Evacuate intraluminal contents
   - NG
   - Prokinetic
   - Minimize enteral nutrition
   - Enemas
   - Colonoscopic decompression
   - Discontinue enteral nutrition
2. Evacuate Abdominal SOLs
   - Abdo US to identify
   - Abdo CT
   - Perc. drainage
   - Consider surgery
3. Improve abdominal wall compliance
   - Sedation/Analgaesia
   - Remove dressings/eschars
   - Avoid prone and Head > 20 deg
   - ? Reverse trendelendburg
   - Neuromuscular blockade
4. Optimise fluid administration
   - Avoid excess
   - Negative balance by day 3
   - Resus with hypertonic fluids/colloids
   - Judicious diuresis
   - Ultrafiltration
5. Optimize systemic/regional (perfusion)
   - goal directed fluid resus
   - APP > 60
   - HD monitoring
   - Vasoactive meds to maintain APP > 60