1. Intra-abdominal Pressure Monitoring Clinical Background
HOLTECH MEDICAL
Intra-abdominal Pressure Monitoring
Clinical Background
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2. www.WSACS.org Definitions
Normal range: IAP<10-12 mmHg
Intra-abdominal Hypertension = IAH
IAH = IAP > 12 mmHg
ACS = IAP > 20 mmHg+1 new organ failure
APP (abdominal perfusion pressure) = MAP – IAP (same concept as CPP)
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3. Why monitor IAP?
IAH occurs  in more than 50% of all surgical and medical ICU patients (ref. 1)
IAH adversely affects venous return and microcirculation
IAH is associated with significantly increased morbidity and mortality (ref. 2)
IAH adversely affects all organs and promotes MOF (ref. 3)
IAH causes a covert elevation of CVP, PAOP, ICP (ref. 4)
Ref. 1: Manu Malbrain et al: Prevalence of intra-abdominal hypertension in critically ill patients: A multicentre epidemiological study. ICM 2004, 30:
Ref. 2: Manu LNG Malbrain et al: Incidence and prognosis of Intraabdominal hypertension in a mixed population of critically ill patients: A multicentre epidemiological study. CCM 2005 Vol. 33, No. 2.
Ref. 3: Manu LNG Malbrain: Is it wise not to think about intraabdominal hypertension in the ICU? Curr Opin Crit Care 2004; 10:
Ref. 4: Cheatham ML et al: Preload assessment in patients with an open abdomen. J Trauma 1999; 46:
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4. CENTRAL NERVOUS SYSTEM CARDIOVASCULAR SYSTEM GASTRO-INTESTINAL SYSTEM
Pathophysiology
CENTRAL NERVOUS SYSTEM
Intracranial pressure 
Cerebral perfusion pressure
Idiopathic intracranial hypertension (obesity)
CARDIOVASCULAR SYSTEM
Difficult preload assessment
Wedge pressure 
Central venous pressure 
Intra thoracic blood volume index =
Extra vascular lung water =
Right ventricular end-diastolic volume index =
Cardiac output 
Venous return 
Systemic vascular resistance 
Venous thrombosis 
Pulmonary embolism 
Heart rate  =
Mean arterial pressure  =
Pulmonary artery pressure 
RESPIRATORY SYSTEM
Intrathoracic pressure 
Pleural pressure 
Functional residual capacity 
All lung volumes 
(~restrictive disease)
Auto-PEEP  ?
Peak airway pressure 
Plateau pressures 
Dynamic compliance 
Static compliance 
Chest wall compliance 
Hypercarbia 
PaO2 
PaO2/FiO2 
Dead-space ventilation 
Intrapulmonary shunt 
Lower inflection point 
Upper inflection point 
Prolonged ventilation ?
Difficult weaning ?
RENAL SYSTEM
Renal blood flow 
Diuresis 
Tubular dysfunction 
Glomerular filtration rate 
Renal vascular resistance 
Renal vein compression 
Compression ureters 
Anti-diuretic hormone 
Adrenal blood flow =
GASTRO-INTESTINAL SYSTEM
Celiac blood flow 
Superior mesenteric artery blood flow 
Blood flow to intra-abdominal organs 
Mucosal blood flow 
Mesenteric vein compression 
Intramucosal pH 
Regional CO2 
CO2-gap 
Success enteral feeding  ?
Intestinal permeability 
Bacterial translocation  ?
Multiple organ failure  ?
Gastro-intestinal (re)bleeding 
HEPATIC SYSTEM
Hepatic arterial flow 
Portal venous blood flow 
Portocollateral flow 
Lactate clearance 
Glucose metabolism 
Mitochondrial function 
Cytochrome p450 function 
ABDOMINAL WALL
Compliance 
Rectus sheath blood flow 
Wound complications 
Incisional hernia 
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Malbrain. Current Opinion Crit Care 2004; 10(2):

5. IAP affects blood pressure
IAP affects all blood pressures
CVP increases by 3-6mmHg when IAP increases by 10mmHg. An example:
IAP=10mmHg, CVP=10mmHg. A sudden increase of IAP to 20mmHg changes CVP to 15mmHg. Now, what’s the correct CVP?
PAOP, ICP, and lung pressures are also affected by IAP.
Correct interpretation of pressures is supported by IAP monitoring
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6. IAH prevalence in 13 EU ICUs
Cut-Off
Total
(n=97)
Medical
(n=57)
Surgery
(n=40)
IAPmax>= 12 mmHg
57(58.8%)
31(54.4%)
26(65%)
IAPmax>= 15 mmHg
28(28.9%)
17(29.8%)
11(27.5%)
IAPmax>=20 mmHg
8(8.2%)
6(10.5%)
2(5%)
IAPmean>=12 mmHg
23(23.7%)
14(24.6%)
9(22.5%)
IAPmean>=15 mmHg
9(9.3%)
7(12.3%)
IAPmean>=20 mmHg
4(4.1%)
2(3.5%)
Malbrain. Intensive Care Med DOI /s (online first)
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7. 265 pts in 14 ICUs in EU 24. november 2017 www.holtech-medical.com
28-day Mortality:
23%
38%
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8. Indications for IAP monitoring
Postoperative (abdom. Surgery) pts
Pts with abdominal trauma
Ventilated pts with other Organ Failure
Pts with signs of ACS:
Oliguria, hypoxia, hypotension, acidosis, mesenteric ischemia, ileus, elevated ICP.
Pts with high cumulative fluid balance
Pts with abdominal packing
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9. Which IAP measurement interval?
IAH may develop rapidly
Monitor the trend: rising IAP or sustained IAH poor prognosis
Recommendation: Measure IAP at each Urine Output determination
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10. IAH treatment options Non-surgical treatment options:
WSACS recommendations
Non-surgical treatment options:
Paracenthesis
Gastric suctioning, enemas
Gastro/colon prokinetics
Furosemide, with or without albumin
CVVH with aggressive ultrafiltration
Sedation or curarisation
Surgical: Decompression
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11. WSACS’ protocol
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12. University of Utah: IAP monitoring algorithm
Entry criteria defined in table
Nurse is empowered to enter any patient fulfilling these criteria
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13. University of Utah: IAP Monitoring Protocol
IAP monitoring Q1-2 hours for first
12 hours
IAP
consistently
<12 mm Hg
IAP 12 to 15
mm Hg
IAP mm Hg
with no evidence
of organ dysfunction/
ischemia (ACS)
IAP >20 mm Hg OR
APP< mm Hg?
Plus evidence of
organ dysfunction/
ischemia (ACS)
Optimize Abdominal perfusion pressure
Careful fluid management
Pressors
Reduce IAP
measurements
to Q4-6 hours
for 24 hours
Consider Medical Management
Sedation/Neuromuscular blockade
Paracentesis of free fluid
Other options
Gastric suction, cathartics
Rectal tube/enemas
Continuous filtration
Colloids
Surgical
Decompression
“Second Hit” pt.
develops new
indication for IAP
monitoring
IAP remains
<12 mm Hg
discontinue
monitoring
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14. Why monitor IAP rather than ACS
Monitoring IAP and normalizing IAH may prevent ACS from happening. It´s like having a SMOKE DETECTOR in your home: It gives you time to locate the smoke (IAH) and cure the problem before the house catches fire (ACS)
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15. How to measure IAP? Patient position: Supine Bladder must be empty
Always use same 0 mmHg reference = symph. pubis, or mid-axillary line.
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16. The easy way: 24. november 2017 www.holtech-medical.com
40 mmHg
1. Urine drainage:
The urine fills the FoleyManometer and
flows on to the urine collection device
Pves
Mid-ax line = 0mmHg
2. Measure intra-vesical pressure:
The urine in the vertical manometer tube
returns to the bladder when the vent clamp
is opened. Hold the “0 mmHg” mark of the
manometer at the midaxillary line/iliac crest, and read Pvesical at the position of the meniscus
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17. Find more information World Society on ACS www.wsacs.org
Complete reference list
Consensus definitions
IAP discussion list
Links
Product information
Clinical issues
Key references
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