Surg - Intra-abdominal Compartment Syndrome

Question 1

What is normal intra-abdominal pressure?

Answer 1

5-7 mmHg

Question 2

What is intra-abdominal compartment syndrome?

Answer 2

World society for abdominal compartment syndrome definition:- ACS is sustained IAP >20 mmHg with new organ dysfunction (APP should be >60 (APP= MAP - IAP))- it may be primary (abdominal pathology) or secondary (extra-abdominal processes)- Intra-abdominal hypertension is sustained IAP >12 mmHg:- grade 1 (12-15)- grade 2 (16-20)- grade 3 (21-25)- grade 4 (>26)

Question 3

What are the risk factors/causes of IAH?

Answer 3

1. Decreased abdominal wall compliance- tight primary closure post surgery- trauma/burns- prone positioning2. Increased abdominal contents:- intraluminal (gastroparesis, pseudo-obstruction)- extraluminal (ascites - cirrhosis/pancreatitis/fluid resus/sepsis, haemo/pneumoperitoneum)3. Mechanical ventilation

Question 4

How is IAP measured?

Answer 4

1. Direct measure - needle or catheter attached to manometer into peritoneal cavity.2. Indirect (via urinary catheter)- ANTT- patient in supine position- bladder allowed to empty then drainage line clamped distal to transducer line- transducer attached in 3-way tap circuit at level of iliac crest and mid axilla line- 25ml sterile saline into bladder- allowed to settle for 60 secs and transducer zeroed to atmospheric pressure.- transducer opened to bladder and pressure measured (usually intermittently at 4-6 hourly intervals)

Question 5

What are the complications of intra-abdominal hypertension?

Answer 5

1. Respiratory:- basal atelectasis and reduced compliance- hypoxaemia and hypercapnia2. Cardiovascular- impaired venous return (increased intrathoracic pressure and reduced abdominal venous return) reducing cardiac output- increased afterload3. Neurological:- raised ICP (intraabdominal and thoracic pressure causing impaired cerebral venous blood flow)- hypoxaemia and hypercapnia worsening raised ICP4. Renal:- reduced renal blood flow and filtration gradient- external compression of renal outflow5. GI:- visceral ischaemia and oedema- impaired portal return- biliary stasis

Question 6

How can you manage raised abdominal pressure?

Answer 6

1. Medical management:- evacuate intraluminal contents- evacuate extraluminal contents- improve abdominal wall compliance- optimise fluid balance- optimise organ perfusion2. Surgery if refractory to medical therapy- laparotomy +/- open abdomen- escharotomy