Trauma - Abdominal compartment syndrome

Question 1

What are the grades of intraabdominal compartment syndrome? What are the threshholds for each grade?

Answer 1

Grading

Grade I – IAP 12-15mmHg

Grade II – IAP 15-20mmHg

Grade III – IAP 20-25mmHg

Grade IV – IAP>25mmHg

Question 2

What is normal IAP?

Answer 2

Normal IAP is 5-7mmHg in critically ill adults

Question 3

What pressure defines intraabdominal hypertension?

Answer 3

Intraabdominal hypertension (IAH) is >12mmHg

Question 4

How do you calculate abdominal perfusion pressure?

Answer 4

= MAP - IAP

Question 5

Define ACS

Answer 5

ACS = IAP or > 20mmHg + associated with new organ dysfunction

Key is that it causes impaired organ perfusion and end organ dysfunction

Question 6

What is the incidence of ACS?

Question 7

How are intraabdominal compartment syndromes categorised/classified?

Answer 7

Primary

arising from injury or illness originating in abdomino-pelvic

Causes include: trauma, DCS, massive bleeding, or severe pancreatics

Secondary

Arising from causees orginging from outside the abdomen

Causes include: sepsis, major burns, aggressive fluid resusitation/oedema

Question 8

What are the two causes of IACS?

Answer 8

1. Reduced abdominal Compliance
2. Increased Intra-abdominal volume

Question 9

What are the causes of reduced intraabdominal compliance

Answer 9

1. Abdo wall is injured or fixed:

Abdominal/pelvic trauma

Multiple prev Operation

2. Abdo wall is immobile:

Obesity

Prone Positioning

Mechanical ventilation

Question 10

What are the three contributors/locations of increased intraabdominal pressure?

Answer 10

1. Luminal

Gastropersis/ileus/mechanical obstruction

2. Mural/visceral Oedema

Massive resuscitation/Sepsis/ischemia/burns

3. Extra-mural

Massive bleeding/ascites/masses/abscess

Question 11

What are the four sequelae of ICS

Answer 11

1. Respiratory complications
2. Renal complications
3. Reduced visceral perfusion
4. Cardiac complications

Question 12

What are the respiratory effects of ACS?

Answer 12

Increased diaphragmatic splinting

Restricts ventilation → Reduced tidal volume

Decreased lung compliance → Increased airway pressure

Tachypnea, wheeze, increase ventilation pressure, poor ventilation/oxygenation

Question 13

What are the renal effects of ACS?

Answer 13

Increased renal vascular resistance and reduced cardiac output

Reduction in urine output. Redcued GFR (IAP beyond 15mmHg has effect on renal function)

Oligouria and progressive renal failure

Question 14

What are the cardiovascular effects of ACS?

Answer 14

Increased IAP = IVC compression, reduces cardiac output, increases CVP, systemic vascular resistance, pulmonary artery pressure and pulmonary wedge pressure

CO decreases due to reduces SV which in turn is due to reduced pre-load and increased after-load

Further aggravated by hypovolaemia, hypotension, tachycardia

Question 15

What are the visceral effects of ACS?

Answer 15

Compresion of GI veins, Reduced visceral blood flow, even at IAP of 15mmHg

Muscoal oedema, hypoperfusion, mucosal injury

Ischemia, bactermia and sepsis

Question 16

How do you diagnose ACS?

Answer 16

This is a clinical diangosis = ↑IAP + End organ dysfunction

Question 17

How may ACS appear on CT?

Answer 17

CT imaging has low utility for diagnosis

Associated signs can include elevated hemidiaphragm, collapse IVC, oedema

Screen for aetiology

Question 18

Describe how you would measure IAP

Answer 18

foley catheter, with T piece bladder pressure device between urinary catheter and drainage tubing

Connected to pressure transducer

Levelled/zeroed

Transducer positioned at level of mid-axillary line, at iliac crest

Urinary bag clamped

25mls isotonic saline instilled into bladder

After zeroing, the pressure is recorded

Question 19

How may IAP measurements be standardised?

Answer 19

Patient positioned flat on bed

End of expiration

Ideally when paralysed abdominal wall is not contracting

Question 20

Non operative management of ACS:

Answer 20

Confirm diagnosis

Regular measurement

Organ support

Optimise systemic perfusion in grades I and II

Improve ventilation, alveolar recruitment

Address underlying causes - by aetiology

Question 21

Give five nonoperative methods for reducing IAP in ACS

Answer 21

Improve Abdominal wall compliance: Analgesia/ Sedation/ neuromascular blockage

Evacuate intra-luminal contents: NGT decompression/ Rectal decompression/ Prokenetics

Correct positive fluid balance reduce Visceral oedema: Avoid excessive fluids, Diuretics/haemodialysis

Evacuate abdominal collections

Paracentesis/percutaneous drainage

Question 22

When is surgery for ACS indicated?

Answer 22

In true ACS (grade III and IV with new organ failure) - give decompressive laparostomy

Grade three is IAP >20mmHg