Ruptured AAA

Definitions:

• AAA with extra-luminal blood, either on CT or noted at surgery
• Contained rupture - blood outside the aneurysm sac, but confined to the retroperitoneal space
• Free rupture - bleeding directly into peritoneal cavity
• Symptomatic non-ruptured AAA: back pain or tenderness over the aorta on deep palpation, but with an intact aneurysm on CT/surgery
  • The pain is thought to be secondary to acute expansion of the wall, intramural haemorrhage, wall degeneration or bleeding into the thrombus and is considered a prelude to rupture
  • Much better prognosis than ruptured, but still require urgent management to prevent rupture

Pathophysiology

• RAAA represents failure of the aortic wall to bear the load
• Aortic thrombus plays a role - this impedes blood supply to the wall. Thicker mural thrombus means more likely to rupture.

Pre-op prognosis

• Mortality 80-90% overall (30% if they make it to OT)
• Predictors of mortality:
  • Hardman index/Glagow aneurysm score, RAAA-POSSUM, Edinburgh Ruptured Aneurysm Score
  • None of those is accurate enough to deny repair
  • Loss of consciousness - OR 2.6
  • Pre-op cardiac arrest - OR 4.3
  • Pre-existing CCF
  • Pre-existing renal insufficiency
  • Advanced age (>76yo) - OR 5.3
  • Female
  • Suprarenal clamp - OR 2.4

Presentation

• Classic triad:
  • Hypotension
  • Abdo/back pain - typically severe and unrelenting
  • Pulsatile abdominal mass
• Frequently appears pale and diaphoretic
• Flank ecchymosis is a late sign

Differential diagnosis

• Renal colic
• Diverticulitis
• MI
• Pancreatitis
• GIT bleed
• Perforated ulcer

Investigation:

• AXR
  • Enlargement of calcified aortic wall beyond normal limits
  • Loss of psoas shadow from retroperitoneal haemorrhage
• USS
  • FAST
    • Excellent for identifying AAA in trained hands
    • Not sufficiently accurate to exclude rupture
• CT
  • Most accurate method for diagnosis, ideally with contrast, to plan open or EVAR
  • Do it if the patient is stable

Management

Initial management

• • Immediate vascular consult
  • Permissive hypotension - SBP around 80
    • Maintain consciousness, minimise organ ischaemia, prevent ST depression
    • Be very judicious with fluids. Increased fluids increases mortality. Overall risk of harm is low if the diagnosis is wrong.
    • Blood or fluids can be given
  • Dual large-bore access
  • Art line?
  • IDC?
  • Crossmatch
  • Avoid intubation if they can protect own airway
  • CT-A would be very useful if possible - look for periaortic stranding to suggest imminent rupture - however the patient has to be well enough to go to CT
  • NGT

Open vs EVAR

• EVAR is preferred if possible
• Need a CTA for EVAR - patient has to be stable
• Anatomy is most important (see open AAA repair page for considerations)
• Overall about half of RAAA patients are suitable for EVAR

Operative setup:

• Prep, drape THEN intubate
• Consider art line/IDC
• Cell saver
• Avoid hypothermia

Open repair:

• Proximal aortic control - laparotomy, retract left lobe of liver and stomach to right, divide gastrohepatic ligament, retract oesophagus to left, access aorta and clamp it.
• Dissect infra-renal aortic neck. The clamp can be repositioned here if there is space
• Tube graft is most commonly used
• Close abdomen primarily if possible. Can't close in 25% due to tension. Early mesh closure may be an option.

EVAR:

• Can be done under local + sedation (maintain sympathetic tone) or GA
• Can be either percutaneous access or cutdown
• Stable patients can have GA and a cutdown
• Can do balloon occlusion first

Complications

• Often start to go downhill on day 2
• Lower extremity ischaemia
  • Either distal embolization or occlusion
  • Often kinking or compression of graft if done via EVAR
• Abdominal compartment syndrome
  • More common after EVAR, but can also occur after open - esp if significant haemorrhage or oedematous bowel
  • Often manifests as renal failure secondary to renal vein compression, or rising peak airway pressures, reduced cardiac output, oliguria
  • Decompressive laparotomy for intra-abdominal HTN > 25mmHg
• Ischaemic colitis
  • See separate topic under 'open AAA repair'
• Infection
  • Graft infection is rare but devastating
  • Often requires complete excision of graft
• Groin access complication