Aortic aneurysm, acute and chronic ischaemia Flashcards
what is an abdominal aortic aneurysm?
a permanent pathological dilation of the aorta with a diameter >1.5x the expected anterior posterior diameter of that segment.
most commonly adopted threshold is >3cm
where are most AAA’s located ?
90% below the level of the renal arteries
what are the S&S of AAA?
asymptomatic
palpable, pulsatile, expansile abdominal mass
how are suspected AAA’s investigated?
abdo US
follow up CT scan with contrast if >5.5cm
how are AAA’s managed ?
- 0 – 4.4cm: yearly ultrasound
- 5 – 5.4cm: 3-monthly ultrasound
Medical
- Smoking cessation
- Improve blood pressure control
- Commence statin and aspirin therapy
- Weight loss and increased exercise
Surgical
- Open repair involves a midline laparotomy or long transverse incision, exposing the aorta, and clamping the aorta proximally and the iliac arteries distally, before the segment is then removed and replaced with a prosthetic graft
- Endovascular repair involves introducing a graft via the femoral arteries and fixing the stent across the aneurysm
what are the S&S of a ruptured AAA?
sudden, severe onset epigastic pain and/or back/loin pain
sudden collapse
Hx of AAA
rapid onset hypotension, pain and sweating
what is the emergency management of ruptured AAA?
call for senior and anaesthetist permissive hypotension IV access, cross match, order FFP and platelets modest analgesia (morphine 5-10mg) straight to threatre ABx prophylaxis aortic cross clamping distal anastamoses
what causes acute limb ischaemia?
acute thrombosis in vessel with pre-existing atherosclerosis (60%)
Emboli (30%)
rare causes
- aortic dissection
- intra arterial drug use
- trauma
what are the S&S of acute limb ischaemia ?
Pain Pallor Pulselessness Paraesthesia Paralysis Perishingly cold
How is acute limb ischaemia classified?
The Rutherford classification
Stage 1 = limb not immediately threatened
- no sensory loss or muscle weakness
- pedal and popliteal arteries audible on doppler
Stage 2a = limb marginally threatened
- minimal sensory loss, no muscle weakness
- popliteal arteries audible, pedal not
Stage 2b = limb immediately threatened
- pain at rest, moderate muscle weakness
- popliteal audible, pedal not
Stage 3 = limb irreversibly damaged
- profound pain, muscle paralysis
- popliteal and pedal inaudible
what are the InV done in acute limb ischaemia?
Duplex/doppler US ECG - look for AF Basic bloods Lactate - assess ischaemia CT/MR angiography to guide revascularisation
what is the management of acute limb ischaemia ?
initial
- emergency assessment by vascular surgeon
- systemic anticoagulation with heparin
- paracetamol and morphine
Surgical
- revascularisation via thrombectomy or embolectomy. Percutaneous catheter directed thrombolysis. Bypass graft surgery
- amputation
what are the complications of acute limb ischaemia ?
death in 15-20%
Reperfusion injury
- compartment syndrome (due to oedema)
- hyperkalaemia (due to K+ release)
- systemic acidosis from H+ release
- AKI
Peripheral nerve injury (leading to chronic neuropathic pain)
what is compartment syndrome?
Compartment syndrome is a pathological condition characterised by elevated interstitial pressure in a closed osteofascial compartment that results in microvascular compromise (restriction of capillary blood flow)
what causes compartment syndrome?
Elevated interstitial pressure in a closed osteofascial compartment may be secondary to several different factors. Haemorrhage within the compartment or direct trauma to the muscles with subsequent oedema can lead to increased pressure to above the capillary level, which restricts capillary flow. This results in tissue necrosis secondary to oxygen deprivation.
