Acute Limb Ischaemia Flashcards
Definition of acute limb ischaemia…
A sudden lack of arterial blood supply to a previously stable limb over a period of less than two weeks, which is likely to lead to limb threatening ischaemia
What are the main causes of acute limb ischaemia?
- Embolus: cardiac (AF, mural thrombus post MI), arterial (aortic, femoral, popliteal), venous (passing into arterial system via PFO)
- Thrombosis: stenosis of vessel that is affected by atherosclerosis (acute on chronic event)
- Trauma: compression/ dissection of an artery can lead to acute lack of blood supply e.g. supracondylar humerus fracture, posterior knee dislocation
Why is thrombosis less likely to cause acute limb ischaemia?
Thrombosis occurs over time and so collaterals begin to develop to compensate for the poor blood supply.
Presentation of acute limb ischaemia…
6 Ps:
- Perishingly cold
- Painful
- Pulseless
- Pallor
- Parasthesia
- Paralysis
Key differential diagnoses for presentation of acute limb ischaemia?
Painful limb with reduced muscle power and sensation…
- DVT (if lower limb)
- Cellulitis
- Compartment syndrome
What is the management of acute limb ischaemia?
*A-E assessment should be used, patient kept NBM in case they require emergency surgery
- 15L High flow oxygen - increase oxygenation to help with perfusion of affected limb
- IV access:
- Take bloods from cannula (FBC, clotting profile, G&S,
U&E, glucose and lipids (risk factor), ESR (connective
tissue disease.
- IV 5-10mg morphine as pain relief
- ABG to assess lactate (measure of hypoxia)
- 12 lead ECG for checking AF
- Give 5000 IU of unfractionated heparin as a bolus, then start 1000IU /hr IV infusion by aiming for APTT 2-2.5x normal (normal=30-40s)
-Tissue viabilty assessment to be carried out by senior to guide the management
*Most likely will require urgent surgery
Why is anti-coagulation given in these patients?
Anti-coagulation is given to prevent the clot spreading further - not to break down the current clot.
What are the surgical options for limb ischaemia?
- Embolectomy
- Catheter directed localised thrombolysis, angioplasty +/- stent
- Trauma repair
- Amputation may be last resort
What is Virchow’s triad?
Three factors believed to predispose to formation of clots/ thrombus:
- Stasis of blood flow
- Hypercoagulability
- Endothelial injury
Name some major risk factors for DVT …
- Surgery - especially orthopaedic
- Pregnancy - especially 3rd trimester
- Advanced malignancy
- Reduced mobility
- Lower limb disease e.g. varicose veins
- Previous VTE
Name some minor risk factors for DVT…
- Congenital heart disease e.g. VSD
- OCP/ HRT use
- Nephrotic syndrome
- Dialysis
- Pro-thrombotic disease
- Long distance sedentary travel
How does OCP predispose people to DVT?
Oestrogen is a hormone that increases the gene transcription of clotting factors II,VII,X,XII,XIII - therefore there is increased risk of clot formation.
Presentation of DVT…
- Pain and tenderness
- Unilateral swelling of calf or thigh, with increased skin temp, erythema, cyanosis
- Distension of superficial veins
- Pitting oedema
What is the Well’s score?
Well's score is used to risk stratify patients with possible DVT: - Active malignancy = 1 - Immobilisation = 1 - Localised deep vein tenderness = 1 - Swelling = 1 - Pitting oedema = 1 - Collateral superficial veins = 1 - Previous DVT = 1 Score =/>2: DVT likely Score =/<1 :DVT unlikely
What investigations are carried out after Well’s score is calculated?
SCORE =/>2: DVT likely
- Proximal leg vein duplex USS –> if -ve D dimer is required
- If proximal leg vein duplex USS cannot be carried out within 4 hrs, do D dimer and give UFH whilst waiting for USS
SCORE=/<1: DVT unlikely
- Perform D dimer test –> if +ve arrange for proximal leg vein duplex USS within 24 hrs
- Give UFH if proximal leg vein duplex USS is not available within next 4 hrs
