Vascular Emergencies Flashcards
State some of the vascular emergencies you need to be aware of
- Ruptured AAA
- Acute limb ischaemia
- Acute mesenteric ischaemia (see GI surgery)
Describe the two types of AAA rupture
Discuss the prognosis of each
Intraperitoneal (20%)
- Rupture anteriorly into intraperitoneal space
- ~23L fluid capacity
- Cardiac output ~51L/min
Retroperitoneal (80%)
- Rupture posteriorly into retroperitoneal space
- Usually survive to get to hospital
- Will eventually rupture intraperitoneally
Ruptured AAA has a high mortality; true or false?
True (>75%)
Describe the presentation of a ruptured AAA
- Known AAA or pulsatile mass in abodmen
- Severe abdominal pain, non-specific, may radiate to back or loin
- Haemodynamic instability: tachycardia, hypotension, weak pulse
- Pale, cold, sweaty
- Mimic acute abdomen (bleeding causes peritoneal irritation)
Classic triad= abdo/back pain, pulsatile mass and hypotension. However, less than 1/3 o pts will have this triad.
State some potential differential diagnoses for someone presenting with what appears to be a ruptured AAA
- MI with cardiogenic shock
- Massive PE
- Acute pancreatitis
Someone has come in to A&E with ruptured AAA, what is your initial management?
- Oxygen 15L non-rebreath mask
- Gain IV access- 2 wide bore cannulas in antecubital fossa
- Take bloods (FBCs, U&Es, clotting, crossmatch minimum 6 units)
- Maintenance IV fluids to maintain systolic at <100mmHg
- Catheterise
- CONTACT VASCULAR SURGEON ASAP
What is permissive hypotension?
Why do we aim for permissive hypotension in ruptured AAA?
- Permissive hypotension or hypotensive resuscitation is the use of restrictive fluid therapy, specifically in the trauma patient, that increases systemic blood pressure without reaching normotension
- Raising BP too much will dislodge any clots and may precipitate further bleeding. As long as pt is cerebrating BP is generally adequete
Discuss the management (following immediate management) of a AAA if pt is:
- Haemodynamically stable
- Haemodynamically unstable
- Haemodynamically stable: CT angiogram to determine if suitable for endovascular repair
- Haemodynamicaly unstable: transfer straight to theatre for open surgical repair
Define acute limb ischaemia
Sudden deterioration in aterial supply, in a previously stable limb, resulting in rest pain and/or other features of severe ischaemia of less than two weeks duration
Why is it important that acute limb ischaemia is treated promptly?
Complete acute ischaemia will lead to extensive tissue necrosis within 6hrs of onset unless arterial circulation is restored. Prompt assessment & management to prevent limb loss.
State some causes of acute limb ischaemia
*HINT: can be classified into three categories
-
Embolisation *80% have cardiac cause
- AF
- MI
- Ventricular aneurysm
- AAA
- Prosthetic heart valve
- Mural thrombosis
-
Thrombosis *60% is acute thrombosis in vessle with pre-existing atherosclerosis
- Atherosclerosis
- Popliteal aneurysm
- Thrombotic conditions
- Malignancy
- Dehydration
- Polycythaemia
-
Others
- Dissection
- Trauma
- Compartment syndrome
- External compression
Describe the presentation of acute limb ischaemia
Present with 6P’s (first 3 most common):
- Pain
- Pallor
- Pulselessness
- Parasthesia
- Parlysis
- Perishingly cold
State some clinical features that are suggestive of an embolic cause of acute limb ischaemia
- Sudden onset
- Known embolic source
- Absence of previous claudication
- Normal pulses in other limb
State some clinical features that suggest a thrombotic cause of acute limb ischaemia
- Previous history of intermittent claudication
- Slow onset or incomplete occlusion
- No obvious source of emboli
- Reduced or absent pulses on contralateral limb
If pt with suspected acute limb ischaemia has ‘marble white’ limb what does this suggest?
Embolic cause (if was atherosclerotic collaterals may have formed due to pre-exisiting peripheral arterial disease)
What does fixed/non-blanching mottling suggest?
Irreversible ischaemia
What investigations would you do if you suspect acute limb ischaemia, include:
- Bedside
- Bloods
- Imaging
Bedside
- ECG: determine whether in AF
- VBG: lactate quicker
Bloods
- FBC
- Troponin
- Group & save
- Coagulation
- Thrombophilia screen
- U&Es
- Glucose
Imaging
- Hand-held arterial doppler
- Duplex USS both limbs: look for occlusion
- Consider CT angiography following USS: can prvice more information regarding anatomical location of occlusion to help decide operative approach
Discuss the initial management of acute limb ischaemia
- 15L oxygen non-rebreathe mask
- IV heparin (5000U bolus then infusion of 1000U per hour)
- Appropriate analgesia e.g. morphine 1-10mg
- Correct hypotension if present with IV fluids
- Start treatment for associated cardiac condition if present (e.g. AF, MI)
The Rutherford classification helps us determine suitable definitive management of acute limb ischaemia; describe the Rutherford criteria
Conservative management of acute limb ischaemia can be considered in those with Rutherford categories ___ and ____?
What is the conservative mangement?
Rutherford categories 1 and 2a can be managed conservatively.
Give prolonged course of heparin. Monitor APPT regularly and review pt to check effectiveness. Surgical intervention may be required if no significant improvement seen.
Discuss the management of rutherford category 2b acute limb ischaemia (following initial management)
Surgical intervention is mandatory- cannot wait overnight. Any imaging should not delay treatment. Treatment depends on is source is embolic or thrombotic:
Embolic
- Embolectomy via Fogarty catheter under LA or GA
- Bypass surgery
Thrombotic
- Angioplasty
- Bypass surgery
- Local intra-arterial thrombolysis
Discuss the management of irreversible limb ischaemia (mottled, non-blanching apppearance with hard woody muscles/Rutherford category 3)
- Amputation
- Or palliative approach
Discuss the long term management of acute limb ischaemia
Centred around reduced CVD risk and preventing reoccurence:
- Lifestyle (smoking cessation, regular exercise, weight loss)
- Treat underlying conditions that predispose to acute limb ischaemia
- Anti-platelet agents e.g. aspirin or clopidogrel
- Anticoagulation e.g. warfarin or DOAC
- If had amputation, require physio, OT & rehabilitation
Reperfusion injury is one of the main complications of acute limb ischaemia. Explain what reperfusion injury is
Sudden return of oxygenated blood to the ischaemic muscles generates and releases oxygen radicals that cause cellular injury & oedema. This can lead to:
- Compartment syndrome
- Release of substances from cells:
- Hyperkalaemia
- Acidosis (H+)
- AKI (myoglobin)
Hence most post-operative cases are managed in high dependency unit to monitor for these complications.
