acute limb ischemia site
TRANSCRIPT
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Acute Limb Ischemia
Ali SABBOUR
Prof. of Vascular Surgery, Ain Shams University
Acute Limb Ischemia
Definition, Etiology & Patophysiology
Acute Limb Ischemia
Clinical Evaluation & Classes
Acute Limb Ischemia
Management
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Definition of Acute Limb Ischemia
Suddendecrease of
arterial limb perfusioncausing threat to limb
viability
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Etiology of acute limb ischemia
Acute arterial embolism:
Acute traumatic ischemia:
Of a relatively health arterial tree
Acute arterial thrombosis: Of a previously diseased arterial tree
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Patho-pysiology
Acute EmbolicIschemia
Acute ThromboticIschemia
An embolussuddenly
occludes arelativelyhealthy
arterial tree
Atherosclerosiscauses
progressivenarrowing of the
arterial tree
Stimulatesdevelopment of
collaterals
Sluggish flow &rough surfacewill favor acute
thrombosis
It usuallyarrest atarterial
bifurcationAortic bifurcation
Iliac bifurcation
Femoral bifurcation
Popliteal trifurcation
An embolus can originate from the heart (MS with atrial fibrillation,MI with mural thrombus)
or dilated diseased arteries(aortic aneurism)
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It is important to differentiate between embolic &thrombotic ischemia: Because the
managementis different
Clinical Features Suggestive of acute Embolism:
Sudden onset of symptomsKnown embolic source
Absence of previous claudication
Normal pulse in the other limb
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The severity of acute ischemia depends on:
a) Capability of existing collaterals to carry blood around the acute obstruction
(collaterals are more developedin patients with preexistingchronic ischemia)Accordingly, arterial embolism is
more likely to produce suddensymptoms & severe ischemiathen arterial thrombosis
b) The location of obstruction in relation to the number of axial arteries
Postgraduates
Aorta & common iliac One axial a. with limited collateral pathways
Internal & external iliac Two axial aa. With better collateral potentials
Two axial aa. With better collateral potentialsSuperficial & deep femoral
Popliteal artery One axial a. with limited collateral pathways
Three axial aa. with better collateral potentialsTibial arteries
c) The extent of obstructionThe larger the obstruction, the more collaterals arelost
d)The duration
Flow distal to the obstruction is sluggish. If collaterals cannotincrease the flow above a critical point, a stagnation clot will
develop in the distal arterial tee. This the reason why heparinshould be given as early as possible
For Example:
Popliteal a occlusion (a
single axial a.) results insevere ischemia, whileposterior tibial occlusionmay be asymptomatic ifother leg arteries arepatent
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Definition:Suddendecrease of arterial limb perfusion causing threat to limb viability
Etiology:1-Embolic (Rh.heart w mitral stenosis & AForIschemic heart w acute myocardialinfarction & mural thrombusorextra-cardiac embolism from aneurismal arteries)
2-Thrombotic acute ischemia on top of atherosclerotic arterial stenosis
Pathology: onset of symptoms is more acute in embolic ischemia (absent collaterals)
Other factors determine the severity of acute ischemia
Clinical Picture
Management
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Clinical Evaluation of Acute Ischemia(Clinical Picture)
Symptoms of acute ischemia:
Pain: Diffuse foot & leg severe aching pain of acute onset (more acute inembolic ischemia)
Pain may diminish in intensity by time if collaterals open improving circulation, or ifischemia progresses causing ischemic sensory loss
Coldness is an early symptom
Numbness followed by sensory loss (late)
Muscle weakness (heavy limb) followed by paralysis (late)
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Clinical Evaluation of Acute Ischemia(Clinical Picture)
History
Aim of your questions
1- To know whether these symptoms are of acute ischemia or not
(DD of acute ischemia : acute DVT[phlegmasia], hypo-perfusion states[e.g. heart
failure specially if associated with chronic ischemia]
2- To know the severity of acute ischemia
(ask about symptoms of different classes of acute ischemiasee later)
3- To look for the underlying etiology
(ask about Rh. Heart Ds, claudication, recent arterial interventione.g. cardiac cath.,
risk factors for atherosclerosis:hypertension, diabetes, smoking, hyperlipedemia,family history of cardio-vascular disease)
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Clinical Evaluation of Acute Ischemia (Clinical Picture)
Signs of acute ischemia
5PsPain: symptom
+
Pulseless
Pale
Parathesia
Paralysis
Inspection
COLOR:
Early: pale
Later: cyanosed mottling fixedmottling & cyanosis
Pallor
Reversiblemottling
An area offixed cyanosissurrounded by
reversiblemottling
Empty veins:compare the Rt.(ischemic) & Lt.(normal)
Fixedmottling &cyanosis
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Clinical Evaluation of Acute Ischemia (Clinical Picture)
Signs of acute ischemia
5PsPain: symptom
+
Pulseless
Pale
Parathesia
Paralysis
Palpation
Femoral Popliteal
Posterior tibial Dorsalis pedis
Palpate peripheral pulses, compare with theother side & write it down on a sketch
Temperature: the limb is cold with a level oftemperature change (compare the two limbs)
Slow capillary refilling of the skin afterfinger pressure
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Clinical Evaluation of Acute Ischemia (Clinical Picture)
Signs of acute ischemia
5PsPain: symptom
+
Pulseless
Pale
Parathesia
Paralysis
Palpation
Loss of sensory function
Numbness will progress to anesthesia
Progress of Sensory loss
Light touch
Vibration sense
Proprioreception
Deep pain
Pressure sense
Late
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Clinical Evaluation of Acute Ischemia (Clinical Picture)
Signs of acute ischemia
5PsPain: symptom
+
Pulseless
Pale
Parathesia
Paralysis
Palpation
Loss of motor function:
Indicates advancedlimb threateningischemia
Late irreversibleischemia: Muscle turgidity
Intrinsic foot muscles are affected
first, followed by the leg muscles
Detecting early muscle weakness isdifficult because toes movements areproduced mainly by leg muscles
Postgraduates
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Classes of Acute Ischemia
Clinical Findings Doppler Prognosis
Class Sensoryloss
Motorweakness
Arterialsignals
VenousSignals
I.Viable -ve -ve audible audible Not immediatelythreatened
II.aMarginalthreat
Minimalsensory loss
No muscleweakness
Often notaudible
audible Salvageable if promptttt (there is time for
angiography)
II.b Immediatethreat
Rest pain wsensory lossmore than toes
Mild tomoderate
Usuallynot
audible
audible Salvageable withimmediate ttt (no time
for angiography)
III.Irreversible Severeanesthesia
Paralysis wmuscle rigor
Inaudible Inaudible Not salvageable,permanent N. & muscle
damage ,needs amputation
Postgraduates
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Definition:Suddendecrease of arterial limb perfusion causing threat to limb viability
Etiology:1-Embolic (Rh.heart w mitral stenosis & AForIschemic heart w acute myocardialinfarction & mural thrombusorextra-cardiac embolism from aneurismal arteries)
2-Thrombotic acute ischemia on top of atherosclerotic arterial stenosis
Pathology: onset of symptoms is more acute in embolic ischemia (absent collaterals)
Other factors determine the severity of acute ischemia
Clinical Picture
Management
The limb is described as having 5 Ps :
Pain, Pale, Pulseless, Parathesia, Paralysis
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Investigations of acute limb ischemia
The severity and duration of ischemia at the time of presentation provides a
narrow margin of time for investigations
Doppler US
It is important to look forarterial Doppler signalsto assess the level of
obstruction & severity ofischemia
The presence of pedal signals
usually indicates that there istime for conventionalarteriography & proper patientpreparation
The ABI is not of value inacute ischemia. If it can bemeasured, the limb is notthreatened
Postgraduates
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Arteriography
Investigations of acute limb ischemia
Patients with high clinical probability of embolic ischemia do NOT need angiography
If the differentiation betweenembolic & thrombotic ischemia isnot clear clinically, and if the limb
condition permits,
DO ANGIOGRAPHY
Value of angiography
Localizes the obstruction
Visualize the arterial tree & distalrun-off
Can diagnose an embolus:
Sharp cutoff, reversed meniscus or clot
silhouette
Popliteal embolism
Reversed meniscus sign
Lt. iliac embolism
Clot silhouette
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Treatment of acute limb ischemia
A Once you diagnose
Immediate anticoagulation with heparin to avoid clotpropagation
Appropriate analgesia
Simple measures to improve existing perfusion:
Keep the foot dependant
Avoid pressure over the heal
Avoid extremes of temperature (cold induces vasospasm, heal raises themetabolic rate)
Maximum tissue oxygenation (oxygen inhalation)
Correct hypotension
Start treatment of other associated cardiac conditions (CHF, AF)
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Treatment of acute limb ischemia
B Catheter directed thrombolysis
Indications:
1. Viable or marginally threatened limb (class I, IIa)
2. Recent acute thrombosis (not suitable for embolism or old thrombi)
3. Avoid patients with contraindications
Agents used: Streptokinase,Urokinase, tissue plasminogen
activator
Contraindications:
Absolute:
1. Cerebro-vascular stroke within previous 2 months
2. Active bleeding or recent GI bleeding within previous 10 days
3. Intracranial trauma or neurosurgery within previous 3 months
Relative:
1. Cardio-pulmonary resuscitation within previous 10 days
2. Major surgery or trauma within previous 10 days
3. Uncontrolled hypertension
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Treatment of acute limb ischemia
C Surgery
1- Acute embolism: Catheter embolectomy under local anesthesia
2- Immediate surgical revascularization is indicated in class IIb, or class I, IIa
when thrombolysis is not possible or contraindicated
A combination of different procedures can be done:
Arterial exploration at different sites
Arterial thrombectomy
Bypass surgery based on pre-operativeangiography if available or intra-operativeangiography
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Following revascularization:
The sudden return of oxygenated blood to the acutely
ischemic muscles generates & releases oxygen free radicalsthat causes cellular injury and severe edema
Compartment syndrome
& muscle necrosis
ttt
FasciotomyLongitudinal incision of the skin & deep fascia to release pressure over swollen muscles
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Amputation:
Done for irreversible ischemia with permanent tissuedamage (turgid muscles, fixed cyanosis)
The level of amputation is decided according to the level of
palpable pulse.
Palpable popliteal pulse -------------- Below knee amputation
Absent popliteal pulse ---------------- Above knee amputation
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Definition:Suddendecrease of arterial limb perfusion causing threat to limb viability
Etiology:1-Embolic (Rh.heart w mitral stenosis & AForIschemic heart w acute myocardialinfarction & mural thrombusorextra-cardiac embolism from aneurismal arteries)
2-Thrombotic acute ischemia on top of atherosclerotic arterial stenosis
Pathology: onset of symptoms is more acute in embolic ischemia (absent collaterals)
Other factors determine the severity of acute ischemia
Clinical Picture
Investigations
The limb is described as having 5 Ps :
Pain, Pale, Pulseless, Parathesia, Paralysis
Doppler to evaluate level & degree of ischemia
Conventional angiography in class I & IIa
Intraoperative angiography in class IIb
Treatment HeparinCatheter directed thrombolysisOperative revascularizationAmputation in irreversible ischemia