Arterial.2.Acute ischemia Flashcards
DEFINITION of LIMB ISCHEMIA
Ischemia means diminished arterial blood sufficient to interfere with nutrition of the part.
ETIOLOGY of Ischemia
A) Acute Ischemia
B) Chronic Ischemia
All causes of acute ischemia
- Embolism “acute embolic ischaemia” : Commonest cause.
- Acute thrombosis “acute thrombotic ischaemia”
- Arterial injuries.
- Dissecting aneurysm.
- Phlegmasia cerulae or alba dolens.
- Arterial spasm due to ergot poisoning
7 : lntra-arterial injection.
All causes of chronic ischemia
- Atherosclerosis (commonest cause).
- Diabetic presenile atherosclerosis.
- Buerger’s disease.
- Vasospastic conditions
- Incomplete recovery after treatment of acute ischemia
- Aneurysm.
- Vascular compression : Thoracic outlet syndrome
Definition of acute ischemia
lt is SUDDEN decrease in arterial limb perfusion causing THREAT to limb vitality
No time for collaterals formation and gangrene occurs in 24 hours.
The Problem about acute ischemia
No time for collaterals formation and gangrene occurs in 24 hours.
Clinical picture of acute ischemia 6P
- Pain
- Paresis & muscle weakness “early” passing to paralysis “late”.
- Paraesthesia & numbness “early” followed by sensory loss “late”.
- Pulselessness : The distal pulsations are lost.
- Pallor “early”, then mottling & cyanosis “late”.
- Progressive coldness is an early symptom.
Pain in Clinical picture of acute ischemia
- onset
- character
- site and radiation
- what increase.
- what decrease
onset of Pain in Clinical picture of acute ischemia
sudden onset.
character of Pain in Clinical picture of acute ischemia
Bursting or stabbing in character.
site and radtiation of Pain in Clinical picture of acute ischemia
Starts at the point of occlusion and shoots distalty
what increase.Pain in Clinical picture of acute ischemia
movement and warmth.
what decrease Pain in Clinical picture of acute ischemia
- Pain may diminish in intensity by time if
- collaterals open improving the circulation “as in cases of acute thrombotic ischemia”
OR
- ischemia progresses causing ischemic sensory loss.
the reason why the pain in acute ischemia is bursting
Accumultion of metabolites ~~ V.D ~~ severe interstial edema ~~ bursting pain
collateral occur in which type of acute ischemia
acute thrombotic type
Paresis & muscle weakness “early” passing to paralysis “late” in Clinical picture of acute ischemia
1st muscle group affected by acute ischemia
The reason why detection of early muscle weakness is difficult in acute ischemia
1st muscle group affected by acute ischemia in Clinical picture of acute ischemia
intrinsic foot muscles followed by the leg muscles
the reason why detection of early muscle weakness is difficult in acute ischemia
because toes movements are produced mainly by leg muscles.
Paraesthesia & numbness “early” followed by sensory loss “late”. in Clinical picture of acute ischemia
order of frequency of sensory affection :
- Light (Crude) touch
- Vibration sense.
- Proprioception.
- Deep pain “late”.
- Pressure sense “late”
First to be affected from sensory due to acute ischemia
Light (Crude) touch
meaning of mottling
- V.D of vessels by Accumulation of metabolites
* Extravasation of RBCs due to ischaemic endothelial damage
Complications of acute ischemia
- Extension thrombosis
- Muscle necrosis occurs after 6-12 hours.
- Moist aseptic gangrene :
- Chronic ischaemia in low level occlusion only.
- Reperfusion syndrome :
Pathogenesis of Extension thrombosis in Complications of acute ischemia
After circulatory arrest )> widespread distal intravascular thrombosis
Moist aseptic gangrene in acute ischemia
Pathogenesis
the reason why it’s moist
the reason why Development of collaterals may fail in acute ischemia
pathogenesis of Moist aseptic gangrene in acute ischemia
If occlusion is not relieved by surgical intervention or the collaterals are inadequate, the thrombosis extends further & the ischaemic changes progress to moist aseptic gangrene within 24 hours.
the reason why gangrene in acute ischemia is moist gangrene
Accumultion of metabolites ~~ V.D ~~ severe interstial edema
Development of collaterals may fail in acute ischemia due to
a. Reflex vasoconstriction of collaterals.
b. Spreading thrombus in the collaterals.
the reason why Chronic ischaemia complicates acute ischemia in low level occlusion only.
Infra popliteal region is supplied by 3 vessels
Etiology of Reperfusion syndrome in complication of acute ischemia
a. compartmental syndrome
b. cardiac arrhythmia or cardiac arrest
c. crush syndrome
compartmental syndrome in complication of acute ischemia
- Definition
- in a phrase
- pathogenesis
- Treatment
Definition of compartmental syndrome in complication of acute ischemia
Means increased pressure in a closed fascial compartment (e.g, the anterior compartment of the Ieg) more than pressure needed for tissue perfusion.
compartmental syndrome in a phrase
acute ischemia with a pulse as the capillary bed is occluded
pathogenesis of compartmental syndrome in complication of acute ischemia
- Released inflammatory mediators as a result of muscle ischemia causes vasodilatation of the blood vessels & damage of the endothelial lining.
- Later on after perfusion, severe edema occurs raising the pressure in the closed compartment
Treatment of compartmental syndrome in complication of acute ischemia
Fasciotomy
cardiac arrest and cardiac arrhythmia in complication of acute ischemia
pathogenesis
Treatment
pathogenesis of cardiac arrest and cardiac arrhythmia in complication of acute ischemia
Due to flooding the circulation with:
- excess acid metabolites (resulting from anaerobic metabolism of the tissues)
- excess potassium from cell damage.
Treatment of cardiac arrest and cardiac arrhythmia in complication of acute ischemia
with NaHCO3 + Glucose-insulin infusion to stimulate intracellular shift of K+
crush syndrome in complication of acute ischemia
Pathogenesis
Treatment
Pathogenesis of crush syndrome in complication of acute ischemia
Acute tubular necrosis due to release of myoglobin from ischaemic muscles which the blocks renal tubules leading to acute renal failure.
Treatment of crush syndrome in complication of acute ischemia
mannitol infusion & dialysis if anuria developed
Definition of acute embolic ischemia
Embolism means sudden impaction of an embolus in a relatively healthy arterial tree causing obstruction & loss of function.
sources of Embolism
(A) cardiac:
(B) Arterial wall :
cardiac sources of Embolism
- Left atrium in atrial fibrillation.
- Left ventricle after recent myocardial infarction
- Thrombi may form on prosthetic valves
- The valves in S.B.E
Arterial wall sources of Embolism
The aorta from an aneurysm
Site of impaction of an embolus is Bifurcation of vessels due to :
- Decrease in diameter.
- Slowing of the circulating blood.
- Turbulence.
Commonest site of impaction of an embolus ; In order of frequency
Common femoral bifurcation
Aortic bifurcation.
Popliteal bifurcation.
Saddle embolus
Embolus impacted at aortic bifurcation.
Clinical picture of acute embolic ischemia
Very important
6P + clinical features suggestive of acute embolism
clinical features suggestive of acute embolism
- Sudden onset of symptoms.
- Known source of emboli.
- No previous history of claudication pain & chronic ischaemia.
- Normal pulse in the other limb or A.F.
D.D of acute embolic ischemia
Commonly, acute thrombosis arises in an artery previously narrowed by atherosclerosis
Difference between acute embolism and acute thrombosis is done by
Age
Past history
Commonest site.
Radial pulse.
Pulse in other limb.
Arteriography.
Age of acute embolism
Commoner in young age
Age of acute thrombosis
Commoner in old age
Past history of acute embolism
Cardiac troubles
Past history of acute thrombosis
Intermittent claudication
Commonest site of acute embolism
Bifurcation of common femoral artery
Commonest site of acute thrombosis
Lower end of femoral artery.
Radial pulse of acute embolism
A.F (commonest cause).
Radial pulse of acute thrombosis
Usually regular.
Pulse in other limb of acute embolism
Normal.
Pulse in other limb of acute thrombosis
Weak.
Arteriography of acute embolism
Minimal collaterals
Arteriography of acute thrombosis
Exlensive collaterals
commonest cause of acute emoblism
A.F
Investigations of acute embolic ischemia
- Arterial duplex scanning.:
- ECG, echocardiography.
- Arteriography usually not needed better to be done intraoperative
Arterial duplex scanning in Investigations of acute embolic ischemia, show
Inaudible arterial signals at the level of obstruction.
Postgraduate note : The presence of pedal signals in Arterial duplex scanning in Investigations of acute embolic ischemia, usually indicates
that there is time for conventional arteriography & proper patient preparation.
Arteriography in Investigations of acute embolic ischemia
indications
value of Pre-operative arteriography
Indications of Arteriography in Investigations of acute embolic ischemia
- usually not needed better to be done intraoperative
- Pre-operative arteriography in acute ischemia is done ONLY If differentiation between acute embolic ischemia & acute thrombotic ischemia is not clear clinically provided that the condition of the limb permits
value of Pre-operative arteriography in Investigations of acute embolic ischemia
a) Localizes the exact site of obstruction.
b) Visualizes the arterial tree & distal run-off.
c) Can diagnose an embolus by:
Pre-operative arteriography in Investigations of acute embolic ischemia can diagnose an embolus by :
1) Sharp cut-off
2) Reversed meniscus sign
3) Clot silhouette.
Reversed meniscus sign
Crescentic filling defect in arteriography of actue ischemia
Clot silhouette.
Its Shadow
Filling defect in arteriography of actue ischemia
Treatment of acute embolic ischemia
(A) General rules
(B) Immediate Embolectomy
(C) prevention of complications
(D) Prevention of further emboli
(E) Delayed embolectomy
(F) Amputation
General rules in treatment of acute embolic ischemia
- Immediate heparinisation : (most important)
- Appropriate analgesia.
- Start TTT of associated cardiac condition as A.F
- Simple measures to increase existing perfusion :
the reason why we do immediate heparinisation in General rules in treatment of acute embolic ischemia
To prevent propagation of thrombosis
Simple measures to increase existing perfusion in General rules in treatment of acute embolic ischemia
i) Keep the foot dependant.
ii) Avoid extremes of temperature (cold induces vosospasm & heat raises the metabolic rate
iii) Maximum tissue oxygenation
most important General rule in treatment of acute embolic ischemia
Immediate heparinisation
Immediate Embolectomy in treatment of acute embolic ischemia
Procedure
Indications
Signs of adequate embolectomy
Complications
Prognosis:
Procedures of Immediate Embolectomy in treatment of acute embolic ischemia
Using Fogarty balloon catheter:
It is done under local anesthesia.
Indications of Immediate Embolectomy in treatment of acute embolic ischemia
Done as long as the limb is viable.
- no fixed mottling.
- No muscle turgor.
- Intact capillary circulation.
indications of viable limb in cases of acute embolic ischemia
- no fixed mottling.
- No muscle turgor.
- Intact capillary circulation.
Signs of adequate embolectomy in Immediate Embolectomy in treatment of acute embolic ischemia
- Back bleeding. .
- Pulses are felt during the operation.
- Intraoperative angiography.
Complications of Immediate Embolectomy in treatment of acute embolic ischemia
- Rupture of the artery.
- Dissection.
- Distal embolization
Prognosis of Immediate Embolectomy in treatment of acute embolic ischemia
Removal of embolus within 6-10 hrs of onset of symptoms can result in saving the limb completely
Prevention of complications in treatment of acute embolic ischemia
Fasciotomy
NaHCO3 + Glucose-insulin infusion
mannitol infusion & dialysis if anuria developed.:
the reason why we do Fasciotomy
To prevent compartmental syndrome
the reason why we give NaHCO3 + Glucose-insulin infusion
To stimulate intracellular shift of K+ :
To prevent cardia arrest and cardiac arrhythmia
the reason why we give mannitol infusion & dialysis if anuria developed
to prevent crush syndrome
Prevention of further emboli in treatment of acute embolic ischemia
- Long term anticoagulants e.g. warfarin.
2. Treatment of the underlying cause whenever possible.
indication of delayed embolectomy
If the patient is presented after 24 hours
It’s done to save the profunda femoris artery & hence a safe AKA.
Amputation in treatment of acute embolic ischemia
indications
Rule
indications of Amputation in treatment of acute embolic ischemia
irreversible ischemia with permanent tissue damage
Permanent tissue damage in acute embolic ischemia is known by
turgid muscles
or
fixed mottling & cyanosis
turgid muscles
Like rigor mortis
Pathogenesis of fixed mottling in Permanent tissue damage in acute embolic ischemia
Thrombosis reached vasodilated skin blood vessels
Rule of amputation in treatment of acute embolic ischemia
Palpable popliteal pulse)> Below knee amputation “BKA”.
Absent popliteal pulse)> Above knee amputation “AKA”.
ETIOLOGY of acute thrombotic ischemia
what changes the condition from chronic to acute
- Atherosclerosis.
- Typhoid fever.
- Polycythaemia.
- Dehydration e.g. with diarrhea.
- Prolonged immobilization.
Clinical picture of acute thrombotic ischemia
6Ps + previous history of chronic ischaemia.
the reason why acute thrombotic ischemia is less severe than acute embolic ischaemia.
Collaterals are more developed in patients with preexisting chronic ischemia
Investigations of acute thrombotic ischemia
- Arterial duplex scanning.
- Urgent arteriography is a MUST.
- ECG, echocardiography.
the reason why Urgent arteriography is a MUST in case of acute thrombotic ischemia
To detect run off
If present )> by pass surgery
Treatment of acute thrombotic ischemia
Acute arterial thrombosis is an emergency.
- Bypass graft
- lntra-arterial thrombolysis by streptokinase, urokinase or TPA is another option of treatment:
indications of Bypass graft in Treatment of acute thrombotic ischemia
if there is good run-off.
Indications of lntra-arterial thrombolysis by streptokinase, urokinase or TPA
- if there is no run-off.
* High risk patient for bypass graft.