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 :