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Surgery M4 part 1 > Acute Ischemia > Flashcards

Acute Ischemia Flashcards

1
Q

Using a Doppler if the artery is normal what type of sound will be heard?

A

Triphasic signal

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2
Q

If an artery is obstructed what kind of sound will be heard on a Doppler?

A

Multiphasic (biphasic) flow

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3
Q

If there is a marked obstruction in an artery what should be heard on a Doppler?

A

Monophonic flow

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4
Q

How to differentiate between arterial & venous flow on a Doppler?

A

Arterial: triphasic signal
Venous: uniphasic signal (flow in one direction)

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5
Q

What is the first line of investigation for ischemia, vascular malformation, or vascular injury?

A

Colored duplex

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6
Q

What information could be obtained from a colored duplex?

A
  • vessel lumen
  • vessel wall
  • hemodynamic information
  • evaluation of venous disorders
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7
Q

What are the disadvantages of duplex?

A
  • operator dependent
  • not accurate in operative or interventional planning
  • certain blind spots

Only used for superficial vessels

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8
Q

What is the most accurate method to identify the diseased segment of an artery?

A

Conventional angiography

DIAGNOSTIC & THERAPEUTIC

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9
Q

Which method of investigation can reveal distal run-off & state of collaterals?

A

Conventional angiography (arteriography)

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10
Q

What are the hazards on angiography?

A

INVASIVE

  • blood extravasation
  • thrombosis
  • arterial dissection
  • distal embolization
  • renal dysfunction
  • allergic reaction (due to injected dye)
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11
Q

What is the disadvantage of using CT angiography?

A

NOT THERAPEUTIC

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12
Q

What is used instead of the duplex for investigation of deeper blood vessels?

A

MR angiography

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13
Q

What are the factors affecting ischemia?

A
  • rate of occlusion
  • degree of obstruction
  • state of collaterals
  • type of artery
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14
Q

What is the difference between chronic & acute ischemia?

A

ACUTE

  • NO collaterals
  • sudden & complete occlusion of arterial supply

CHRONIC

  • progressive opening of collaterals
  • gradual diminution of blood supply
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15
Q

What are the intrinsic causes of acute ischemia?

A
  • embolism
  • acute thrombosis
  • instrumentation
  • intra-arterial drug injection
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16
Q

What are the extrinsic causes of acute ischemia?

A
  • trauma (arterial injury)
  • venous outflow blockage
  • fractures
  • compartment syndrome
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17
Q

What are the local effects of acute ischemia?

A

1) acute occlusion
2) stasis in distal arterial circulation
3) propagating thrombus
4) cellular hypoxia

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18
Q

What will hypoxia in acute ischemia lead to?

A

Intravascular blebs leading to IMPAIRED REFLOW PHENOMENOM

19
Q

What are the systemic consequences of acute ischemia?

A
  • LACTIC ACIDOSIS due to anaerobic oxidations
  • HYPERKALEMIA leading to arrhythmia
  • MYOGLOBINURIA leading to renal failure
20
Q

What is the cause of reperfusion syndrome?

A

Revascularization of the limb leading to sudden flooding of systemic circulation

21
Q

What is the DIAGNOSTIC criteria of acute ischemia?

A

6 Ps

Pain 
Pallor
Paresthesia
Pulselessness 
Paralysis 
Poikilothermia (progressive coldness)
22
Q

What is the importance of the light touch sensation in acute ischemia?

A
  • if FELT: further investigation could be done (duplex is first-line)
  • if NOT FELT: urgent intervention
23
Q

What is the preoperative treatment given to an acute ischemia patient?

A
  • Analgesia: MORPHIA
  • IV fluids
  • prophylactic antibiotic
  • heparinization (to prevent propagating thrombus)
24
Q

What is the post-operative management in acute ischemia?

A
  • management of pre-operative cause
  • treatment of complications
    - gangrene: amputation
    - acidosis: Na bicarbonate
    - Crush syndrome:
    • hyperkalemia: glucose + insulin
    • myoglobinuria: mannitol to ensure diuresis
25
Q

What is the most common source of embolic limb ischemia?

A

LEFT ATRIUM in atrial fibrillation

26
Q

What are the sources of embolism?

A

HEART

  • left atrium: atrial fibrillation
  • left ventricular mural thrombus following MI
  • vegetations on heart valves in infective endocarditis

ARTERIES
- thrombi in aneurysm & atherosclerotic plaque

AIR EMBOLUS

27
Q

What is the usual site of arrest of an embolus? What does it lead to?

A

anatomical narrowing or bifurcation

- immediate cut-off of blood supply causing severe ischemia
if there are collaterals vasoconstriction will occur

28
Q

Compare between the clinical presentations of embolic ischemia & thrombotic ischemia.

A

EMBOLIC THROMBOTIC

  • young patients - older patients
  • no claudication - history of claudication
  • atrial fibrillation - no AF
  • abrupt onset (minutes) - less dramatic onset due to collaterals present (days)
  • contralateral - bilateral
29
Q

How should acute embolic ischemia be managed?

A
  • no time consuming investigation should be done (ischemia beyond 6 hours is irreversible)
  • preoperative preparation (morphia, fluids, prophylactic antibiotic, heparinization)
  • URGENT EMBOLECTOMY using Fogarty (balloon) catheter
    - local anesthesia
    - felt pulsation
    - restoration of normal color & temperature
    - good back bleeding
    - completion of arteriography
  • FASCIOTOMY if compartment syndrome is suspected to occur after prolonged ischemia
  • postoperative: heparin until patient is ambulant and source of embolism is controlled
30
Q

What is the cause of acute thrombotic limb ischemia?

A
  • Virchow’s triad (abnormal vessel wall, viscosity, & velocity)
  • narrowed atherosclerotic segment
  • thromboangitis obliterans
31
Q

Sudden worsening of intermittent claudication is a non-fibrillating patient is an indication of?

A

acute thrombotic limb ischemia

32
Q

How should acute thrombotic ischemic limb be treated?

A
  • angiography:
    - irregular artery wall
    - stenotic segment
    - extensive collaterals
    - distal run-off
  • preop prep
  • fibrinolytic therapy (ONLY IF LIGHT TOUCH IS PRESERVED)
33
Q

What are the indications for fibrinolytic therapy?

A
  • preservation of light touch sensation
  • recent thrombosis
  • patient not fit for surgery
  • absence of distal run-off
34
Q

How should acute thrombotic limb ischemia be treated if light touch sensation is lost?

A

ARTERIAL RECONSTRUCTIVE PROCEDURE

35
Q

What are the indications for arterial reconstructive procedures?

A
  • if light touch sensation is lost
  • if fibrinolytic therapy failed
  • if limb is threatened
  • electively after improvement from fibrinolytic therapy
36
Q

Restoration of blood flow to irreversible ischemic tissue will cause?

A

REPERFUSION INJURY

  • increase K –> hyperkalemia & fatal cardiac arrhythmias
  • myoglobin –> acute tubular necrosis (renal failure)
  • lactic acid –> metabolic acidosis
37
Q

What are the types of arterial injuries?

A

WITH TEAR
complete (may bleed less) or partial (bleeds more)

WITHOUT TEAR
spasm (distal acute ischemia without bleeding)

38
Q

False aneurysm or AV fistula may be caused with which type of arterial injury?

A

partial arterial tear

39
Q

What are the effects of arterial injury?

A
  • hemorrhage
  • acute ischemia
  • false aneurysm
  • AV fistula
40
Q

What are the hard signs that require urgent exploration surgery in arterial injury?

A 
6Ps (ISCHEMIC LIMB)
- pulselessness 
- pallor 
- pain
- paresthesia 
- paralysis 
- poikilothermia 
PULSATILE BLEEDING
EXPANDING HEMATOMA
SHOCK
PALPABLE THRILL OR AUDIBLE BRUIT
41
Q

What are the soft signs of arterial injury that require further investigation?

A
  • history of active bleeding
  • decreased pulse
  • non-expanding hematoma
  • injury to adjacent nerve
  • penetrating injury close to major vessel
42
Q

What is the first-line of treatment in a fractured limb presenting with pulselessness?

A

REDUCE FRACTURE
wait for 20 minutes
if pulse doesn’t return explore

43
Q

a patient presents with severe burning pain, limb coldness & cyanosis, preserved pulsation, gangrene of distal fingers. Brachial artery is affected. What is the cause of these symptoms and how should it be treated?

A

INTRA-ARTERIAL DRUG INJECTION

  • elevation of limb
  • morphia
  • continuous heparin infusion
  • dextran (to decrease platelet aggregation)
  • steroid
  • fasciotomy
  • chemical sympathectomy

Surgery M4 part 1 (47 decks)

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