Abdominal Aortic Aneurysm Flashcards

1
Q

List the common causes for severe abdominal pain of sudden onset accompanied by the clinical signs mentioned above (fast pulse, low BP, cold/clammy hands, pale, CRT > 5s)

A
  1. Perforated viscus (i.e. perforated gastric/duodenal ulcer)
  2. Acute pancreatitis
  3. Biliary colic/acute cholangitis
  4. Acute mesenteric occlusion
  5. Ruptured/leaking abdominal aortic aneurysm
  6. Basal pneumonia (rare)
  7. Inferior MI (rare)
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2
Q

What are the branches of the celiac trunk?

A
  1. L gastric artery
  2. Splenic artery
  3. Common hepatic artery
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3
Q

Discuss the relevance of AAA clamping on patient outcome

A

Supra-coeliac clamping: highest stress on the heart, iscahemia to all organs below the coeliac artery with subsequent reperfusion injury.

Supra-renal clamp: high stress on the heart, ischaemia to all organs below the superior mesenteric artery with subsequent reperfusion injury.

Infra-renal clamp: relatively less stress on the heart, ischaemia to all organs below the kidneys with subsequent reperfusion injury.

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4
Q

What are the signs of ruptured AAA? Dissection/PVD?

A

Shock + bilateral limb schema

Shock + unilateral limb ischemia

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5
Q

What should you suspect in a male > 60y with first presentation of renal colic?

A

Aortic aneurysm rupture

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6
Q

What should you suspect in a patient with GI bleed + PMH of aortic surgery?

A

Aorto-enteric fistula (until proven otherwise)

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7
Q

What is the transfusion management of major hemorrhage?

A
  • Reverse anticoagulation (vitamin K, prothrombin complex concentrate)
  • Tranexamic acid (antifibrinolytic agent) within 1st hour
  • Bloods (FBC, U&E, Ca2+, LFTs, PT, APTT, Fibrinogen, crossmatch)
  • Request (Red cells, FFP, platelets)
  • Request O RhD negative = extreme emergency only!
  • Within 15min from sample arriving in the lab = can receive group specific (ABO + RhD compatible)
  • Safest product if time allows (45-60min after arriving in lab) = Crossmatched (fully screened for antibodies)

Pack 1: 4U red cells, 4U fresh frozen plasma

Pack 2: 4U red cells, 4U FFP, 1 dose platelets, 2 packs cryoprecipitate
** Red cells don’t control coagulopathy!!

Try to keep blood results at the following ranges:
Fibrinogen > 1.5g/L
PT/APTT < 1.5
Hb 80-100g/L
Platelets > 75 x 10^9L
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8
Q

How do cardiac output and blood pressure change in a patient who is losing blood?

A

As shown in the figure, the body is able to maintain pressure (at the expense of cardiac output and tissue blood flow) until a large volume of blood has been lost. In other words, it is only when the compensatory mechanisms are unable to cope that the blood pressure begins to fall. Therefore, any person (particularly young subjects with good physiological reflexes) who have a low blood pressure in the context of acute blood loss, is extremely ill and needs urgent medical attention.

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9
Q

What causes the formation of an atherosclerotic plaque?

A
  1. Smooth muscle proliferation/migration
  2. Inflammation
  3. Lipid deposit
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10
Q

What is the cause of chronic ischemia? Acute ischemia?

A

Chronic ischemia = decreased diameter of lumen due to atherosclerosis

Acute ischemia = rupture of atherosclerotic plaque

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11
Q

What are risk factors for PVD?

A
  1. Increased age
  2. Male
  3. Family history
  4. Smoking
  5. HTN
  6. Cholesterol
  7. Diabetes
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12
Q

What are the 6Ps of limb ischemia?

A
  1. Pale
  2. Perishingly cold
  3. Pulseless
    (onset within 4h of acute ischemia)
  4. Paraesthesia
  5. Pain
    (within 6h)
  6. Paralyzed (irreversible)
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13
Q

How is chronic ischemia classified?

A

Fontaine Classification system

I = asymptomatic
II = claudication
III = rest pain
IV = tissue loss (i.e. ulcers, gangrene)
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14
Q

What is the treatment of limb ischemia?

A
  • Stop smoking
  • Antiplatelet therapy (aspirin)
  • BP control
  • Cholesterol control
  • Exercise
  • Lose weight
  • Strict diabetic control
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15
Q

What is the cause of cerebrovascular disease?

A

Atheroma

  • Affects the carotids
  • Leads to stroke, TIA, Amaurosis fugax (transient blindness in ipsilateral eye)
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16
Q

What investigations are done in CVD?

A
  • Duplex
  • Angiography
  • MR/CT
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17
Q

What are the indications for carotid surgery?

A
  • Symptomatic patients (in last 6mo)
  • > 70% stenosis of ICA
  • 2yr life expectancy
  • Fit for surgery (2.6% risk of stroke, 2% risk of death, 1% risk of nerve palsy - CN 9/10)
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18
Q

What are abdominal aneurysms? How are they treated?

A

> 50% of normal transverse diameter.
Ectasia = dilation of up to 50%

Either saccular or fusiform in shape
Above umbilicus = AAA
Below umbilicus = iliac aneurysm

Small AAA < 4.5cm
Large AAA > 5.5cm -> requires surgery!

EVAR: endovascular aneurysm repair

  • 70% pts suitable on anatomical basis: proximal infrarenal aortic neck, iliac arteries
  • Lifelong CT/duplex follow-up
  • 8% chance of 2nd procedure needed -> endoleak: sac repressurization
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19
Q

What signs would lead you to believe there was a suspected rupture

A
  1. collapse
  2. hypotension
  3. low back/flank pain
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20
Q

What is an aortic dissection?

A
  • Separation of layers in wall of aorta
  • Layers of artery (adventitia, media-muscle layer, intima)
  • Tear in intima, blood enters between intimacy + media = increased tearing OR exit tear allowing blood to re-enter aorta (false lumen formed) -> hypotension, shock
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21
Q

What are the causes of aortic dissection?

A
  • Chronic HTN
  • Connective tissue disorder (Marfan’s, Ehler-Danlos)
  • Aneurysm
  • Chest trauma
  • Males
  • Increased age (50-65y)
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22
Q

How are aortic dissections classified?

A

Stanford System

Type A: ascending aorta (surgical treatment)
Type B: Descending aorta after L subclavian artery (medical treatment)

  • Most common site = 2cm above aortic root (type A)
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23
Q

What are the symptoms of aortic dissection?

A
  • Severe central chest pain “tearing” to the back
  • Sweating, Nausea, SOB, Syncope, Weakness
  • Abdo pain (if abdominal aortic dissection)
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24
Q

How is an aortic dissection diagnosed?

A
  • CT scan with contrast (GOLD STANDARD!)
  • MR angiogram
  • Transesophageal echocardiogram (TEE) - shows thoracic aorta + aortic valve only
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25
Q

What is shock?

A

An acute clinical syndrome initiated by ineffective perfusion and cellular hypoxia, resulting in severe dysfunction of organs vital to survival

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26
Q

What are the key features of shock?

A
  • Acute tissue/organ hypo-perfusion
  • Impaired delivery of oxygen to cells
  • Supply inadequate to meet demand
  • Generalised cellular hypoxia
  • Consequences for cellular respiration
  • Hemodynamic abnormalities but shock isn’t simply the presence of hypotension
  • Oxygen utilization may be abnormal
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27
Q

What are the 4 types of shock?

A
  1. Hypovolemic (reduced intravascular volume)
  2. Cardiogenic (intrinsic cardiac pump failure)
  3. Distributive (Vasodilation + malperfusion)
  4. Obstructive (failure of circulatory flow)
28
Q

What are clinical examples of each of the 4 types of shock?

A
  1. Hypovolemic:
    - Hemorrhage
    - Burns
    - GI losses (vomiting, diarrhea, fistula)
    - Dehydration (heat exposure, polyuria - DKA)
  2. Distributive:
    - SIRS related - sepsis, pancreatitis, trauma, burns
    - Neurogenic - spinal cord injury
    - Anaphylaxis
  3. Cardiogenic:
    - Myocardial infarction/ischemia
    - Arrhythmia
    - Acute valve pathology
  4. Obstructive:
    - Tension pneumothorax
    - Pericardial tamponade
    - Pulomonary embolism
29
Q

What is the pathophysiology of hypovolemia?

A
  • Sudden, severe blood loss
  • Reduction in venous return
  • Fall in stroke volume + cardiac output
  • Hypotension
  • Hypoperfusion of organs
  • Onset of organ dysfunction
30
Q

What is Starling’s law of the heart?

A

A relationship between stroke volume and ventricular end-diastolic volume (preload).

As blood loss increases, preload and stroke volume decreases.

31
Q

What are the physiological responses to blood loss?

A
  • Sympathetic system activated
  • Adrenal catecholamine release
  • Compensatory cardiovascular responses
  • Sodium + water retention
  • Coagulation system activation
  • Cortisol release
32
Q

What are the signs of organ hypoperfusion?

A
  • Skin (pale, CRT > 2s)
  • Oliguria
  • Cognitive changes
  • Metabolic acidosis
33
Q

What are the management principles for hypo perfusion?

A
  • Restore tissue perfusion + oxygen delivery to cells as rapidly as possible
  • ABC (2x large bore IV cannulas 14/16G)
  • Administer oxygen
  • Give IV fluids (1L warmed Hartmann’s given stat, colloids, blood requested)
  • Treat the cause
  • Resuscitation begins concurrently or ahead of the diagnostic process
  • Aiming to prevent irreversible organ injury + failure
  • Blood tests (crossmatch 6u red cells, FBC, clotting, U&E, glucose, LFTs, bone, lactate)
  • Ultrasound of abdomen (FAST scan)
  • ECG
  • Measure core temperature + maintain
34
Q

How can other types of shock be diagnosed?

A

Cardiogenic:

  • History
  • Signs of cardiac failure
  • ECG evidence

Obstructive:

  • Impaired cardiac filling
  • Obstructed forward flow
  • Specific symptoms + signs

Distributive:

  • Vasodilated
  • Markers of infection
  • Capillary leak
35
Q

What are further management strategies for shock?

A
  • Surgery
  • Fluid management = increase preload
  • Invasive lines
  • Drugs (inotropes) = increase contractility
  • Monitoring
  • ICU
36
Q

What is the result of administrating inotropes on Starling’s law? Fluids?

A

Inotropes:
- Increase stroke volume without large increase in preload

Fluids:
- Increase both preload + stroke volume

37
Q

What are the consequences of shock?

A
  1. Mortality (cariogenic > septic)
  2. Prolonged organ hypo perfusion + tissue hypoxia
  3. Multi-organ dysfunction then failure
  4. Cellular injury + death
38
Q

What is sepsis?

A
  1. Widespread inflammation due to infection
  2. Vasodilation and capillary leak
  3. When severe can rapidly progress to shock
  4. Treatment principles the same, plus: - piperacillin/tazobactam
    - Noradrenaline
    - IV fluids
39
Q

Define allogenic and autologous

A

Allogenic = blood product donated from another person

Autologous = re-infusion of the person’s own blood products for transplant

40
Q

What is transfusion associated acute lung injury? What is Transfusion Associated Circulatory Overload?

A

Transfusion Associated Acute Lung Injury:

  • Sudden acute respiratory distress following transfusion
  • Occurs within 6h of blood transfusion

Transfusion Associated Circulatory Overload:

  • Common transfusion reaction in which pulmonary oedema
  • Develops primarily due to volume excess or circulatory overload.
  • Typically occurs in patients who receive a large volume of a transfused product over a short period of time, or in those with underlying cardiovascular or renal disease.
  • Respond well to diuretics
41
Q

Why did Mr Simpson develop abnormal clotting after his blood transfusion?

A

Abnormalities in clotting is a common complication associated with massive blood transfusion. Dilution of platelets and clotting factors are recognised causes for this state of coagulopathy. Which is why patients who receive massive transfusions require careful monitoring of their coagulation status and transfusion of blood products - including Platelets, FFP, Cryoprecipitate and single clotting factors. This is a complex area and such patients should be managed in consultation with the Haematologists.

42
Q

List 5 recognized complications of ICU patients once discharged

A
  1. Muscle weakness + wasting
  2. Nutritional deficits
  3. Recurrent chest infections
  4. Sleep disorders
  5. Inability to swallow effectively and microaspiration of food
43
Q

What are 5 complications that can occur due to a transfusion?

A

Transfusion coagulopathy can occur due to increased circulatory toxins leading to:

  1. Acute lung injury
  2. Renal failure
  3. Gut sepsis
  4. DIC (coagulation failure)
  5. ACoTS (acute coagulation of trauma shock)
44
Q

What is PT? What is APTT?

A

PT:

  • Looks at extrinsic pathway
  • Monitor warfarin
  • Increased in liver disease
  • Blood clot test produced within 12s

APTT:

  • Looks at intrinsic pathway
  • Monitor heparin therapy (not DOACs)
  • Increased in hemophilia/vWB disease
  • Blood clot test -> clotting within 42s
45
Q

What are the 3 stages of cell-based model of hemostasis?

A

Need tissue factor (TF) and platelets

  1. Initiation
    - TF binds to VIIa
    - Activates IV + X
    - Factor Xa activates V
    - Small amounts of thrombin generated
  2. Amplification
    - Thrombin activates platelets
    - FV + FIX activated (activated platelets)
    - Va removes vWF from VIII
  3. Propagation
    - IVa + VIIIa on platelets surface activate factor X
    - Activation occurs on platelet surface
    - Factor Xa generates large amounts of thrombin = thrombin burst
    - Thrombin splits fibrinogen into fibrin monomers
46
Q

List 4 groups of antiplatelet drugs

A
  1. Aspirin (thromboxane A2 - prostaglandin)
  2. Clopidogrel/ticlopidine (ADP inhibitor)
  3. Thrombin inhibitor
  4. Glycoprotein IIb/IIIa inhibitors

*Multiplate = to monitor platelet function

47
Q

What does the fibrinolytic system do? Name a antifibrinolytic and thrombolytic agent.

A

Breaks down clot (i.e. FDP = fibrin degradation product, D-dimer)

Thrombolytic = tPA = streptokinase

Antifibrinolytics = increase clotting of blood = tranexamic acid

48
Q

How is clot forming limited?

A
  1. Location of initiation and amplification (Tissue factor then platelets)
  2. Serum protease inhibitors
  3. Healthy endothelium secretes thrombomodulin (especially smaller vessels)
  4. TM-thrombin-aPC complexes cleave factor Va to factor VIIIa
49
Q

What occurs in DIC?

A
  • Increased thrombin, increased fibrin, increased clots
  • Increased FDP + D-dimer

Causes:

  • Trauma
  • Cytokines (IL1, endotoxin)

DIC Shock:

  • Hypoperfusion
  • Increased protein C
  • Hyperfibrinolysis
50
Q

What is the treatment for transfusion coagulopathy?

A
  • FFP, platelets (gently rocked to prevent aggregation)
  • Blood transfusion (“cell-saver” = heperanize patients own cells then transfuse back into the patient)
  • Potential for viral transmission + immunosuppression
  • Keep patient warm
  • Reverse anticoagulation
  • Inhibit fibrinolysis (tranexamic acid)
  • All of the above = “shock packs”
  • *DVT prophylaxis post-tx of DIC (i.e. Heparin)
  • Look out for HIT (heparin induced thrombocytopenia)!
51
Q

Name 2 medications where ankle oedema is a common side effect

A
  1. Sitagliptan

2. Amlodipine

52
Q

What are the components of Tazocin?

A

Tazobactam + Piperacillin

** Contains penicillin!

53
Q

A patient who is in hypovolemic shock has the following clinical signs:

Heart rate 120 beats/minute, systolic blood pressure 80mmHg and urine output 20mL. After administering an IV fluid bolus, what is the best indication of improved tissue perfusion?

A

Urine output improves to > 30mls/hr

54
Q

The same patient with hypovolaemic shock is transfused 2 units of blood. What measurement indicates his plasma volume is adequately restored to prevent a cardiac arrest?

A

Lactate < 2mmol/l

55
Q

List 5 complications of a massive blood transfusion

A
  1. Hypocalcemia (citrate binds with ionized calcium)
  2. Hypothermia
  3. DIC
  4. Transfusion related acute lung injury
  5. Hemolytic reactions - immediate and delayed
    - Immediate = ABO incompatability
    - Delayed = Rhesus antibody reactions
56
Q

What are the symptoms of local compression of AAA on neighbouring structures?

A
  • Early satiety
  • N/V
  • Urinary symptoms
  • Venous thrombosis from venous compression
57
Q

What are the symptoms of embolic disease from aneurysm?

A

Blue toes, thromboembolism lodges and ischemia distally

58
Q

Which organs are affected by PVD?

A
  • Brain
  • Eyes
  • Heart
  • Kidneys
  • Gut (mesenteric ischemia)
  • Muscles
  • PVD
59
Q

What medications will a patient be put on if found to have an AAA < 5.5cm?

A

Aspirin + statin + quit smoking

- Thought to reduce growth of aneurysm

60
Q

What is the triad indicative of cardiac tamponade?

A
  1. Increased JVP
  2. Muffled heart sounds
  3. Syncope
61
Q

What is the gold standard imaging for AAA?

A

CT scan

USS

62
Q

What is the lethal triad?

A
  1. Hypothermia
  2. Coagulopathy
  3. Metabolic acidosis
63
Q

What classifications are used to grade aortic dissections?

A
  • DeBakey (I-III)

- Stanford (1 or 2)

64
Q

What are the signs of aortic dissection?

A
  • > 20mmHg difference between arms
  • Aortic regurgitation
  • Cardiac tamponade
  • Acute occlusion of arteries arising from aorta (malperfusion)
  • Brachiocephalic (UL limb ischemia)
  • Stroke (spinal artery)
  • Celiac trunk (mesenteric ischemia)
  • Renal artery (oliguria - renal artery stenosis)
  • SMA, IMA (abdo pain)
  • Ischemic leg
  • Widened mediastinum on xray (i.e. cardiac tamponade)
65
Q

What’s the treatment for aortic dissection?

A
  • Lower BP + surgery!
66
Q

What is mesenteric ischemia?

A
  • Ischemia/infarct affecting any/all 3 mesenteric arteries (SMA, IMA)
  • Sudden pain + metabolic acidosis = acute presentation
  • Post-prandial pain + weight loss (‘fear of food’) = chronic presentation