Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Medicine year 3 ANNA > Clotting Disorders > Flashcards

Clotting Disorders Flashcards

1
Q

Any bruising or bleeding in a non-ambulant child must be considered ‘non-accidental’ until proven otherwise - True or Flase?

A

True

  • The ‘Safety First’ policy can make parents/carers of young children wary of bringin children to health professionals with bruising/bleeding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the most notable FDP (fibrin degradation product)?

What endogenous protein has fibrinolytic effect on clots?

A

D-dimer

Plasmin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The ‘Clotting Cascade’ involves intrinsic and extrinsic pathways. Which of these pathways requires 1) Ca2+ 2) Platelets

A

BOTH intrinsic and extrinsic clotting pathways requires Ca2+ AND platelets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are normal ranges for Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT)?

A

PT = 10-14s (depends on trust)

APTT = 20-30s (depends on trust)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is Tissue Factor?

A
  • Tissue Factor (TF or Factor III) = receptor for factor VII/VIIa
  • It is required to activate the extrinsic pathway of clotting
  • TF is expressed on sub-endothelial cells (cells not normally exposed to blood) e.g. fibroblasts, macrophages, smooth muscle –> blood vessel damage exposes these cells to stimulate clotting
    • Endothelial cells express TF ONLY in response to inflammatory molexules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

PT evaluates the presence of which 5 clotting factors?

A
  1. VII
  2. V
  3. X
  4. Prothrombin (Factor II)
  5. Fibrinogen (Factor I)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

APTT evaluates the presence of which 4 factors of the ‘intrinsic’ pathway and which 4 factors of the common pathway?

A

Intrinsic:

  1. XII
  2. XI
  3. VIII
  4. IX

Common:

  1. X
  2. V
  3. Prothrombin (Factor II)
  4. Fibrinogen (Factor I)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Does an ↑ in PT and/or APTT mean a patient will bleed more during surgery or if injured?

A

Not necessarily!!

  • AP/APTT aren’t definitive in their conclusions as the mechanism of clotting involves more cross talk/interactions than is known - this is demonstrated in patients with ↑ AP/APTT and no ↑ in bleeding during surgery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which clotting pathway does PT/INR assess?

A

Extrinsic (+ common)

  • Prior to the common pathway only factor VII is involved in the extrinsic pathway (isolated deficiencies of factor VII are RARE)
  • Hence, PT/INR is only really affected by; 1) global reduction in clotting factor synthesis or 2) increased consumption of clotting factors. E.g.
    • Vitamin K deficiency / Warfarin
    • Liver disease
    • DIC (Disseminated intravascular coagulation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name 3 conditions that cause ↑ PT/INR and ↑ APTT

A
  1. Vitamin K deficiency / Warfarin
  2. Liver disease
  3. DIC (Disseminated intravascular coagulation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which clotting pathway does APTT assess?

What conditions can affect APTT?

A

Intrinsic (+ common)

  1. Conditions which also affect extrinsic pathway; Vitamin K deficiency, Warfarin, Liver disease, DIC
  2. Haemophilia A - factor 8 (VIII)
  3. Von Willebrands Disease (commonly types 1 and 2 don’t ↑ APTT, type 3 always does)
  4. Haemophilia B - factor 9 (IX)
  5. Haemophilia C - factor 11 (XI)
  6. Factor 12 (XII) deficiencies (RARE) - doesn’t cause bruising/bleeding
  7. Heparin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does a ‘Bleeding Time’ test involve and test?

A
  • Process: Make patient bleed and time how long until it stops
  • Tests: measures platelet plug formation - so is only affected by conditions affecting:
    • 1) platelet quanitity
    • 2) platelet function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which clotting factors are Vitamin K dependant?

A

2, 7, 9 and 10, Protein C and S

  • Vitamin K deficiency affects both intrinsic and extrinsic pathways
  • Intrinsic (9)
  • Extrinsic (7)
  • Common (2 and 10)
  • Protein C and S are intrinsic inhibitors of coagulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the incidences of Haemophilia A, B?

A
  • A = 1 in 5000 male births
  • B = 1 in 30,000 male births
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If an X-linked recessive mother (Xgood Xbad) has children with an unaffected father what is the chance of;

  1. An affected child? What gender are they?
  2. A carrier child? What gender are they?
  3. An unaffected child?
A
  1. 1/4 (boy)
  2. 1/4 (girl)
  3. 1/2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is Vitamin K absorbed?

A
  • Vitamin K is fat-soluable, thus is absorbed via the gut with the aid of bile
  • Patient with fat malabsorption due to biliary obstruction may also be vitamin K deficient –> check LFTs for ↑↑ Alkaline phosphatase compared to ↑ AST/ALT (obstructive picture)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the name for Vitamin K in drug form?

A

Phytomenadione (also called Phylloquinone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe DIC (disseminated intravascular coagulation)

A
  • DIC = blood clots forms in small blood vessels throughout the body and use up all clotting factors + platelets –> ↑ risk of bleeding due to inability to clot
  • Aetiology:
    • ​Surgery, major trauma, burns, obstetric disorders (exlampsia, retained dead fetus etc) –> cause tissue factor (abundant in the brain, lungs and placenta) exposure due to vascular damage –> which stimulates clotting
    • Sepsis, some malignances (e.g. acute myelocytic leukemia), organ failure (pancreas or liver) –> tissue factor release in response to cytokines/TNF –> stimualtes clotting
  • Investigations:
    • ​Thrombocytopenia (↓ platelets)
    • ↑ PT/INR
    • ↑ APTT
    • ↑ D-dimer
    • Microscopy - Schistocyte formation (fragmented RBCs due to shredding of RBCs caused by mechanical damage from fibrin)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which clotting factors does Warfarin (Vitamin K antagonist) reduce?

A

2, 7, 9 and 10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does Heparin work?

A

Binds to the enzyme Antithrombin III (AT) –> ↑ activity

Antithrombin III inactivates:

  • Thrombin (IIa) and factor 10 (X) - mainly these two
  • Factors; 9, 10, 11 and 12
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the two most common forms of Heparin?

What are the 4 side-effects of Heparin?

A
  1. Low Molecular Weight Heparin (LMWH) - consits of only short chain heparins, binds to specific part of antithrombin III so that it only inhibits factor 10
    • Subcutaneous
    • Long duration of action
    • Routine monitoring not required (can be monitored via anti-factor Xa)
    • Uses: VTE treatments and ACS prophylaxis
  2. Unfractionated Heparin - consists of heparin chains of various lengths, binds to antithrombin III causing inhibition of factors; 9, 10, 11, 12 and thrombin
    • IV
    • Short duration of action (4hrs)
    • Monitor via APTT
    • Uses: prophylactic anticoagulation in pts with reduced renal function (unfractionated is partially cleared by liver, LMWH is not)

Side Effects:

  1. Bleeding
  2. HIT (heparin induced thrombocytopenia)
  3. Osteoporosis (↑ risk of fractures)
  4. Hyperkalaemia (thought to be due to inhibition of aldosterone secretion)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What drug can be given to reverse Heparin?

A

Protamine sulphate

  • Only partially reverses LMWH (fully for unfractionated)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the common signs/symptoms of Congenital Haemophilia?

A
  1. Male
  2. Hx of recurrent excessive bleeding after; surgery, dentisty, trauma, haematuria, mucosa bleeding (epistaxis >30min, gum bleeding), easy bruising
  3. Musculoskeletal bleeding (hallmark symptom) - pain, swelling, erythema, local warmth
    • Muscle bleeding e.g. quadriceps, biceps, iliopsoas (lower abdo/back pain with flexed hip gait - urgent treatment)
    • Haemoarthrosis - joint welling e.g. knees, elbows and ankles (bleeding typically occurs in a single joint), if recurrent can cause joint deformity
  4. Menorrhagia or excessive childbirth bleeding - in women who are carriers of haemophilia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is Von Willebrand’s Disease?

A
  • Most common inherited bleeding disorder
  • Responsible for 15% of menorrhagia
  • Majority of cases are autosomal dominant
  • Type 1 (80%) = partial reduction in vWF (autosomal dominant)
    • Desmopressin + Tranexamic acid
    • Iron in pts who become deficient due to bleeding
  • Type 2 = abnormal form of vWF
    • NO desmopressin in type 2b (overactive abnormal vWF)
    • Iron in pts who become deficient due to bleeding
    • vWB factor given
  • Type 3 = total lack of vWF (autosomal recessive) - severe form
    • vWB factor given

vWF Function:

  • Carrier molecule for factor 8 (prevents it beging broken down)
  • Promotes platelet adhesion to damaged endothelium

Presentation:

  • Behaves like platelet disorder i.e. epistaxis (>30min, menorrhagia , petichiae, gum bleeding = COMMON, whilst haemoarthrosis and muscle haematomas are rare
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What score on Well’s Criteria for DVT is considered low risk?

A

Well’s Score < 2 = low risk of DVT

  1. D-dimer test
    • If negative –> sufficient to rule out DVT
    • If positive –> proceed to US test
  2. US test
    • If negative –> rules out DVT
    • If positive –> consider anticoagulation
26
Q

How do the following differ for Haemophilia A, vWB disease and Vitamin K deficiency?

  1. Bleeding Time
  2. PT/INR
  3. APTT
  4. Factor VIII levels
  5. vWF levels
A
27
Q

What are the target INR levels for the following;

  1. DVT/PE, hypercoaguable states, AF
  2. Aortic metallic heart valve
  3. Mitral metallic heart valve
A
  1. INR 2-3
  2. INR 2.5-3.5
  3. INR 3-4
28
Q

How long do the following take to affect blood clotting?

  1. Oral Vitamin K
  2. IV Vitamin K
  3. Prothrombin Complex Concentrate (PCC) - factors 2, 9 and 10
A
  1. 24-48 hours
  2. 6 hours
  3. 15 minutes
29
Q

What is the role of Kallikrein and High molecular weight Kininogen?

A
  • Pre-kallikrein complexes with High molecular weight Kininogen
  • Pre-Kallikrein is cleaved by factor 12 (XII) to form Kallikrein
  • Kallikrein is a serine protease enzyme which:
    • Converts plasminogen –> plasmin (fibrinolytic)
    • Cleaves high molecular weight kininogen –> Bradykinin (inflammatory mediator which causes vasodilation
30
Q

Protein C and Protein S are ‘natural inhibitors’ of coagulation. They from a complex which acts to inactivate which 2 clotting factors?

A

Activated factors 5 and 8 (Va + VIIIa)

31
Q

How does a 50/50 mixture test work?

A
  1. If pt has a ↑ PT or APTT –> redo test with 50:50 mix of normal plasma
  2. If PT/APTT correct = a factor deficiency
  3. If PT/APTT doesn’t correct = a factor inhibitor
32
Q

What 4 factors are used to estimate severity of Haemophilia?

A
  1. Factor 8 level (VIII)
  2. Bleeding spontaneity
  3. Frequency of bleeding
  4. Site of bleeding
33
Q

Main component of bleeding disorder treatment is to give the missing clotting factor, however other things are important as well …

What does the treatment acronymn (RICE) for Haemophilia stand for?

A
  • R = Rest
  • I = Immobilise
  • C = Cool
  • E = Elevate
34
Q

What is the factor used to treat Haemophilia A?

How is the amount of this factor calculated?

A

Factor 8 (VIII) half life = 8hrs –> thus given 1-3 times daily

Amount needed = (Rise x weight) / 2

Rise = increase in iU required

  • Normal range for factor VIII = 50-150 iu/dL
35
Q

What is the factor used to treat Haemophilia B?

How is the amount of this factor calculated?

A

Factor 9 (IX) half life = 18-24hrs –> thus given once daily

Amount needed = Rise x weight

Rise = increase in iU required

36
Q

How does Desmopressin (DDAVP) act to treat Haemophilia A?

A
  • Desmopressin = analogue of vasopressin i.e. antiduretic - stims V2 receptors in renal collecting duct –> ↑ aquaporins
  • Vasopressin also –> stims release of vWF + factor 8, thus …
  • Desmopressin –> stims release of of von Willebrand Factor –> ↑ survival of factor 8 by 2/3 times (vWF binds circulating factor 8 and prevents it’s breakdown)
  • Desmopressin is only useful in mild cases of Haemophilia A and vWB disease with quantitative reduction in functional protein (not qualitative e.g. vWB Type 2)
    *
37
Q

In which Haemophilia’s (A and/or B) can Tranexamic Acid be used?

And what is it’s mechanism of action?

A

Used in BOTH haemophilia A and B

  • Tranexamic acid = anti-fibrinolytic
  • It acts on plasminogen to prevent it’s conversion to plasmin –> thus preventing fibrin degradation by plasmin
38
Q

How does Varicose Veins in the leg predispose a patient to getting DVT?

A

Varicose veins allow backflow of blood –> veins bulge and blood pools –> venous blood stasis –> encourages clot formation

39
Q

What are the 3 factors of Virchow’s Triad?

What does the triad indicate risk of?

A

Triad indicates risk of Thrombosis

  1. Stasis of blood flow e.g. immobile (long flight, hospital stay) varicose veins
  2. Endothelial injury (e.g. surgery, trauma, HTN)
  3. Hypercoaguability (e.g. infection, trauma, cancer, smoking, contraceptive pill, obesity etc - acute phase reactant proteins include; vWF, factor VIII and fibrinogen)
40
Q

What Mechanical methods can be used to reduce risk of DVT + PE?

A
  1. Anti-embolism stockings (AES)
  2. Intermittent pneumatic compression sleeves (IPC)

Pros:

  • Cheap
  • Don’t affect coagulation system

Cons:

  • Poor compliance with optimum fitting AES
  • May exacerbate pre-existing arterial insufficiency
  • Less effective than pharmacological management
41
Q

What Pharmacological options are available to ↓ risk of DVT + PE?

A
  1. LMWH - low molecular weight heparin
  2. UFH - unfractionated heparin
  3. DOACs - direct anti-Xa and anti-thrombin drugs
  4. DO NOT USE WARFARIN!! (intensity of anticoagulation is less predictable and bleeding risk higher than heparin or DOAC)

Pros:

  • Highly effective

Cons:

  • Expensive
  • Risk of bleeding
  • Allergies
  • Heparin induced thrombocytopenia and thrombosis (HITT)
42
Q

What is Fondaparinux and its mechanism of action?

A

A anticoagulant medication related to LMWH

  • Uses: prophylaxis of DVT/PE, diagnosed DVT/PE and ACS
  • Lower risk of heparin-induced thrombocytopenia vs LMWH or uncractionated heparin
  • MoA: binds antithrombin III at alternative site (similar to LMWH) –> stims inhibition of factor 10
43
Q

What score on Well’s Criteria for DVT is considered high risk?

A

Wells score 3 or higher = high risk

  1. D-dimer test
    • If negative –> US test
    • If positive –> US test
  2. US test
    • If D-dimer + US negative –> DVT ruled out
    • if D-dimer negative + US positive –> anticoagulation
    • if D-dimer positive + US negative –> repeat US in 1 week
    • if D-dimer + US positive –> anticoagulation
44
Q

How does a DVT present?

Name 3 other conditions can present this way?

A

Unilateral, swollen, painful leg

  1. Cellulitis
  2. Muscle Haematoma
  3. Rupture Baker’s cyst (popliteal cyst)
    • Not a true cyst (isn’t a closed sac with a distinct membrane/division from nearby tissue)
    • Are distension of gastrocnemius-semimembranosus bursa
    • Primary: no underlying pathology (typically in children)
    • Secondary): underlying pathology e.g. osteoarthritis (typically in adults)
    • Presents as swelling of popliteal fossa, rupture may occur producing; redness, pain, swelling (although majority are asymptomatic)
45
Q

On Examination what signs indicate DVT?

A
  • Unilateral leg swelling
  • Warm
  • Calf tenderness
    • Homan’s Sign - worse with dorsiflexion of ankle
  • Calf circumference >3cm compared with unafffected leg
    • Measure 10cm below tibial tuberosity (make mark on leg)
46
Q

What are the ‘typical’ signs and symptoms of a PE?

A

Symptoms: (only 10% present with this triad)

  1. Sudden onset pleuritic chest pain
  2. SoB
  3. Haemoptysis

Other Symptoms by commonality:

  • Crackles
  • Fever
  • Cough
  • Syncope - can occur in massive PE
  • Hypotension (systolic BP < 100mmHg) / cardiogenic shock / arrest - this can occur in massive PE in right heart or saddle PE (both pulmonary arteries)

Signs:

  1. ↑ RR
  2. ↑ HR (Tachyarrythmias - commonest is sinus tachycardia but can be AF)
  3. DVT signs
47
Q

How might a PE present on an ECG?

A

Most often - Sinus tachycardia

  • Can present as ‘S1Q3T3’ pattern of acute cor pulmonale ‘McGinn-White Sign’ (10% of cases)
    • Large S-wave in lead I
    • Q-wave in Lead III
    • Inverted T-wave in lead III
48
Q

What might you see on an ABG for a PE?

A

Hypoxia or type 1 respiratory failure

49
Q

How is Sensitvity Calculated?

A

No. of True positives / (True positives + False negatives)

  • True positives + false negatives = Total no. of people WITH condition
  • True positive = Has condition + test says has condition
  • False negative = Has condition + test says doesn’t have condition

SNOUT:

  • Sensitivity
  • Negatives
  • OUT - sensitivity rules out i.e. a sensitive test rules out disease with high confidence (-ve result = no condition)
50
Q

How is Specificty Calculated?

A

No. of True negatives / (True negatives + False positives)

  • True negatives + false positives = Total no. of people WITHOUT condition
  • True negative = no condition + test says hasn’t got condition
  • False positive = no condition + test says has condition

SPIN:

  • Specificity
  • Positives
  • IN - specificity rules in i.e. a specific test rules in disease with high confidence (positive test = has condition)
51
Q

Which patient group can Well’s Criterias for DVT and PE not be used?

A

Pregnant women (they were excluded from the trials for validated the score)

52
Q

What is the platelet threshold for being ‘haemostatic’ i.e. capable of clotting sufficiently?

A

> 90 x109/L (normal range = 150-400)

53
Q

Fibrinogen (factor 1) is converted enzymatically by thrombin to form fibrin (factor 1a) which aids clot formation.

What is the normal Fibrinogen range?

A

2.4-4.0 g/L

54
Q

Which of the following should be monitored for a patient taking LMWH, ramipril and omeprazole?

Results so far:

  • Hb = normal
  • Platelets = normal
  • eGFR = 50 mL/min (>90)
  1. Anti-Factor Xa
  2. APTT
  3. PT/INR
  4. Potassium
  5. Sodium
A

Potassium

  1. Routine monitoring of anti factor Xa activity is not usually needed when on LMWH. But may be necessary in patients with increased risk of bleeding (renal impairment and those that are over- or underweight)
  2. APTT is not routinely monitored when on LMWH
  3. INR is not monitored when on LMWH
  4. Potassium should be monitored if patients take LMWH for > 7 days
    • Pts with; diabetes, chronic renal impairment and on medication that can increase potassium levels are more susceptible to hyperkalamia (patient was taking ramipril)
  5. Not a routine investigation when on LMWH
    • N.B. PPI (omeprazole) –> can cause hyponatraemia
55
Q

The endogenous anticoagulation pathway involves 3 enzymes/mechanisms - what are they?

A
  1. Antithrombin:
    • Inhibits thrombin (IIa) and Xa - mainly these
    • Also inhibits factors; 7, 9, 11 and 12
  2. Thrombomodulin:
    • Healthy endothelium express thrombomodulin (TM) on the cell surface
    • TM binds thrombin –> forming thrombomodulin-thrombin complex –> which activates Protein C
    • Protein C –> inhibits factors 5a and 8a
  3. Tissue Plasminogen Activator (t-PA)
    • t-PA converts plasminogen (from liver) –> plasmin (which breaks down clots)
56
Q

When should you use fresh frozen plasma?

A

When PT:APPT is >1.5

57
Q

what is the management for vonwillebrand;s?

A
  1. TXA
  2. desmopressin
  3. factor 8 concentrate
  4. In emergencies: cryoprecipitate
58
Q

When would you use prothrombin complex concentrate?

A

to reverse anticoagulants or prophylaxis in risky surgery

59
Q

If I mix patients blood with normal blood, what will happen if there is a deficiency in factors?

A

It will correct

60
Q

What will PT, APPT, bleeding time and platelets do in:

  1. Warfarin or vit k deficiency
  2. haemophilia
  3. VW factor
  4. DIC
  5. ITP/TTP
A
  1. Up, Up, normal normal
  2. normal up normal normal
  3. normal up up normal
  4. up up up down!
  5. normal normal up down

Medicine year 3 ANNA (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions