VTE

Question 0

How do you get obstructive shock in PE?

Answer 0

Pulmonary artery obstruction by thrombus -> decreased LV filling

If massive PE -> pulm vasoconstriction -> increased RV AFTERLOAD -> RV unable to compensate -> RV dilation which reduced LV CO

Question 1

What are the sources of PE?

Answer 1

90% from DVT, illiofemoral
Renal vein from nephrotic syndrome
Upper extremity if cancer associated

Question 2

What factors influence the effect of PE?

Answer 2

Level of reduction of blood flow
How quickly reduction occurs
Underlying cardiopulmonary reserve

Question 3

Why does PE cause hypocapnia?

Answer 3

V/Q mismatch leads to dead anatomical space leads to HYPERVENTILATION leads to hypocapnia

Question 4

Risk factors for VTE?

Answer 4

Previous DVT
Smoking/OCP/chemo
Surgery 
Travel
Inherited thrombophilias

Question 5

Signs and symptoms of PE?

Answer 5

SOB - sudden, worsening.
DVT - warm, swollen calves. Fever.
If pulm infarction - pleuritic chest pain, HAEMOPTYSIS.

TACHYCARDIA AND TACHYPNOEA

Question 6

What criteria used to risk stratify PE?

Answer 6

Wells criteria used to determine clinical probability which is used in investigation work up.

Question 7

What LAB Ix?

Answer 7

CBE EUC LFT 
COAGS
D-DIMER 
ABG
THROMBOPHILIA SCREEN 
IF THROMBOLYSIS: TROP, BNP

Question 8

What RADIOLOGICAL Ix?

Answer 8

CTPA
VQ scan if contraindicated (renal, allergy to contrast, young)
DOPPLER US
ECHO if critically unwell enough for CT.
ECG
CXR

Question 9

What ECG findings in PE?

Answer 9

Sinus tachy
Right heart strain: tall P, RAD, RBBB
S1 Q3 T3
AF

Question 10

Short term management of PE?

Answer 10

If STABLE: supportive medical care (O2 and analgesia) and anti coagulate

If UNSTABLE: supportive medical care, anti-coagulate and consider thrombolysis.
Anticoagulate with IV UFH? (APTT monitored) for five days until INR > 2
Start warfarin within 48 hours.

Question 11

What needs to be monitored after anticoagulant therapy?

Answer 11

Platelet count for heparin induced thrombocytopenia

Question 12

How can heparin be reversed?

Answer 12

Protamine sulfate.

Question 13

What anticoagulant used in renal impairment?

Answer 13

UFH.

This is because enozaparin and fondaparinaux are renally cleared.

Question 14

Long term management of VTE?

Answer 14

Warfarin for min 3 months if provoked, 6 months if unprovoked.

Can use dabigatran instead of warfarin as no need to monitor and there is a fixed dose.

Question 15

Management of DVT?

Answer 15

Non-pharm: mobilisation, compression stockings
Anticoagulate
- first get COAGS (APTT, PT and platelet count)
- LMWH
- oral warfarin to get INR 2-3

Question 16

UFH mechanism of action? How do you reverse?

Answer 16

Indirectly activates thrombin and FXa

Protamine sulfate

Question 17

Advantages of LMWH to UFH?

Answer 17

More predictable
Longer half life
Less risk of thrombocytopenia
Negative is significant renal impairment

Question 18

Warfarin MOA? Reversal? Contraindications? How often monitor it with chronic therapy?

Answer 18

Inhibits vitamin K dependent synthesis of F2,7,9,10 and protein C and S.

Reversed with vit K and coagulation factors (prothrombin)

Monitor INR monthly if given chronically once stable.

Big contraindications -> pregnancy

Question 19

Approach if INR < 5, 5-9, > 9 and if clinically significant bleeding?

Answer 19

< 5 -> lower/omit next dose, resume lower dose once INR stable

5-9 -> cease warfarin, give vit k, measure INR 24 hr

> 9 -> cease warfarin, give vit k, measure INR in 6-12hr and resume once INR lower than < 5

Question 20

What is pulsus paradoxus? Why can it be caused by a PE?

Answer 20

Abnormally large decrease in systolic BP on inspiration. Usually > 10.

PE -> increased RV filling
Inspiration -> increased RV filling

Increased RV filling -> dilating -> compression of septum into LV -> reduced CO -> reduced BP systolic