Pulmonary embolism

Question 1

What are the risk factors for PE

Answer 1

Strong risk factors:
1) Fracture lower limb
2) Hospitalisation for the past 3m for CCF/ AF
3) MI for the past 3m
4) Hip/ knee replacement
5) Major trauma
6) Spinal cord injury
7) Previous VTE

Moderate risk:
1) Autoimmune
2) Post-partum
3) IVF
4) Hormone replacement therapy, OCP
5) Infection
6) Chemo/ cancer
7) Stroke

Low risk:
1) Bed rest >3d
2) DM
3) Obesity
4) Pregnancy
5) Prolonged sitting
6) Varicose vein

Question 1

Urgent Mx of pt with haemodynamic instability with high suspicion of PE

Answer 1

Need to to heparin bolus while waiting for CTPA to confirm the PE.
Do not give LMWH or Warfarin ivo the potential need for reperfusion therapy - either with surgical embolectomy/ catheter embolectomy/ thrombolysis.

Question 2

What is the definition of haemodynamic instability in PE?

Answer 2

1) Cardiogenic arrest - requires resuscitation

2) Obstructive shock -
SBP <90 or requires inotrope to keep it ≥90, and signs of hypopersuion (altered GCS, clammy, oliguria, raised lactate)

3) Persistent hypotension -
SBP <90 for ≥15 mins, and not due to arrhythmia/ infection/ hypoV

Question 3

Screening tool for PE

Answer 3

Wells criteria:
1) Previous VTE
2) HR >100
3) Surgery/ immobility for the past 4w
4) Haemoptysis
5) Active cancer
6) Signs of DVT
7) Alternative Dx apart from PE is less likely

Result: PE likely if score ≥2

Another screening tool is Geneva rule

Question 4

What is the tool used to assess PE severity?

Answer 4

PE Severity Index (PESI score): (risk of mortality in 30d)

There is the original PESI score, and simplified PESI score.

Simplified PESI:
Age >80
Cancer
CCF/ chronic lung disease
HR ≥ 110
SPB ≤100
SpO2 <90%

30d mortality at 11% if ≥1 points

Question 5

Ix in PE

Answer 5

1) D-dimer
- Use age-adjusted cutoff
- Negative predictive value is high –> normal value: unlikely VTE
- Can be positive in: Ca, severe infection, inflam disease, pregnancy

2) CTPA
Sens 83%, spec 96%

3) VQ scan
- Lower radiation –> suitable for low clinical probability, young female, pregnant, contrast allergy & severe CKD

4) Echocardiogram
- Detects RV overload pressure and dysfunction
- Negative predictive value only 40-50% –> cannot exclude PE if negative
- In suspected high-risk PE, absence of RV overload/ dysfunction rules out PE as the cause of shock

5) Doppler US of LL
- Sens >90%, spec 95% for prox DVT
- No need for further imaging if prox DVT detected.
- If only distal DVT is seen, further test required to confirm PE

6) CXR – TRO other causes

7) ECG:
RV strain pattern: TWI V1-V4, R axis deviation, tall R in V1
S1Q3T3,
sinus tachy,
AF,
atrial arrhythmia,
Incomplete or complete RBBB

8) Thrombophilia screen: to Ax the need for indefinite VTE Rx

Question 6

Mx of PE

Answer 6

Acute phase:
1) O2 supplement
2) BP Mx:
- IVF,
- inotrope & vasopressor:(norad 0.2-1mcg/kg/min + dobutamine 2-20mcg/kg/min)
- ECMO
3) Resus

Thrombolysis therapy:
1) indication:
a) haemodynamic instability, or haemodynamic deterioration in pts already on anticoagulation (rescue thrombolysis)
b) Rx to be initiated within 48h of Sx, but still useful up to 14d

2) method:
- Use UFH until reperfusion therapy (do not use LMWH or others)
- 1st line: systemic thrombotic therapy
- 2nd line: surgical embolectomy or catheter-directed Rx (if systemic Rx is contraindicated or requiring ECMO)
- Consider ECMO in refractory circulatory/ cardiac arrest

Anticoagulant:
- 1st line: NOAC or LMWH (use UFH in CrCl ≤30 or severe obesity)
- 2nd line: Warfarin is alternative to NOAC

• In malignancy related PE:
• 1st line: rivaroxaban (except in GI Ca)
  2nd line: LMWH
• Duration: ≥3m for all pts
  Lifelong:
  a) Antiphospholipid syndrome (use warfarin) (recommended)
  b) Not related to major transient or reversible risk factors

Extended duration beyond 3m: (to be considered for indefinite Rx)
a) no identifiable risk factors
b) Persistent risk factors (e.g. carriers of hereditary thrombophilia)
c) Minor transient/ reversible risk factor
d) In active Ca pts until Ca is cured

NOAC is contraindicated in:
Severe renal impairment
Pregnancy
Lactation
Antiphospholipid syndrome

In pregnancy:
- Use LMWH or fondaparinux (these do not cross placenta. VKA & NOAC cross placenta),
- Duration for ≥3m (with at least ≥6w post partum).
- Thrombolysis should NOT be used unless life-threatening.
- UFH can be used in acute Rx

Question 7

Indications for IVC filters in PE Mx

Answer 7

Indication:
1) prox DVT and
2) absolute contraindication to anticoagulant Rx,
3) recurrent PE despite adequate anticoag
4) primary prophylaxis in high risk VTE
5) Acute PE with active bleeding - to restart anticozag once bleeding ceases & remove IVC filters

Question 8

PE Mx in specific conditions

Answer 8

1) Segmental PE
a) Single segmental found incidentally with no cancer: surveillance
b) with cancer: anticoag

2) PE in acute bleeding:
- insert IVC filter.
- resume anticoag once bleeding settled and remove IVC filter

3) Frail pt
- NOAC preferable, but not suitable for renal impairment –> give warfarin

4) in ESRF pt with PE
- initially heparin, consider anti-Xa

5) PE in preg: LMWH throughout preg & >6w postpartum

6) PE in cancer
a) in active cancer: LMWH or Rivaroxaban lifelong
b) in remission: NOAC or VKA

Question 9

CTEPH

Answer 9

= Persistent obstruction of pulm art by organized thrombi –> redistribution of flow and remodelling of pulm microvasc
- Risk: 0.1-9% in first 2y of PE
- Rx:
a) Surgical pulm endarterectomy (PEA)
b) Balloon pulm angioplasty (BPA)
c) Pharmacological – anticoag + diuretic + O2
d) Anticoag used in CTEPH is VKA (NOAC does not have enough data)
d) Pulm HTN Rx: riociguat