Pulmonary embolism

Question 1

Pulmonary embolism occurs when

Answer 1

there is an obstruction from a thrombus in the pulmonary artery or one of its branches

Question 2

Symptoms of pulmonary embolism

Answer 2

Asymptomatic sometimes
Breathlessness*
Pleuritic chest pain*
Cough*
Haemoptysis
Low grade fever
Syncope
Sudden CVS collapse

Question 3

Risk factors of PE

Answer 3

same as DVT - Virchow’s triad

Question 4

Physical examination findings for pulmonary embolism

Answer 4

Haemodynamics: a low BP with hypoxia = massive PE
*in early PE -> patient is hypo ventilation -> hypocapnia -> respiratory alkalosis

NORMAL auscultatory findings
Unilateral limb swelling = DVT

Question 5

1st step of diagnostic approach to PE

Answer 5

Wells score - determine pretest probability of PE
3 tiered:
IF <2 (low): PERC TRO PE
- Do D dimer if cannot apply PERC or at least one PERC criteria is positive
IF 2-6 (intermediate): Do D dimer
IF >6 (high): Do CT pulmonary angiography

2 tiered:
IF </=4 (unlikely): Do D dimer
IF >/=4.5 (likely): CTPA

Question 6

Well’s score for PE

Answer 6

+3
Alternative diagnosis is less likely than PE
Clinical signs and symptoms of DVT

+1.5
Previous dx of PE or DVT
Immobilisation 3 or more consecutive days or surgery in prev 4 weeks
Heart rate > 100bp

+1
Malignancy (in last 6 months/palliative)
Haemoptysis

Question 7

PERC score

Answer 7

Used to RULE OUT PE after patient is stratified as LOW risk
If none of the 8 criteria are present, unlikely PE -> D dimer not required

+1
Age >/= 50yo
HR >/= 100
SpO2 <95%
Unilateral leg swelling
Haemoptysis
Recent surgery or trauma
Prior PE or DVT
Hormone use

Question 8

Investigations for Pulmonary Embolism

Answer 8

POCT
- ECG TRO other ddx (AMI)
- ABG for reduced PaO2
- Cardiac U/S TRO other causes (aortic dissection, cardiac tamponade) and look for features of PE

Labs
- Cardiac enzymes: Troponin (high a/w adverse outcome), ProBNP (high in PE)
- D-dimer (only do in low/intermediate risk; DON’T do in high risk)
- Lactate TRO end organ hypoperfusion
- Renal panel for contrast nephropathy
- FBC, PT/INR, GXM

Imaging
- CXR TRO other ddx (pneumothorax, pneumonia)
- Venous compression ultrasound TRO DVT in LL
- CT pulmonary angiography to confirm PE
- V/Q scan/lung scintigraphy (if CTPA is C/I)

Question 9

ECG findings in pulmonary embolism

Answer 9

Sinus tachycardia
S1Q3T3
- S wave in lead 1 (first dip, negative wave after R)
- Q wave in lead 3 (first dip, negative wave before R)
- inverted T wave in lead 3
AFib

Question 10

CXR signs that suggest PE

Answer 10

usually NORMAL CXR
Late signs:
- Hampton’s hump: Wedge-shaped peripheral opacities with apex pointing towards hilum with base against pleural surface
- Fleischner sign: Distended central pulmonary artery due to presence of a large clot
- Westermark sign

Question 11

Severity of PE classification

Answer 11

Massive PE
- Cardiac arrest/pulselessness
- Persistent hypotension (SBP < 90mmHg/ decrease in SBP > 40mmHg from baseline for >15 mins/ requires inotropes)

Subacute PE
Without hypotension with:
- Myocardial necrosis (elevated trops)
- Right heart strain

Low risk PE
- Haemodynamically stable

Question 12

Management of pulmonary embolism

Answer 12

• Secure ABCs
• Manage in P1: vital signs, continuous cardiac monitoring
• Supplemental O2 for hypoxic patients

Massive PE
- IV unfractionated heparin
- Then, IV alteplase
- If C/I, percutaneous catheter directed thrombolysis or open surgical embolectomy

Submassive PE/Low-risk PE
- Anticoagulation with SC LMWH clexane then PO warfarin OR DOACs (rivaroxaban)
- Long term anticoagulation (same as DVT)

Question 13

Feature of PE on cardiac ultrasound

Answer 13

Right ventricular enlargement
D-shaped septum

Question 14

Scenario 1: Patient presents with clinical symptoms of PE but still hemodynamically stable + unilateral leg swelling (likely DVT)

What to do next?

Answer 14

Venous compression ultrasound
- this is submassive PE + DVT so just need to confirm that there is a CLOT present because regardless treatment for both is anticoagulation
- less invasive way of confirming would thus be compression ultrasound

Question 15

Scenario 2: Patient presents with clinical symptoms of PE but still hemodynamically stable but NO unilateral leg swelling (likely no DVT)

What to do next?

Answer 15

Submassive PE
- CT pulmonary angiogram

Question 16

Scenario 3: Patient presents with clinical symptoms of PE and hemodynamically unstable + unilateral leg swelling (likely DVT)

What to do next?

Answer 16

Massive PE
- CT PA
- even though there’s DVT as well, management for MASSIVE PE involves systemic thrombolysis / surgical thrombectomy on top of anticoagulation hence CTPA is required to guide further management