15.2 PE

Question 1

A 54-year-old inpatient collapses in the toilet.

a) What symptoms (15%) and signs (15%) might suggest acute pulmonary thrombo-embolism (PTE) as
the cause of this acute event?

Answer 1

Symptoms:
» Sudden onset of dyspnoea.

> > Pleuritic chest pain.

> > Haemoptysis.

> > Syncope.

> > Anxiety.

> > Light headedness.

Signs:
» Cyanosis.

> > Pleural rub.

> > Tachypnoea, increased work of breathing.

> > Wheeze.

> > Tachycardia.

> > Hypotension.

>> Signs of acute 
right ventricular dysfunction: 
distended neck veins,
parasternal heave, 
accentuated P2, 
tricuspid regurgitation.

> > Progression to cardiac arrest.

> > Swollen, erythematous, tender calf.

Question 2

b) List investigations and their characteristic findings that might be of further assistance in establishing
the diagnosis of PTE. (40%)

Answer 2

1. D-dimer
   Elevated
   Very nonspecific
2. Arterial blood gas
   Low PaO2, low PaCO2. High A-a gradient
   Nonspecific

3. ECG 
Tachycardia. 
Atrial fibrillation.
Right axis deviation
S1Q3T3 (less than 20% cases)
Poor specificity and sensitivity – 
may help exclude
alternative cause

4. Chest radiograph 
Hypovascularity, 
peripherally-located wedge-shaped
area of consolidation
Nonspecific and non-sensitive – 
may help with
alternative diagnosis

5. Ultrasound
   Evidence of thrombus in leg veins
   Supportive of diagnosis if present
6. Lung scintigraphy – V/Q scan
   V/Q mismatch
   High negative predictive value
   but frequently inconclusive
7. Computerised tomographic pulmonary angiography (CTPA)

Thrombus visualised in pulmonary artery.
Will also give information about chronicity of clot,
and consequences
(right heart strain)

Highly specific and sensitive.
Also useful to exclude
alternate causes

Caution in renal impairment
Increased risk of consequences of
ionising radiation in
pregnant or recently post-partum women

8. Magnetic resonance angiography

Thrombus visualised in pulmonary artery
Diagnostic accuracy not as good as CT,
and not as universally available

9. Echocardiography
   Acute right heart strain:
   dilated right atrium and ventricle,
   impaired right ventricular function

Sometimes, thrombus can be visualised

Transoesophageal echo can detect
intracardiac or pulmonary clot more reliably

Bedside test for unstable patient too unwell for
transfer to radiology

10. Pulmonary angiography
    Absence of blood flow in affected pulmonary artery Invasive, rarely used for diagnosis

Question 3

c) What are the principles of management
of a shocked patient resulting
from massive acute PTE? (30%)

Answer 3

PTE is classified as 
massive 
(hypotension and cardiogenic shock), 
submassive 
(haemodynamically stable but 
right heart strain evident on echo)

and non-massive.

This is a medical emergency. I would call for help and assess and manage the patient simultaneously adopting an ABC approach.

Resuscitation:

> > 100% oxygen, intubation likely to be required.

> > Precise management depends on clinical situation.

>> Intravenous access, 
cautious intravenous fluid 
(may exacerbate right heart failure) 
and inotropic support with phenylephrine or adrenaline,
depends on patient condition.

> > Prepare for possible cardiac arrest,
call for drugs and defibrillator.

Likely rhythm would be PEA and resuscitation efforts should be prolonged
(if appropriate to the patient’s overall condition)
once thrombolysis is given.

Definitive management:

> > Definitive treatment should not be delayed and is based on clinical findings and, if possible, bedside echo.

> > Thrombolysis with alteplase.
Assessment for contraindications but risk/ benefit analysis in arrest or peri-arrest situations favours thrombolysis.

> > Unfractionated heparin infusion to follow thrombolysis.

> > Invasive techniques
(thrombus fragmentation and IVC filter)
should be considered in centres
where expertise and facilities available.